Orthopaedic Surgery - Lumbar Disc Herniation

Basics

Lumbar disc herniation is a common cause of acute and chronic low back pain and may also produce radicular symptoms in the lower extremity.

Low back pain affects a large proportion of the population at some point during life.

When disc material compresses or irritates a lumbar nerve root, patients may develop:

Leg pain, numbness, paresthesia, weakness, or reflex changes, commonly referred to as sciatica.

Synonyms

Lumbar disc herniation may also be called:

Herniated nucleus pulposus, slipped disc, ruptured disc, or lumbar radiculopathy with sciatica.

Classification by Location

Disc herniations may be classified according to their location within the spinal canal.

Posterolateral Herniation

Posterolateral herniations are the most common.

The posterior annulus is relatively vulnerable, and disc material usually compresses the traversing ipsilateral nerve root.

For example:

An L4–L5 posterolateral herniation usually affects the L5 nerve root.

Far-Lateral Herniation

Far-lateral or foraminal herniations lie outside or within the neural foramen.

They usually compress the exiting nerve root at that level.

For example:

A far-lateral L4–L5 disc herniation may compress the L4 nerve root.

Central Herniation

Central disc herniations may produce:

Predominantly axial back pain or bilateral neurologic symptoms.

A large central herniation can compress multiple nerve roots and cause cauda equina syndrome.

Classification by Morphology

Disc Protrusion

A protrusion is a localized displacement of disc material in which the herniated portion remains broadly connected to the parent disc.

The annulus may be stretched or partially disrupted.

Disc Extrusion

In an extrusion, disc material extends through a defect in the annulus and has a narrower connection with the parent disc.

Sequestered Disc

A sequestered disc occurs when a fragment becomes completely separated from the parent disc and lies freely within the spinal canal.

Epidemiology

Lumbar disc herniation most commonly affects adults between approximately 30 and 50 years of age.

It is unusual before the age of 20.

Men are affected somewhat more frequently than women in many series.

Common Levels

The lumbar spine is the most frequently affected region of the spine.

The most common levels are:

L4–L5, followed by L5–S1.

Risk Factors

Important risk factors include:

Tobacco smoking, obesity, repetitive heavy lifting, occupational spinal loading, and repeated bending or twisting.

Genetics

A genetic contribution to disc degeneration and herniation has been proposed.

However, disc herniation is multifactorial, and the relative importance of genetic susceptibility varies among individuals.

Anatomy and Pathophysiology

The intervertebral disc consists of:

An inner nucleus pulposus and an outer annulus fibrosus.

Nucleus Pulposus

The nucleus pulposus is rich in water and proteoglycans and helps distribute compressive forces.

Annulus Fibrosus

The annulus fibrosus consists of concentric collagenous layers that contain the nucleus.

Blood vessels and sensory nerves are largely limited to the outer peripheral annulus.

Disc Nutrition

The adult intervertebral disc has very limited direct blood supply.

Nutrients reach the disc primarily by diffusion through the cartilaginous vertebral endplates.

Age-Related Degeneration

Disc degeneration can begin relatively early in adulthood.

With increasing age, the nucleus gradually:

Loses water, proteoglycan content, height, and viscoelastic properties.

The disc becomes less capable of distributing load, and annular fissures may develop.

Etiology

Lumbar disc herniation usually results from a combination of:

Age-related degeneration and mechanical stress.

Trauma

A specific traumatic event may precipitate symptoms when a degenerating disc is already vulnerable.

Repetitive Loading

Repeated:

Heavy lifting, bending, twisting, and occupational spinal loading

may accelerate annular degeneration or provoke herniation.

Diagnosis

Signs and Symptoms

Pain is the most common presenting symptom.

Patients may have:

Low back pain alone, leg pain alone, or a combination of both.

Radicular Pain

Radicular pain typically follows the distribution of an affected nerve root.

It may be described as:

Sharp, burning, electric, or shooting pain radiating from the back or buttock into the leg.

Effect of Lumbar Motion

Symptoms often worsen with:

Lumbar flexion, prolonged sitting, coughing, sneezing, or straining.

Extension may relieve symptoms in some patients, although response varies according to the location and mechanics of the herniation.

Sensory Symptoms

Numbness or paresthesia may develop in the dermatome of the compressed nerve root.

Motor Symptoms

Weakness may occur in muscles supplied by the affected root.

A careful motor examination is therefore essential.

L3–L4 Disc Herniation

An L3–L4 disc herniation commonly compresses the L4 nerve root.

Findings may include:

Weakness of knee extension or ankle dorsiflexion, diminished patellar reflex, and sensory disturbance over the medial leg.

L4–L5 Disc Herniation

An L4–L5 herniation usually affects the L5 nerve root.

Typical findings include:

Weakness of great-toe extension, possible ankle dorsiflexion weakness, and altered sensation over the lateral leg and dorsum of the foot, including the first dorsal web space.

Extensor hallucis longus weakness is particularly useful clinically.

L5–S1 Disc Herniation

An L5–S1 herniation usually compresses the S1 nerve root.

Typical findings include:

Weak plantarflexion, reduced Achilles reflex, and diminished sensation along the lateral foot.

The patient may have difficulty performing repeated single-leg heel raises.

Cauda Equina Syndrome

A large central disc herniation may compress multiple lumbosacral nerve roots and produce cauda equina syndrome.

Warning signs include:

Saddle anesthesia

Urinary retention or overflow incontinence

Loss of bowel control

Bilateral leg weakness or numbness

Progressive neurologic deficits

This is a surgical emergency requiring urgent imaging and decompression.

History

A thorough history should establish:

Time of symptom onset, progression, pain distribution, occupational demands, smoking history, trauma, previous episodes, and neurologic symptoms.

Bowel and Bladder Function

Ask specifically about:

Urinary retention, difficulty initiating urination, incontinence, bowel dysfunction, and saddle numbness.

These symptoms may indicate cauda equina compression.

Constitutional Symptoms

Ask about:

Fever, night sweats, unexplained weight loss, cancer history, immunosuppression, or recent infection.

These findings may suggest an alternative diagnosis such as infection or malignancy.

Physical Examination

A detailed neurologic examination is the most important component.

Sensory Examination

Assess sensation throughout the major lower-extremity dermatomes.

Motor Examination

Document strength of the major muscle groups, including:

Hip flexion

Knee extension

Ankle dorsiflexion

Great-toe extension

Ankle plantarflexion

Reflexes

Evaluate:

Patellar and Achilles reflexes, comparing both sides.

Gait

Observe for:

Antalgic gait, foot drop, inability to heel walk, or inability to toe walk.

These findings may reflect motor root compression.

Straight-Leg Raise Test

The straight-leg raise test is used to assess lower lumbar nerve-root irritation.

Technique

With the patient supine, gradually elevate the straight leg while keeping the knee extended.

Reproduction of radicular pain radiating below the knee suggests nerve-root tension.

Ankle Dorsiflexion

Dorsiflexing the ankle during the test may further increase nerve tension and reproduce symptoms.

Crossed Straight-Leg Raise

In the crossed straight-leg raise, elevation of the asymptomatic leg reproduces radicular pain in the symptomatic leg.

Although less sensitive, a positive test is relatively specific for a substantial lumbar disc herniation.

Sacral Examination

When cauda equina syndrome is suspected, evaluate:

Perianal sensation, anal sphincter tone, and sacral neurologic function.

Urgent MRI should not be delayed in a patient with convincing clinical signs.

Imaging

Plain Radiographs

Routine radiographs are usually unnecessary during the first several weeks of uncomplicated acute radicular symptoms.

They may be considered when:

Symptoms persist beyond approximately 6 weeks, significant trauma has occurred, deformity is suspected, or another structural diagnosis is being considered.

Radiographs do not directly visualize disc herniation.

MRI

MRI is the preferred imaging study for suspected lumbar disc herniation when advanced imaging is indicated.

It demonstrates:

Disc morphology, nerve-root compression, spinal stenosis, and other soft-tissue abnormalities.

Indications

MRI is particularly appropriate when:

Surgery is being considered

Symptoms persist despite appropriate nonoperative treatment

A significant or progressive neurologic deficit is present

Cauda equina syndrome is suspected

Infection or tumor is a concern

Incidental MRI Findings

Disc bulges and herniations are common in asymptomatic individuals.

Therefore, MRI abnormalities must be correlated with:

The patient’s symptoms, neurologic examination, and affected nerve-root distribution.

CT Myelography

CT myelography may be useful when MRI cannot be performed or is nondiagnostic.

However, it is more invasive and involves:

Ionizing radiation and intrathecal contrast.

MRI has largely replaced it for routine evaluation.

Discography

Provocative discography has occasionally been used to investigate suspected discogenic back pain.

Its clinical role remains controversial and it is not routinely used for uncomplicated lumbar disc herniation.

Pathological Findings

Herniated nucleus pulposus material extends through defects in the annulus fibrosus.

Symptoms result from a combination of:

Mechanical nerve-root compression and local inflammatory irritation.

Inflammatory Component

Chemical mediators released from degenerating disc tissue may produce:

Nerve-root inflammation and radicular pain, even when mechanical compression is modest.

Differential Diagnosis

Important alternatives include:

Lumbar spinal stenosis

Peripheral sciatic nerve entrapment

Spondylolysis or spondylolisthesis

Mechanical muscular back pain

Degenerative disc disease

Hip pathology

Tumor

Spinal infection

Treatment

Initial Stabilization

Short-term relative rest may be appropriate during the most painful acute period.

Prolonged bed rest should be avoided.

If bed rest is needed, it should generally be limited to approximately 1–2 days, followed by gradual resumption of activity as tolerated.

General Principles

Most lumbar disc herniations are initially treated nonoperatively.

A substantial proportion improve spontaneously as:

Inflammation settles and the herniated fragment shrinks or resorbs.

Early Activity

Early return to tolerable daily activity is encouraged.

Patients should avoid:

Prolonged inactivity and movements that clearly exacerbate radicular symptoms.

Analgesia

Common first-line options include:

Acetaminophen and NSAIDs, when not contraindicated.

Muscle Relaxants

Muscle relaxants may have a limited short-term role when substantial paraspinal spasm accompanies the acute episode.

They do not treat the underlying disc herniation.

Opioids

Opioid medication should generally be reserved for:

Severe acute pain that cannot be controlled with safer alternatives, and should be used for the shortest practical duration.

Epidural Steroid Injection

An epidural corticosteroid injection may reduce radicular pain in selected patients.

Its principal role is to:

Provide temporary symptom relief and facilitate activity and rehabilitation while natural recovery occurs.

It does not remove the disc herniation itself.

Manipulation and Traction

Manual therapy or traction may provide short-term symptomatic relief in selected patients.

They should be used cautiously and are not substitutes for appropriate neurologic evaluation.

Manipulation should be avoided when:

Progressive neurologic deficit, fracture, infection, malignancy, or cauda equina syndrome is suspected.

Physical Therapy

Physical therapy is useful for many patients once acute pain permits participation.

Goals

Therapy focuses on:

Restoring motion, maintaining activity, improving trunk control, and preventing recurrence.

Strengthening

Programs commonly emphasize:

Abdominal muscles, spinal extensors, hip musculature, and overall core stabilization.

Lower-Extremity Flexibility

Stretching and strengthening of the lower extremities may help improve:

Movement mechanics and tolerance for daily activity.

Medication

First-Line Therapy

Common initial medications include:

Acetaminophen and NSAIDs.

A short course of opioid medication may occasionally be used for severe acute symptoms.

Second-Line Options

Selected patients may receive:

Short courses of oral corticosteroids

Muscle relaxants

Neuropathic pain medications in selected situations

Epidural corticosteroid injections

The benefit of drugs such as gabapentin for true sciatica is variable and should be weighed against adverse effects.

Surgery

The decision to proceed with surgery should be individualized and based on:

Symptoms, neurologic findings, duration, imaging correlation, functional impairment, and patient preferences.

Indications for Elective Surgery

Surgery may be considered when:

Persistent radicular pain remains disabling despite appropriate nonoperative care

Imaging demonstrates a corresponding compressive lesion

Neurologic weakness persists or progresses

The patient’s quality of life remains substantially impaired

Emergency Surgical Indications

Urgent surgery is indicated for:

Cauda equina syndrome or severe progressive neurologic deficit.

Surgical Benefit

Disc surgery generally provides more reliable relief of:

Leg-dominant radicular pain

than of nonspecific axial low back pain.

Surgical Options

Open Discectomy

The herniated disc fragment is removed through an open posterior approach.

Laminotomy

A small portion of lamina may be removed to provide access to the compressed nerve root and disc.

Laminectomy

More extensive removal of the lamina may be necessary when significant spinal stenosis accompanies the herniation.

Microdiscectomy

Microdiscectomy uses magnification and a smaller surgical exposure to remove the offending disc fragment.

It is a common surgical technique for symptomatic lumbar disc herniation.

Endoscopic Discectomy

Selected disc herniations may be treated through an endoscopic approach using very small incisions.

Patient selection and surgeon experience are important.

Obsolete or Rarely Used Techniques

Chemonucleolysis and similar invasive nonsurgical disc-decompression methods have largely fallen out of favor because of:

Variable effectiveness and potential complications.

Postoperative Care

Patients should be monitored for:

New neurologic deficits, wound infection, recurrent radicular pain, hematoma, and cerebrospinal fluid leak.

Activity After Surgery

Older protocols routinely imposed strict activity restrictions for approximately 6 weeks.

Modern postoperative recommendations vary according to:

Procedure, surgeon preference, symptoms, and patient occupation.

Heavy lifting, repetitive bending, and twisting are generally limited during early healing.

Follow-Up

Patients treated nonoperatively should be reassessed if symptoms persist or worsen.

Historical follow-up schedules used visits approximately every 6 weeks for 12–18 weeks, followed by review as needed.

Prognosis

The overall prognosis is excellent for most patients.

Many improve substantially with nonoperative treatment.

Even large disc herniations may decrease in size over time.

Persistent Symptoms

Some patients continue to experience:

Intermittent low back pain, residual numbness, weakness, or recurrent radiculopathy.

Recurrent Herniation

Disc herniation may recur at:

The same spinal level or a different level.

Recurrent symptoms should be reassessed clinically and with imaging when appropriate.

Postoperative Back Pain

Some patients develop persistent or recurrent low back pain after discectomy even when leg symptoms improve.

Potential causes include:

Progressive disc degeneration, facet disease, recurrent herniation, scar formation, or another pain generator.

Complications

Potential complications include:

Persistent pain

Degenerative disc disease

Recurrent disc herniation

Neurologic deficit

Wound infection

Disc-space infection

Dural tear or cerebrospinal fluid leak

Scar-related nerve irritation

Rarely, adhesive arachnoiditis may occur.

Patient Monitoring

Clinical progress is primarily monitored through:

Pain severity, neurologic function, walking ability, sensory changes, strength, reflexes, and return of daily function.

Serial imaging is not routinely necessary when symptoms are improving.

New or worsening:

Weakness, saddle anesthesia, urinary retention, bowel dysfunction, fever, or severe unremitting pain

should prompt urgent reassessment.

Orthopaedic Surgery - Lisfranc Fracture–Dislocation

Basics

A Lisfranc fracture-dislocation is an injury involving the tarsometatarsal (TMT) joint complex of the midfoot.

The injury may consist primarily of ligament disruption, fracture, joint dislocation, or a combination of these abnormalities.

Lisfranc injuries can occur at any age and may range from subtle low-energy instability to severe high-energy fracture-dislocations associated with extensive soft-tissue damage.

Fractures involving the:

Metatarsal bases, cuneiforms, and cuboid

commonly accompany the ligamentous injury.

Classification

A traditional classification describes the direction and extent of TMT incongruity.

Type A

Type A injuries demonstrate total incongruity of the tarsometatarsal joint complex, with the metatarsals displaced together as a unit.

Type B

Type B injuries show partial incongruity.

Displacement may involve either the:

Medial portion or lateral portion of the TMT complex.

Type C

Type C injuries demonstrate a divergent pattern.

Typically:

The first metatarsal displaces medially, while the second through fifth metatarsals displace laterally.

Epidemiology

Lisfranc injuries represent an important proportion of midfoot trauma.

Historical series suggest that they may account for approximately one-third of midfoot injuries.

The true incidence is probably underestimated because subtle injuries may be overlooked initially.

Risk Factors

Risk is increased with:

Motor vehicle collisions, motorcycle crashes, high-energy trauma, and sports involving axial loading or twisting of a plantarflexed foot.

Etiology

The mechanism ranges from relatively minor twisting to severe crush injury.

Low-Energy Mechanism

A low-energy injury may occur when a plantarflexed forefoot is twisted or axially loaded.

This is common in sports.

High-Energy Mechanism

High-energy Lisfranc injuries may result from:

Motor vehicle collisions, motorcycle crashes, falls from height, or crushing trauma.

These injuries are more likely to be associated with fractures, soft-tissue compromise, and compartment syndrome.

Automobile and Motorcycle Injury

A classic mechanism occurs when the patient braces against a brake pedal with the foot plantarflexed during a collision.

Axial force transmitted through the forefoot may disrupt the Lisfranc complex.

Sports Injuries

Athletic injuries may occur during:

Running, twisting, tackling, jumping, or axial loading of a plantarflexed foot.

Sports-related Lisfranc injuries may be subtle and predominantly ligamentous.

Associated Conditions

Lisfranc injuries may occur with:

Comminuted fractures of the metatarsal bases

Cuneiform fractures

Cuboid fractures

Severe soft-tissue injury

Compartment syndrome

Open fractures

High-energy trauma should prompt careful examination of the entire foot and lower extremity.

Diagnosis

Signs and Symptoms

Typical findings include:

Midfoot pain, swelling, deformity, bruising, and difficulty or inability to bear weight.

Some injuries spontaneously reduce before evaluation, so obvious deformity may be absent.

Plantar Ecchymosis

Bruising on the plantar midfoot is an important clinical clue and should raise strong suspicion for a Lisfranc injury.

Physical Examination

Inspection

Assess for:

Swelling, dorsal or plantar ecchymosis, deformity, skin compromise, blistering, and open wounds.

Palpation

Focal tenderness is often greatest around the first and second TMT joints, particularly over the base of the second metatarsal.

Forefoot Stress

Rotational or abduction-pronation stress applied to the forefoot may reproduce pain at the Lisfranc joint complex.

Pain with this maneuver suggests instability.

Weight Bearing

Patients may have substantial pain during standing or walking.

In subtle injuries, inability to perform a single-leg heel rise or push off normally may be a useful clue.

Neurovascular Examination

A complete distal neurovascular examination should be documented.

Assess:

Pulses, capillary refill, skin temperature, motor function, and sensation.

Compartment Syndrome

High-energy midfoot injuries carry a risk of compartment syndrome.

The patient should be monitored for:

Severe or increasing pain, pain with passive toe movement, tense swelling, sensory changes, and progressive neurologic dysfunction.

Imaging

Plain Radiographs

Standard radiographs should include:

AP, lateral, and oblique views of the foot.

When the patient can tolerate it safely, weight-bearing bilateral radiographs may improve detection of subtle instability.

AP View

On the AP radiograph, the:

Medial border of the second metatarsal base should align with the medial border of the middle cuneiform.

Loss of this relationship suggests TMT displacement.

Oblique View

On the oblique view, the:

Medial border of the fourth metatarsal base should align with the medial border of the cuboid.

Disruption suggests lateral-column injury.

Lateral View

On the lateral radiograph, the dorsal surfaces of the metatarsal bases should align smoothly with their corresponding tarsal bones.

Dorsal displacement of the metatarsals relative to the cuneiforms suggests Lisfranc instability.

Fleck Sign

A small avulsion fragment between the base of the second metatarsal and medial cuneiform is called the fleck sign.

It strongly supports injury to the Lisfranc ligament complex.

Cuboid Compression Injury

Compression or impaction of the cuboid may accompany severe lateral-column injury and should raise suspicion for a broader Lisfranc fracture-dislocation pattern.

Stress Imaging

When plain films appear normal but clinical suspicion remains high, especially after spontaneous reduction, further evaluation may include:

Weight-bearing radiographs, stress fluoroscopy, CT, or MRI.

CT

CT is an important adjunct for defining:

Small fractures, articular impaction, subtle displacement, comminution, and operative anatomy.

Lisfranc injuries may be missed on standard radiographs, particularly when displacement is minimal.

MRI

MRI is useful when a predominantly ligamentous injury is suspected despite nondiagnostic radiographs or CT.

It can evaluate:

The Lisfranc ligament complex, surrounding soft tissues, bone marrow edema, and occult fracture.

Differential Diagnosis

Important alternatives include:

Midfoot contusion, ligament sprain, isolated metatarsal fracture, cuneiform fracture, cuboid fracture, navicular injury, and other tarsometatarsal injuries.

Treatment

General Principles

The main treatment goal is to:

Restore and maintain anatomic alignment of the tarsometatarsal joints so that the ligaments and articular surfaces can heal in a stable position.

Even small residual malalignment may increase the risk of chronic pain and post-traumatic arthritis.

Initial Management

Before definitive treatment, evaluate for:

Compartment syndrome, vascular compromise, open injury, and severe soft-tissue swelling.

Immobilization

The foot should be placed in a well-padded splint and elevated.

Swelling Control

Measures may include:

Ice, elevation, compression when safe, and careful soft-tissue monitoring.

Definitive surgery may be delayed until swelling improves if the soft tissues are severely compromised.

Nonoperative Treatment

Stable, nondisplaced Lisfranc injuries without instability on weight-bearing imaging may be treated nonoperatively.

Management generally involves:

Immobilization and strict protection from weight bearing for several weeks, followed by gradual progression if alignment remains stable.

Close radiographic monitoring is required.

Operative Treatment

Displaced or unstable injuries usually require surgery.

The two principal strategies are:

Open reduction and internal fixation

or

Primary arthrodesis of selected TMT joints.

Open Reduction and Internal Fixation

Surgical exposure is commonly obtained through one or more dorsal longitudinal incisions.

The goal is precise reduction of the TMT joints, especially the:

First and second rays and the Lisfranc interval between the medial cuneiform and second metatarsal base.

Fixation

Fixation may involve:

Screws, plates, bridge plates, or Kirschner wires, depending on the injury pattern and involved columns.

Historically, 3.5-mm cortical screws have been widely used.

Kirschner-Wire Fixation

K-wires may be used for selected lateral-column injuries.

They are usually temporary and can often be removed after several weeks once sufficient stability has developed.

Screw or Plate Fixation

Rigid fixation of the medial and middle columns is commonly maintained longer because these joints contribute importantly to midfoot stability.

Weight bearing is restricted until healing and fixation stability are sufficient.

Primary Arthrodesis

Primary fusion of selected TMT joints is increasingly used for certain injuries, particularly:

Severe purely ligamentous injuries, major articular destruction, or injuries in which reliable joint preservation is unlikely.

The medial and middle columns are the most common fusion targets.

Salvage Arthrodesis

Arthrodesis is also an important salvage procedure for:

Painful post-traumatic midfoot arthritis, chronic instability, or late deformity after failed initial treatment.

Physical Therapy

Postoperative rehabilitation begins with protection of the repair.

Gait Training

Patients usually require training with:

Crutches, walker, or other assistive devices while non-weight bearing.

Edema Control

Therapy may include:

Elevation, compression when appropriate, and active toe movement.

Range of Motion

Motion of the:

Ankle and toes

should be maintained when permitted to reduce stiffness.

Weight Bearing

The timing of weight-bearing progression depends on:

The injury pattern, fixation method, soft-tissue condition, radiographic healing, and surgeon protocol.

Patients are generally kept non-weight bearing initially and then progress to protected weight bearing once healing and stability are adequate.

Follow-Up

Prognosis

The most important predictor of outcome is restoration and maintenance of anatomic alignment.

Patients with accurate reduction generally have better outcomes than those with persistent displacement.

Factors Associated With Poorer Outcome

Results are less favorable with:

Nonanatomic reduction, severe articular damage, delayed diagnosis, extensive soft-tissue injury, or high-energy trauma.

Primary Arthrodesis Outcomes

For selected unstable or predominantly ligamentous injuries, primary arthrodesis may provide outcomes comparable to or better than fixation alone.

The optimal strategy depends on:

Injury pattern, joint destruction, patient activity level, and surgeon judgment.

Complications

Post-Traumatic Arthritis

Post-traumatic arthritis is one of the most common long-term complications.

It results from:

Initial cartilage injury, residual incongruity, or chronic instability.

Fixed Deformity

Malalignment may lead to:

Midfoot collapse, abduction deformity, altered arch height, chronic pain, and difficulty with footwear.

Chronic Instability

Failure of ligament healing or loss of fixation may produce persistent instability and pain during push-off.

Delayed Diagnosis

Lisfranc injuries diagnosed late, particularly after approximately 7–8 weeks, have a worse prognosis because:

Soft-tissue contracture, malalignment, cartilage injury, and early arthritis may already be present.

Late Treatment

Patients with chronic painful deformity or arthritis may be better treated with:

Corrective arthrodesis rather than delayed joint-preserving fixation.

Hardware Problems

Screws, plates, or pins may become:

Prominent, painful, loose, or broken.

Selected implants may require later removal.

Infection

Superficial or deep infection may occur after open injury or operative treatment.

Risk is greater with severe soft-tissue trauma.

Patient Monitoring

Serial follow-up is necessary to ensure the Lisfranc complex remains anatomically aligned.

Radiographs are often obtained at intervals during early healing, historically around monthly, although timing should be individualized.

Monitoring should assess:

Joint alignment, hardware position, fracture healing, midfoot stability, pain, swelling, and progression of weight bearing.

Persistent pain or loss of alignment should prompt reevaluation for instability, nonunion, hardware failure, or post-traumatic arthritis.

Orthopaedic Surgery - Limb Lengthening

Basics

Limb lengthening is based on the biologic principle of distraction osteogenesis, in which new bone forms when a surgically divided bone is gradually and carefully separated.

The process allows controlled correction of a variety of congenital and acquired limb abnormalities while new bone develops within the progressively expanding gap.

This technique is also known as callotasis.

Principles of Distraction Osteogenesis

Methods of gradual limb reconstruction have been developed by several surgeons, including:

Anderson, Wagner, Ilizarov, Taylor, and others.

Although the devices differ, the basic principle is the same:

A controlled osteotomy is performed, followed by gradual distraction that stimulates formation of new bone and adaptation of the surrounding soft tissues.

External Lengthening

External lengthening uses an external fixation frame attached securely to the bone.

The system may contain:

Pins, tensioned wires, circular rings, connecting rods, or other modular components.

The frame is assembled according to the individual patient’s anatomy and the correction required.

Circular External Fixation

The Ilizarov method uses circular rings attached to bone by:

Tensioned wires and/or half-pins.

The rings are connected by threaded rods or struts.

Gradual adjustment separates or repositions the bone segments.

Advantages

Circular systems are highly versatile and can simultaneously correct:

Length, translation, angulation, rotation, and certain complex multiplanar deformities.

Their main disadvantage is that the frames may be relatively bulky and demanding for the patient.

Monolateral External Fixation

When complex rotational or angular correction is unnecessary, a simpler monolateral fixator may be used.

These devices place fixation pins along one side of the limb and can be particularly useful for:

Straightforward lengthening or simpler angular correction.

Spatial Frames

Computer-assisted spatial frames use multiple adjustable struts to correct complex deformities gradually.

They permit simultaneous modification of:

Length, angulation, translation, and rotation.

Internal Lengthening Devices

Modern internal lengthening nails allow gradual bone distraction without an external frame.

Many contemporary systems use magnetically controlled intramedullary rods.

An external controller activates the internal mechanism to lengthen the nail in small increments.

Advantages

Internal devices avoid:

External pins, pin-site care, bulky frames, and many external-fixator-related complications.

They are especially useful when the bone is relatively straight and the primary goal is simple lengthening.

Limitations

External fixation may still be preferable when there is:

Major angular deformity, rotational deformity, bone loss, active nonunion, complex multiplanar correction, or anatomy unsuitable for intramedullary fixation.

Anatomic Applications

Distraction osteogenesis can be used in both upper and lower extremities.

It is used most frequently in the lower limbs, where leg length and mechanical alignment have particularly important effects on gait and joint loading.

Age Considerations

The ideal age depends on the indication.

For many elective reconstructive procedures, the preteen and adolescent years are particularly suitable.

At this age:

Most future skeletal growth can be estimated, healing potential remains high, remodeling remains effective, and the patient is usually mature enough to participate in a demanding treatment program.

Younger Children

Lengthening may be performed earlier in children with:

Severe congenital limb deficiency or major deformity requiring staged reconstruction.

Adults

Adults may undergo distraction osteogenesis for:

Nonunion, acquired limb-length discrepancy, segmental bone loss, deformity correction, or selected stature-lengthening procedures.

Bone regeneration generally becomes slower with increasing age.

Types of Procedures

Distraction-based reconstruction can be used for several purposes.

Extremity Lengthening

A short limb can be lengthened gradually to improve limb-length equality and function.

Angular Correction

Varus, valgus, procurvatum, recurvatum, or multiplanar deformity can be corrected gradually.

Nonunion Treatment

Certain difficult nonunions can be treated with:

Compression, distraction, improved alignment, and stimulation of new bone formation.

Bone-Defect Reconstruction

Segmental bone loss can be reconstructed with bone transport, in which a bone segment is gradually moved through a defect while new bone forms behind it.

Contracture Correction

Gradual distraction may also be used to correct selected:

Joint contractures and soft-tissue deformities.

Fracture Management

External fixation and gradual correction principles may be incorporated into treatment of:

Complex fractures, malunions, infected fractures, and fractures associated with severe soft-tissue injury.

Selecting Internal Versus External Lengthening

Internal magnetic nails are most commonly used when the bone is:

Relatively straight, of sufficient size, and requires primarily linear lengthening.

External fixators are particularly useful when treatment also requires:

Angular correction, rotational correction, bone transport, management of nonunion, or treatment of abnormal bone geometry.

Diagnosis and Patient Selection

Successful limb lengthening requires careful selection.

The surgeon must evaluate not only the deformity but also the patient’s ability to tolerate a prolonged treatment process.

History

Important considerations include:

Degree of functional impairment, magnitude of limb-length discrepancy or deformity, adaptation to the existing condition, goals and expectations, emotional maturity, family support, and motivation.

Treatment may last for many months and requires substantial cooperation.

Alternative Treatments

Before choosing limb lengthening, simpler alternatives should be discussed.

Depending on the clinical problem, alternatives may include:

Shoe lifts, shortening of the longer limb, epiphysiodesis or other growth-guidance procedures, corrective osteotomy without lengthening, prosthetic management, or observation.

Physical Examination

Before treatment, the patient should undergo a comprehensive examination of:

Limb length, alignment, joint motion, muscle strength, neurologic function, vascular status, skin condition, and gait.

During Treatment

At every follow-up visit, particular attention should be paid to:

Pin sites, nerve function, joint range of motion, muscle tightness, alignment, and progression of correction.

Physical Therapy

Physical therapy is an essential part of limb lengthening.

Without adequate rehabilitation, soft tissues may fail to adapt to the increasing bone length.

Weight Bearing

Patients are instructed in appropriate:

Weight bearing, transfers, crutch or walker use, and gait mechanics.

The amount of permitted loading depends on the implant and phase of treatment.

Range of Motion

Joint motion must be maintained throughout treatment.

Particular attention is required at joints adjacent to the lengthened bone because muscles and tendons are being stretched continuously.

Strengthening

Therapy should preserve:

Muscle strength, balance, and functional control of the extremity.

Daily Monitoring

The rehabilitation team also helps monitor whether gradual correction is causing:

Joint contracture, nerve irritation, muscle tightness, abnormal gait, or loss of alignment.

Medication

Analgesia may be required during treatment.

Prolonged or excessive NSAID use is often avoided because of concern that it may interfere with bone healing, although the clinical importance depends on dose and duration.

Surgery

The initial operation is usually performed under general anesthesia.

The procedure includes:

Placement of the external fixator or internal lengthening device and creation of a low-energy osteotomy or corticotomy.

Actual lengthening generally begins several days later rather than during the operation itself.

External Frame Application

The external frame is assembled specifically for the patient’s:

Limb shape, deformity, intended correction, and treatment goals.

Several fixation points are usually placed above and below the osteotomy.

Fixation

The frame may use:

Pins, wires, rings, or combinations of these elements.

Stable fixation is necessary to control the bone segments during distraction.

Distraction Mechanism

Threaded rods or adjustable struts are positioned to generate the planned correction gradually.

The system can be adjusted over time to modify:

Length and, when needed, alignment or rotation.

Osteotomy

Once the bone is stabilized, an osteotomy or corticotomy is performed.

Technique

The procedure should minimize disruption of the periosteum and surrounding blood supply.

A small incision and low-energy technique are typically used.

Preservation of local biology is essential for formation of healthy regenerate bone.

Extending the Frame Across Adjacent Bones or Joints

In selected cases, the frame may be extended to an adjacent bone or across a nearby joint to provide:

Additional stability, protection, or control of alignment.

Latency Period

Lengthening usually does not begin immediately after surgery.

A short latency period allows an early healing response to develop.

Timing

Distraction commonly begins approximately 5–10 days after osteotomy, often around the time early callus is beginning to form.

The exact timing varies according to:

Age, bone, procedure, and underlying condition.

Distraction Phase

The bone segments are gradually separated while the immature regenerate tissue is stretched.

This stimulates continuous new bone formation.

Standard Rate

A common distraction rate is approximately:

1 mm per day.

Rhythm

The total daily distraction is usually divided into 3–4 smaller adjustments, such as approximately 0.25 mm at a time.

This avoids excessive sudden stretching of:

Bone, muscle, nerves, vessels, skin, and other soft tissues.

Distraction Osteogenesis

As the gap slowly widens, organized new bone forms within it.

The regenerate initially appears as immature callus and progressively develops:

Trabecular structure, corticalization, and mechanical strength.

Consolidation Phase

Once the desired length or correction has been achieved, distraction stops.

The new bone is then allowed to mature during the consolidation phase.

Weight Bearing

Appropriate mechanical loading can stimulate maturation and strengthening of the regenerate.

The degree of permitted weight bearing depends on:

Bone quality, implant stability, lengthening site, and radiographic appearance.

Implant Removal

The external fixator or internal nail is not removed until the newly formed bone is strong enough to tolerate physiologic loading safely.

Radiographs should show satisfactory maturation before device removal.

Lengthening Index

The duration of treatment can be estimated using a lengthening or external fixation index.

This expresses the amount of treatment time required for each centimeter of gained length.

Historical averages are approximately:

1–1.6 months per centimeter.

The value varies substantially according to:

Age, bone involved, amount of lengthening, underlying diagnosis, regenerate quality, and complications.

Follow-Up

Patients require frequent follow-up during both distraction and consolidation.

Visits assess:

Rate of correction, regenerate formation, alignment, joint motion, neurologic function, pin sites, pain, and overall function.

Serial radiographs are usually required.

Prognosis

When carefully planned and monitored, limb lengthening generally produces good results.

Historical series have reported approximately 80–90% success, although many patients require additional procedures during treatment.

Treatment Duration

Healing is often prolonged.

The overall process may last many months because both:

Distraction and consolidation must be completed before unrestricted activity is possible.

Complications

Limb lengthening has a relatively high burden of minor and major complications because bone and soft tissues are being changed gradually over a prolonged period.

Nonunion or Poor Regenerate Formation

Failure of adequate bone formation can produce:

Delayed union, poor regenerate, or nonunion.

Management may require:

Slowing or stopping distraction, compression, bone grafting, revision fixation, or additional biologic treatment.

Joint Stiffness

Muscles and tendons may fail to lengthen as rapidly as the bone.

This can result in:

Joint contracture and loss of range of motion.

Consistent physical therapy is therefore critical.

Joint Subluxation

Severe soft-tissue tension may gradually pull an adjacent joint out of normal alignment.

Joint subluxation is particularly concerning during substantial lengthening around the:

Hip, knee, or ankle.

Fracture

The regenerate bone remains vulnerable for a period after treatment.

Fracture can occur:

During consolidation, after premature frame removal, or shortly after implant removal.

Nerve Injury

Rapid or excessive distraction can stretch peripheral nerves.

Symptoms may include:

Pain, paresthesia, numbness, or weakness.

Neurologic symptoms should prompt immediate reassessment of the distraction rate.

Pin-Tract Problems

External fixation introduces additional potential complications, especially:

Pin-site irritation and pin-tract infection.

Pin sites should be inspected regularly and treated early when infection develops.

Malalignment

If correction progresses unevenly, the limb may develop:

Translation, angulation, or rotational deformity.

Frequent clinical and radiographic monitoring permits adjustments before the error becomes severe.

Patient Monitoring

Close surveillance is essential throughout treatment.

Patients should be seen periodically to evaluate:

Bone regeneration, rate and direction of correction, pin or implant condition, joint motion, nerve function, skin integrity, and overall limb alignment.

Radiographic Monitoring

Serial radiographs are used to assess:

Regenerate density, cortical formation, alignment, progression of distraction, and readiness for weight-bearing advancement or implant removal.

Key Principle

Successful limb lengthening depends less on the specific device than on adherence to the biologic principles of:

Stable fixation, preservation of blood supply, gradual distraction, appropriate rhythm and rate, soft-tissue management, rehabilitation, and careful long-term monitoring.

Orthopaedic Surgery - Kyphosis

Basics

Kyphosis is a sagittal-plane curvature of the spine characterized by anterior concavity and posterior convexity.

Some degree of kyphosis is normal, particularly in the thoracic and sacral regions.

Normal thoracic kyphosis is approximately 20–45° in children, with somewhat greater values possible in adults.

When thoracic kyphosis becomes excessive, the deformity may be caused by:

Postural kyphosis, Scheuermann disease, congenital vertebral abnormalities, osteoporosis, ankylosing spondylitis, neuromuscular disease, myelomeningocele, trauma, infection, prior surgery, or malignancy.

Significant kyphotic deformity, particularly curves greater than approximately 50°, may be associated with increased back pain, compensatory lumbar lordosis, spondylolysis, and, in sharply angular congenital or infectious deformities, neurologic compromise.

Prevention

Postural Kyphosis

Postural kyphosis may be influenced by:

Attention to posture, strengthening, flexibility exercises, and avoidance of prolonged poor postural habits.

Osteoporotic Kyphosis

Prevention of osteoporosis and vertebral compression fractures can decrease the likelihood of progressive age-related kyphosis.

Important measures include:

Adequate calcium and vitamin D, weight-bearing exercise, fall prevention, and pharmacologic osteoporosis treatment when indicated.

Epidemiology

Kyphotic deformity may occur as part of numerous congenital, metabolic, inflammatory, or neurologic disorders.

Associated conditions include:

Neurofibromatosis, mucopolysaccharidoses, achondroplasia, myelomeningocele, ankylosing spondylitis, and benign or malignant spinal tumors.

Incidence and Prevalence

Osteoporotic vertebral compression fractures are an important cause of kyphosis in older adults.

Historical studies have reported kyphotic deformity related to osteoporotic fractures in approximately 15% of Caucasian women.

Spinal Tuberculosis

Tuberculous involvement of the spine may lead to vertebral destruction and angular kyphosis.

Spinal disease represents a minority of tuberculosis cases overall but is particularly important because of its potential to cause:

Severe deformity, abscess formation, and neurologic compromise.

Postural Kyphosis

Postural kyphosis is often seen in adolescents, particularly those who are taller than their peers.

The curve is usually flexible and does not result from structural vertebral abnormalities.

Congenital Kyphosis

Congenital kyphosis is uncommon.

It results from abnormal formation or segmentation of the vertebrae and may progress rapidly during growth.

Scheuermann Kyphosis

Scheuermann disease has historically been reported in approximately 0.4–8.3% of the population.

Males may be affected somewhat more often than females.

Osteoporosis

Osteoporosis is particularly common in patients who are:

Older, female, postmenopausal, of Caucasian or Asian ancestry, chronically exposed to corticosteroids, or affected by other disorders that reduce bone density.

Risk Factors

Important risk factors for abnormal kyphosis include:

Osteoporosis, family history of spinal deformity, previous vertebral fracture, repetitive heavy spinal loading during adolescence, exposure to tuberculosis, and malignancy.

Genetics

Some conditions associated with kyphosis have a genetic component.

Examples include:

Ankylosing spondylitis, osteoporosis, and Scheuermann disease.

The degree of heritability varies substantially according to the underlying disorder.

Etiology

Postural Kyphosis

Postural kyphosis results largely from:

Poor posture, ligamentous stretching, and muscular imbalance.

The vertebral bodies themselves remain normally formed.

The curve is generally flexible.

Scheuermann Kyphosis

Scheuermann kyphosis is a structural growth disorder involving anterior wedging of the vertebral bodies.

It typically appears during early adolescence.

Unlike postural kyphosis, the deformity is relatively rigid and cannot be fully corrected by voluntary posture.

Congenital Kyphosis

Congenital kyphosis is present from birth and results from abnormalities such as:

Failure of vertebral formation, hemivertebrae, or anterior failure of vertebral segmentation.

Because the deformity may be sharply angular, the spinal cord can be placed at substantial risk as the child grows.

Osteoporotic Kyphosis

In osteoporosis, progressive kyphosis results from:

Anterior wedge compression fractures of thoracic or lumbar vertebral bodies.

Multiple adjacent compression fractures can produce substantial loss of height and a rounded thoracic posture.

Infectious Kyphosis

Tuberculosis and other spinal infections may destroy vertebral bodies and intervertebral discs.

Collapse of the anterior spinal column can produce a focal angular kyphosis or gibbus deformity.

Associated Conditions

Congenital Kyphosis

Congenital kyphosis may progress rapidly across a short spinal segment.

The resulting angular deformity can stretch or compress the spinal cord and lead to neurologic deterioration.

Patients should also be evaluated for associated:

Cardiac, renal, pulmonary, auditory, and other congenital abnormalities.

Intraspinal Abnormalities

Congenital scoliosis or kyphosis may be associated with intraspinal abnormalities in approximately 30% of patients in some series.

Examples include:

Tethered cord, syringomyelia, diastematomyelia, and other neural-axis anomalies.

Scheuermann Disease Associations

Patients with Scheuermann kyphosis commonly develop compensatory lumbar hyperlordosis.

Spondylolysis has historically been reported in a substantial proportion of affected patients.

Approximately one-third may also have a mild associated scoliosis, commonly around 10–20°.

Osteoporosis Associations

Patients with osteoporosis are also at increased risk for insufficiency fractures involving the:

Hip, pelvis, and wrist.

Diagnosis

Signs and Symptoms

Presentation depends on the underlying cause.

Congenital Kyphosis

Congenital deformity may occasionally be detected prenatally but is more commonly identified when a parent or physician notices:

A visible spinal prominence, abnormal posture, or progressive deformity.

Scheuermann Kyphosis

Typical findings include:

Apparent poor posture, a relatively sharp thoracic kyphotic apex, stiffness, and pain localized near the apex of the curve.

Osteoporotic Kyphosis

Patients may report:

Progressive loss of height, increasing spinal curvature, back pain, and previous fragility fractures.

Infection or Malignancy

Red-flag symptoms include:

Night sweats, weight loss, fever, progressive deformity, night pain, and new neurologic deficits.

These findings raise concern for infection or tumor.

Postsurgical Kyphosis

Postlaminectomy or other postsurgical deformity may be detected by comparing:

Previous examinations, prior radiographs, and serial changes in alignment.

History

Important historical features include:

Congenital abnormalities, family history of spinal deformity, progression of kyphosis, onset of neurologic symptoms, constitutional symptoms, chronic corticosteroid use, fragility fractures, trauma, infection exposure, and previous spine surgery.

Physical Examination

Standing Examination

Examine the patient in a neutral standing position.

Assess:

Overall sagittal balance, shoulder height, head position, thoracic contour, lumbar lordosis, pelvic position, and associated scoliosis.

Forward Bending

Forward bending accentuates a structural kyphotic deformity and may help identify:

A sharp angular apex or associated rotational deformity.

Flexibility Assessment

Curve flexibility may be assessed by:

Prone hyperextension or supported hyperextension over a bolster.

Interpretation

A flexible curve is more consistent with postural kyphosis, whereas a rigid curve suggests:

Scheuermann disease, congenital deformity, ankylosing spondylitis, or another structural abnormality.

Neurologic Examination

A complete neurologic examination is essential.

Assess:

Strength, sensation, reflexes, gait, balance, bowel and bladder symptoms, and signs of myelopathy or spinal cord compression.

Laboratory Tests

Routine laboratory tests are often normal in uncomplicated kyphosis.

Testing should be directed by the suspected cause.

Suspected Infection

Appropriate studies may include:

Complete blood count, ESR, CRP, and blood cultures.

Suspected Tuberculosis

Testing may include:

Tuberculosis skin testing or interferon-gamma release testing, depending on the clinical context.

If the causative organism remains uncertain, biopsy may be necessary.

Osteoporosis

Routine serum tests may be normal even when osteoporosis is present.

Additional studies may be ordered to identify secondary causes of low bone density.

Ankylosing Spondylitis

HLA-B27 may be present in patients with ankylosing spondylitis, but diagnosis depends primarily on:

Clinical findings, imaging, and the overall inflammatory pattern rather than HLA-B27 alone.

Imaging

Standing Radiographs

For most forms of kyphosis, obtain:

Standing AP and lateral radiographs of the entire spine.

These allow measurement of:

Curve magnitude, sagittal balance, associated scoliosis, vertebral wedging, and compensatory alignment.

Focused Radiographs

Additional views may be used to assess:

Vertebral anomalies, fractures, focal destruction, or congenital abnormalities.

Hyperextension Radiographs

A lateral radiograph obtained while the patient hyperextends over a bolster may help determine:

The flexibility of the kyphotic curve.

Skeletal Maturity

The Risser sign can often be assessed on the AP radiograph and helps estimate remaining skeletal growth.

MRI

MRI is particularly indicated in patients with:

Congenital kyphosis, neurologic deficits, suspicion of malignancy, suspected infection, or concern for neural-axis abnormalities.

MRI evaluates:

The spinal cord, nerve roots, discs, marrow, epidural space, and surrounding soft tissues.

Renal Ultrasound

Children with congenital kyphosis may undergo renal ultrasound because congenital vertebral abnormalities can be associated with renal malformations.

DEXA

Bone-density testing with DEXA should be considered when osteoporotic kyphosis is suspected or when baseline bone mass assessment will influence treatment.

Pathological Findings

Scheuermann Kyphosis

Scheuermann disease has typical and atypical patterns.

Typical Scheuermann Disease

The classic radiographic criterion is:

Anterior wedging of at least 5° in three or more consecutive vertebral bodies.

The apex frequently lies between approximately T7 and T9.

Other findings may include:

Endplate irregularity and Schmorl nodes.

Atypical Scheuermann Disease

Atypical cases may demonstrate:

Endplate irregularities, Schmorl nodes, and disc-space narrowing

without meeting the classic criterion of three consecutively wedged vertebrae.

Osteoporotic Kyphosis

Osteoporosis commonly produces:

Anterior vertebral body wedging, compression fractures, and generalized reduction in bone density.

Ankylosing Spondylitis

Advanced ankylosing spondylitis may produce:

Rigid kyphotic alignment, vertebral wedging, syndesmophyte formation, and eventual spinal fusion.

Infection or Tumor

Infectious or neoplastic kyphosis may be associated with:

Vertebral body destruction, soft-tissue mass, epidural extension, or spinal canal narrowing.

Differential Diagnosis

Kyphosis should be distinguished from:

Scoliosis, neuromuscular spinal deformity, postsurgical deformity, vertebral fracture, congenital vertebral malformation, ankylosing spondylitis, infection, and malignancy.

Scoliosis

Thoracic scoliosis may create a prominent rib hump that superficially resembles kyphosis.

However, many patients with thoracic scoliosis actually have reduced rather than increased thoracic kyphosis.

Neuromuscular Kyphosis

Neuromuscular disorders may produce kyphosis because of:

Weak trunk musculature, poor postural control, or abnormal muscle tone.

Postlaminectomy Kyphosis

Removal of posterior spinal elements in a growing child can destabilize the spine and result in progressive kyphotic deformity.

Treatment

Observation

Mild, stable deformities may be managed with observation and periodic clinical or radiographic assessment.

This is particularly appropriate when:

The patient is asymptomatic, the curve is flexible, and there is little or no progression.

Exercise

Exercise is an important component of treatment for many patients with painful or flexible kyphosis.

Postural Kyphosis

Postural training and strengthening are the primary treatments.

Painful Kyphosis

Exercises may help reduce pain by improving:

Spinal mobility, posture, muscular endurance, and flexibility.

Bracing

The role of bracing depends on the type of kyphosis.

Congenital Kyphosis

Bracing is generally not effective because the deformity results from structural vertebral abnormalities.

Scheuermann Kyphosis

Bracing may be considered in growing adolescents with:

Flexible or partially flexible Scheuermann curves, particularly those approximately 40–70° and with substantial remaining growth.

Bracing is often most effective when the apex is below the upper thoracic region.

Osteoporotic Compression Fracture

Temporary bracing may be used in selected patients with an acute painful osteoporotic vertebral fracture.

Congenital Kyphosis

Progressive congenital kyphosis in a growing child often requires surgical treatment because severe progression can produce neurologic compromise.

Physical Therapy

Physical therapy can improve pain and function in many patients.

Stretching

Programs may include stretching of:

Hamstrings, anterior chest and shoulder structures, hip flexors, and other tight tissues contributing to compensatory posture.

Strengthening

Strengthening should emphasize:

Back extensors, abdominal musculature, scapular stabilizers, and core muscles.

Medication

Analgesics

Intermittent back pain may be managed with:

NSAIDs or acetaminophen, provided there are no contraindications.

Osteoporosis Treatment

Patients at risk for osteoporosis should receive appropriate bone-health management.

This may include:

Calcium and vitamin D supplementation and antiresorptive or anabolic osteoporosis therapy when indicated.

Older references described estrogen therapy and diphosphonates; current treatment should be individualized according to age, sex, fracture risk, and medical status.

Tuberculosis Treatment

Tuberculous spinal infection requires multidrug antituberculous therapy.

Surgical treatment is added when indicated by instability, deformity, abscess, or neurologic compromise.

Surgery

Surgery is considered when kyphosis causes:

Progressive deformity, neurologic compromise, severe refractory pain, cardiopulmonary compromise, or unacceptable functional or cosmetic disability.

Congenital Kyphosis Surgery

Progressive congenital kyphosis often requires surgery except in very mild stable cases.

Options may include:

In situ fusion, corrective osteotomy, posterior instrumentation, or combined anterior and posterior reconstruction.

Scheuermann Kyphosis Surgery

Indications may include:

Persistent severe pain despite nonoperative care, progressive deformity, neurologic compromise, cardiopulmonary limitation, or severe unacceptable kyphosis.

Modern treatment typically uses posterior spinal fusion with instrumentation, sometimes combined with osteotomies to improve correction.

Osteoporotic Vertebral Fractures

Most osteoporotic compression fractures are managed nonoperatively.

Selected patients with persistent severe pain from an acute compression fracture may be considered for vertebral augmentation procedures.

Kyphoplasty

Kyphoplasty may provide pain relief and can sometimes restore a portion of vertebral body height.

Vertebroplasty

Vertebroplasty may provide pain relief in selected patients, although patient selection is important.

Infection and Malignancy

When spinal infection or tumor causes neurologic compromise or mechanical instability, treatment may require:

Decompression, deformity correction, stabilization, and disease-specific medical or oncologic therapy.

Follow-Up

Prognosis

The natural history depends strongly on the underlying cause.

Kyphosis may progress with age, particularly when structural deformity, osteoporosis, or degenerative disease is present.

Pain and Function

Back and neck pain can range from mild and intermittent to chronic.

Most patients remain capable of independent activity and employment, although heavy physical work may become limited in more severe cases.

Complications

Neurologic Compromise

Severe, sharply angular kyphosis may compress or stretch the spinal cord at the apex.

Neurologic decline may occur gradually or be precipitated by:

A fall, fracture, or other traumatic event.

Surgical Neurologic Risk

Corrective surgery for severe kyphosis carries a meaningful risk of neurologic injury because:

The spinal cord may already be stretched across a rigid angular deformity.

This risk may be greater than for a scoliosis of comparable angular magnitude.

Pseudarthrosis

Failure of the intended spinal fusion can result in:

Persistent pain, implant failure, and progressive deformity.

Curve Progression

Progressive kyphosis may occur despite treatment, particularly in:

Young children with congenital deformity, severe Scheuermann disease, osteoporosis, or persistent underlying disease.

Patient Monitoring

Growing patients should be followed regularly to identify progression.

Clinical and radiographic reassessment approximately every 4–6 months may be appropriate during periods of rapid growth.

Monitoring should include:

Curve magnitude, skeletal maturity, pain, neurologic status, balance, and associated deformity.

Adults with stable kyphosis may be reviewed according to symptoms and the underlying cause.

Orthopaedic Surgery - Köhler Disease

Basics

Köhler disease is an osteochondrosis of the tarsal navicular bone, characterized by temporary impairment of its blood supply during childhood.

The disorder produces osteonecrosis followed by sclerosis, flattening, fragmentation, and eventual reossification of the navicular.

The typical patient is a child approximately 3–7 years of age who develops pain over the medial midfoot.

Symptoms usually increase with physical activity and improve with rest.

Despite occasionally striking radiographic abnormalities, the long-term clinical outcome is generally excellent.

Synonyms

Köhler disease may also be described as:

Osteochondrosis, osteonecrosis, or osteochondritis of the tarsal navicular.

Classification

Köhler disease belongs to the group of disorders known as osteochondroses.

These conditions involve temporary vascular disturbance of a developing ossification center.

Other disorders in this general category include:

Legg–Calvé–Perthes disease and Osgood–Schlatter disease, although their specific pathophysiology and anatomic sites differ.

Prevention

No practical preventive strategy has been established.

The disease is uncommon and generally cannot be predicted before symptoms develop.

Epidemiology

Köhler disease occurs predominantly in young children.

Sex

Boys are affected approximately 2–3 times more often than girls.

Incidence

The disease is uncommon.

Risk Factors

Reported associations include:

Male sex, high activity level, and participation in sports involving repeated running or kicking.

However, the condition may also occur in otherwise healthy children without identifiable risk factors.

Genetics

No recognized pattern of genetic transmission has been established.

Köhler disease is generally considered sporadic.

Etiology

The exact cause is not completely established, but the most widely accepted mechanism involves repetitive mechanical compression of the developing navicular with temporary compromise of its blood supply.

Navicular Development

The navicular is one of the last tarsal bones to ossify.

Its ossification center usually becomes visible at approximately 2–3 years of age.

During early development, the bone may initially ossify from several small centers that eventually merge.

Mechanical Compression

The navicular lies at the apex of the medial longitudinal arch and is positioned between the talar head proximally and the cuneiforms distally.

As the child walks, the developing navicular is subjected to substantial compressive forces.

Because the bone is relatively soft and incompletely ossified at this stage, repeated compression may compromise local vascularity.

Osteonecrosis and Healing

Temporary ischemia produces:

Bone necrosis, resorption of dead bone, sclerosis, flattening, and later reossification.

As vascularity returns, the navicular gradually remodels and resumes normal growth.

Associated Conditions

A mild association with Legg–Calvé–Perthes disease has been described in some series.

Both disorders involve temporary osteonecrosis during skeletal development, although they affect different bones.

Diagnosis

Signs and Symptoms

The characteristic presentation is:

Medial midfoot pain in a young child, aggravated by activity and relieved by rest.

Tenderness

There is usually focal tenderness directly over the tarsal navicular.

Limp

Pain during weight bearing may produce an antalgic gait.

Altered Foot Loading

Some children walk preferentially on the lateral border of the foot to reduce pressure through the medial midfoot and navicular.

Physical Examination

Inspection

Look for:

Swelling over the medial midfoot, altered gait, and avoidance of normal medial-foot loading.

Palpation

Focal tenderness over the navicular is a typical finding.

Mild surrounding soft-tissue swelling may also be present.

Gait Examination

The child may demonstrate:

A limp, shortened stance phase on the affected side, or walking along the outer border of the foot.

This compensatory pattern decreases compression through the painful navicular.

Range of Motion

Ankle and subtalar range of motion is usually relatively preserved.

Pain is primarily generated by loading or direct palpation of the navicular rather than by a primary ankle-joint disorder.

Imaging

Plain Radiographs

Plain radiographs are generally sufficient to establish the diagnosis once characteristic changes have developed.

AP, lateral, and oblique views of the foot may be obtained.

Normal Navicular Ossification

The normal navicular begins to ossify at approximately 2–3 years of age.

Multiple early ossification centers may be visible before they coalesce.

Awareness of this normal developmental appearance prevents overdiagnosis.

Radiographic Findings

Characteristic findings in Köhler disease include:

Flattening of the navicular in its anteroposterior dimension, increased sclerosis, irregularity, fragmentation, and apparent collapse.

The navicular may appear unusually dense compared with the surrounding tarsal bones.

Bilateral Disease

Radiographic abnormalities may occasionally be bilateral, although symptoms do not necessarily occur to the same degree on both sides.

MRI

MRI is usually unnecessary when plain radiographs demonstrate characteristic changes.

It may be useful when:

Clinical suspicion remains high despite normal or equivocal radiographs or when another diagnosis needs to be excluded.

MRI can demonstrate:

Abnormal bone marrow signal, edema, and changes compatible with impaired navicular perfusion.

Healing on Imaging

As the disorder resolves, radiographs show:

Progressive reossification, restoration of bone density, remodeling, and gradual recovery of navicular shape and growth.

Radiographic recovery may take considerably longer than symptomatic improvement.

Pathological Findings

Biopsy is not routinely performed and is unnecessary for diagnosis.

Historical pathologic specimens demonstrate typical features of healing osteonecrosis, including:

Areas of necrotic bone, resorption of dead trabeculae, and subsequent formation of new bone.

Differential Diagnosis

Important alternative causes of medial midfoot pain include:

Navicular fracture, accessory navicular, ankle or foot sprain, soft-tissue infection, and other occult fractures.

Navicular Fracture

A traumatic navicular fracture should be considered when there is:

A clear injury, acute severe pain, marked swelling, or a fracture line inconsistent with developmental osteochondrosis.

Accessory Navicular

An accessory navicular may also cause medial midfoot prominence and pain.

It usually occurs near the insertion of the posterior tibial tendon and has a different radiographic appearance.

Soft-Tissue Infection

Infection should be considered when pain is associated with:

Erythema, significant warmth, fever, systemic illness, or abnormal inflammatory markers.

These findings are not typical of Köhler disease.

Treatment

General Principles

Treatment is primarily symptomatic because Köhler disease is a self-limited condition.

Management depends on symptom severity.

Options include:

Rest, activity modification, arch support, analgesia, and temporary immobilization.

Mild Symptoms

Children with minimal discomfort may need only:

Reduction of strenuous activity and use of a supportive shoe or medial arch support.

Moderate to Severe Symptoms

More symptomatic children may benefit from a:

Below-knee walking cast with appropriate arch molding for approximately 4–8 weeks.

Immobilization can substantially reduce pain and may shorten the symptomatic period.

Weight Bearing

Most children can bear weight according to comfort.

If symptoms are particularly severe, temporary non-weight bearing or protected weight bearing may be appropriate.

After Cast Removal

Once tenderness has largely resolved, treatment can transition to:

Arch support, supportive footwear, and gradual return to normal activities.

Return should be guided by the clinical examination rather than persistent radiographic abnormalities.

Activity Modification

Activities that reproduce pain should temporarily be avoided.

These commonly include:

Running, jumping, kicking, and high-impact sports.

Return to Sport

After pain and focal tenderness resolve, activity can be increased gradually.

An arch support may be used during the transition back to sports.

Physical Therapy

Formal physical therapy is generally unnecessary.

Activity can usually be advanced by the parents according to the child’s symptoms and physician guidance.

Medication

Analgesics may be used when required.

Appropriate options include:

Acetaminophen or NSAIDs.

Medication is used for symptom relief rather than to alter the natural history of the disorder.

Surgery

Surgery is almost never necessary in childhood.

Because spontaneous healing and remodeling are expected, operative treatment should not be performed simply because the navicular appears abnormal on radiographs.

Persistent Adult Symptoms

Very rarely, residual painful degeneration persists after skeletal maturity.

In severe refractory cases, a salvage procedure such as talonavicular fusion has historically been used.

Follow-Up

Prognosis

The prognosis is excellent.

Symptoms typically resolve as the navicular revascularizes and remodels.

Radiographic Recovery

Within approximately 2–3 years, the navicular usually regains a near-normal radiographic appearance.

Clinical symptoms typically resolve considerably earlier.

Complications

Complications are uncommon.

Rarely, patients may continue to have:

Residual aching, medial midfoot tenderness, or activity-related discomfort.

These symptoms are usually treated conservatively with:

Activity modification, rest, supportive footwear, or arch support.

Patient Monitoring

Follow-up should be guided mainly by the child’s clinical recovery rather than serial radiographic appearance.

Important findings to monitor include:

Navicular tenderness, limp, activity-related pain, and ability to resume normal walking and sports.

Repeated radiographs are usually unnecessary once the diagnosis is established and the child is improving clinically.

Persistent pain, worsening symptoms, or failure to follow the expected benign course should prompt reconsideration of alternative diagnoses such as fracture, accessory navicular, infection, or another structural foot disorder.

Orthopaedic Surgery - Knee Supracondylar Fracture

Basics

A supracondylar fracture of the knee is a fracture involving the metaphyseal region of the distal femur, just proximal to the femoral condyles.

These injuries are also commonly referred to as distal femur fractures.

Fractures may remain extra-articular or extend into one or both femoral condyles and the knee joint.

Because the distal femur contributes directly to knee alignment, joint congruity, and lower-extremity mechanics, accurate reduction and stable fixation are important.

Classification

The AO/ASIF classification divides distal femoral fractures into three major groups.

Type A: Extra-Articular Fractures

The fracture does not involve the articular surface.

A1

Simple extra-articular fracture.

A2

Metaphyseal wedge fracture.

A3

Comminuted metaphyseal fracture.

Type B: Partial Articular or Unicondylar Fractures

A portion of the articular surface remains connected to the femoral shaft.

B1

Lateral condyle fracture.

B2

Medial condyle fracture.

B3

Frontal-plane fracture involving the posterior femoral condyle.

Type C: Complete Articular Fractures

The articular block is completely separated from the femoral shaft.

C1

Simple articular fracture combined with a simple metaphyseal fracture.

C2

Simple articular fracture with metaphyseal comminution.

C3

Articular comminution with a complex distal femoral fracture pattern.

Epidemiology

Distal femur fractures are less common than femoral shaft fractures but represent an important subgroup of femoral injuries.

Some series report that they account for up to approximately 30% of femoral fractures, depending on the population studied.

Age Distribution

A bimodal distribution is typical.

Younger Patients

Patients younger than approximately 35 years usually sustain these fractures through high-energy mechanisms.

Young men are affected more often in this group.

Older Patients

Patients older than approximately 50 years more commonly sustain distal femoral fractures after low-energy trauma.

Older women are disproportionately affected because of:

Osteopenia, osteoporosis, and increased fall risk.

Pediatric Population

Most pediatric distal femoral supracondylar fractures occur in adolescents.

In younger skeletally immature patients, fractures may involve the distal femoral physis.

Risk Factors

Important risk factors include:

Osteopenia, osteoporosis, advanced age, previous fragility fractures, and increased fall risk.

Etiology

The mechanism varies according to age.

Younger Adults

Common causes include:

Motor vehicle collisions, falls from height, and other high-energy trauma.

Older Adults

The typical mechanism is a low-energy fall, often with the knee flexed.

Periprosthetic Fracture

Distal femoral fracture may occur as a complication around a total knee arthroplasty.

The pattern depends on implant position, bone quality, and whether the prosthesis remains stable.

Pediatric Injury

In children, injury is usually traumatic.

Physeal fractures may exit through the metaphysis on the compression side, producing a pattern resembling a Salter-Harris type II injury.

Associated Injuries

High-energy distal femoral fractures may occur with:

Acetabular fracture, hip dislocation, femoral neck fracture, femoral shaft fracture, ligamentous knee injury, tibial plateau fracture, tibial shaft fracture, and vascular injury.

Diagnosis

Signs and Symptoms

Typical findings include:

Severe pain, focal tenderness, swelling, bruising, deformity, and inability to bear weight or walk.

Physical Examination

A complete musculoskeletal and neurovascular examination is essential.

Inspection

Assess for:

Deformity, swelling, ecchymosis, skin tenting, wounds, and evidence of an open fracture.

Neurovascular Examination

Document distal:

Pulses, capillary refill, motor function, and sensation.

Special attention should be paid to:

Peroneal nerve function and distal arterial perfusion.

Knee Examination

A complete ligamentous examination may be difficult because of pain and instability.

A more detailed examination can often be performed after fracture stabilization.

Pathophysiology and Deformity

Muscle forces commonly produce characteristic displacement.

Shortening

Muscle spasm may cause overlap of the fracture fragments and apparent shortening of the femur and limb.

Sagittal Deformity

The gastrocnemius originates from the distal femur and may pull the distal fragment posteriorly.

This often creates:

Anterior displacement of the proximal shaft and an apex-anterior deformity.

Coronal Deformity

The adductor muscles may pull the distal segment into varus alignment.

Imaging

Knee Radiographs

Obtain:

AP and lateral radiographs of the knee and distal femur.

Oblique Views

Oblique views may be useful when:

Intercondylar or articular extension is suspected.

Trauma Imaging

In high-energy trauma, additional imaging may be required.

Pelvis

An AP pelvis radiograph helps identify associated pelvic or proximal femoral injury.

Hip and Entire Femur

AP and lateral views of the:

Hip and entire femur

should be obtained when clinically indicated to exclude associated proximal fractures.

Vascular Imaging

If the distal vascular examination is abnormal or uncertain, further vascular assessment may be required.

Modern evaluation commonly uses:

CT angiography, although formal angiography may be used in selected circumstances.

CT

CT is particularly useful for:

Complex articular fractures, severe comminution, and operative planning.

It can define the number, size, and position of intra-articular fragments.

Pediatric Imaging

Standard trauma radiographs should be obtained.

Stress views may occasionally be considered when an occult physeal injury is suspected, although advanced imaging may be preferable in many situations.

The distal femoral physis remains visible until adolescence and is normally several millimeters thick.

Differential Diagnosis

Important alternative or associated diagnoses include:

Soft-tissue contusion, major knee ligament injury, patellar fracture, proximal tibial fracture, and tibial plateau fracture.

Treatment

General Principles

Treatment aims to restore:

Articular congruity, limb length, coronal and sagittal alignment, rotational alignment, and knee stability.

For intra-articular fractures, anatomical reconstruction of the joint surface is particularly important.

Nondisplaced or Impacted Fractures

Selected stable fractures may be managed with:

A splint, cast, or functional fracture brace.

Close radiographic surveillance is required because displacement can occur.

Skeletal Traction

Skeletal traction may occasionally be used:

Temporarily in medically unstable patients or when immediate fixation is not possible.

It is now less commonly used as definitive treatment.

External Fixation

External fixation is useful for:

Severe open fractures, extensive soft-tissue injury, temporary damage-control stabilization, or unstable polytrauma patients.

A spanning fixator may cross the knee initially.

Once soft tissues improve, conversion to internal fixation may be considered.

Operative Treatment

Most displaced closed distal femoral fractures are treated surgically.

The goals are:

Stable fixation, restoration of alignment, and early knee motion.

Pediatric Treatment

In skeletally immature patients, stable physeal injuries may sometimes be treated with:

Closed reduction and casting.

Displaced or unstable fractures may require:

Percutaneous pinning or open reduction and internal fixation.

Care must be taken to minimize damage to the distal femoral physis.

Activity

Initially, the injured extremity is generally kept non-weight bearing.

Weight bearing is advanced gradually once healing progresses.

Progression

Limited or toe-touch weight bearing may be started in selected cases once:

Fixation is stable, callus is developing, and pain is decreasing.

Progressive full weight bearing generally follows clinical and radiographic evidence of union.

Physical Therapy

Early rehabilitation is important after stable fixation.

Range of Motion

Knee motion should begin as soon as soft tissues and fixation permit.

This reduces the risk of arthrofibrosis.

Strengthening

Therapy emphasizes:

Quadriceps and hamstring activation and strengthening.

Gait Training

As weight bearing progresses, therapy advances to:

Walker or crutch use, gait retraining, balance, and progressive resistance exercises.

Healing Time

Early radiographic healing commonly becomes apparent by approximately 2–3 months.

Complete union may require approximately 4–6 months, depending on fracture severity and patient factors.

Medication

Pain control may include:

Acetaminophen and short-term opioid analgesics when necessary.

The effect of NSAIDs on fracture healing remains debated, so their use may be limited in selected patients at risk for impaired union.

Surgery

Indications

Common operative indications include:

Open fracture, displacement, vascular compromise, irreducibility, multiple injuries, ipsilateral lower-extremity fractures, and unstable intra-articular injury.

Relative Contraindications

Relative reasons to delay or modify surgery include:

Active local infection, severe medical instability, or exceptionally poor bone quality.

Fixation Options

Possible implants include:

Locked plates, fixed-angle plates, condylar plates, intramedullary nails, external fixation, and selected arthroplasty constructs.

Plate Fixation

Modern distal femoral plates are available in multiple shapes and designs.

They can be used for:

Simple fractures, comminuted fractures, osteoporotic fractures, and periarticular injuries.

Minimally Invasive Plating

Some plates can be inserted through limited incisions and passed submuscularly, reducing disruption of fracture-site blood supply.

Locked Plates

Locked plates are particularly useful in:

Osteoporotic bone and metaphyseal comminution, where conventional screw purchase may be limited.

Intramedullary Nailing

Intramedullary nails can stabilize selected extra-articular or simple articular distal femoral fractures.

They may be inserted:

Antegrade or retrograde.

Retrograde nails are commonly used for fractures closer to the knee.

External Fixation

External fixation is most commonly used as a temporary stabilizing measure when:

Soft tissues are severely damaged or the patient is physiologically unstable.

Distal Femoral Replacement

In selected elderly patients with:

Severe osteoporosis, unreconstructable comminution, preexisting advanced knee arthritis, or failed fixation, distal femoral replacement may be considered.

Periprosthetic Distal Femur Fracture

Treatment depends on:

Fracture location, implant design, available distal bone stock, and whether the knee prosthesis is stable.

Stable Prosthesis

When the implant is well fixed, treatment may include:

Locked plating or retrograde intramedullary nailing, depending on fracture pattern and implant compatibility.

Loose Prosthesis

If the femoral component is loose or the fracture is too distal for reliable fixation, revision arthroplasty or distal femoral replacement may be required.

Pediatric Considerations

Closed reduction with percutaneous pin fixation can produce good results in displaced pediatric fractures when appropriate.

If the fracture remains unstable, open reduction and internal fixation may be necessary.

Postoperative Immobilization

In some pediatric cases, the knee may be immobilized in slight flexion, historically around 10°, until early healing is visible.

Immobilization duration is individualized, commonly around several weeks.

Follow-Up

Early Monitoring

Patients should be monitored carefully after injury for:

Neurovascular deterioration, progressive swelling, and compartment syndrome of the thigh.

Prognosis

Outcome depends primarily on:

Fracture complexity, degree of articular damage, soft-tissue injury, age, bone quality, and quality of reduction.

Simple fractures generally have better outcomes than extensively comminuted intra-articular injuries.

With appropriate treatment, many patients achieve good to excellent function.

Periprosthetic Fracture Prognosis

Modern fixation, including appropriately selected intramedullary nails or locked plates, can provide favorable midterm results in periprosthetic fractures when the prosthesis remains stable.

Complications

Knee Stiffness

Arthrofibrosis is one of the most common complications.

Risk increases with:

Severe trauma, intra-articular injury, prolonged immobilization, and delayed rehabilitation.

Infection

Infection may occur, particularly in:

Open fractures, extensive soft-tissue injury, and major reconstructive procedures.

Nonunion

Failure of union is associated with:

Comminution, bone loss, poor fixation, infection, smoking, severe osteoporosis, and compromised biology.

Malunion

Healing with abnormal alignment may cause:

Varus, valgus, flexion, extension, rotational deformity, limb shortening, or altered gait.

Loss of Fixation

Mechanical failure may result from:

Poor bone quality, inadequate fixation, premature loading, or severe fracture comminution.

Post-Traumatic Arthritis

Intra-articular fractures may damage the articular cartilage and lead to:

Progressive degenerative arthritis of the knee.

Risk is greater when joint congruity cannot be restored.

Compartment Syndrome

Although less common than in the leg, compartment syndrome of the thigh can occur after major distal femoral trauma.

It requires urgent recognition and treatment.

Physeal Injury

In children, injury to the distal femoral growth plate is particularly important because this physis contributes substantially to lower-extremity growth.

Complications may include:

Growth arrest, angular deformity, and leg-length discrepancy.

Limb-Length Discrepancy

Significant discrepancy may require procedures such as:

Contralateral epiphysiodesis, femoral shortening, or ipsilateral femoral lengthening, depending on remaining growth and projected inequality.

A discrepancy greater than approximately 2.5 cm may become clinically important.

Patient Monitoring

Patients are usually reassessed within the first several weeks after definitive treatment and then periodically, often approximately monthly during active healing.

Monitoring should include:

Pain, tenderness, range of motion, alignment, neurovascular status, and serial radiographs.

Radiographic Healing

Follow-up imaging should demonstrate:

Progressive callus formation, maintenance of alignment, stable implants, and eventual bridging union.

Weight-Bearing Progression

Limited weight bearing may begin when:

Good callus formation is visible, fixation is stable, and fracture-site tenderness has substantially decreased.

Full weight bearing should be advanced according to clinical and radiographic healing rather than time alone.

Orthopaedic Surgery - Knee Replacement

Basics

Total knee arthroplasty is a highly effective surgical treatment for advanced, disabling arthritis of the knee.

The operation resurfaces the damaged articular surfaces of the femur and tibia with metallic components separated by a polyethylene bearing surface. Depending on the procedure, the patellar surface may also be resurfaced.

The prosthetic components are shaped to reproduce normal knee geometry as closely as possible while restoring alignment, stability, and motion.

Classification by Compartment

Knee arthritis can primarily involve one or more compartments.

The major compartments are:

Medial tibiofemoral compartment

Lateral tibiofemoral compartment

Patellofemoral compartment

The distribution of arthritis helps determine whether a patient is a candidate for partial or total knee replacement.

Epidemiology

Knee arthroplasty is performed commonly and its use has continued to increase.

Historically, approximately 61% of total knee replacements have been performed in women.

Older U.S. data recorded approximately 418,000 procedures in 2003, and the annual number has increased substantially since that time.

The average age at surgery in older series was approximately 67 years, although arthroplasty is now performed across a broader age range.

Risk Factors

Factors that contribute to knee degeneration severe enough to require replacement include:

Previous trauma, meniscectomy, obesity, malalignment, inflammatory disease, and chronic joint overload.

Etiology

Osteoarthritis

Primary osteoarthritis is the most common indication for knee replacement.

In many cases it is idiopathic, although age, obesity, genetics, previous injury, and joint mechanics may contribute.

Post-Traumatic Arthritis

Post-traumatic arthritis may develop after:

Sports injuries, fractures, ligament injuries, meniscal loss, falls, or motor vehicle trauma.

Previous injury may produce altered alignment or instability that accelerates cartilage degeneration.

Inflammatory Arthritis

Inflammatory joint disease may also lead to severe cartilage destruction.

Examples include:

Rheumatoid arthritis, gout, pseudogout, and other inflammatory arthropathies.

Associated Conditions

Patients with advanced knee arthritis often have degenerative disease elsewhere.

Common associated conditions include:

Hip arthritis, lumbar spinal stenosis, and foot or ankle arthritis.

In patients with rheumatoid arthritis, foot and ankle deformity may be particularly severe and may influence gait and rehabilitation.

Diagnosis

Signs and Symptoms

Common signs include:

Joint effusion, joint-line tenderness, deformity, reduced motion, and an antalgic gait.

Deformity

Osteoarthritis commonly produces a varus deformity, particularly when the medial compartment is most affected.

Valgus deformity may occur with lateral compartment disease and has historically been associated with inflammatory arthritis such as rheumatoid arthritis.

Symptoms

Typical complaints include:

Pain, start-up pain, swelling, catching, instability or giving way, stiffness, and progressive limitation of daily activities.

History

The patient often reports pain that has progressively worsened despite appropriate nonoperative treatment.

Important historical features include:

Duration of symptoms, walking tolerance, night pain, stair difficulty, need for assistive devices, previous knee surgery, instability, and response to medication or injections.

Persistent pain that is no longer adequately relieved by conservative treatment supports consideration of arthroplasty when imaging findings are compatible.

Physical Examination

The knee should be examined systematically for signs of arthritis.

Effusion

An effusion may reflect:

Synovitis, degenerative disease, inflammatory arthritis, or another intra-articular process.

Joint-Line Tenderness

Medial or lateral joint-line tenderness may result from:

Compartmental arthritis or meniscal pathology.

Other Tenderness

The examiner should assess for tenderness over:

The patellofemoral joint, collateral ligaments, pes anserine region, patellar tendon, and surrounding soft tissues.

Range of Motion

Document:

Flexion, extension, flexion contracture, extension lag, and pain through the arc of motion.

Marked loss of motion may affect both operative planning and postoperative rehabilitation.

Gait

Assess for:

Antalgic gait, varus or valgus thrust, flexion contracture, instability, and use of walking aids.

Laboratory Tests

Routine laboratory testing does not diagnose osteoarthritis.

Testing is directed toward alternative diagnoses or preoperative assessment.

Suspected Infection

If infection is a concern, useful studies include:

C-reactive protein and ESR.

Further investigation may require aspiration.

Suspected Gout

Serum uric acid may be obtained, although the diagnosis of gout is established more reliably through synovial fluid crystal analysis.

Imaging

Plain Radiographs

Weight-bearing radiographs are the first-line imaging study for knee arthritis.

Standing AP or PA View

A standing view can demonstrate subtle or advanced loss of joint-space width and allows comparison of medial and lateral compartments under physiologic load.

Lateral View

The lateral radiograph helps assess:

Patellofemoral degeneration, posterior osteophytes, alignment, and flexion deformity.

Patellofemoral View

A tangential or skyline view is useful for assessing:

Patellar alignment, trochlear disease, and patellofemoral joint-space loss.

MRI

MRI is not routinely required before knee replacement when the diagnosis of advanced osteoarthritis is clear on weight-bearing radiographs.

It may be useful in selected cases to evaluate:

Meniscal pathology, synovial proliferative disorders such as PVNS, osteonecrosis, occult tumor, or focal cartilage injury.

Arthrocentesis

Joint aspiration can be extremely helpful when the diagnosis is uncertain.

It may help evaluate for:

Septic arthritis, gout, or pseudogout.

Synovial fluid may be sent for:

Cell count, differential, Gram stain, culture, and crystal analysis.

Pathophysiology

The common feature of end-stage arthritis is progressive loss of articular cartilage.

Proteoglycans and normal cartilage matrix are lost, causing thinning and eventual exposure of subchondral bone.

As cartilage disappears, patients may develop:

Painful bone-on-bone contact, deformity, osteophytes, sclerosis, cyst formation, and progressive loss of motion.

Differential Diagnosis

Conditions that may mimic or coexist with knee arthritis include:

Septic arthritis, osteomyelitis, patellofemoral pain or instability, meniscal tears, crystal arthropathy, and tumor.

Treatment

General Principles

Nonoperative treatment should generally be attempted before elective knee replacement.

Options include:

NSAIDs, acetaminophen, weight reduction when appropriate, walking aids, braces, exercise-based physical therapy, activity modification, and intra-articular injections.

Younger Patients

In younger patients, especially those under approximately 50 years, joint-preserving procedures may be considered when disease is localized and anatomy is suitable.

These may include:

Realignment osteotomy or selected arthroscopic procedures for focal mechanical pathology.

The goal is to delay arthroplasty when possible without leaving the patient severely disabled.

Decision for Surgery

Knee replacement is considered when:

Pain and functional limitation are substantial, radiographs demonstrate significant joint degeneration, and appropriate nonoperative treatment has failed.

The patient should receive a detailed discussion of:

Expected benefits, limitations, rehabilitation, implant longevity, and potential complications.

Preoperative Preparation

Patients undergo a complete medical evaluation before surgery.

Important issues include:

Cardiovascular status, pulmonary disease, anemia, infection risk, anticoagulation, diabetes control, and nutritional status.

Routine preoperative autologous blood donation is now uncommon.

Anticoagulants and certain medications may need to be adjusted before surgery according to individual risk and perioperative guidance.

Physical Therapy

Physical therapy is a central component of recovery.

Range of Motion

A common early goal is to regain approximately:

0–110° of knee motion within the first several weeks, although individual recovery varies.

Strengthening

Rehabilitation emphasizes:

Quadriceps strength, hamstring strength, gait training, balance, transfers, and functional independence.

Weight Bearing

Most modern total knee replacement protocols allow early full weight bearing as tolerated when medically and surgically appropriate.

Medication

Postoperative Analgesia

Effective pain control is necessary to permit early mobilization and participation in therapy.

Modern care usually relies on a multimodal analgesic strategy, which may include:

Acetaminophen, NSAIDs when appropriate, regional anesthesia, periarticular injections, and limited opioid use for breakthrough pain.

Long-term opioid use is generally avoided.

Surgery

Knee replacement may be either:

Partial or total.

Unicompartmental Knee Replacement

A unicompartmental or partial knee replacement resurfaces only one diseased tibiofemoral compartment.

Indications

It is appropriate only when arthritis is isolated to a single compartment and the remaining knee structures are suitable.

Important considerations include:

Intact or functionally adequate ligaments, correctable deformity, preserved opposite compartment cartilage, and appropriate patient selection.

Compartments

Unicompartmental replacement may be performed for:

Medial or lateral compartment arthritis.

Patellofemoral Arthroplasty

Isolated patellofemoral replacement is another form of partial arthroplasty used in selected patients with disease confined to the patellofemoral compartment.

Total Knee Replacement

Total knee arthroplasty resurfaces the distal femur and proximal tibia and may also resurface the patella.

Surgical Exposure

A midline skin incision with a standard arthrotomy is commonly used.

Bone Preparation

Specialized guides or navigation systems are used to make femoral and tibial bone cuts and establish:

Alignment, component rotation, joint-line position, ligament balance, and flexion-extension gaps.

Component Fixation

Components may be:

Cemented, uncemented, or hybrid.

Cemented fixation remains common, while modern porous-coated components may permit biologic ingrowth.

Patellar Resurfacing

The patellar articular surface may be resurfaced depending on:

Surgeon preference, patellar cartilage condition, implant system, and patient factors.

Bearing Surface

The femoral component articulates against highly cross-linked polyethylene on the tibial side.

This metal-on-polyethylene articulation is the standard bearing configuration.

Cruciate-Retaining Design

In a cruciate-retaining knee replacement, the PCL is preserved.

The implant relies in part on the native PCL for femoral rollback and stability.

Posterior-Stabilized Design

In a posterior-stabilized design, the PCL is resected.

A cam-and-post mechanism built into the femoral component and polyethylene liner substitutes for part of the PCL function.

Long-term outcomes of well-performed cruciate-retaining and posterior-stabilized designs are generally similar.

Computer-Assisted and Robotic Surgery

Computer navigation and robotic-assisted systems can help improve the precision of:

Bone cuts, alignment, component positioning, and soft-tissue balancing.

These technologies are now used clinically in many centers rather than only in research settings.

Their effect on long-term implant survivorship continues to be evaluated.

Venous Thromboembolism Prophylaxis

Patients require prophylaxis against DVT and pulmonary embolism.

Modern strategies may include:

Aspirin, low-molecular-weight heparin, direct oral anticoagulants, or other agents, selected according to patient risk.

Mechanical compression and early mobilization are also important.

Routine use of warfarin for every patient is no longer standard.

Follow-Up

Referral After Surgery

Urgent reassessment is required for:

Severe or increasing pain, marked swelling, erythema, wound drainage, fever, new instability, calf pain, dyspnea, or neurovascular symptoms.

Prognosis

Long-term outcomes of total knee replacement are excellent.

Most patients experience substantial improvement in:

Pain, walking ability, function, and quality of life.

Implant Survivorship

Historical studies have reported approximately:

91% survivorship at 10 years and 78% at 20 years for older implant designs.

Newer prosthetic systems have demonstrated even higher short- and intermediate-term survival in many series.

Unicompartmental Replacement Prognosis

Older studies have reported approximately 95% survival at 10 years in selected patients.

However, arthritis may continue to progress in the unreplaced compartments over time.

Complications

Infection

Periprosthetic joint infection occurs in a small percentage of patients, historically around 1% after primary replacement.

It may require:

Antibiotics, irrigation and debridement, component exchange, or staged revision surgery.

Aseptic Loosening

Components may loosen over time because of:

Mechanical stress, wear debris, osteolysis, or failure of bone-cement or bone-implant fixation.

Polyethylene Wear and Osteolysis

Wear particles can stimulate an inflammatory reaction that leads to:

Periprosthetic bone loss and eventual component loosening.

Modern polyethylene has reduced this problem compared with older materials.

Patellofemoral Complications

Possible complications include:

Patellar maltracking, subluxation, dislocation, fracture, instability, and anterior knee pain.

Periprosthetic Fracture

Fractures may occur around the:

Distal femur, proximal tibia, or patella.

These injuries are uncommon but can be complex, particularly in osteoporotic patients.

Extensor Mechanism Rupture

Disruption may involve the:

Quadriceps tendon or patellar tendon.

This can cause major functional impairment and often requires operative repair or reconstruction.

Venous Thromboembolism

DVT and pulmonary embolism remain important postoperative risks.

Prophylaxis and early mobilization reduce their incidence.

Medical Complications

Potential medical complications include:

Myocardial infarction, pneumonia, urinary infection, delirium, and, rarely, death.

Stiffness

Some patients develop persistent loss of motion.

Contributing factors include:

Preoperative stiffness, pain, scar formation, infection, malposition, and inadequate rehabilitation.

Selected patients may require manipulation under anesthesia or further surgery.

Sensory Changes

Numbness near the incision is common because small superficial sensory nerves may be divided during surgical exposure.

The numb area may decrease with time but can persist.

Persistent Pain

A minority of patients continue to experience pain despite technically successful replacement.

Potential causes include:

Infection, loosening, instability, patellofemoral problems, referred pain, bursitis, neuroma, stiffness, or unexplained persistent pain.

Pes Anserine Bursitis

Pes anserine irritation can occur after arthroplasty and may contribute to medial knee pain.

Patient Monitoring

Patients should be followed closely during the early postoperative period until:

The wound has healed, pain is controlled, gait is safe, and functional range of motion has been achieved.

Long-Term Follow-Up

Periodic long-term review is recommended.

Plain radiographs are used to monitor:

Component position, fixation, polyethylene wear, osteolysis, periprosthetic fracture, and progressive loosening.

The frequency of surveillance varies according to implant age, symptoms, and surgeon preference.

Orthopaedic Surgery - Knee Pain

Basics

Knee pain has a broad differential diagnosis and may arise from pathology within the knee itself or from disorders elsewhere that refer pain to the knee.

Pain may be diffuse or localized to a particular region.

In many patients, a careful history combined with a focused physical examination substantially narrows the diagnosis.

Knee pain can be broadly classified as:

Traumatic or acquired/nontraumatic.

Risk Factors

Factors that increase the likelihood of knee pain include:

Athletic activity, lower-extremity malalignment, ligamentous instability, obesity, and physical deconditioning or sedentary behavior.

Etiology

Major causes include:

Acute traumatic injury, repetitive overuse, degenerative disease, inflammatory disease, infection, and abnormalities involving structures around the knee.

Associated Conditions

Systemic disorders that may produce knee symptoms include:

Rheumatoid arthritis, gout, pseudogout, and other inflammatory arthropathies.

Increasing physical activity may also uncover previously asymptomatic structural abnormalities or overuse conditions.

Diagnosis

History

The history should clarify:

Onset, mechanism, pain location, swelling, locking, popping, instability, activity relationship, night pain, and functional limitations.

Symptoms such as difficulty climbing stairs or rising from a chair may point toward specific patterns of knee pathology.

General Symptoms

Common complaints include:

Swelling, locking, popping, giving way, difficulty using stairs, difficulty rising from a chair, and chronic pain that worsens with activity.

Patellofemoral Disorders

Patellofemoral Pain Syndrome

Patellofemoral pain commonly occurs in adolescents and young adults.

Pain is usually located at the anterior knee and is worsened by activities that increase patellofemoral joint loading, such as:

Climbing or descending stairs, squatting, prolonged sitting, and rising from a chair.

Crepitus may occur during knee motion.

Compression of the patella against the femoral trochlea may reproduce symptoms.

Patellofemoral pain is not synonymous with cartilage softening, although chondral abnormalities may coexist.

Patellar Subluxation and Dislocation

Patellar instability may be traumatic or related to underlying anatomy.

Predisposing factors can include:

Increased femoral anteversion, genu valgum, trochlear dysplasia, patella alta, abnormal rotational alignment, and increased lateralizing forces on the patella.

A positive J sign, in which the patella shifts laterally near terminal extension, may indicate abnormal tracking.

Articular Cartilage Injury

Articular cartilage injuries frequently follow trauma but may also result from chronic degenerative disease.

Pain is usually worsened by:

Weight bearing, impact activity, or repetitive loading.

Associated symptoms may include swelling, catching, or mechanical discomfort.

Meniscal Injury

Meniscal pathology may be:

Acute and traumatic or degenerative and related to chronic tissue deterioration.

Symptoms

Patients commonly report:

Joint-line pain, intermittent swelling, catching, locking, or giving way.

Effusion often develops gradually rather than immediately and may fluctuate with activity.

Location

Medial meniscal pathology causes medial joint-line pain, whereas lateral meniscal disease produces lateral joint-line symptoms.

Knee Arthritis

Arthritic symptoms typically have a gradual and progressive onset, although an acute osteochondral event may suddenly worsen a previously chronic condition.

Pain generally:

Increases with activity and improves with rest.

Patients may also develop pain:

At night after an active day or after prolonged periods of inactivity, such as a long car ride or bed rest.

Stiffness, swelling, crepitus, and loss of motion are common as arthritis progresses.

Anterior Cruciate Ligament Injury

The ACL primarily prevents anterior translation of the tibia relative to the femur and contributes importantly to rotational stability.

Mechanism

ACL injuries commonly occur through noncontact mechanisms such as:

Sudden deceleration, pivoting, cutting, or landing from a jump.

An audible or palpable pop and rapid swelling are common.

Reinjury Risk

A previous ACL tear increases the risk of:

Recurrent ACL injury in the reconstructed or previously injured knee and ACL injury in the contralateral knee.

Posterior Cruciate Ligament Injury

The PCL is the primary restraint to posterior translation of the tibia.

Mechanism

A classic mechanism is a direct blow to the anterior proximal tibia when the knee is flexed, such as a dashboard injury.

Symptoms

Pain and swelling occur acutely after injury and often improve over several weeks.

Chronic PCL deficiency may later contribute to:

Medial-compartment and patellofemoral degenerative symptoms.

Medial Collateral Ligament Injury

The MCL is the primary restraint to valgus stress.

Pain is typically located along the medial knee and may extend proximally or distally along the course of the ligament.

Mechanism

An isolated MCL injury commonly follows a direct blow to the lateral side of the knee, creating valgus stress.

MCL injury may also occur together with:

ACL tears, meniscal injury, or other multiligament trauma.

Lateral Collateral Ligament Injury

The LCL extends from the lateral femoral epicondyle to the fibular head and resists varus stress.

Isolated LCL injury is relatively uncommon.

It is often associated with:

Cruciate ligament or posterolateral corner injury.

Because of the proximity of the common peroneal nerve to the fibular head, motor and sensory function should be assessed carefully.

Quadriceps and Patellar Tendon Rupture

Disruption of either the quadriceps tendon or patellar tendon impairs the extensor mechanism.

Symptoms

Patients may have:

Anterior knee pain, effusion, inability to actively extend the knee, and inability to perform a straight-leg raise.

Examination

A palpable defect may be present.

Patellar position may also be abnormal:

Patella baja may occur with quadriceps tendon rupture, whereas patella alta may occur with patellar tendon rupture.

Mechanism

These injuries may follow:

Direct trauma or sudden forced knee flexion against a maximally contracting quadriceps muscle.

Bursitis and Tendinopathy

Inflammation or irritation may develop at bursae or tendon insertions around the knee.

The diagnosis is commonly suggested by localized tenderness directly over the involved structure.

Common Bursae

Common symptomatic locations include:

Prepatellar and pes anserine bursae.

Common Tendons

Tendinopathy frequently involves the:

Patellar tendon or distal quadriceps tendon.

Osteochondritis Dissecans

Osteochondritis dissecans commonly affects active children, adolescents, and young adults.

It involves a localized abnormality of the subchondral bone and overlying articular cartilage.

Symptoms

Patients may develop:

Activity-related pain, effusion, localized tenderness, catching, or locking.

Mechanical symptoms become more likely if an unstable fragment separates and becomes a loose body.

Osgood–Schlatter Disease

Osgood–Schlatter disease is a traction apophysitis of the tibial tubercle.

It is common in active growing children and adolescents.

Repetitive traction from the patellar tendon produces:

Pain, swelling, and tenderness over the tibial tubercle.

Symptoms are aggravated by running, jumping, kneeling, and resisted extension.

Baker Cyst

A Baker or popliteal cyst is a distension of the posterior knee capsule or bursa that often communicates with the knee joint.

It is frequently associated with intra-articular pathology, including:

Meniscal tears, arthritis, and chronic synovitis.

Presentation

Patients may complain of:

A posterior knee mass, fullness, or pressure.

The underlying intra-articular disease may itself produce few symptoms.

Fracture

A fracture around the knee must be considered after significant trauma.

Potential sites include:

Distal femur, proximal tibia, tibial plateau, and patella.

Plain radiographs are usually the initial diagnostic study.

Bone Tumor

Bone tumors are uncommon but should remain in the differential diagnosis, especially when pain is:

Persistent, progressive, present at night, unrelated to activity, or associated with constitutional symptoms.

Symptoms

Patients may describe:

Deep, dull, aching pain that gradually becomes constant.

Additional findings may include:

Swelling, reduced function, fatigue, low-grade fever, weight loss, or a pathologic fracture.

Physical Examination

Palpation

Palpate the knee for:

Effusion, localized swelling, warmth, and focal tenderness.

Joint-Line Tenderness

Medial or lateral joint-line tenderness may suggest:

Meniscal pathology or compartmental arthritis.

Other Tender Areas

Palpate the:

Pes anserine bursa, patellar tendon, quadriceps tendon, patella, collateral ligaments, and other symptomatic structures.

Range of Motion

Compare the affected knee with the contralateral side.

Assess:

Flexion, extension, presence of contracture, pain, crepitus, and extension lag.

Patellar Tracking

Observe the patella as the knee moves from flexion into extension.

Abnormal lateral translation or a J sign may indicate patellar maltracking or instability.

Ligament Stability

Assess the major ligament groups systematically.

MCL

Use valgus stress testing.

LCL

Use varus stress testing.

ACL

Use the:

Lachman test and anterior drawer test.

The Lachman test is generally the more sensitive examination maneuver.

PCL

Assess with:

Posterior drawer, posterior sag, and quadriceps active testing.

Laboratory Tests

Laboratory testing should be guided by the suspected diagnosis rather than ordered routinely for all patients with knee pain.

Suspected Septic Arthritis

Appropriate studies may include:

Complete blood count with differential, ESR, CRP, blood cultures when indicated, and urgent synovial fluid analysis.

Suspected Inflammatory Arthritis

Targeted evaluation may include:

Rheumatoid factor, anti-CCP antibodies, ANA, ESR, CRP, and other tests depending on the clinical context.

Suspected Gout

Serum uric acid may be obtained, although a normal value does not exclude an acute gout attack.

Definitive diagnosis is made by synovial crystal analysis.

Imaging

Plain Radiographs

Radiographs are usually the first imaging study when structural pathology is suspected.

Useful views include:

Weight-bearing AP or PA, lateral, and tangential patellofemoral views such as Merchant or sunrise views.

Depending on the clinical question, additional views may be obtained.

MRI

MRI is useful for evaluating:

Meniscal tears, ligament injuries, articular cartilage lesions, osteochondral abnormalities, synovial proliferative disorders, tumors, and osteonecrosis.

MRI should be obtained when the result is expected to alter diagnosis or management.

Arthrocentesis

Joint aspiration can provide critical diagnostic information in a patient with an unexplained effusion.

Septic Arthritis

Synovial findings may include:

High white blood cell count with neutrophil predominance and positive bacterial culture.

A count above approximately 50,000 cells/mm³ strongly raises suspicion, although infection may occur at lower values and inflammatory arthritis may occasionally produce similarly high counts.

Gout

Gout is characterized by:

Monosodium urate crystals that are needle-shaped and strongly negatively birefringent under polarized light.

Synovial leukocytosis is common and may occasionally be substantial.

Pseudogout

Calcium pyrophosphate deposition disease demonstrates:

Rhomboid-shaped, weakly positively birefringent crystals.

Fat Droplets

Fat droplets within aspirated joint fluid may suggest an intra-articular fracture with marrow communication.

Pathological Findings

Pathologic findings vary entirely according to the underlying disorder.

Differential Diagnosis

Common diagnostic categories include:

Patellofemoral disorders

Articular cartilage and osteochondral injuries

Meniscal disease

Osteoarthritis and inflammatory arthritis

Ligament tears

Tendinopathy and tendon rupture

Osteochondritis dissecans

Osgood–Schlatter disease

Baker cyst

Gout and pseudogout

Fracture

Tumor

The diagnosis is established by integrating the history, pain location, physical examination, laboratory studies when appropriate, and imaging.

Clinical Clues From History and Pain Location

Certain patterns are particularly useful.

Locking with medial or lateral joint-line pain suggests a meniscal tear.

A pop during a sudden pivot followed by swelling suggests ACL injury.

Anterior knee pain with stairs or rising from a chair suggests patellofemoral pathology.

A direct blow to the proximal tibia with the knee flexed suggests PCL injury.

Side impact with medial or lateral pain suggests collateral ligament injury.

Chronic activity-related pain with stiffness suggests arthritis or another degenerative process.

Treatment

Treatment depends on the underlying diagnosis.

Patellofemoral Pain

Initial treatment commonly includes:

Activity modification, NSAIDs or other simple analgesia when appropriate, and exercise-based physical therapy.

Therapy should focus on:

Quadriceps strength, hip and core strength, flexibility, and correction of movement patterns.

Patellar Instability

Many first-time or mild cases can be managed with:

Physical therapy, activity modification, and selected patellar-stabilizing braces.

Recurrent instability or major structural abnormalities may require surgical evaluation.

Arthritis

Initial nonoperative management may include:

Analgesics, NSAIDs, activity modification, weight reduction when appropriate, physical therapy, assistive devices, unloader bracing for selected unicompartmental disease, and intra-articular injections.

Bursitis and Tendinopathy

Treatment generally consists of:

Activity modification, ice, topical or oral analgesic therapy, and correction of contributing mechanical factors.

Routine aspiration of uncomplicated bursitis is usually avoided unless infection or another specific indication is suspected.

Osgood–Schlatter Disease

Treatment includes:

Relative rest, activity modification, stretching, and anti-inflammatory medication when appropriate.

Most cases resolve as skeletal maturity is reached.

Ligament and Meniscal Injuries

Initial management may include:

Protected weight bearing, controlled range of motion, ice, analgesia, and orthopaedic or sports-medicine referral when indicated.

Treatment depends on:

Patient age, instability, tear pattern, activity level, associated injuries, and chronicity.

Physical Therapy

Physical therapy is highly useful for many causes of knee pain.

Common goals include:

Restoring range of motion, strengthening the quadriceps and hamstrings, improving hip and core strength, increasing flexibility, correcting gait and movement mechanics, and restoring proprioception.

Adjunctive modalities may include:

Cryotherapy and selected electrical stimulation.

Exercise-based rehabilitation is generally the core of treatment.

Medication

Common medication options include:

NSAIDs and acetaminophen.

Long-term opioid therapy generally should be avoided for routine musculoskeletal knee pain.

Intra-Articular Therapy

For selected patients with arthritis, intra-articular treatment may include:

Corticosteroid injections and, in some settings, hyaluronic acid products.

Expected benefit varies according to the underlying diagnosis and patient factors.

Surgery

Knee surgery can broadly be grouped into three categories.

Arthritis Surgery

Potential procedures include:

Osteotomy, unicompartmental knee arthroplasty, and total knee arthroplasty.

Arthroscopic debridement has a limited role in routine degenerative osteoarthritis and is generally reserved for selected mechanical pathology rather than arthritis alone.

Sports Medicine Procedures

These include:

Arthroscopic meniscal treatment, ligament reconstruction, cartilage procedures, and patellar stabilization or realignment surgery.

Trauma Surgery

Trauma procedures include:

Internal fixation of fractures and repair of quadriceps or patellar tendon rupture.

Follow-Up

Prognosis

The prognosis is generally excellent when:

The underlying diagnosis is accurately identified and appropriate operative or nonoperative treatment is provided.

Outcome depends on the severity and chronicity of the underlying disorder.

Complications

Potential consequences of inadequately treated knee pathology include:

Loss of motion, loss of function, impaired weight bearing, persistent instability, progressive arthritis, and chronic pain.

Patient Monitoring

Patients should be reassessed according to the severity of the underlying diagnosis.

For many musculoskeletal conditions, follow-up at approximately 4–6 week intervals is appropriate until:

Range of motion, strength, stability, and function have substantially recovered.

Persistent swelling, mechanical locking, night pain, fever, progressive weakness, or failure to improve should prompt reconsideration of the diagnosis and further investigation.

Orthopaedic Surgery - Knee Injection

Basics

Knee aspiration and intra-articular injection are commonly performed for both diagnostic and therapeutic purposes.

Aspiration removes fluid from the knee joint, whereas injection introduces medication or another solution into the joint.

Indications for Knee Injection

Injection may be performed for:

Delivery of medication for treatment of knee pain or inflammation

Administration of local anesthetic to facilitate diagnostic examination

Selected diagnostic procedures involving intra-articular fluid administration

Historically, saline load testing was used to evaluate whether a traumatic periarticular wound communicated with the knee joint, although other imaging-based approaches may also be used depending on the clinical setting.

Indications for Knee Aspiration

Arthrocentesis may be indicated for:

Large symptomatic effusion

Large hemarthrosis

Evaluation for septic arthritis

Investigation of inflammatory synovitis or arthritis

Aspiration may also relieve pain and improve motion when a tense effusion is present.

Equipment

Typical equipment includes:

Antiseptic skin-preparation solution

Sterile gloves

Large-bore needle, commonly approximately 18 gauge

20–60 mL syringes

Additional supplies may include:

Sterile drapes, local anesthetic, dressings, specimen containers, and ultrasound equipment when needed.

Technique

Several approaches to the knee joint are possible.

The superolateral approach is particularly reliable for aspiration of a large effusion.

Patient Position

Place the patient supine with the knee fully extended.

The quadriceps should be relaxed to facilitate access to the suprapatellar pouch.

Sterile Preparation

Perform a wide sterile preparation of the knee.

A broad preparation is useful because manipulation of the patella or knee may be required during the procedure.

Superolateral Entry Site

Identify a point approximately:

1 cm proximal to the superior pole of the patella and 1 cm lateral to its lateral border.

This provides access to the suprapatellar pouch.

Needle Insertion

Advance the needle through the:

Skin, subcutaneous tissues, and lateral retinaculum

toward the suprapatellar pouch between the quadriceps tendon and distal femur.

Once the needle enters the joint, apply gentle suction with the syringe.

Aspiration

Withdraw as much joint fluid as required.

The aspirated fluid should be inspected for:

Color, clarity, viscosity, turbidity, and the presence of blood or purulence.

Large Effusions

If the syringe becomes full before the joint has been adequately decompressed, the syringe can be exchanged while the needle remains within the joint.

A clamp or other sterile stabilization method can be used to prevent movement of the needle during syringe exchange.

Aspiration continues until sufficient fluid has been removed.

Completion of Aspiration

After aspiration is complete:

Remove the needle and apply a sterile dressing or adhesive bandage.

When clinically indicated, synovial fluid should be sent promptly for laboratory analysis.

Synovial Fluid Analysis

Depending on the clinical question, studies may include:

Cell count with differential, Gram stain, bacterial culture, crystal analysis, and other targeted tests.

When septic arthritis is suspected, specimens should be obtained before intra-articular corticosteroid administration.

Therapeutic Injection After Aspiration

If an intra-articular medication is to be administered, the aspiration syringe may be exchanged for the medication syringe while maintaining sterile needle position.

The medication should enter the joint with minimal resistance when the needle is correctly positioned.

Marked resistance should prompt reassessment of needle position rather than forceful injection.

Technical Pearls

Wide Sterile Preparation

Preparing a large area allows the examiner to manipulate the patella or reposition the knee without contaminating the sterile field.

Large-Bore Needle

Synovium, fibrin, or clotted blood may obstruct a smaller needle.

An 18-gauge needle is often useful when aspirating thick fluid or hemarthrosis.

Local Anesthesia

Pain at the puncture site can be reduced with:

A small amount of infiltrated lidocaine or a topical vapocoolant such as ethyl chloride.

Ultrasound Guidance

Ultrasound can improve confidence in needle placement and may be especially helpful in:

Obese patients, small or loculated effusions, distorted anatomy, or previously unsuccessful aspiration attempts.

It also allows visualization of the effusion and surrounding soft tissues.

Contraindication: Overlying Cellulitis

A knee should not be aspirated or injected through infected or cellulitic skin because the needle may introduce organisms into the joint.

An alternative entry site or another diagnostic strategy should be used.

Medications

Lidocaine

Lidocaine may be used as a local or intra-articular anesthetic.

Diagnostic anesthetic injection can temporarily decrease pain and permit a more complete knee examination.

Lidocaine may also be combined with corticosteroid to reduce injection discomfort.

Bupivacaine

Bupivacaine provides a longer duration of local anesthesia than lidocaine.

However, concerns exist regarding dose-dependent chondrotoxicity, particularly with prolonged or continuous intra-articular exposure.

For this reason, intra-articular local anesthetics should be used judiciously.

Corticosteroid

Intra-articular corticosteroid may provide temporary relief of inflammatory knee pain.

It is essential to exclude joint infection before administration.

Typical Preparation

A commonly used preparation is triamcinolone acetonide, historically given as approximately:

40 mg, or 1 mL of a 40 mg/mL preparation, depending on the indication and clinical protocol.

It may be combined with a small amount of local anesthetic.

Corticosteroid Adverse Effects

The most common short-term adverse event is a post-injection flare, consisting of temporary worsening of pain and inflammation after the procedure.

Patients should be warned about this possibility.

Other potential complications include:

Skin depigmentation, subcutaneous fat atrophy, transient hyperglycemia, infection, and, with repeated exposure, concern for cartilage effects.

Hyaluronic Acid

Hyaluronic acid injections have been used for symptomatic treatment of mild to moderate knee osteoarthritis.

Potential benefits include:

Reduction in pain, decreased stiffness, and improvement in function in selected patients.

The magnitude and consistency of benefit vary among patients and products.

Administration

Hyaluronic acid may be given as:

A single injection or as a series of injections, depending on the preparation used.

Complications

Potential complications of knee aspiration or injection include:

Pain, bleeding, hemarthrosis, infection, vasovagal reaction, damage to adjacent structures, post-injection flare, and failure to enter the joint.

Sterile technique and careful anatomic localization reduce these risks.

Patient Monitoring

After injection or aspiration, the patient should be instructed to monitor for:

Increasing pain, progressive swelling, erythema, fever, drainage, or inability to bear weight.

These findings may indicate infection or another significant complication and warrant prompt reassessment.

Patients receiving therapeutic injections should also be counseled regarding the expected duration of symptom relief and the need for further evaluation if symptoms persist or recur.

Orthopaedic Surgery - Knee Examination in the Child

Basics

Examination of the pediatric knee must take the child’s age, stage of skeletal development, normal alignment changes, and age-specific disorders into account.

The differential diagnosis differs considerably between infants, young children, and adolescents. Normal developmental variants must be distinguished from pathologic deformities, infection, trauma, inflammatory disease, and tumors.

Because pain from the hip frequently presents as knee pain, evaluation of the pediatric knee should routinely include assessment of the hip and entire lower extremity.

Congenital Hyperextension and Dislocation of the Knee

Congenital knee hyperextension represents a spectrum ranging from simple hyperextension to fixed anterior dislocation of the tibia relative to the femur.

The deformity is evident at birth.

A flexible hyperextended knee may resolve spontaneously or respond to gentle conservative treatment, whereas a fixed congenital knee dislocation often requires more intensive treatment and occasionally surgery.

Blount Disease

Blount disease, or tibia vara, results from abnormal development of the medial proximal tibial physis, producing progressive bowing of the lower extremity.

It occurs in infantile and adolescent forms.

Normal Varus-Valgus Development

Normal coronal alignment changes with growth.

At birth, children normally have approximately 10–15° of genu varum.

By approximately 12–18 months, the legs become nearly neutral.

Between approximately 3 and 5 years, physiologic valgus reaches its maximum, often around 10–15°.

During later childhood and early adolescence, valgus gradually decreases toward the adult range of approximately 5–10°.

Persistent or progressive deformity outside this expected pattern should be investigated.

Infantile Tibia Vara

Infantile Blount disease usually presents between approximately 2 and 4 years of age.

The child commonly has painless, progressive bowing of the legs.

Adolescent Tibia Vara

Adolescent Blount disease usually becomes apparent after approximately 9–10 years of age.

It is increasingly associated with obesity and mechanical overload of the proximal tibial growth plate.

Discoid Meniscus

A discoid meniscus is a congenital abnormality in which the meniscus, usually the lateral meniscus, remains abnormally broad and disc-shaped.

This morphology makes it more susceptible to:

Tearing, instability, snapping, pain, and mechanical symptoms.

Septic Arthritis of the Knee

Septic arthritis is a pyogenic infection of the knee joint.

Approximately two-thirds of pediatric cases historically occur before 3 years of age.

Affected children typically appear acutely ill and may present with:

Fever, joint swelling, severe pain, restricted motion, and refusal to bear weight.

Popliteal Cyst

A popliteal or Baker cyst arises from the posterior aspect of the knee.

In children, it commonly presents as:

An asymptomatic or minimally painful posteromedial mass at the popliteal crease.

Tibial Spine Fracture

A tibial spine fracture is an avulsion fracture involving the tibial insertion of the ACL.

It commonly occurs after:

Bicycle falls, sporting injuries, or other indirect twisting trauma.

In skeletally immature patients, the tibial spine may fail before the ACL itself ruptures.

Genu Valgum

Physiologic genu valgum normally decreases after early childhood.

Valgus deformity that becomes progressively greater after approximately 7 years of age should not be considered physiologic.

Significant deformity may be associated with knee pain and abnormal mechanical loading.

Juvenile Idiopathic Arthritis

Juvenile idiopathic arthritis may involve the knee and produce:

Persistent swelling, warmth, stiffness, synovitis, reduced motion, and sometimes pain.

Substantial effusion may be present despite relatively mild discomfort.

Osgood–Schlatter Disease

Osgood–Schlatter disease is a traction apophysitis of the tibial tubercle.

It occurs most commonly during rapid skeletal growth, usually between approximately 9 and 14 years of age.

Typical symptoms include:

Pain and tenderness over the tibial tubercle, aggravated by running, jumping, kneeling, and resisted knee extension.

Osteochondritis Dissecans

Osteochondritis dissecans is an osteochondral disorder in which a segment of subchondral bone and its overlying cartilage becomes abnormal.

The precise cause is uncertain.

The classic juvenile lesion occurs along the lateral aspect of the medial femoral condyle.

Iliotibial Band Syndrome

Iliotibial band syndrome is a common cause of lateral knee pain in athletes.

It is an overuse condition related to repetitive irritation of the iliotibial band near the lateral femoral epicondyle.

Pain is usually aggravated by running, cycling, or repetitive flexion and extension.

ACL Injury

ACL injuries occur through two broad mechanisms.

Younger children may sustain injury after direct trauma, whereas older children and adolescents more commonly experience:

Twisting, pivoting, or other indirect noncontact mechanisms.

Lyme Disease

Early Lyme disease may present with:

Fever and migratory arthralgia, often with little or no joint swelling.

Lyme Arthritis

Late Lyme arthritis may occur months or years after the initial infection.

The knee is commonly affected and may demonstrate:

A large but relatively painless effusion with low-grade inflammatory synovitis.

Slipped Capital Femoral Epiphysis

SCFE is an important cause of referred knee pain.

It typically affects an overweight child or adolescent, often between approximately 6 and 14 years of age.

Because knee pain may be the principal complaint, SCFE can be missed if the hip is not examined.

Unexplained knee pain associated with limp or limited hip rotation should therefore prompt hip examination and appropriate hip radiographs.

Diagnosis

History

The history should characterize:

Onset, duration, pain location, trauma, activity relationship, swelling, mechanical symptoms, instability, constitutional symptoms, and night pain.

Acute Pain

Acute pediatric knee pain may result from:

Ligament injury, meniscal tear, fracture, patellar instability, or septic arthritis.

Chronic Pain

Chronic or recurrent symptoms may occur with:

Genu valgum, juvenile idiopathic arthritis, Osgood–Schlatter disease, Sinding-Larsen–Johansson syndrome, osteochondritis dissecans, iliotibial band syndrome, Lyme disease, tendinopathy, or neoplasm.

Pain Location

The location of pain provides useful diagnostic information.

Anterior Knee Pain

Possible causes include:

Patellofemoral pain syndrome, patellar maltracking, symptomatic plica, and symptomatic bipartite patella.

Lateral Knee Pain

Pain over the lateral femoral epicondyle, particularly in an athlete, is suggestive of:

Iliotibial band syndrome.

Tibial Tubercle Pain

Pain localized to the tibial tubercle is typical of:

Osgood–Schlatter disease.

Inferior Patellar Pain

Pain at the inferior pole of the patella may represent:

Sinding-Larsen–Johansson syndrome.

Night Pain

Persistent or progressive night pain should raise concern for serious pathology, including:

Osteosarcoma, Ewing sarcoma, infection, or another neoplasm.

Swelling

Acute Swelling

Acute effusion may accompany:

Ligament tears, meniscal injuries, fractures, patellar dislocation, or septic arthritis.

Chronic Swelling

Persistent swelling may be associated with:

Juvenile idiopathic arthritis, Lyme arthritis, chronic synovitis, osteochondral disease, or neoplasm.

Mechanical Symptoms

Catching or Locking

These symptoms suggest:

Meniscal tearing, articular cartilage injury, or loose bodies, including fragments associated with osteochondritis dissecans.

Giving Way

A sensation that the knee is buckling or coming apart may indicate significant ligamentous instability.

Physical Examination

General Principles

The entire lower extremity should be exposed sufficiently to evaluate:

Alignment, swelling, muscle bulk, deformity, and gait.

When palpating, begin with the normal knee for comparison and to help relax the child.

Nonpainful examination maneuvers should be performed before potentially painful tests.

Inspection

Anterior View

Assess for:

Genu varum, genu valgum, effusion, patellar position, swelling, and muscular asymmetry.

In adolescence, normal standing alignment usually demonstrates mild valgus of approximately 5–10°.

Lateral View

Look for:

Flexion contracture, inability to reach full extension, or excessive hyperextension such as genu recurvatum.

Tibial Tuberosities

Compare the position and prominence of the tibial tubercles.

Asymmetry may suggest rotational deformity or developmental abnormality.

Palpation

Assess for warmth and tenderness along the:

Medial and lateral joint lines, MCL, LCL, patella, quadriceps tendon, patellar tendon, femoral condyles, tibial condyles, and tibial tubercle.

Localized tenderness should be correlated with the underlying anatomy.

Hip Examination

Because hip disorders may present entirely as knee pain, hip range of motion should be evaluated in every child with unexplained knee symptoms.

Assess:

Flexion, extension, abduction, internal rotation, and external rotation.

Restricted internal rotation or obligatory external rotation during flexion should raise concern for hip pathology such as SCFE.

Assessment for Knee Effusion

A large effusion obscures the normal contours of the knee and may make the patella ballotable.

Large effusions can occur with:

Hemarthrosis, septic arthritis, inflammatory arthritis, and synovitis.

A smaller effusion may cause only subtle loss of normal landmarks.

Blot and milking tests can help identify low-volume joint fluid.

Patellar Examination

Patellar Inhibition Test

This test assesses whether anterior knee pain is arising from the patellofemoral articulation.

With the patient supine and the knee extended, ask the child to perform a straight-leg raise while the examiner restricts superior movement of the patella.

Reproduction of anterior knee pain suggests patellofemoral pathology.

J Sign

The J sign evaluates patellar tracking.

Observe the patella while the patient actively extends the knee.

Normally, the patella tracks within the femoral trochlea.

A positive J sign occurs when the patella moves abruptly laterally near terminal extension, producing an upside-down J-shaped path.

This finding suggests:

Lateral patellar maltracking or instability.

Meniscal Examination

McMurray Test

The McMurray test is used to evaluate meniscal tears.

Medial Meniscus

Flex the hip and knee maximally.

Externally rotate the tibia and apply a valgus force while gradually extending the knee.

A painful palpable click or snap along the medial joint line suggests medial meniscal injury.

Lateral Meniscus

Flex the knee, internally rotate the tibia, and apply a varus force while extending the knee.

A painful click along the lateral joint line suggests lateral meniscal pathology.

Range of Motion

Flexion

Normal knee flexion is approximately 130–140°.

The patient can be examined sitting, supine, or prone.

Extension

Children commonly reach neutral extension and may demonstrate approximately 5° of physiologic hyperextension.

Comparison with the opposite knee is important.

Ober Test

The Ober test evaluates iliotibial band flexibility.

Technique

The patient lies on the unaffected side.

The pelvis is stabilized while the symptomatic hip is abducted and extended with the knee flexed.

The examiner then allows the thigh to fall into adduction.

Positive Test

If the thigh remains elevated and does not fall toward the examination table, the test suggests iliotibial band tightness.

This may support a diagnosis of iliotibial band syndrome.

Stability Testing

Anterior-posterior stability is provided predominantly by the:

ACL and PCL.

Mediolateral stability is provided primarily by the:

MCL and LCL.

ACL

The ACL is evaluated with:

Lachman and anterior drawer tests.

PCL

The PCL is evaluated with:

Posterior drawer and posterior sag tests.

Collateral Ligaments

Varus and valgus stress testing assesses the:

LCL and MCL, respectively.

Pediatric ligamentous laxity varies, so comparison with the opposite knee is especially useful.

Neurovascular Examination

A neurovascular examination is particularly important after acute injury.

Sensory Testing

Test sensation in the distributions of the:

Common peroneal, superficial peroneal, deep peroneal, and tibial nerves.

Motor Testing

Apply resistance while the patient:

Dorsiflexes and plantarflexes the ankle, inverts and everts the foot, and extends and flexes the great toe.

Pulses

Palpate the:

Popliteal, dorsalis pedis, and posterior tibial pulses.

Capillary refill and limb temperature should also be assessed if vascular injury is a concern.

Imaging

Standard Knee Radiographs

Common views include:

AP, lateral, tunnel, and patellofemoral axial views.

The specific views obtained should be tailored to the suspected diagnosis.

Skyline / Merchant View

The skyline or Merchant view is an axial image of the patellofemoral joint, usually obtained with approximately 35–45° of knee flexion.

It helps evaluate:

Patellar position, trochlear morphology, patellofemoral congruence, and osteochondral abnormalities.

Tunnel View

A flexed-knee AP or tunnel view is particularly helpful for identifying:

Osteochondritis dissecans lesions of the femoral condyles.

Standing Long-Leg Radiographs

A standing radiograph extending from the:

Hips through the knees to the ankles

is used to evaluate the mechanical axis and coronal alignment.

This is particularly useful for:

Blount disease and genu valgum.

MRI

MRI is the most useful advanced imaging modality for:

Meniscal tears, ligament injury, articular cartilage pathology, osteochondral lesions, and soft-tissue masses.

Congenital Knee Dislocation Imaging

Plain radiographs help distinguish:

Flexible hyperextension from fixed anterior tibial dislocation relative to the distal femur.

Blount Disease and Genu Valgum Imaging

The preferred study is an:

AP standing long-cassette radiograph of both lower extremities including the hips, knees, and ankles.

This demonstrates:

Mechanical-axis deviation, proximal tibial deformity, and abnormalities in joint orientation.

Discoid Meniscus Imaging

MRI is the most useful examination.

It can define:

Meniscal shape, thickness, tearing, and instability.

Plain radiographs may occasionally show:

Widening of the lateral joint space or squaring of the lateral femoral condyle.

Septic Arthritis Imaging

Early plain radiographs are often nonspecific and may show only:

Soft-tissue swelling or apparent joint-space widening caused by effusion.

Ultrasound may demonstrate an effusion and can guide aspiration.

MRI is useful when adjacent osteomyelitis or deeper infection is suspected.

Popliteal Cyst Imaging

Plain radiographs are generally normal and are usually needed only when pain or another diagnosis requires exclusion.

Ultrasound

Ultrasound can confirm the fluid-filled nature of the cyst and distinguish it from a solid soft-tissue mass.

MRI

MRI may be obtained when ultrasound findings are atypical or the lesion does not appear to be a simple homogeneous cyst.

Tibial Spine Fracture Imaging

AP and lateral radiographs are essential.

The lateral view is particularly useful for assessing the degree of displacement of the tibial spine fragment.

Juvenile Idiopathic Arthritis Imaging

Radiographs may remain normal early in the disease.

With progression, findings can include:

Periarticular osteopenia, soft-tissue swelling, synovial hypertrophy, effusion, and eventually joint-space loss or erosive changes.

Osgood–Schlatter Disease

Diagnosis is usually clinical.

Radiographs may demonstrate:

Irregularity, fragmentation, or prominence of the tibial tubercle apophysis.

Routine radiographs may be unnecessary in a typical bilateral presentation.

Unilateral, atypical, or severe symptoms should prompt imaging to exclude:

Neoplasm, infection, or fracture.

Sinding-Larsen–Johansson Syndrome

Radiographs may demonstrate irregularity or ossification at the inferior pole of the patella.

Diagnosis is primarily clinical.

Osteochondritis Dissecans Imaging

Plain radiographs may show:

A subchondral bone fragment separated from adjacent bone by a radiolucent line.

The classic lesion occurs along the lateral aspect of the medial femoral condyle, commonly involving its posterior portion.

Recommended views include:

AP, lateral, and tunnel radiographs.

MRI

MRI helps determine:

Lesion size, cartilage involvement, stability, and surrounding bone changes.

Iliotibial Band Syndrome Imaging

Routine radiographs are generally unnecessary because the diagnosis is usually based on history and examination.

Imaging is reserved for atypical cases or when another diagnosis is suspected.

ACL Injury Imaging

ACL injury is diagnosed primarily by physical examination.

Plain radiographs should nevertheless be obtained in children with significant suspected ligament trauma because they may reveal:

Tibial spine avulsion, fracture, osteochondral injury, or physeal injury.

MRI

MRI is useful when:

The examination is difficult to interpret, effusion persists, motion does not recover, or associated meniscal, ligamentous, or cartilage injuries require definition.

Patella Alta

Patellar position is best evaluated on a lateral radiograph with the knee flexed approximately 30°.

Insall–Salvati Ratio

The Insall–Salvati ratio compares:

Patellar tendon length with the greatest diagonal length of the patella.

A value near 1.0 is typical.

A deviation of more than approximately 20% may suggest:

Patella alta or patella baja.

Lyme Disease Imaging and Testing

Plain radiographs are generally nonspecific and mainly help exclude other causes of knee swelling.

Diagnosis of Lyme arthritis relies primarily on:

Clinical findings, appropriate exposure history, and positive serologic testing.

Important Clinical Principle

Pediatric knee symptoms should always be interpreted in relation to the child’s:

Age, skeletal maturity, alignment, activity level, gait, hip examination, pain location, swelling, and systemic symptoms.

Particularly important diagnoses not to miss include:

Septic arthritis, SCFE presenting as knee pain, malignancy, osteomyelitis, unstable osteochondral lesions, and major ligament or physeal injury.