Orthopaedic Surgery - Perthes Disease

Basics

Perthes disease, also known as Legg–Calvé–Perthes disease, is a self-limited childhood disorder characterized by temporary interruption of the blood supply to the developing femoral head.

The resulting ischemic injury produces a sequence of:

Femoral head necrosis

Bone resorption

Fragmentation

Reossification

and ultimately

Healing and remodeling.

Although many children recover with a functional hip, severe disease can result in:

Femoral head collapse

Loss of sphericity

Hip incongruity

and later

Degenerative osteoarthritis.

Synonyms

Other names include:

Legg–Calvé–Perthes disease

and the historical term:

Osteochondritis deformans juvenilis.

Natural History

The disease progresses through several stages:

Ischemia or necrosis

Fragmentation and resorption

Reossification or repair

Healed/remodeled stage

The ultimate prognosis depends on how well the femoral head maintains or regains:

Sphericity

Containment

and

Congruence with the acetabulum.

Long-Term Degeneration

Residual femoral head deformity may lead to:

Femoroacetabular impingement

Loss of motion

Secondary osteoarthritis

and, in some patients,

Total hip arthroplasty later in life.

Historical long-term series have reported disabling arthritis in a substantial proportion of severely affected patients by middle or later adulthood.

Classification

Several radiographic classification systems are used to describe:

Extent of femoral head involvement

Stage of disease

and

Final shape after healing.

Lateral Pillar Classification

The Herring lateral pillar classification assesses preservation of the lateral portion of the femoral head during the fragmentation stage.

Group A

There is:

Essentially preserved height of the lateral pillar, with little or no collapse.

These lesions generally have the best prognosis.

Group B

More than approximately:

50% of lateral pillar height is maintained.

Group C

Less than approximately:

50% of lateral pillar height remains.

These lesions generally carry a less favorable prognosis.

A borderline B/C group is also recognized in modern use for hips that lie between classic B and C categories.

Modified Waldenström Classification

The modified Waldenström system describes:

The timing and stage of the disease process.

The stages include:

Initial stage

Fragmentation stage

Reossification or healing stage

Healed stage

Some modifications subdivide early stages according to:

Minimal versus greater flattening

and

Early versus advanced fragmentation.

Stulberg Classification

The Stulberg classification evaluates the:

Shape and congruence of the healed hip at skeletal maturity

and helps estimate the risk of later degenerative arthritis.

Stulberg Class I

Normal spherical femoral head and congruent hip.

Stulberg Class II

The femoral head remains:

Spherical

but may have abnormalities such as:

Shortened femoral neck

Coxa magna

or altered acetabular morphology.

Stulberg Class III

The femoral head is:

Nonspherical but not completely flat, often ovoid or mushroom-shaped.

Stulberg Class IV

The femoral head is:

Flat but remains relatively congruent with the acetabulum.

Stulberg Class V

The femoral head is:

Flat and incongruent with the acetabulum.

This carries the greatest risk of early degenerative change.

Epidemiology

Perthes disease most commonly affects children between:

4 and 10 years of age.

Cases have been reported from approximately:

2 years of age through adolescence.

Sex

Boys are affected approximately:

4–5 times more often than girls.

When girls develop the disease, the clinical course may sometimes be more severe because they often present at a later skeletal age.

Ethnicity

Historically, Perthes disease has been reported more commonly in:

White populations

and some

Asian populations

than in African-American and Native American populations.

Bilateral Disease

Approximately:

10% of patients

have bilateral involvement.

Bilateral disease is usually:

Asynchronous, with one hip affected before the other.

Symmetric Bilateral Disease

Simultaneous and symmetric epiphyseal abnormalities should raise suspicion for a systemic skeletal disorder rather than classic Perthes disease.

Examples include:

Hypothyroidism

Multiple epiphyseal dysplasia

Spondyloepiphyseal dysplasia

Incidence

Perthes disease is uncommon and affects substantially less than:

1% of children.

Reported incidence varies considerably by geographic and ethnic population.

Risk Factors

Reported associations include:

Small stature

Low birth weight in some populations

Older parental age

Urban residence

Certain ethnic backgrounds

Exposure to tobacco smoke in some studies

These associations do not establish a direct cause.

Genetics

A positive family history has been reported in approximately:

2–10% of cases.

No single inheritance pattern explains most cases.

Etiology

The exact cause remains unknown.

The central mechanism is believed to involve:

Temporary disruption of the blood supply to the femoral head.

Proposed Vascular Mechanisms

Potential contributors include:

Repeated vascular interruption

Venous hypertension or obstruction

Abnormal coagulation

Minor trauma

Anatomic vulnerability of the developing femoral head circulation

Hypercoagulability

Abnormal coagulation has been investigated as a possible contributor in selected patients.

Routine thrombophilia testing is not required in every child, but it may be considered when the presentation is:

Atypical

or associated with other thrombotic risk factors.

Trauma

Minor trauma may draw attention to symptoms or theoretically contribute to vascular compromise, but most cases are not explained by a single injury.

Associated Conditions

Children with Perthes disease may demonstrate:

Mild short stature

or delayed skeletal maturation.

Diagnosis

Diagnosis is based primarily on:

History

Physical examination

and

Plain radiographs.

Signs and Symptoms

The typical presentation is:

An insidious limp with little or only mild pain.

Limp

The limp is often the earliest and most noticeable symptom.

The child may demonstrate:

Shortened stance phase

Quick steps

or

Trunk lean over the affected side.

Trendelenburg-Type Gait

Weakness and altered hip mechanics may produce a:

Trendelenburg gait

with lateral trunk shift over the involved limb.

Pain

Pain may be:

Absent

or

Mild and activity related.

It typically improves with:

Rest.

Pain Location

Pain may be felt in the:

Groin

Anterior or medial thigh

or

Knee.

Referred knee pain can delay diagnosis if the hip is not examined.

Range of Motion

The earliest characteristic limitations are usually:

Hip abduction

and

Internal rotation.

Chronic Findings

With prolonged disease, the patient may develop:

Thigh atrophy

Calf atrophy

Gluteal atrophy

Leg-length discrepancy

History

Important questions include:

When did the limp begin?

Is there hip, thigh, or knee pain?

Is pain worse with activity?

Is there a history of trauma?

Have symptoms been progressive?

Physical Examination

Gait

Observe the child walking for:

Antalgic gait

Trendelenburg pattern

Shortened stance phase

Trunk shift

Hip Motion

Compare both hips for:

Internal rotation

External rotation

Abduction

Flexion

Restriction of:

Abduction and internal rotation

is particularly typical.

Pelvic Stabilization

When measuring abduction, stabilize the pelvis to prevent:

Pelvic tilt from falsely increasing apparent hip motion.

Muscle Bulk

Compare the thighs, calves, and buttocks for:

Atrophy or asymmetry.

Leg Length

Later disease may produce:

Apparent or true shortening of the affected limb

because of femoral head collapse and neck shortening.

Laboratory Tests

There is no diagnostic laboratory test for Perthes disease.

Laboratory studies may be ordered when another condition is suspected, such as:

Septic arthritis

Inflammatory disease

Endocrine disorder

Sickle cell disease

Imaging

Plain Radiographs

Radiographs are the most important routine imaging study.

Typical views include:

AP pelvis

and

Frog-leg lateral views, when clinically appropriate.

Initial Phase

Early findings may include:

Smaller appearance of the affected epiphysis

Widening of the medial joint space

Increased density of the femoral head

Physeal irregularity

Subchondral radiolucency

Crescent Sign

A subchondral radiolucent line may represent:

Subchondral fracture

and is sometimes called the:

Crescent sign.

Fragmentation Phase

During fragmentation:

Necrotic bone is resorbed

and the epiphysis develops:

Mixed areas of lucency and sclerosis

Fragmentation

Loss of height

Possible lateral extrusion

Reparative Phase

During reossification:

New bone density gradually returns.

The final shape of the:

Femoral head

and

Femoral neck

becomes increasingly apparent.

Healed Phase

Once healing is complete, residual deformity may include:

Coxa magna

Coxa breva

Short femoral neck

Flattened femoral head

Trochanteric overgrowth

Acetabular dysplasia

Head-at-Risk Signs

Classic radiographic findings associated with a less favorable prognosis include:

Gage sign

Lateral calcification

Lateral subluxation or extrusion of the femoral head

Horizontal physis

Gage Sign

The Gage sign is a:

V-shaped radiolucency along the lateral epiphysis.

It reflects significant lateral femoral head involvement.

MRI

MRI can detect:

Femoral head ischemia and marrow abnormalities

before radiographic changes are fully developed.

However, routine MRI is not always necessary when the diagnosis and stage are clear on plain radiographs.

Perfusion MRI

Contrast-enhanced perfusion MRI is increasingly used in specialized centers to evaluate:

Early femoral head perfusion

and may help estimate:

Prognosis

and

Potential response to containment procedures.

Arthrography

Hip arthrography can help assess:

Femoral head shape

Containability

Hip congruence

It may be particularly useful before surgery when plain radiographs do not fully define the relationship between the femoral head and acetabulum.

Pathological Findings

The underlying process is:

Ischemic necrosis of the femoral epiphysis.

Growth Plate

The physis may demonstrate:

Structural clefts and irregularities.

Bone Resorption

During fragmentation, resorption of necrotic bone may exceed new bone formation.

This temporarily weakens the femoral head and predisposes to:

Collapse and deformation.

Cartilage Changes

Cartilage may remain relatively viable even when underlying bone is necrotic.

Clusters of cartilage may extend toward the:

Metaphysis.

Differential Diagnosis

Important alternatives include:

Transient synovitis

Septic arthritis

Slipped capital femoral epiphysis

Juvenile idiopathic arthritis

Hypothyroidism

Multiple epiphyseal dysplasia

Spondyloepiphyseal dysplasia

Sickle cell disease

Gaucher disease

Glycogen storage disease

Osteoid osteoma

Pigmented villonodular synovitis

Steroid-associated osteonecrosis

Traumatic osteonecrosis

Tuberculous arthritis

Tumor

Fracture

Transient Synovitis

Transient synovitis may present with:

Limp

Hip pain

Reduced motion

but usually resolves over a much shorter period and does not produce progressive epiphyseal changes.

Septic Arthritis

Septic arthritis should be considered when there is:

Fever

Acute severe pain

Marked restriction of motion

Elevated inflammatory markers

This is an urgent diagnosis.

Slipped Capital Femoral Epiphysis

SCFE generally occurs in:

Older, often overweight adolescents

and produces characteristic displacement of the proximal femoral epiphysis rather than the ischemic fragmentation seen in Perthes disease.

Treatment

General Principles

The goals of treatment are to:

Maintain hip motion

Keep the femoral head contained within the acetabulum

Minimize collapse

Promote remodeling toward a spherical, congruent hip

Containment

Containment means maintaining the femoral head deeply seated within the acetabulum so that the acetabulum acts as a:

Mold during healing and remodeling.

Determining Containability

Containment is assessed using:

Plain radiographs

and, in selected cases,

Arthrography.

The hip is generally best contained in:

Abduction, provided the femoral head remains congruent.

Range of Motion

Preservation or restoration of:

Abduction

and

Internal rotation

is critical.

A stiff hip is difficult to contain and is associated with a worse prognosis.

Nonoperative Treatment

Many younger children can be managed with:

Observation

Activity modification

Physical therapy

Temporary protected weight bearing

provided the femoral head remains adequately contained.

Bracing and Casting

Historically, abduction braces and casts were used extensively to maintain containment.

They may still be used selectively, although prolonged bracing is less common in modern management than in older protocols.

Weight Bearing

If weight bearing causes significant pain, the child may use:

Crutches

or another method of protected ambulation.

Stiffness

If substantial stiffness develops, activity should be reduced and motion restored before further containment treatment is considered.

Physical Therapy

Physical therapy is useful for maintaining:

Hip range of motion

with particular emphasis on:

Abduction

and

Internal rotation.

Medication

Pain may be treated with age-appropriate doses of:

Acetaminophen

or

NSAIDs.

Surgery

Surgery is reserved for children whose age, stage, and degree of femoral head involvement suggest a significant risk of poor outcome without operative containment.

Age and Surgery

Children younger than approximately:

6 years

usually have excellent remodeling potential and often do not require surgery unless there is substantial:

Extrusion, loss of containment, or severe disease.

Older Children

Children presenting after approximately:

6–8 years of age

with extensive femoral head involvement are more likely to benefit from containment surgery.

Timing

Containment surgery is most effective before:

Advanced fragmentation and irreversible femoral head deformation.

Femoral Osteotomy

A proximal femoral varus osteotomy can position the femoral head:

More deeply within the acetabulum.

Internal fixation is used to maintain the correction while healing occurs.

Pelvic Osteotomy

A pelvic osteotomy may increase:

Acetabular coverage of the femoral head.

Procedures are selected according to:

Age

Hip anatomy

Containability

Surgeon preference

Combined Procedures

In selected severe cases, both:

Femoral

and

Pelvic osteotomy

may be used to improve containment.

Salvage Procedures

When the femoral head is no longer containable or major deformity has already developed, salvage procedures may be considered to:

Reduce pain

Improve motion

Correct impingement

Address leg-length discrepancy

Implant Removal

Internal fixation may be removed after osteotomy healing when appropriate, particularly in children who may require future reconstructive procedures.

Adult Reconstruction

Patients who later develop severe secondary osteoarthritis may ultimately require:

Total hip arthroplasty.

Follow-Up

All children with Perthes disease should be monitored by:

An orthopaedic surgeon, preferably one experienced in pediatric hip disorders.

Prognosis

The most important prognostic factor is:

Age at onset or healing.

Younger children have greater potential for:

Femoral head remodeling.

Children Younger Than 6 Years

Poor outcomes are relatively uncommon when onset occurs before approximately:

6 years of age, especially when disease involvement is limited.

Older Children

A less favorable prognosis is associated with presentation at:

8 years of age or older.

Other Poor Prognostic Factors

Additional unfavorable features include:

Extensive lateral pillar involvement

Poor hip range of motion

Femoral head extrusion

Loss of containment

Nonspherical healing

Hip incongruity

Symptoms After Healing

Many children become:

Pain-free during adolescence

after the active disease has healed.

However, residual deformity may later produce:

Impingement

Labral pathology

Degenerative arthritis

Long-Term Arthritis

Severe residual deformity substantially increases the risk of:

Premature hip osteoarthritis.

Some historical cohorts have reported eventual total hip replacement in a large proportion of severely affected patients by:

Middle or later adulthood.

Complications

Femoral Head Collapse

Loss of structural support during fragmentation may lead to:

Flattening and loss of sphericity.

Coxa Magna

The healed femoral head may become:

Enlarged and deformed.

Coxa Breva

Femoral neck growth disturbance may result in:

A shortened femoral neck.

Trochanteric Overgrowth

Relative overgrowth of the greater trochanter may impair:

Abductor mechanics

and contribute to:

Trendelenburg gait.

Leg-Length Discrepancy

Femoral neck shortening and growth disturbance can produce:

Limb shortening.

Loss of Motion

Patients may develop:

Flexion contracture

Adduction contracture

Reduced abduction

Reduced internal rotation

Degenerative Joint Disease

Residual incongruity can lead to:

Early osteoarthritis

and chronic adult hip pain.

Patient Monitoring

During the active disease phase, patients are commonly reviewed approximately every:

4–8 weeks, depending on severity and treatment.

Range-of-Motion Monitoring

Children using braces or casts should be periodically examined out of the device to assess:

Abduction

Internal rotation

Hip stiffness

Radiographic Monitoring

Serial radiographs are used to follow:

Fragmentation

Containment

Reossification

Femoral head shape

Duration of Containment

Historical brace or cast containment often continued for approximately:

6–18 months

or until sufficient reossification occurred and the risk of further collapse decreased.

Modern duration is individualized.

Follow-Up to Maturity

Patients with significant disease should continue follow-up through:

Skeletal maturity

to assess final hip shape, congruity, limb length, and function.

Key Principle

Perthes disease is a childhood ischemic disorder of the femoral head that progresses through necrosis, fragmentation, reossification, and healing.

The central treatment goals are:

Maintaining hip motion and preserving containment of the femoral head within the acetabulum while remodeling occurs.

The strongest predictors of outcome are:

Age at onset, extent of lateral pillar involvement, hip range of motion, and final femoral head congruity.