Orthopaedic Surgery - Osteoarthritis

Basics

Osteoarthritis is the most common form of arthritis and may affect nearly any synovial joint.

It is a chronic degenerative joint disorder characterized by progressive loss of articular cartilage, accompanied by secondary changes in the subchondral bone.

Typical structural changes include:

Joint-space narrowing

Osteophyte formation

Subchondral sclerosis

Subchondral cyst formation

The disease may involve a single joint or multiple joints.

There is currently no definitive cure, and advanced disease can result in substantial:

Pain

Stiffness

Deformity

Loss of function

Synonyms

Osteoarthritis is also called:

Degenerative joint disease

Degenerative arthritis

Wear-and-tear arthritis

The term “wear-and-tear” is commonly used but is an oversimplification because osteoarthritis results from complex mechanical, biologic, genetic, and inflammatory processes.

Classification

Osteoarthritis can be classified according to:

Number of joints involved

and

Underlying cause.

Primary Osteoarthritis

Primary osteoarthritis develops without a single identifiable precipitating disorder.

It commonly affects joints such as:

Knees

Hips

Hands

Spine

Secondary Osteoarthritis

Secondary osteoarthritis occurs after a known process has damaged the joint.

Examples include:

Trauma

Septic arthritis

Avascular necrosis

Congenital or developmental deformity

Inflammatory disease

Epidemiology

Osteoarthritis becomes increasingly common with age.

It is especially prevalent in adults older than approximately 60 years.

Commonly Affected Joints

The knee is among the most commonly affected major weight-bearing joints.

Other frequently affected sites include:

Hands

Hips

Spine

First metatarsophalangeal joint

Historical Prevalence Data

In one older study of women older than 65 years:

Knee osteoarthritis was identified in approximately 30%

Hand osteoarthritis in approximately 15%

Hip osteoarthritis in approximately 8%

Another study found hand osteoarthritis in approximately 23% of women older than 65 years.

Hand Osteoarthritis

The hand joints most commonly involved include:

Distal interphalangeal joints

and

First carpometacarpal joint of the thumb.

Sex Distribution

Osteoarthritis occurs more frequently in women than men, particularly after middle age.

Risk Factors

Important risk factors include:

Advancing age

Obesity

Female sex

Previous joint injury

Avascular necrosis

Previous septic arthritis

Malalignment

Repetitive joint loading

Obesity

Obesity substantially increases loading across weight-bearing joints, especially the:

Knees

and may accelerate symptom development and structural progression.

Metabolic factors may also contribute.

Previous Joint Injury

Prior trauma may damage:

Articular cartilage

Menisci

Ligaments

Subchondral bone

and increase the risk of later post-traumatic osteoarthritis.

Genetics

Osteoarthritis has a significant genetic component.

Susceptibility is polygenic, meaning that multiple genes interact with:

Age

Mechanical loading

Body weight

Joint anatomy

Environmental factors

to influence disease development.

Etiology

The exact cause of primary osteoarthritis is multifactorial.

The final common pathway involves:

Progressive cartilage degeneration

with increasing mechanical stress on the remaining joint surfaces.

Cartilage Degeneration

As cartilage deteriorates:

Proteoglycan content decreases

Collagen architecture becomes disrupted

Cartilage softens and fibrillates

Cartilage thickness progressively decreases

Eventually, areas of subchondral bone may become exposed.

Secondary Bone Changes

Abnormal load transmission produces characteristic osseous responses, including:

Subchondral sclerosis

Osteophytes

Subchondral cysts

Remodeling and deformity

Secondary Osteoarthritis

Any process that significantly damages the articular surface can produce secondary osteoarthritis.

Post-Traumatic Arthritis

Fractures involving the joint surface, ligament instability, or meniscal injury may result in:

Abnormal contact forces and progressive cartilage deterioration.

Postinfectious Arthritis

Septic arthritis may rapidly destroy articular cartilage and later produce severe degenerative changes.

Osteoarthritis Associated With Avascular Necrosis

Collapse of necrotic subchondral bone can distort the articular surface and cause secondary joint degeneration.

Associated Conditions

Osteoarthritis is primarily a joint disorder rather than a systemic disease.

However, it may occur secondary to many disorders that alter:

Cartilage integrity

Joint alignment

Bone structure

Joint stability

Diagnosis

Diagnosis is based on:

Symptoms

Physical examination

and

Characteristic imaging findings.

Signs and Symptoms

Typical symptoms include:

Pain with weight bearing

Pain with joint movement

Stiffness

Reduced range of motion

Functional limitation

Pain Pattern

Pain commonly worsens with:

Activity

Prolonged standing or walking

Repetitive joint use

Some patients also experience stiffness after:

Prolonged inactivity or rest.

Functional Limitation

Progressive osteoarthritis may interfere with:

Heavy physical work

Walking long distances

Climbing stairs

Putting on shoes

Tying shoelaces

Getting into or out of a chair

Daily self-care activities

History

Important historical features include:

Duration of pain

Activity-related symptoms

Morning or post-rest stiffness

Swelling

Previous trauma

Prior infection

Previous surgery

Functional limitations

Pain and swelling often worsen with increased use.

Physical Examination

The principal findings include:

Joint stiffness

Loss of range of motion

Pain with movement

Joint effusion

Crepitus

Angular deformity

Gait abnormality

Range of Motion

Range of motion may become progressively restricted because of:

Osteophytes

Capsular contracture

Pain

Joint deformity

Joint Effusion

A small or moderate joint effusion may occur, particularly in the knee.

This reflects a degree of secondary synovial inflammation.

Deformity

Advanced disease may produce:

Varus or valgus alignment

Fixed flexion deformity

Joint enlargement

Loss of normal contour

Gait

Lower-extremity osteoarthritis may produce:

Antalgic gait

Reduced walking speed

Shortened stance phase on the painful limb

Laboratory Tests

There is no specific laboratory test for osteoarthritis.

Routine inflammatory markers are typically normal unless another disorder is present.

Laboratory testing is useful primarily when excluding conditions such as:

Inflammatory arthritis

Infection

Crystal arthropathy

Imaging

Plain Radiographs

Plain radiographs remain the main imaging modality.

Standard studies usually include:

AP

and

Lateral views

with additional views depending on the joint.

Weight-Bearing Radiographs

Weight-bearing radiographs are particularly important for:

Knee

Foot

Ankle

because they demonstrate joint-space narrowing and alignment under physiologic load.

Typical Radiographic Findings

Classic features include:

Joint-space narrowing

Marginal osteophytes

Subchondral sclerosis

Subchondral cysts

Bone remodeling

MRI

MRI is not routinely required for typical established osteoarthritis.

It may be useful to evaluate alternative or associated diagnoses such as:

Avascular necrosis

Occult or stress fracture

Neoplasm

Meniscal or ligament injury

Early cartilage or subchondral disease

Pathological Findings

The principal abnormality is loss of normal articular cartilage structure.

Pathologic changes include:

Loss of cartilage thickness

Disorganization of the collagen matrix

Reduction in proteoglycan content

Surface fibrillation

Full-thickness cartilage loss in advanced disease

Subchondral Bone

As the cartilage deteriorates, subchondral bone becomes exposed to increased load.

This results in:

Sclerosis

Cyst formation

Microfracture

Remodeling

Differential Diagnosis

Moderate or advanced osteoarthritis is usually straightforward to diagnose.

Early disease may resemble other conditions.

Tendinitis and Bursitis

Periarticular disorders may produce pain around a joint without true cartilage degeneration.

Stress Fracture

Stress fractures can cause activity-related pain similar to osteoarthritis.

MRI or other imaging may be required when radiographs are normal but suspicion remains high.

Synovial Proliferative Disorders

Conditions involving abnormal synovial proliferation may produce:

Pain

Swelling

Effusion

and can occasionally mimic osteoarthritis.

Other Differential Diagnoses

Additional considerations include:

Inflammatory arthritis

Crystal arthropathy

Avascular necrosis

Infection

Occult malignancy

Treatment

General Principles

Treatment is initially nonoperative and aims to:

Reduce pain

Maintain mobility

Improve strength

Preserve independence

Delay functional deterioration

Activity Modification

Activities that consistently provoke severe pain should be modified.

High-impact activities such as:

Running

Contact sports

Heavy repetitive loading

may worsen symptoms in advanced disease.

Low-impact alternatives include:

Cycling

Swimming

Walking

Elliptical exercise

Rest

Short periods of rest may help during symptom flares.

Prolonged inactivity should be avoided because it contributes to:

Muscle weakness

Joint stiffness

Loss of conditioning

Weight Loss

Weight reduction is particularly important in overweight patients with lower-extremity osteoarthritis.

Even modest weight loss may reduce:

Joint loading

Pain

Functional limitation

Assistive Devices

A cane can decrease forces across the painful lower-extremity joint.

For hip or knee arthritis, the cane is generally held in the:

Contralateral hand.

This may improve:

Balance

Gait

Pain

Physical Therapy

Exercise therapy is an important component of treatment.

Goals include:

Maintaining range of motion

Preserving muscle strength

Preventing contractures

Improving balance

Maintaining aerobic conditioning

Strengthening

For knee osteoarthritis, strengthening of the:

Quadriceps

Hip abductors

Hamstrings

may improve function and reduce symptoms.

Range-of-Motion Exercises

Regular motion helps minimize:

Capsular stiffness

Contracture

Loss of function

Complementary Therapies

Acupuncture may provide short-term pain relief for some patients, particularly with knee osteoarthritis.

The clinical benefit varies among individuals.

Herbal and Nutritional Products

Numerous herbal preparations are marketed for osteoarthritis.

Evidence supporting many of these treatments remains limited or inconsistent.

Medication

NSAIDs

NSAIDs are among the most commonly used medications for symptomatic osteoarthritis.

They can reduce:

Pain

and

Inflammatory symptoms

but do not reverse cartilage damage.

NSAID Adverse Effects

Potential complications include:

Gastritis

Gastrointestinal ulceration or bleeding

Renal dysfunction

Fluid retention

Cardiovascular adverse effects

Risk increases with:

Older age

Higher doses

Long-term use

Relevant comorbidities

COX-2 Inhibitors

Selective COX-2 inhibitors may provide similar analgesic effects with a different gastrointestinal risk profile.

They still require consideration of:

Cardiovascular and renal risks.

Acetaminophen

Acetaminophen may provide modest pain relief and is an alternative for patients unable to tolerate NSAIDs.

Its benefit is generally less pronounced than that of NSAIDs for many patients.

Glucosamine and Chondroitin

The effectiveness of:

Glucosamine

and

Chondroitin sulfate

remains controversial.

Large studies have generally not demonstrated consistent clinically important benefit.

Intra-Articular Corticosteroid Injection

Corticosteroid injections can provide:

Short-term reduction in joint pain

and may be useful during symptomatic flares.

Relief is usually temporary and may last:

Several weeks.

Hyaluronic Acid Injection

Viscosupplementation with hyaluronic acid has been used for knee osteoarthritis.

Some patients report modest symptom improvement, but overall benefit is variable and remains debated.

Opioids

Opioids are generally avoided for routine long-term osteoarthritis treatment because of:

Tolerance

Dependence

Sedation

Falls

Other adverse effects

They may occasionally be considered in carefully selected patients with severe pain who are not surgical candidates and have exhausted safer options.

Surgery

Two major reconstructive strategies are:

Realignment osteotomy

and

Joint replacement.

Realignment Osteotomy

An osteotomy changes the mechanical axis of the limb by cutting and repositioning bone.

The objective is to:

Transfer load away from the diseased portion of the joint toward healthier cartilage.

Indications for Osteotomy

Osteotomy is most useful in selected patients with:

Unicompartmental disease

Correctable malalignment

Preserved motion

Relatively healthy opposing joint surfaces

It may occasionally be combined with:

Ligament reconstruction

Meniscal procedures

Arthroplasty

Joint replacement removes or resurfaces the damaged articular surfaces and replaces them with prosthetic components.

Common procedures include:

Total hip arthroplasty

Total knee arthroplasty

Total shoulder arthroplasty

Bearing Surfaces

Common arthroplasty bearing combinations include:

Metal or ceramic components articulating with highly cross-linked polyethylene, depending on the joint and implant design.

Indications for Joint Replacement

Arthroplasty is generally considered when the patient has:

Severe pain

Major functional limitation

Advanced radiographic arthritis

Failure of appropriate nonoperative treatment

Referral

Patients with:

Severe pain

Progressive deformity

Marked loss of function

Advanced arthritis

should be referred to an orthopaedic surgeon before severe fixed contractures or profound deconditioning develop.

Follow-Up

The interval between visits depends on:

Severity of symptoms

Rate of progression

Type of treatment

Patients may be reviewed every:

3–12 months

when symptoms are stable.

Imaging frequency should be based on clinical need rather than a fixed schedule.

Prognosis

Osteoarthritis is generally a progressive disorder, although the rate of progression varies substantially.

Symptoms may fluctuate over time.

There is no treatment that reliably restores normal cartilage once advanced degeneration has occurred.

Joint Replacement Prognosis

Modern joint replacement can provide substantial:

Pain relief

Improvement in mobility

Restoration of function

for appropriately selected patients.

Long-term implant survival is generally very good, although no prosthetic joint lasts indefinitely.

Complications of Osteoarthritis

Progressive disease can produce:

Increasing stiffness

Joint deformity

Loss of mobility

Muscle weakness

Reduced independence

Lower-Extremity Disease

Severe hip or knee osteoarthritis may eventually result in:

Marked walking limitation

Dependence on walking aids

and, in advanced cases,

Wheelchair dependence.

Upper-Extremity Disease

Severe arthritis of the shoulder, elbow, wrist, or hand may interfere with:

Dressing

Personal hygiene

Eating

Work

Other activities of daily living

Treatment Complications

Treatment itself may cause complications.

NSAIDs

Potential complications include:

Gastritis

Peptic ulceration

Gastrointestinal bleeding

Renal impairment

Cardiovascular events

Surgical Complications

Potential complications after arthroplasty include:

Infection

Deep-vein thrombosis

Pulmonary embolism

Dislocation

Periprosthetic fracture

Implant loosening or wear

Need for revision surgery

Patient Monitoring

Patients should be monitored for:

Pain progression

Loss of function

Joint deformity

Range-of-motion loss

Medication adverse effects

Need for assistive devices

Failure of conservative therapy

Key Principle

Osteoarthritis is a progressive degenerative joint disorder characterized by cartilage loss and secondary subchondral bone changes.

Management is directed toward:

Pain control, preservation of motion and strength, weight management, activity modification, and maintenance of function, with osteotomy or joint replacement reserved for appropriately selected patients with advanced symptomatic disease.