Orthopaedic Surgery - Hip Arthritis

Basics

Hip arthritis results from progressive loss of the articular cartilage covering the femoral head and acetabulum.

As cartilage deteriorates, the underlying subchondral bone is increasingly exposed to abnormal mechanical loading. This produces pain with weight bearing, progressive restriction of motion, gait disturbance, and eventually substantial functional disability.

Prevention and Risk Reduction

Although not all hip arthritis can be prevented, symptoms and mechanical stress may be reduced through:

Low-impact exercise, activity modification, maintenance of healthy body weight, and avoidance of repetitive high-impact loading when symptoms are present.

Suitable activities often include swimming, cycling, and walking within a tolerable range.

Epidemiology

Hip arthritis is a common cause of pain and disability in adults.

Some hips appear particularly susceptible because of subtle or overt abnormalities of joint anatomy, including developmental dysplasia and femoroacetabular impingement.

Prevalence

Arthritis overall affects a substantial proportion of the population, with older estimates suggesting that approximately 12% of the U.S. population has some form of arthritis.

The prevalence of symptomatic hip osteoarthritis increases with age.

Risk Factors

Important risk factors and underlying conditions include:

Previous trauma, osteonecrosis, infection, hemophilia, developmental hip dysplasia, femoroacetabular impingement, Legg-Calvé-Perthes disease, slipped capital femoral epiphysis, and inflammatory arthritides.

Inflammatory Arthritis

Inflammatory disorders that may involve the hip include:

Rheumatoid arthritis, systemic lupus erythematosus, and psoriatic arthritis.

Etiology

The exact cause of primary osteoarthritis is multifactorial and incompletely understood.

Contributing factors probably include differences in cartilage biology, genetics, aging, loading patterns, and joint morphology.

Mechanical Factors

Abnormal hip alignment can increase focal contact stress.

Important examples include acetabular dysplasia and femoroacetabular impingement, both of which can lead to premature cartilage and labral damage.

Classification

Hip arthritis can be broadly divided into:

Primary osteoarthritis, inflammatory arthritis, and secondary osteoarthritis.

Primary Osteoarthritis

Primary osteoarthritis develops without a single clearly identifiable initiating disorder, although subtle structural abnormalities may still contribute.

Secondary Osteoarthritis

Secondary osteoarthritis results from an underlying condition such as:

Trauma, dysplasia, osteonecrosis, Perthes disease, slipped capital femoral epiphysis, infection, or femoroacetabular impingement.

Associated Conditions

Patients may also have degenerative disease elsewhere in the musculoskeletal system, particularly:

Lumbar degenerative disc disease and knee osteoarthritis.

These conditions may complicate localization of the primary source of pain.

Diagnosis

Signs and Symptoms

Patients usually present with a deep, diffuse ache around the hip.

The classic location is the anterior groin.

Pain Distribution

Pain may radiate into the:

Buttock, thigh, or knee, often along the medial side of the thigh.

In some patients, knee pain is the predominant complaint despite the underlying pathology being located in the hip.

Gait Symptoms

Patients frequently report:

Limping, fatigue with walking, reduced walking distance, and difficulty with prolonged standing.

Functional Limitation

As hip motion decreases, patients may have difficulty:

Tying shoes, putting on socks, cutting toenails, getting into or out of a car, climbing stairs, or rising from a low chair.

History

The pain of osteoarthritis usually develops gradually over months or years.

It is generally aggravated by activity and relieved by rest, particularly early in the disease.

Activity-Related Pain

Pain with walking, prolonged standing, or other weight-bearing activity is characteristic of hip arthritis.

Night Pain

Advanced osteoarthritis may produce pain at rest or at night.

However, new severe constant pain, especially with systemic symptoms or an atypical clinical pattern, should prompt consideration of infection, tumor, occult fracture, or another diagnosis.

Age

Primary osteoarthritis is most commonly encountered in adults older than approximately 50 years.

Hip arthritis in a younger patient should prompt evaluation for a secondary cause such as trauma, dysplasia, osteonecrosis, Perthes disease, SCFE, or femoroacetabular impingement.

Physical Examination

Range of Motion

Hip range of motion should be measured and compared with the opposite side.

Internal Rotation

Loss of internal rotation is one of the earliest and most characteristic findings of hip osteoarthritis.

Pain with internal rotation is also common.

Flexion

Hip flexion gradually becomes restricted as arthritis progresses.

Flexion Contracture

A fixed flexion contracture should be assessed because it can alter standing posture, pelvic tilt, and lumbar mechanics.

Gait

The patient should be observed for:

Antalgic gait, Trendelenburg pattern, reduced stance time, short stride, or other compensatory abnormalities.

Leg-Length Discrepancy

True and apparent leg lengths should be assessed.

Progressive joint-space loss, deformity, contracture, or pelvic tilt may create actual or functional limb shortening.

Muscle Strength

Hip abductor and flexor strength should be assessed.

Chronic pain and disuse can produce substantial muscle weakness.

Stinchfield Test

A resisted straight-leg raise, commonly called the Stinchfield test, places load across the hip joint.

Reproduction of groin or deep hip pain supports an intra-articular source.

Greater Trochanter Examination

The greater trochanter should be palpated for tenderness.

Localized lateral tenderness suggests greater trochanteric pain syndrome or trochanteric bursitis rather than isolated intra-articular arthritis.

Neurologic Examination

A careful neurologic examination is necessary because lumbar radiculopathy may mimic hip disease.

Straight-Leg Raise

The straight-leg raise test can help identify radicular symptoms, particularly those arising from the lumbar spine.

Spine and Pelvis

The lumbar spine should be examined for:

Tenderness, restricted motion, scoliosis, or radicular signs.

Pelvic tilt should also be assessed because it can affect apparent limb length and hip mechanics.

Laboratory Tests

Routine laboratory studies are generally unnecessary for uncomplicated osteoarthritis.

If inflammatory arthritis is suspected, appropriate rheumatologic testing should be obtained.

Inflammatory Arthritis Evaluation

Depending on the clinical context, studies may include:

ESR, C-reactive protein, rheumatoid factor, anti-CCP antibodies, and other disease-specific tests.

Imaging

Plain Radiographs

Plain radiographs are the first-line imaging study.

A typical evaluation includes an AP pelvis and dedicated AP and lateral views of the involved hip.

Radiographic Features

Characteristic findings include:

Joint-space narrowing, osteophyte formation, subchondral sclerosis, and subchondral cyst formation.

Advanced disease may also produce femoral head deformity and acetabular remodeling.

Lumbar Spine Radiographs

If radiculopathy or substantial spinal pathology is suspected, AP and lateral radiographs of the lumbosacral spine may be useful.

Bone Scintigraphy

Technetium bone scanning can occasionally help identify occult skeletal disease when the patient has severe unexplained pain and the source remains unclear.

Its use has decreased as MRI has become more widely available.

MRI

MRI is useful for evaluating disorders that may not be visible on plain radiographs.

It is particularly effective for detecting:

Osteonecrosis, occult fracture, bone marrow abnormalities, soft-tissue disease, labral pathology, and neoplasm.

The suspected region must be adequately included within the imaging field.

Diagnostic Injection

An intra-articular hip injection containing local anesthetic can be used diagnostically when the source of pain is uncertain.

Substantial temporary pain relief after injection supports the hip joint as the major pain generator.

Differential Diagnosis

The differential diagnosis of hip pain is extensive.

Neoplasm

In younger patients, important malignant bone tumors include:

Osteosarcoma and Ewing sarcoma.

In older adults, consideration should be given to:

Metastatic bone disease and multiple myeloma.

Femoral Neck Stress Fracture

Stress fractures should be considered in:

Runners, military recruits, patients with osteoporosis, and individuals with sudden increases in physical activity.

Greater Trochanteric Pain Syndrome

Lateral hip pain with focal tenderness over the greater trochanter suggests pathology outside the hip joint.

Lumbar Radiculopathy

Pain radiating below the knee, neurologic symptoms, or positive nerve-tension testing increases suspicion for a spinal source.

Treatment

General Principles

Initial treatment is usually nonoperative.

The main goals are to reduce pain, maintain mobility, preserve strength, and delay or avoid surgery when symptoms remain manageable.

Activity Modification

Activities that consistently worsen symptoms should be reduced or modified.

Running, repetitive impact loading, deep squatting, and heavy lifting may need to be limited.

Low-impact activities are generally better tolerated.

Weight Reduction

Weight loss can reduce joint loading and improve mobility in overweight patients.

It may also reduce perioperative risk if arthroplasty is ultimately required.

Cane Use

A cane should generally be held in the hand opposite the affected hip.

This reduces hip abductor demand and can decrease joint reaction forces during walking.

Physical Therapy

Physical therapy may help maintain:

Hip range of motion, muscle strength, gait efficiency, and overall mobility.

Contracture Prevention

Stretching and range-of-motion exercises can help delay development of fixed hip contractures.

Strengthening

Strengthening the hip abductors, extensors, flexors, and surrounding lower-extremity musculature may improve function and prepare the patient for later surgery if necessary.

Medication

Acetaminophen

Acetaminophen may provide symptomatic relief, particularly in patients who cannot take NSAIDs.

NSAIDs

NSAIDs are commonly used for pain relief when there are no contraindications.

They should be used at the lowest effective dose for an appropriate duration, particularly in patients with gastrointestinal, renal, or cardiovascular risk.

Intra-Articular Corticosteroid Injection

Occasional image-guided intra-articular corticosteroid injections may provide temporary relief in selected patients.

They are not a definitive treatment for cartilage loss.

Glucosamine

Glucosamine has been used by some patients with osteoarthritis, although evidence for clinically meaningful benefit in hip osteoarthritis remains inconsistent.

Complementary and Alternative Therapies

A variety of supplements and topical therapies have been studied for osteoarthritis.

Older reports have suggested possible benefit from agents such as:

Devil’s claw, avocado-soybean unsaponifiables, capsaicin, and certain herbal anti-inflammatory preparations.

Evidence is variable, and these products should not replace established treatments.

There is limited evidence supporting magnet or laser therapy, while the role of acupuncture remains uncertain.

Surgery

Surgery is considered when pain and functional limitation remain substantial despite appropriate nonoperative treatment.

Osteonecrosis

In selected patients with early femoral head osteonecrosis before collapse, core decompression may be considered.

Hip-Preserving Osteotomy

Young patients with structural abnormalities may benefit from corrective osteotomy.

Acetabular Dysplasia

A periacetabular osteotomy can improve femoral head coverage and redistribute joint loading in appropriately selected patients with symptomatic dysplasia and preserved cartilage.

Proximal Femoral Deformity

Femoral osteotomy may be useful in selected deformities of the proximal femur.

Femoroacetabular Impingement

Young patients with symptomatic femoroacetabular impingement and limited arthritic change may benefit from procedures that reshape the femoral head-neck junction, acetabulum, or both.

Hip Arthrodesis

Hip fusion has historically been used in selected young, highly active patients when arthroplasty was undesirable.

It is now performed infrequently because of its effects on the lumbar spine, ipsilateral knee, and gait.

Total Hip Arthroplasty

Total hip replacement is the principal surgical treatment for advanced symptomatic hip arthritis.

The diseased femoral head and acetabular cartilage are replaced with prosthetic components.

Follow-Up

Prognosis With Nonoperative Treatment

Patients with mild or early arthritis may obtain substantial symptom relief from:

Activity modification, weight reduction, analgesics, NSAIDs, physical therapy, and assistive devices.

Prognosis After Total Hip Arthroplasty

The prognosis after modern total hip replacement is generally excellent.

Most appropriately selected patients achieve:

Major pain relief, improved range of motion, better walking ability, and substantial improvement in overall function.

Complications of Untreated or Progressive Hip Arthritis

Progressive disease may lead to:

Hip stiffness, flexion contracture, limp, leg-length discrepancy, muscle weakness, reduced walking tolerance, and inability to perform activities of daily living.

Complications of Total Hip Arthroplasty

Potential complications include:

Infection, dislocation, periprosthetic femoral or acetabular fracture, nerve palsy, deep venous thrombosis, pulmonary embolism, heterotopic ossification, implant loosening, liner wear, osteolysis, and stiffness.

Dislocation

Dislocation is an important complication and is generally more common after revision arthroplasty than after uncomplicated primary hip replacement.

Nerve Injury

When nerve palsy occurs, the sciatic nerve is the nerve most commonly affected.

Implant Wear and Osteolysis

Long-term prosthetic wear can generate particulate debris that contributes to bone resorption around the implant.

This process can eventually cause loosening and may require revision surgery.

Patient Monitoring

Patients with hip arthritis should be reassessed when symptoms worsen, function declines, or the pattern of pain changes.

Follow-up should monitor:

Pain severity, walking tolerance, range of motion, gait, muscle strength, limb length, response to nonoperative treatment, and radiographic progression when clinically indicated.

A sudden or atypical increase in pain should prompt evaluation for alternative diagnoses such as occult fracture, osteonecrosis, infection, or neoplasm.