What is the treatment for osteonecrosis of the hip?

Treatment of Osteonecrosis of the Hip

For early-stage hip osteonecrosis (pre-collapse), core decompression is the surgical intervention of choice when conservative measures fail, while advanced disease with articular collapse requires hip arthroplasty. 1

Risk Stratification Determines Treatment Pathway

The extent of necrotic involvement is the single most critical factor determining treatment approach and prognosis:

• Lesions involving <30% of the femoral head have <5% risk of progression to collapse and may be managed conservatively 1
• Lesions involving >30% of the femoral head have 46-83% risk of progression to collapse and warrant aggressive intervention 1
• Additional poor prognostic factors include age >40 years, BMI >24 kg/m², joint effusion, bone marrow edema, corticosteroid therapy, alcohol use, HIV, blood dyscrasias, chemotherapy, and radiation therapy 1

Stage-Based Treatment Algorithm

Early-Stage Disease (Pre-Collapse)

First-line conservative management includes noninvasive therapies, though supporting data remains limited 1:

• Pharmacological options: bisphosphonates, statins, anticoagulants 1
• Biophysical modalities: extracorporeal shock wave therapy, hyperbaric oxygen 1

Core decompression is indicated when conservative measures fail, with success rates of 94% for Stage I and 88% for Stage II disease 2:

• Can be supplemented with autologous bone marrow cell injection, vascular fibular grafting, or electric stimulation 1
• The procedure aims to reduce intraosseous pressure and prevent articular collapse 1

Advanced Disease (Post-Collapse)

Hip arthroplasty is the definitive treatment for collapsed femoral heads 1:

• Resurfacing hemiarthroplasty or total hip arthroplasty for late-stage disease with articular collapse 1
• Total hip arthroplasty is preferred when secondary osteoarthritis involves both femoral head and acetabulum 1

Critical Management Pitfalls

Always evaluate the contralateral hip, as 70-80% of nontraumatic cases are bilateral 1. Failure to screen for bilateral disease is a common oversight that delays appropriate management.

Screen for multifocal involvement, as osteonecrosis can simultaneously affect the knee (44%), ankle (17%), and shoulder (15%) 3. This is particularly important in patients on corticosteroids.

Do not delay intervention in asymptomatic or minimally symptomatic hips. Pain level does not predict outcome before collapse—asymptomatic hips with large lesions (>30%) still progress to collapse at the same rate as symptomatic hips 4. Prophylactic treatment should not be withheld based on absence of pain 4.

Early diagnosis is crucial to prevent articular collapse and preserve treatment options 1. Once collapse occurs, only arthroplasty remains as a viable option, eliminating the possibility of joint-preserving procedures.

MRI is mandatory for diagnosis and staging, as plain radiographs are insensitive for early disease 1. Relying solely on radiographs will miss early-stage disease when joint-preserving interventions are most effective.

Diagnostic Imaging Sequence

• Begin with plain radiographs (AP and frog-leg lateral) to exclude other causes of hip pain 3
• Proceed immediately to MRI without contrast when osteonecrosis is suspected, as it is the gold standard for early detection and quantifies necrotic volume 1
• CT imaging is essential for surgical planning when intervention is considered 3