Can avascular necrosis of the femoral heads be managed on an outpatient basis?

Management of Avascular Necrosis of the Femoral Heads

Avascular necrosis of the femoral heads can be managed on an outpatient basis, particularly in early stages without femoral head collapse, though regular follow-up is essential to monitor for disease progression. 1

Staging and Risk Assessment

• Avascular necrosis (osteonecrosis) is characterized by bone death due to inadequate vascular supply, commonly affecting the femoral head 1
• The extent of necrosis is a critical prognostic factor:
  • Lesions involving <30% of the femoral head have <5% progression to collapse 1, 2
  • Lesions involving >30% of the femoral head have a 46-83% risk of progression to collapse 1
• Risk factors that may influence management decisions include:
  • Corticosteroid therapy, alcohol use, HIV, blood dyscrasias, chemotherapy, radiation therapy 1
  • Patient age >40 years and increased BMI (>24 kg/m²) 1
  • Presence of joint effusion or bone marrow edema 1

Outpatient Management Approach

• Early diagnosis is crucial to prevent articular collapse and the need for joint replacement 1
• Imaging evaluation should include:
  • MRI as the most sensitive diagnostic imaging procedure 3
  • CT scans to exclude subchondral fractures and determine the precise location/extent of the lesion 4, 2

Non-surgical Management

• Noninvasive therapies with limited supporting data include:
  • Pharmacological options: statins, bisphosphonates, anticoagulants 1
  • Other modalities: extracorporeal shock wave therapy, hyperbaric oxygen 1
• Protected weight-bearing is recommended to prevent fracture and disease progression 4, 2
• Regular radiographic follow-up is essential to monitor for disease progression or femoral head collapse 4, 2

Surgical Interventions (Outpatient or Short-Stay)

• Core decompression can be performed for early-stage disease to prevent articular collapse 1
  • Can be supplemented with injection of autologous bone marrow cells, vascular fibular grafting, or electric stimulation 1
  • 3D-printed guide plates can improve surgical precision and decrease operative time 4, 2
• Postoperative management includes protected weight-bearing and regular radiographic follow-up 4, 2

When Inpatient Management May Be Necessary

• Late-stage femoral head osteonecrosis with articular collapse may require:
  • Resurfacing hemiarthroplasty 1
  • Total hip arthroplasty for severe secondary osteoarthritis 1
• Femoral head collapse >3mm at 3 years from symptom onset typically progresses to osteoarthritis requiring more extensive intervention 5

Monitoring and Follow-up

• Regular outpatient follow-up with radiographic evaluation is essential 2
• Even asymptomatic patients with large necrotic lesions (>2/3 of weightbearing portion) require monitoring as 75% become symptomatic over time 6
• Some patients with early-stage disease can be managed conservatively for extended periods (>8 years) without surgical intervention 5

Pitfalls and Caveats

• Avascular necrosis is often bilateral in nontraumatic cases (70-80%), requiring evaluation of both hips 1
• Multifocal osteonecrosis can occur, potentially affecting the knee, ankle, and shoulder 1
• Collapse of the femoral head does not necessarily indicate a poor prognosis; subsequent cessation of collapse can occur in some cases 5
• Asymptomatic lesions can remain radiographically stable for several years despite significant size on MRI 6