Is bosentan (endothelin receptor antagonist) effective for treating avascular necrosis of the hip joint?

Bosentan for Treatment of Avascular Necrosis of Hip Joint

Bosentan is not recommended for the treatment of avascular necrosis of the hip joint as there is no evidence supporting its efficacy for this specific condition. 1

Understanding Avascular Necrosis of the Hip

• Avascular necrosis (AVN) of the hip is characterized by bone death due to interrupted blood supply, leading to eventual collapse of the femoral head and degenerative joint disease if left untreated 1
• AVN accounts for approximately 10% of total hip arthroplasties performed in the United States, with an estimated 20,000-30,000 new cases diagnosed annually 2
• Risk factors include corticosteroid use, alcohol abuse, hemoglobinopathies, hyperlipidemia, and hypercoagulability states 1
• MRI is the gold standard for early diagnosis, as plain radiographs are often insufficient for detecting early changes 1, 2

Current Evidence on Bosentan

• Bosentan, an endothelin receptor antagonist, has been extensively studied and approved for specific indications including:
  • Prevention of new digital ulcers in systemic sclerosis patients, particularly those with diffuse SSc and multiple digital ulcers 3
  • Treatment of pulmonary arterial hypertension (PAH), including PAH associated with connective tissue diseases 3
• Despite its established vasodilatory effects, there are no clinical studies or guidelines supporting bosentan use for avascular necrosis of the hip 1
• Current guidelines do not mention bosentan as a treatment option for avascular necrosis of any joint 1

Evidence-Based Management of Avascular Necrosis

Non-Surgical Management

• Weight reduction and walking aids may help reduce symptoms in early stages 1
• Pharmacological treatments with evidence of benefit include:
  • Bisphosphonates - may help prevent bone collapse in early stages 1, 4
  • NSAIDs and analgesics - provide symptomatic pain relief but do not alter disease progression 1
• There is insufficient evidence supporting routine use of anticoagulants and vasodilators despite some studies showing potential benefit 5

Surgical Management

• Joint-preserving procedures are recommended for pre-collapse stages with minimal symptoms 1, 2
  • Core decompression remains one of the safest and most commonly employed procedures with evidence-based success in pre-collapse AVN 5
  • Bone morphogenic protein and bone marrow stem cells may enhance results of core decompression 5
• Joint replacement procedures are preferred for post-collapse symptomatic stages 2
  • For younger patients with specific anatomical abnormalities, osteotomy may be considered 1
  • For elderly patients, cemented femoral fixation is recommended to reduce periprosthetic fracture risk 1

Treatment Algorithm Based on Disease Stage

• Pre-symptomatic AVN with MRI changes only: Protected weight-bearing is recommended 1
• Early stage (pre-collapse) with minimal symptoms: Joint-preserving procedures like core decompression 1, 2
• Advanced stage (post-collapse) with significant symptoms: Joint replacement procedures 2

Important Considerations and Pitfalls

• Early intervention prior to femoral head collapse is critical for successful outcomes in joint-preserving procedures 2
• Late presentation is a major negative prognostic factor 1
• Untreated AVN inevitably leads to early degenerative joint disease requiring total hip arthroplasty 1
• The lack of level 1 evidence makes it difficult to identify optimal treatment protocols for pre-collapse AVN 2
• Misdiagnosis is common in early stages when radiographs appear normal, emphasizing the importance of MRI for persistent hip pain 6