A 45-year-old man on long-term corticosteroids for systemic lupus erythematosus presents with groin pain and limited hip abduction. Plain radiographs of the hip are normal. MRI shows a characteristic double-line sign in the structure marked **A** with an inner high T2 signal band surrounded by a low T2 signal sclerotic band. What is the most appropriate next management step for this patient?

Explanation

## Why "Protected weight-bearing with bisphosphonates and close imaging follow-up" is right The double-line sign on MRI (high T2 inner reactive band + low T2 outer sclerotic band) is pathognomonic for early-stage avascular necrosis (AVN/osteonecrosis) of the femoral head marked as **A**. This finding appears when plain radiographs are still normal, representing FICAT stage I–II disease. At this early stage, the management strategy is conservative: protected weight-bearing to prevent mechanical stress, bisphosphonates (though benefit remains controversial in literature), and serial imaging to monitor for progression. Core decompression may be considered for small lesions. Total hip replacement is reserved for advanced stages (III–IV) when femoral head collapse has occurred. The patient's corticosteroid use for SLE is the most common non-traumatic cause of AVN. ## Why each distractor is wrong - **Immediate total hip replacement**: Total hip replacement is the definitive treatment for advanced AVN (FICAT stages III–IV with femoral head collapse and secondary osteoarthritis), not early-stage disease. Performing THR in stage I–II would be premature and unnecessarily sacrifice the native joint. - **Intra-articular corticosteroid injection**: This is contraindicated in AVN and may worsen the condition. Corticosteroids are a known risk factor for AVN development; further local injection would be harmful. - **Surgical arthroscopy with synovial debridement**: Arthroscopy has no role in AVN management. AVN is an intraosseous ischemic process affecting the femoral head bone itself, not a synovial or cartilage surface problem amenable to arthroscopic treatment. **High-Yield:** Double-line sign on MRI = early AVN (stage I–II) → conservative management (protected weight-bearing, bisphosphonates, core decompression for small lesions); crescent sign or collapse → advanced disease → THR. [cite: Apley 10e — AVN classification, imaging, and staged management]