Rapidly progressive hip disease—A rare entity in Korean population

INTRODUCTION: The pathophysiology of rapidly progressive hip disease is still unclear. It is a rare subset of osteoarthritis that mainly affects elderly women and presents with new- onset severe hip pain and dysfunction. It is assumed to be triggered by extremely rapid osteoarthritic changes resulting in impaction of the femoral head into the acetabulum, with successive osteonecrosis and insufficiency of the femoral head. PRESENTATION OF THE CASE: A 62- year-old woman reported of right hip pain which succeeded an acetabular fracture for which open reduction and fixation was done. Initial radiographs, post fixation, showed no obvious abnormality. After 2 months of conservative therapy for her right hip pain, radiographs showed joint space reduction and subchondral bone loss. T1 MRI images revealed marrow oedema pattern and depression of the articular surface of the femoral head. DISCUSSION: Differential diagnosis includes conditions which potentially lead to rapid hip destruction, such as metabolic bone diseases, autoimmune inflammatory arthritis and classical osteonecrosis. In patients with rapid worsening of hip symptoms successive X-rays and a high degree of clinical suspicion towards RPHD is essential to avoid extensive joint destruction and to facilitate better arthroplasty outcomes. CONCLUSION: The authors propose that this case represent an uncommon subset of osteoarthritis. Regular review, both clinically and radiologically, is required to assess speed of progression and to prevent rapid loss of bone stock without the surgeon being aware.