SAS weekly rounds: avascular necrosis

Abstract

Osteonecrosis of the femoral head is a condition that affects upwards of 10,000 individuals in the USA each year. The peak incidence is in the fourth decade of life, and overall, there is a male preponderance. The condition accounts for up to 12% of total hip arthroplasties performed in developed countries. The etiology can be traumatic or non-traumatic, with 90% of atraumatic cases attributed to corticosteroid therapy or excess alcohol consumption. Osteonecrosis of the femoral head reflects the final common pathway of a range of insults to the blood supply and ultimately results in femoral head collapse, acetabular involvement, and secondary osteoarthritis. Currently, conservative treatment options, which aim to correct pathophysiologic features allowing revascularization and new bone formation, appear to be able to delay but not halt the progression of this condition. As a consequence of femoral head osteonecrosis, many individuals undergo surgical treatments including: core decompression, osteotomy, non-vascularized bone matrix grafting, free vascularized fibular grafts, limited femoral resurfacing, total hip resurfacing, and total hip arthroplasty.

Fig. 1

Anteroposterior and lateral radiographs of a patient who presented with bilateral osteonecrosis secondary to HIV infection. The right hip demonstrates a reactive sclerotic rim surrounding a lytic necrotic area with segmental articular collapse in keeping with advanced osteonecrosis. The left hip demonstrates widespread articular collapse, joint space narrowing and secondary osteoarthritis

Fig. 2

Coronal T1 (a) and T2-weighted (b) magnetic resonance images of the right hip of another patient presenting with a pain on ambulation. A small osteonecrotic lesion is visible with the loss of the normally high signal intensity reflecting adipocyte necrosis