Radiologic case study. Abrasion chondroplasty mimicking avascular necrosis.

Arthroscopic abrasion arthroplasty, subchondral drilling, and microfracture continue to be performed with some frequency in younger patients with focal chondral defects and occasionally for patients with moderate degenerative knee arthritis. The plain radiographic appearance after those procedures may mimic avascular necrosis, but MRI is a sensitive method used to exclude the diagnosis of avascular necrosis and evaluate the extent to which fibrocartilaginous repair tissue has formed. When combined with an appropriate clinical history, dedicated articular cartilage imaging sequences improve the sensitivity and specificity that MRI provides in these patients with chondral knee injuries.