Histologic analysis of postmeniscectomy osteonecrosis.

Bone marrow signal changes on magnetic resonance imaging (MRI) after meniscectomy have been reported as evidence of postmeniscectomy osteonecrosis, but this pathology is unclear. We conducted a study to follow-up cases with bone marrow signal changes on MRI after meniscectomy and investigate the pathology of underlying lesions. Of 136 patients with no presurgical evidence of osteonecrosis, 29 had juxta-articular bone marrow signal changes on MRI after arthroscopic meniscectomy and subsequently underwent conservative therapy. In 6 of these 29 patients, clinical symptoms and radiographic changes began deteriorating. Based on the Koshino classification, 4 of the 6 patients had Stage-2 knee osteonecrosis and 2 had Stage-3. Arthroscopic and pathologic examinations were performed. Arthroscopic findings were fibrillation (all 6 cases), fissuring (4), ulceration (2), and eburnation (2). Histologic analysis confirmed subchondral bone fractures in all 6 cases, but osteonecrotic lesions were detected only in 2 cases with obvious radiologic deterioration. Postmeniscectomy osteonecrosis might result from subchondral bone fractures. Fracture healing is worse in patients with comorbidities than in those without it; comorbidities might be a risk factor for osteonecrosis.