Medial meniscal tears and spontaneous osteonecrosis of the knee.

We report on a series of 5 patients over 60 years of age who had a symptomatic medial meniscus degenerative tear followed-up with magnetic resonance imaging (MRI) sequence without arthroscopic surgery who developed spontaneous osteonecrosis of the knee. The average patients age was 68 years. Clinically, all 5 patients had tenderness at the medial joint line. At initial evaluation, MRI studies showed degenerative tears of the posterior horn of the medial meniscus with no evidence of osteonecrosis. After a mean time of 2.7 months, all patients had increased pain and were re-evaluated with a second MRI study that showed images compatible with osteonecrosis. The size of the osteonecrotic image shown on the MRI was measured, and values obtained averaged 21% of the femoral condyle with a range from 17% to 26%. Development of osteonecrosis after arthroscopic partial meniscectomy has been previously reported as a rare and unexpected complication. We report an MRI sequence between medial meniscus degenerative tears and the development of spontaneous osteonecrosis without any arthroscopic procedure. Elderly patients with medial meniscal tears should be alerted of this potential sequence of events and the impossibility for the surgeon to predict or prevent this situation at this stage, especially before performing an arthroscopic meniscectomy.