Objective: Recently, idiopathic osteonecrosis of the knees has been diagnosed at an early stage with magnetic resonance imaging (MRI). Patients who were classified as stage 1 by Koshino's classification (1982) underwent conservative treatments and we measured the MRI and radiographic results of these patients.
Patients and Methods: 17 patients who were treated in our hospital from April 2007 to December 2011, were entered into this study. Patients were aged 46-79 years old (mean age 64.6 years). Five males and 12 females were studied, over the observation period of 6-30 months (mean follow up period 12.8 months). Thirteen patients had pathological changes in the medial femoral condyle, and 4 in the medial tibial plateau, and were all classified as stage 1 by Koshino's classification. These patients underwent conservative treatments and were evaluated with MRI and radiographically.
Results: Magentic resonance imaging revealed that low signal areas in T1-weighted images disappeared in 7 patients (41%). However, 12 patients (71%) showed progression of stage by Koshino's classification. With regard to the Kellgren and Lawrence classification, 12 out of 17 patients (71%) revealed progressive arthritic changes.
Conclusions: Seventeen patients classified as stage 1 by Koshino's classification underwent conservative treatments. It appeared that low signal areas in T1-weighted images disappeared in 7 patients (41%), but 12 patients (71%) arthritic changes were progressive. Although the majority of patients with idiopathic osteonecrosis of the knees were classified as stage 1 of Koshino's classification, they only minimally improved with conservative treatment.
