We investigated the repair of femoral head necrosis with extensive necrotic lesions treated by high-degree posterior rotational osteotomy (HDPRO) in young adults and adolescents (mean age; 30.8 years) using magnetic resonance imaging (MRI). HDPRO was performed on 72 hips from 66 cases, and of those, 60 hips from 60 cases were included in this study for data analysis. All cases had extensive collapsed lesion preoperative anteroposterior radiographs. In total, 34 hips were male and 26 were females. In total, 19 had a history of steroid administration, 11 had a previous femoral neck fracture, 7 had no particular etiologic factor, and 4 had a followed slipped capital femoral epiphysis. Antero-inferior viable areas were transferred to the loaded portion below the acetabular roof by this operation. The mean posterior rotational angle was 118.5°. MRI was taken after 1 month, 6 months and 1-year post-operatively. Post-operative necrotic lesion volume compared with the preoperative necrotic lesion volume was defined as lesion volume ratio (%). The reduction of necrotic volume was observed over time, and at 1 year post-operatively, it was 19.4% for patients in their teens, 35.3% for those in twenties, 42.8% for those in their thirties and 59.5% for those in their forties. From this study, we concluded that the extensive necrotic lesions decreased in size within a short period after HDPRO in young patients.
