MRI-CONTROLLED RESULTS OF FEMORAL-HEAD NE CROSIS AND TRANSIENT BONE-MARROW EDEMA FOLLOWING CORE DECOMPRESSION

Purpose: We evaluated the signal changes of avascular necrosis and tra nsient bone marrow oedema before and after core decompression of the f emoral head to deduce prognostic factors for this operative procedure. Method: 38 of 40 cases with core decompression (35 patients: medium a ge 44 years) were analysed with a mean follow-up time of 26 months. Pr eoperatively patients were staged by the ARCO classification. MR-image s were judged in accordance to the criteria of Mitchell and Steinberg. The clinical outcome was analysed according to the hip index of Merle D'Aubigne. Results: All hips with transient bone marrow oedema showed normal signal patterns at an average of 3 months after core decompres sion. In stage I and II, all patients with a preoperative necrosis are a less than 30% of the femoral head showed a reduction of the necrotic zone and good clinical results. An unchanged or progressive appearanc e was observed in necrotic lesions with more than 30% head involvement . Because of failure a renewed operation had to be done in all patient s with stage III and IV. Conclusion: In the case of transient bone mar row oedema, a restitutio ad integrum can be achieved with core decompr ession. In stage I and II of avascular necrosis, the successful outcom e depends on the lesion size of the femoral head. Necrotic lesions les s than 30% seem to have the best prognosis. In stage III and IV, core decompression cannot be recommended.