Osteochondral autogenous transfer for spontaneous osteonecrosis of the medial femoral condyle of the knee in middle-aged and elderly patients

Abstract

Purpose: Osteochondral autogenous transfer (OAT) became widespread for the treatment of spontaneous osteonecrosis of the knee (SONK). And, recently good results after OAT expand surgical indication to older patients as well as to young patients. The purpose of this study was to evaluate clinical outcome of OAT for SONK in middle-aged and elderly patients. Methods: Ten patients were included who received only OAT for SONK between July 2005 and September 2010, and whose age was more than 35 years old. Five was left knee. The average age at the time of OAT was 63.1 years (range 36-72 years). Diagnosis of all cases was done by MRI of the knee. OAT was performed for those whose femorotibial angle (FTA) was under 180° or whose mechanical axis (Mikulics line) passed lateral side of the lesion in standing plain radiographs. Those who underwent re-alignment surgery such as HTO were excluded. Capsulotomy was performed by mini-open medial parapatellar approach. Osteochondral plugs were harvested and transferred from ipsilateral trochlear ridge to the lesion. Postoperative rehabilitaion included non-weight-bearing for three weeks, partial weight-bearing for 4 weeks thereafter, and full weight-bearing was allowed after 7 weeks post-surgery. Result: Mean preoperative Lysholm score was 60.3 points (range 49-73 points). Mean postoperative Lysholm score at one year after operation was 92.5 points (range 85-100 points). All patients became to be able to sit straight in Japanese style. MR images at one year after operation showed that the transferred osteochondral plugs were same intensity as peripheral cancellous bone meaning that the plugs were well integrated. In one case, MRI showed T1 low and T2 high intensity in part of osteochondral plugs indicating poor integration. Lysholm score at one year after operation was 90 points in that case. Conclusion: It is assumed that less ability of cartilage repair and degenerative change of the donor site could affect postoperative outcome of OAT in elderly patients. If chondral lesion is localized and there is no mal-alignment in the knee, OAT is an option for treatment of SONK even in middle-aged and elderly patients.