[Idiopathic osteonecrosis of the internal femoral condyle. Prognostic elements and role of different treatments].

In this retrospective study, 36 patients with a mean age of 72 years (range 60 to 82) underwent surgical treatment for osteonecrosis of the medial femoral condyle. The procedure consisted in tibial valgus osteotomy in 18 cases, unicompartmental arthroplasty in 15 cases, and total knee arthroplasty in 3 cases. Analysis of a number of factors (size of the lesion, knee deformity as assessed by goniometry, condition of the joint...) demonstrated that valgus osteotomy performed to reduce the load experienced by the necrotized area was effective in preventing extension of the lesion and development of a synovial pannus; furthermore, this procedure ensured preservation of the range of motion of the knee and, when performed sufficiently early, prevented deterioration of the medial femorotibial joint space. On the basis of our data, it can be concluded that arthroplasty is warranted only in patients aged 75 years or more and in those with extensive necrosis; unicompartmental arthroplasty should be performed whenever possible; total arthroplasty should be used only when the size of the lesion precludes secure implantation of a single-compartment device.