No abstract

No abstract

This is a prospective study of 105 knees in 91 patients with idiopathic osteonecrosis of the femoral condyles, with an average follow-up of five years in 101 knees. Forty-eight of the 75 patients in whom the body weight was studied were obese and four of the 33 patients in whom a densitometry study was done showed decreased bone density. Prognosis is unfavourable if the lesion is larger than five square centimetres and if its width is more than 40 per cent of that of the condyle. Of the 22 patients followed up after conservative treatment 80 per cent were satisfactory. Of the 11 knees treated by arthrotomy alone 55 per cent were satisfactory. Of the 31 knees treated by osteotomy (21 with associated arthrotomy) 87 per cent were satisfactory. Arthrotomy did not significantly improve the results of osteotomies. The ideal correction was to 10 degrees of valgus. Of the 37 knees treated with replacement 95 per cent were satisfactory, and the best results were obtained with the total-condylar prosthesis.

No abstract

Unicompartmental knee arthroplasty (UKA) is designed for patients presenting arthritic wear limited to a single medial or lateral tibiofemoral compartment. The indication is based on strict criteria. Wear must stem from degenerative osteoarthritis or be secondary to aseptic necrosis of the medial condyle. Inflammatory rheumatism is a contraindication. Age and activity level should be compatible with an indication for arthroplasty. The body mass index should be less than 30 kg/m(2). The ligament system must be intact, particularly both cruciate ligaments. Any pre-existing axis deformity should be moderate and the residual axis deformity, after correction of wear with a unicompartmental tibial augmentation spacer, should not exceed 7-10° varus or valgus. These highly restrictive conditions result in the ideal indications for UKA suitable for no more than 15-20% of knee arthroplasty candidates for most surgeons experienced in this procedure. Although the results of certain early series worried potential users, today it can be asserted that recent series whose indications and technique correspond to modern use criteria, have shown results that are as reliable as those of total knee arthroplasty (TKA) at a 10 years' follow-up. Beyond this time frame, the risk of polyethylene wear related to the technical restrictions of the UKA is another consideration. Indeed, to prevent the risk of rapid extension of osteoarthritis to the opposite compartment, the procedure should be limited to restoring the patient's constitutional axis before wear phenomena had set in. This makes UKA a surgical procedure at risk of failure due to wear phenomena. Much of this paper will describe the precise rules for UKA positioning, which are critical to observe to warrant these implants outcome and longevity.