[Anterior laxity and internal arthritis of the knee. Results of the reconstruction of the anterior cruciate ligament associated with tibial osteotomy].

Fifty-one knees were reviewed out of 53 which had been operated on (between 1981 and 1991) for instability due to a long-standing rupture of the anterior cruciate ligament (A.C.L.), associated with medial arthritis related to a varus deformity. They had undergone a reconstruction of the cruciate ligament using the patellar tendon (5 cases had received an artificial ligament) and a high tibial osteotomy. In 80 per cent of cases this was an opening osteotomy with interposition of a heterologous bone graft, and in 39 cases it was a closing osteotomy. The average age was 37 +/- 6 years. The oldest patient was 58 years old. 80 per cent of cases were men and 88 per cent of the patients practised sport on a regular basis at the time of the accident. The average delay before surgery was 9.5 years. Almost all the patients has already undergone a medial meniscectomy and there were deep cartilaginous lesions and the bone was exposed in 50 per cent of cases. 28 knees were reexamined after a follow-up of over 4 years. Based on the ARPEGE score the results on pain and stability were good. Return to sport has been possible for 43 per cent of patients. Pivot shift, which was constant before surgery (grade 2 or 3), disappeared in 20 cases and was estimated at grade 1 in 8 cases (of which 6 had suffered a rupture of the graft). For the 20 cases in which the reconstruction of the A.C.L. had held, the average anterior radiological subluxation was 4.3 +/- 3.2 mm (from 2 to 14 mm) and the average gain after surgery was 6.7 +/- 3.7 mm (from 2.5 to 18 mm). The femoro-tibial angle went from an average of 6 degrees of varus to 3 degrees of valgus. The opening osteotomy was more precise for correction in the frontal plane. A large valgus (over 3 degrees) was not desirable and a hypercorrection was occasionally difficult to accept by relatively young patients who are likely to take up sport again. The osteotomy often involuntarily modified the normal posterior tibial plateau slope (especially closing osteotomy). A backwards increase of the tibial plateau slope is a factor which increases the anterior subluxation of the femur on the tibia. This is confirmed before and after surgery. It seems preferable to decrease the tibial slope during the osteotomy in order to protect the A.C.L. reconstruction.(ABSTRACT TRUNCATED AT 400 WORDS)