Purpose: Implantation of a single-compartment lateral prosthesis can be proposed to patients with primary or secondary osteoarthritis uniquely involving the lateral femorotibial compartment. Many surgeons hesitate to use this procedure which does not have a particularly good reputation. We report a series analysed retrospectively to determine the impact of aetiology, operative findings, and pre- and post-operative radiographic findings on final outcome. We searched for the ‘ideal’ indication and specific technical difficulties encountered.

Material and methods: The review included 81 single-compartment medial implants (complete pre- and postoperative radiological and clinical data were available for 87% of the files, all were reviewed). Minimum follow-up was two years (mean 6.5 years). Clinical assessment was based on the IKS score and radiological analysis included a complete series (AP, lateral, axial, full knee, preoperative stress views).

Results: Mean IKS score was clearly improved from 49/100 preoperatively to 90.2/100 postoperatively. Severe pain was noted in 12% of the patients preoperatively versus 1.2% postoperatively. Sixty-three percent of the patients had completely forgotten their knee. Mean amplitude was 0.5–123°. Clinical lateral laxity was less than 5° in 93% of the patients and the knee was stable in the sagittal plane in 96.5%. Mean function score improved from 59/100 preoperatively to 73.3/100 postoperatively, limited basically by going up and down stairs (normal values in 36% of the patients). Walking distance was greater than 1 km in 68% of the patients (29% preoperatively). In the frontal plane, the mean mechanical femorotibial angle was 183.31 ± 3.01° (189.9 ± 5° preoperatively) with a mean mechanical femoral angle of 91.06 ± 3.01 (and a mean mechanical tibial angle of 90.6 ± 1°. Implant survival at five years was 97.15% and 93.33% at ten years (three loosenings and one metallosis).

Discussion: At last follow-up, the final result was significantly affected by diverse factors: osteoarthritis status at surgery (p < 0.02), patient age (p < 0.01), raising the anterior tibial tuberosity (p < 0.01), initial aetiology. The results were compared with data in the literature and discussed by type of indication and therapeutic options for lateral femoral osteoarthritis. The problem of indications in case of tibial plateau fractures and lateral meniscectomy is discussed.

Conclusion: These clinical and radiological results show that the lateral single-compartment prosthesis is a safe and reliable procedure for the treatment of primary or secondary osteoarthritis of the lateral femorotibial compartment.

Purpose: We studied the subjective, functional and radiographic results after anterior cruciate ligament repair using the mid-third of the patellar tendon, combined with tibial osteotomy for valgisation during the same operative time.

Material and methods: Between 1983 and 1999, this procedure was performed in 66 knees. We studied 47 knees presenting a remodelled medial compartment or medial fem-orotibial narrowing greater than 50% (preosteoarthritis), excluding three AFTI, 11 lateral decoaptations, and 5 knees with excessive genu varum. We reviewed 34 knees (72.3%) in 32 patients with a mean follow-up of 10.5 years (1–16 years) using the IKDC ratings. A complete series of x-rays were obtained in 33 patients including a comparative single-leg stance view and full leg views. Mean age at surgery was 32 years (18–49); delay from accident to operation was eight years (0.5–33). There was at least one antecedent operation in 24 knee (22 medial menisci). Fourteen knees presented a remodelled medial femorotibial compartment (grade B) and 19 had a medial joint space narrowing > 50% (grade C). The lateral femorotibial compartment was remodelled in four cases (12M%).

Results: At last follow-up, 93% of the patients were satisfied or very satisfied. The mean subjective score including symptoms, function and level of activity was 78.4 (46–96.6). Intense sports activities (ski, tennis) were practised by 46% of the patients. Clinically, five knees were considered normal (A), fifteen nearly normal (B), twelve abnormal (C) and two very abnormal (D). These results were correlated with pre- and postoperative anterior translation of the tibia on single leg stance. Radiologically, among the 1′ knees with a remodelled medial femorotibial component (grade B), three progressed to grade C; among the 19 knees in grade C, two progressed to grade D (narrowing > 50%). Axial correction was significantly greater for grade B knees at review. For the lateral femorotibial compartment, 22 showed remodelling and two narrowing less than 50%. There was no correlation with axial correction. Changes in tibial tilt were studied.

Discussion, conclusion: At ten years, the combined ACL reconstruction, tibial osteotomy for valgisation, led to stabilisation of the osteoarthritic condition and most often led to a stable and satisfactory knee.