Outcome of opening wedge high tibial osteotomy augmented with a Biosorb® wedge and fixed with a plate and screws in 124 patients with a mean of ten years follow-up.

The objective of this work was firstly to evaluate the long-term results of medial opening wedge high tibial osteotomy (HTO) and secondly to evaluate the tolerance and integration of a Biosorb® wedge (β Tricalcium Phosphate, SBM Company, Lourdes, France). The series consisted of 124 knees in 110 patients, 74 men and 36 women, with mean age of 53.23±10.68 years (range 32-74) and treated between June 1995 and November 2000 for medial compartment knee osteoarthritis by the senior author. The mean preoperative Lysholm and Tegner functional score was 65.44±13.32 (range 27-80) and the preoperative HKA angle was 172.51°±3.8° (range 162-179°). According to the modified Ahlbäck classification there were 27 stage I, 42 stage II, 44 stage III and 11 stage IV knees. All patients were reviewed clinically and radiologically with a mean follow-up of 10.39±1.98 years (range 8-14 years). Immediate postoperative complications consisted of nine undisplaced lateral tibial plateau fractures of no clinical significance, two deep vein thromboses and three pulmonary emboli which resolved with appropriate treatment. At a later stage, there were seven delayed unions without development of pseudarthrosis, and three screw breakages when the AO T-plate was used, leading to a secondary angulation in one case, requiring revision by femoral osteotomy. Postoperative mean weightbearing HKA angle was 182°±1.8° (range 178-186°) and 73.4% of axes were 184°±2°. Fifteen knees (12.1%) underwent total knee arthroplasty (TKA) after a mean delay of 8.87±3.04 years and were excluded from the final analysis. Concerning the long-term results (n = 107 knees), the mean Lysholm-Tegner score was 88±12.7 points (51-100) and the KOOS score was 86±14.6 points (25-100) with 94 patients satisfied or very satisfied (87.85%). In terms of the HTO survivorship curve, with failure consisting of revision to TKA or another operation, survival was 88.8% at five years and 74% at ten years. Concerning Biosorb®, this was completely integrated in 100% of cases and there was complete resorption in 12.1% of cases and greater than 50% resorption in 52.3% of cases.