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.