Medial opening-wedge high tibial osteotomy with use of porous hydroxyapatite to treat medial compartment osteoarthritis of the knee

Background: The aims of this study were to investigate the results of opening-wedge high tibial valgus osteotomy in patients with medial compartment osteoarthritis of the knee and to examine the usefulness of hydroxyapatite wedges as the supporting material. Methods: Medial opening-wedge osteotomy was performed in twenty-one osteoarthritic knees in eighteen patients who had a mean age of 66.6 years. The mean duration of follow-up was 78.6 months. A medial transverse osteotomy was performed proximal to the tibial tuberosity, with the most lateral 10% of the tibia left intact. The medial side of the osteotomy site was opened to the desired angle of correction. Two hydroxyapatite wedges of the same size (5.0, 7.5, or 10.0 mm) were inserted into the opened osteotomy site along with bone grafts, and the fragments were fixed with two plates. The angle of correction could be adjusted by altering the direction of wedge insertion. The goal was to achieve a final standing alignment of 100 of anatomical valgus angulation. Results: All patients had pain relief and improvement in walking ability after the osteotomy. The mean knee and function scores of the American Knee Society were 60.2 +/- 5.3 and 48.1 +/- 10.4 points, respectively, before the osteotomy and 94.3 +/- 7.3 and 93.1 +/- 9.8 points, respectively, at the time of the final follow-up. Limb alignment, expressed as the standing femorotibial angle, was corrected from 180degrees 2.9degrees preoperatively to 169.7degrees +/- 3.7degrees (10.3degrees of anatomical valgus angulation) at the time of the latest follow-up. There were no cases of recurrence of varus deformity or collapse of the hydroxyapatite wedges. Conclusions: After a mean duration of follow-up of 6.6 years, we found that the medial opening-wedge osteotomy of the proximal part of the tibia provided satisfactory clinical results for patients with osteoarthritis of the knee. Use of the porous hydroxyapatite wedges resulted in no collapse or subsidence at the osteotomy site. Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See p. 2 for complete description of levels of evidence.