Treatment of aseptic nonunion after medial opening-wedge high tibial osteotomy

Background Nonunion after medial opening-wedge high tibial osteotomy (OWHTO) is a rare but serious complication with very limited data regarding its treatment. The aim of this study was to analyze the healing rate after operative treatment of nonunion after OWHTO. Methods We performed a single-center, retrospective study that included 14 patients with nonunion after OWHTO between 2010 and 2018. The treatment for all patients consisted of local debridement and cancellous bone grafting at the osteotomy gap. Revision osteosynthesis due to a loss of correction/loosening of the locking screws or plates was performed in 5 patients. In 7 patients, lateral hinge fractures were treated with additional lateral plating. Union was confirmed using the modified "Radiographic Union Score for Tibial fractures". Outcome measure was the Lysholm Knee Score at final follow-up. Results The mean age of the patients included in our study was 48.4 +/- 6.7 years. Three patients were female (21.4%). The mean follow-up period was 20.8 +/- 12.8 months. Union was achieved in 12/14 patients (85.7%) after a mean of 6 months (range, 3-13). The mean Lysholm Knee Score at the final follow-up was 83.2 +/- 11.6. Two patients did not reach definitive union during the follow-up. In one patient, an infection of the nonunion following bone grafting was successfully treated with a two-stage procedure. Two patients needed additional cancellous bone grafting 6 and 8 months after the first revision surgery. All patients showed pain-free full weight bearing after union was achieved. Conclusions Nonunions after OWHTO can generally be treated successfully with cancellous bone grafting. For patients who have loss of correction, loosening of the osteosynthetic material or fracture of the lateral hinge, an additional revision or additive osteosynthesis may be required.