We aimed to analyse complication rates following medial opening-wedge high tibial osteotomy (OWHTO) for knee OA. A regional retrospective cohort study of all patients who underwent HTO for isolated medial compartment knee OA from 2003–2013. 115 OWHTO were performed. Mean age = 47 (95%CI 46–48). Mean BMI = 29.1 (95%CI 28.1–30.1). Implants used: 72% (n=83) Tomofix, 21% (n=24) Puddu plate, 7% (n=8) Orthofix Grafts used: 30% (n=35) autologous, 35% (n=40) artificial and 35% (n=40) no graft. 25% (n=29) of patients suffered 36 complications. Complications included minor wound infection 9.6%, major wound infection 3.5%, metalwork irritation necessitating plate removal 7%, non-union requiring revision 4.3%, vascular injury 1.7%, compartment syndrome 0.9%, and other minor complications 4%. Apparent higher rates of non-union occurred with the Puddu plate (8.3%) relative to Tomofix (3.6%) but was not statistically significant. No other significant differences existed in complication rates relative to implant type, bone graft used, patient age or BMI. Serious complications following HTO appear rare. The Tomofix has an apparent lower rate of non-union compared to older implants but greater numbers are required to determine significance. There is no significant difference in union rate relative to whether autologous graft, artificial graft or no graft is used.
