Opening- or closing-wedged high tibial osteotomy: a meta-analysis of clinical and radiological outcomes.

High tibial osteotomy (HTO) has been advocated for the treatment of isolated medial compartment osteoarthritis of the knee. Debate remains over the superiority of performing a medial opening-wedge or lateral closing-wedge HTO. The purpose of this study was to compare the clinical and radiological outcomes, and complications of patients following opening-wedge compared to closing-wedge HTO. A systematic review was undertaken of published and unpublished literature databases from their inception to May 2010. Twelve papers reporting nine clinical trials were found to be suitable for meta-analysis comparing 324 opening-wedge HTOs to 318 closing-wedge HTOs. There was no difference in the incidence of infection, deep vein thrombosis, peroneal nerve palsy, non-union or revision to knee arthroplasty (p>0.05). There was however a significantly greater posterior tibial slope and mean angle of correction, reduced patellar height and hip-knee-ankle angle following opening-wedge HTO (p<0.05). No significant difference was found for any clinical outcome including pain, functional score or complications (p>0.05).