Clinical and radiographic outcomes of medial open-wedge high tibial osteotomy with Anthony-K plate: prospective minimum five year follow-up data

Purpose The purpose of this study was to prospectively evaluate the clinical and radiographic outcomes, and complication rates, after a minimum of five years of follow-up after medial open wedge high tibial osteotomy (MOWHTO) using an Anthony-K plate. Methods MOWHTO was performed on 35 knees of 34 consecutive patients. A visual analogue scale (VAS), and Western Ontario and McMaster University Osteoarthritis (WOMAC) and Lysholm scores, were used in clinical evaluation. Upon radiographic assessment, alignment was expressed as the femorotibial angle (FTA). The posterior tibial slope (PTS) and the Insall-Salvati Index (ISI) were also measured. Results VAS, WOMAC, and Lysholm scores improved significantly upon follow-up (p < 0.001 for all). The overall mean FTA was 4.68 +/- 4.39 degrees varus pre-operatively; at the last post-operative follow-up, the value was 8.43 +/- 2.02 degrees valgus. The mean correction angle was 13.1 +/- 2.7 degrees. A significant increase in PTS was evident (p < 0.01), as was a significant decrease in the ISI (p < 0.01). The overall complication rate was 8.6 %. Conclusions The Anthony-K plate affords accurate correction, initially stabilises the osteotomy after surgery, and maintains such stability until the osteotomy gap is completely healed, without correction loss. The plate survival rate was 97.2 % after a minimum of five years of follow-up. The plate increased the PTS, as do other medial osteotomy fixation plates.