This article describes the complications after medial opening wedge high tibial osteotomy (HTO) with the TomoFix plate. Between June 2003 and July 2005, 40 TomoFix medial opening wedge HTOs were performed. On average, radiological consolidation was reached after 10.4 months. Nonunions were not recorded. In 4 cases (10%), a superficial infection was found. Between operation and consolidation of the osteotomy, an average loss of correction of 0.3 degrees was observed. Loss of correction after removal of the implant was not observed. Excluding the breakage of 1 screw during extraction of the implant, failure did not occur. The fixation of the TomoFix with locking-head screws for the opening wedge HTO, as described in this study, is stable. The planned correction could be reached with high exactitude during the operation.