The high tibial osteotomy (HTO) is a wellestablished and commonly used treatment for younger and active patients with a medial unicompartmental osteoarthritis of the knee and varus malalignment. The aim of this technique is to shift the load to a functional lateral compartment in order to delay total knee arthroplasty.The dome-shaped HTO was introduced by Blaimont et al. (1975) and later popularized by Maquet (1980). Out of 118 cases, 96 cases of overcorrection, 13 cases of undercorrection, and 9 cases with anatomical axes have been reported. After undercorrection, the results were poor or fair in 77% (Hsu, 1989). Despite a complication rate of 35% (thrombophlebitis, necrosis of the extensor hallucis longus, tibial plateau fracture, pin tract infection, over-and undercorrection), the results of the dome-shaped HTO showed good or excellent results in 87% (n=40) of the cases (Krempen and Silver, 1982). Sundaram et al. (1986) confirmed the good results of the dome-shaped osteotomy. The infection rate at the osteotomy side was 7.6%. A delayed union and bone grafting were noticed in 5.7% of the cases. The staples had to be removed in 8.6% of the cases for various reasons. In 14.3% of the cases, complications at the fibula osteotomy (weakness of the extensor hallucis longus in 3 cases, paraesthesia in 4 cases) have arisen. King-Martinez et al. (2007) noted a complication rate of 53% after a dome-shaped HTO.Meanwhile, the open wedge HTO with the TomoFix™ plate, which was introduced by Staubli et al.