We reviewed 189 cases who had HTO operations for varus gonarthrosis. We discussed pitfalls of HTO and divided these into 1) patient selection, 2) operative technique and 3) complication. We prefer HTO to TKR for patients under 60 years of age who are active, even if their knees show osteoarthritic changes in lateral FTJ or PFJ. We experienced 10 cases of pseudoarthrosis postoperatively. We discussed causes and prevention of non-union
