In a series of 260 fractures of one or both tibial condyles, the main indication for surgical treatment was clinical evidence of instability of the extended knee joint. Forty-four per cent of the patients were treated either by closed traction-reduction and internal fixation using a wire loop or by open reconstruction of the joint surface using autogenous bone grafts. Follow-up of 78 per cent of the patients revealed that 87 per cent of them had an acceptable knee function. Post-traumatic osteoarthritis was found in 17 per cent. The relationship between end results and factors such as age, sex, type of fracture, instability, angular deviation, and local deformity of the joint surface is evaluated. The principal factors that led to bad results were residual instability and malalignment.