Corrective osteotomies around the knee joint gained wide acceptance in the treatment of unicompartmental osteoarthritis of the knee joint despite the improvements in total and partial knee arthroplasty. The combination of axial malalignment of the lower limb with degenerative changes of one femorotibial compartment accentuates the stress onto the damaged cartilage with subsequent increase in the magnitude of axial deformity. The reduction of stress can be achieved by realignment of the leg, which in turn redistributes the forces to more normal areas of the joint. The main goals of the osteotomy include relief of pain and improvement of function. Careful patient selection and assessment as well as a precise surgical technique enable the surgeon to more predictive and improved clinical longterm results. The ideal candidate for a corrective osteotomy is in the sixth or seventh decade of life with a clearly localized, activity-related knee pain, axial malalignment of the leg and radiologically unicompartmental degenerative arthritis. Nevertheless, the patient's activity level and his personal expectations after the procedure are worth to be discussed in context with other treatment possibilities. As with prosthetic replacement, the patient has to understand that the surgical procedure will not provide a normal joint: but "buying time" with an osteotomy may be a viable concept.