[Osteotomies in malalignments of the lower extremities]

The surgical correction of malalignments of the lower extremities is a very demanding procedure. It requires extensive knowledge of: (1) fundamental lower extremity biomechanics, (2) various diagnostic modalities, and (3) methodology for multidimensional preoperative planning. Despite advanced techniques in diagnostics and surgery, the history of the patient and a physical examination are still the first steps in the diagnostic chain. The knowledge of the method-dependent normal values, their physiological range and intra-individual differences are a prerequisite. In posttraumatic deformities, the healthy leg is a good reference for the patient's geometric orientation. As a rule, values differing by three times the standard deviation or more are good indications for an operation. These are 15 and 12 mm for the upper and lower leg, 18 and 15 mm for the whole leg and only 3 degrees mm for the mechanical leg axis measured using computer tomography and long standing x-rays, respectively. The indication for surgical correction is not only based on geometric data. The patient's functional needs, symptoms, complaints and compensation possibilities must also be taken into account. The lower extremities have to be assessed in a psychosocial context. Among the huge number of possible surgical techniques, the procedure best suited for the patient has to be selected. This requires extensive knowledge and advanced technical skills from the treating orthopaedic surgeon. In supracondylar or high tibial osteotomies for the treatment of medial arthritis of the knee joint, the patient should be informed of the long term prognosis and endoprosthetic alternatives. Today, percutaneous epiphysiodesis is a very reliable and minimally invasive surgical technique for correcting the length and axis of the lower extremity in children between 10 and 14 years. With well planned epiphysiodesis procedures, it is often possible to avoid complex osteotomies in younger patients.