[The relevant axial deviation: Diagnostics and therapy for correction osteotomies of the femur]

Intraoperative assessment of the femoral axis, length and torsion can be difficult. A postoperative torsional discrepancy is a common but rarely diagnosed condition. A clinical evaluation of femoral torsion is limited, especially in the early postoperative period. Conventional radiographs are a reliable diagnostic tool for evaluation of discrepancies of leg length and axis. Computed tomography remains the gold standard for assessment of torsional discrepancies. Because of the wide variability of the physiological femoral torsion, the clinical impact of a torsional discrepancy in individual cases remains unclear. There is a general recommendation for revision in cases of intraindividual deviations of more than 15°; however, most patients with deviations even greater than 15° are asymptomatic. Therefore, the indications for correction should be carefully considered in each individual case. The patient level of activity is a crucial point in decision-making for correction osteotomy. Before correction osteotomy, the surgeon has to make a detailed biomechanical analysis of the leg. Early correction is recommended in most cases. Detailed knowledge of the patient medical history is needed for preoperative planning. Prior surgeries can have a significant impact on the choice of the surgical approach and stabilization technique.