Computer tomographic determination of leg length and torsion in children and adolescents

Because of different projections and axis constructions, the length and tor sion of the lower extremities are sensitive to the measuring method. To jud ge pathological deformities in children or adolescents it is necessary to k now the reference values. In this study, 78 children and adolescents 2-18 y ears old were included who had a femoral or tibial shaft fracture. Torsion and length were determined by computed tomography at least 3 months after i nternal fixation according the Ulm method. Only healthy bones were consider ed for this study. The mean internal torsion of the femur decreased during the growth period from 34.2 degrees +/- 10.3 degrees ((x) over bar +/- SD) to 19.3 degrees +/- 9.5 degrees. There was only a weak correlation between the age and torsion of the femur. The mean external torsion of the tibia wa s 32.3 +/- 10 degrees. The 95th percentiles of the intraindividual torsiona l differences were 14 degrees ((x) over tilde = 4.1 degrees) of the femur ( n = 30) and 12 degrees ((x) over tilde = 4.7 degrees) of the tibia (n = 48) . The median femoral and tibial intraindividual length differences were 2 m m. The corresponding 95th percentiles were 10 and 9 mm. The aim of the stud y was to determine the age-dependent torsion and length and their respectiv e differences with a standardized CT method. The range of the normal values was much greater than published in the literature.