[Study of torsion defects of the lower limbs using computerized tomography]

January, 1990, to July, 1993, the torsional defects of the lower limbs were studied at the Department of Radiology of the Istituto Ortopedico Rizzoli, Bologna. Ninety-three patients were examined, all of them affected with congenital or acquired (posttraumatic and/or iatrogenic) torsional defects. The torsional angles, i.e., the anteversion acetabulum angle, the anteversion femoral neck angle and the tibial torsion angle, were measured as follows: the patients were laid supine with their limbs either in intrarotation with the patella perpendicular to the table (62 patients) or in neutral rotation with the feet in the pace position (31 patients). The images were always analyzed at the console by two different radiologists in the following days. The electronic lines for measuring torsional angles were drawn by the two radiologists ex novo on the previously acquired CT images. No statistically significant differences were observed between the two groups of patients. The measures were independent of limbs position and the interobserver differences were bigger in children and in the measurement of femoral neck anteversion angle; however, these differences decreased by about 50% with better console use. CT, thanks to its feasibility, has replaced conventional (direct or indirect) radiology to study the torsional defects of the lower limbs. Moreover, CT is extremely useful not only for early disease diagnosis (location, rotation degree and associated joint deformities), but also for treatment planning, be it surgical or conservative.