Measurement of femoral neck anteversion in 3D. Part 2: 3D modelling method.

Femoral neck anteversion is the torsion of the femoral head with reference to the distal femur. Conventional methods that use cross-sectional computed tomography (CT), magnetic resonance or ultrasound images to estimate femoral anteversion have met with several problems owing to the complex three-dimensional (3D) structure of the femur. A 3D imaging method has been developed that virtually measures femoral anteversion on the 3D computer space with continuous CT slices; this 3D method provides more accurate and reliable results than conventional 2D CT measurements. A 3D modelling method is devised for the measurement of femoral neck anteversion. This method has advantages over the 3D imaging method, such as shorter processing time, reduced number of slices and an objective result compared with the 3D imaging method. The results of the 3D modelling method are compared with the conventional CT methods (2D CT method and 3D imaging method) using 20 dried femurs.