Angle estimation of human femora in a three-dimensional virtual environment

MARIANO CASCIARO; LUCAS RITACCO; FEDERICO MILANO; MARCELO RISK; DAMIAN CRAIEM

Buenos Aires, Argentina

Conferencia; 32nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society; 2010

IEEE

The estimation of human femur morphology and certain angulations assessment provide useful information for assisted-surgery, follow-up evaluation and prosthesis design. Particularly, neck-shaft, valgus and anteversion angles are difficult to measure in a planar projection. In this work, we present an automated method to estimate these three angles in a true 3D framework. Femora from 10 patients were scanned using multiscliced computed tomography. Virtual cylinders were fitted to 3 regions of the bone to automatically estimate the angles. Comparisons were made with conventional manual methods. Inter and intra reading measurements were evaluated. We found angles from both methods strongly correlated. Average anteversion, neck-shaft and valgus angles resulted 17.5, 139.5, 99.1, respectively. The repeatability and reproducibility of the automated method showed a 5-fold reduction in inter and intra reading varibility. Accordingly, the coefficients of variation for the manual method were below 25% whereas for the automated method were below 6%. The valgus angle assessment was globally the most accurate with differences below 1. Maximum distances from true bone points and fitting cylinders attained 6mm. The employment of virtual cylinders fitted to different regions of human femora consistently helped to assess true 3D angulations.