Calculation and Visualization of Range of Motion of Hip Joint from MRI

Femoro-Acetabular Impingement (FAI) is a hip joint disease which affects and impairs the range of hip motion during performing activities of daily living, jogging, walking, or climbing stairs due to bony abnormalities of the joint. In this research we introduce a motion simulation and visualization system which helps surgeons to analyze range of hip motions as well as to have a better communication with patients. We evaluate the maximum motion that the joint can achieve from its bony structure if the muscle and other connective tissues are perfectly trained. These goals are achieved by presenting three dimensional (3D) visualizations of motions envelopes by examining maximum possible rotation of the digital hip bones through computer-based simulation. Our computer-based simulation system estimates, analyzes and visualizes the maximum hip range of motion (ROM) for the constructed 3D bone models (femur and pelvis) that are extracted from Magnetic Resonance Images (MRI) after segmenting the bones. These tasks are accomplished first by calculating Hip Joint Center (HJC) which is center of rotation of femoral head followed by simulating hip motions with examining impingement between the femur and the acetabulum using a collision detection system. Six primary plane motions (flexion extension, abduction adduction and internal external rotation) as well as various combinations of these motions and six successive movements are simulated and analyzed along with 3D visualization of estimated range of these motions. Our system by 3D visualization of motions envelopes will provide a platform to understand quicker and better the effect of bony morphology of the hip joint on the possible ROM.