Proof−of−concept of kinematic analysis in FAI patients: a dinamic CT study

Femoroacetabular impingement (FAI) is a condition causing joint pain and restricted movement due to abnormal bone morphology that leads to impingement. Keyhole surgery is a common treatment, but there are no precise guidelines on the amount of bone to remove. This study utilised 4D dynamic CT imaging to analyse hip kinematics to explore its potential use in pre-surgical planning. Dynamic CT scans were conducted during pre-operative assessments with patients’ hips moved to replicate the flexion adduction internal rotation (FADIR) test. Landmark position derived from 3D bone modelling and image registration was used to create local, bone-embedded reference frames. Cardan angles and Finite Helical Axis (FHA) parameters were calculated to evaluate femoral motion relative to the pelvis. Results demonstrated the potential of 4DCT to provide detailed kinematic insights. This approach could improve motion simulation models and enable precise identification of impingement areas, optimising surgical outcomes for FAI patients.