Kinematic Assessment of Real‐time Motion Acquisition of Lower Limb Joints by Dynamic 4D Transversal Imaging (KARMA‐4D)

Evaluating musculoskeletal conditions of the lower limb and understanding the pathophysiology of complex bone kinematics is challenging. Static images do not take into account the dynamic component of relative bone motion and muscle activation. Fluoroscopy and dynamic-MRI have important limitations. Dynamic computer tomography or 4DCT is an emerging alternative that combines high spatial and temporal resolution, with an increased availability in clinical practice. 4DCT allows simultaneous visualisation of bone morphology and joint kinematics. This unique combination makes it an ideal tool to evaluate functional disorders of the musculoskeletal system. In the lower limb, 4DCT has been used to diagnose femoroacetabular impingement, patellofemoral, ankle and subtalar joint instability or reduced range of motion. Dynamic CT has also been used to objectify the effect of surgery, mainly on patellar instability. 4DCT will need further research and validation before it can be widely used in clinical practice. However, we believe it is here to stay and will become a reference in the diagnosis of lower limb conditions and the evaluation of treatment options.