Four-dimensional computed tomography (4DCT) is a novel imaging modality initially used in cardiac imaging but recently applied to the musculoskeletal system; although its methodology has been developed, it is still in its infancy as a powerful clinical tool. Currently, scapholunate interosseous ligament (SLIL) tears, whose early symptoms are elucidated through dynamic movement, are diagnosed with static techniques that cannot visualize dynamic motion; hence, a tool is needed that is responsive and dynamic to visualize subtle abnormal carpal movements indicative of SLIL tears. It is hypothesized that 4DCT can visualize subtle dynamic carpal movements to define uninjured motion as well as differentiate between that and motion from those with SLIL tears. Understanding uninjured wrist motion was done by calculating scaphoid centroid translation and joint surface area (JSA) from kinematic 4DCT scans. The findings agreed with previously reported outcomes. The 4DCT tool was validated against a gold standard (micro-CT). Lastly, the 4DCT tool was provocatively tested to determine kinematic differences between uninjured and SLIL tear cohorts, as well as between types of SLIL tears. The helical axes of the scaphoid and lunate were calculated from 4DCT bone models using custom MATLAB code. Findings suggest that 4DCT shows promise as a diagnostic tool for dynamic injuries and that volar SLIL tears may negatively impact carpal motion.
Keywords:
Four-dimensional computed tomography; wrist; kinematics; scapholunate interosseous ligament tears; joint surface area; helical axes; carpal rotation