A four-dimensional-CT study of in vivo scapholunate rotation axes: possible implications for scapholunate ligament reconstruction

Additional fixation of the palmar scapholunate interosseous ligament has been advocated to improve the longterm results of dorsal scapholunate interosseous ligament reconstruction. To investigate the validity of this approach, we determined normal scapholunate motion patterns and calculated the location of the scapholunate rotation axis. We hypothesized that the optimal location of the scapholunate interosseous ligament insertion could be determined from the scapholunate rotation axis. Four-dimensional computerized tomography was used to study the wrist motion in 21 healthy participants. During flexion–extension motions, the scaphoid rotates 38 (SD 0.6) relative to the lunate; the rotation axis intersects the dorsal ridge of the proximal pole of the scaphoid and the dorsal ridge of the lunate. Minimal scapholunate motion is present during radioulnar deviation. Since the scapholunate rotation axis runs through the dorsal proximal pole of the scaphoid, this is probably the optimal location for attaching the scapholunate ligament during reconstructive surgery

Four-dimensional imaging of scaphoid kinematics

The human wrist contains eight carpal bones in which the scaphoid plays a key role in carpal stability and mechanics. A scaphoid fracture is the most common carpal fracture. When healing of the fracture fails (nonunion), a specific pattern of osteoarthritis occurs, resulting in a carpal collapse. It is unknown how a scaphoid nonunion influences carpal kinematics and results into this carpal collapse. Until now, most research is done with the wrist in a steady state position. This thesis uses a new imaging technique: four-dimensional (4D)-CT imaging, which can analyze scaphoid kinematics during wrist motion. Part one of this thesis contains two reviews which addressed the main issues of the imaging techniques currently used in patients with a scaphoid nonunion. The first chapter evaluates static CT-imaging, the second reviewed dynamic imaging techniques. Part II contains two papers, the first systematically evaluated clinical 4D-CT protocols, and the second systematically evaluated the error in positioning a coordinate system when scanning a shortened radial shaft. Part III addressed the results of two clinical trials and a trial protocol which applied the 4D-CT analysis technique in participants. The healthy carpal motion patterns between the scaphoid and lunate were evaluated in the first chapter. In the second chapter the effect of a scaphoid nonunion on carpal kinematics was described. The third paper describes a prospective trial protocol on acute scaphoid fractures. The final chapters of the thesis provides a general discussion, future perspectives and summary