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.