Analysis of radial to ulna deviation sequences of the scaphoid by volume rendered four dimensional computerized tomography

The carpus is an articulation of eight bones that display complex, small, multidirectional behaviour in dynamic motion. Studies to quantify carpal motion have been inadequate, largely owing to technological limitations. Four dimensional computerized tomography (4D CT) is a novel technology that demonstrates great potential for advancement of kinematic studies of the carpus. However the mathematical methodology to utilize 4D CT for this purpose remains undeveloped. Through this thesis we have demonstrated a rigid body modeling method to describe carpal motion mathematically. A radius-based coordinate system was established using trilateration. Using this radial-based coordinate system, instance center of rotation mapping was used to describe the motion of the scaphoid undergoing neutral - radial - ulna deviation with great success. Utilizing the same coordinate system version change of the scaphoid in its extremities of motion was also defined. Dynamic motion sequences derived from 4D CT also enabled the investigating team to make key observations regarding natural biological motion of the scaphoid which has previously not been possible. The methodology described is not only limited to the use of 4D CT but also can be applied to any volume rendered 3D CT data on any bone to obtain kinematic information.