Kinematic Geometry of the Wrist: Preliminary Report

Abstract

This research significantly advances the state of the art in our ability to visualize the dynamic kinematics of the wrist. Beginning 150 years ago, investigations into the kinematics of the wrist were anatomical descriptions^{5,6,8,10,20,21} with observations made by the eye and including the earliest use of the x-ray after its discovery in 1895. It was not until much later that McConail¹² began to apply basic mechanical laws to the curiosities and movement of the wrist and its complex of eight carpal bones. Motion studies began with cineradiography^1,26 and moved parallel with technological development of optical and electronic methods of measuring minute distances accurately while the joint is moving. Use of LED path generation on photographic plates was used in conjunction with both cineradiographic and cinematographic (movie film)²⁶ methods in an attempt to improve and automate the laborious and error prone requirement of hand digitizing data. With the introduction of the spark gap, or sonic digitizer, 3-D positional data could be taken automatically from moving joint components.^3,4,27 Experimental error associated with the sonic digitizing equipment, its dependency on acoustic related environmental conditions (temperature, humidity, air movement) and the physical size of the spark gap apparatus itself still left much to be desired. Because of these concerns, recent investigators have attempted to return to basic approaches (manual analysis of biplanar radiographs) to increase precision even at the expense of fewer data points and increase in digitization error.^7,9,14