Author: Michael Sandow
Sandow, Michael, 2020 Can the wrist be explained? The application of computer based quantitative analysis to explain carpal biomechanics and identify therapeutic solutions for wrist dysfunction, Flinders University, College of Medicine and Public Health
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The wrist remains a challenge with respect to the mechanical controls and biomechanics and has confounded researchers over many years. No standard wrist exists and current attempts to characterise wrist motion or biomechanics have been unsuccessful. The work undertaken as part of this research is part of a larger project to develop a kinetic model of carpal motion and is an extension of Taleisnik’s concept of carpal columns and rows (Taleisnik 1976). It expands this basic notion to incorporate the Rules Based Motion concept, which states that a motion system, and in particular the wrist, can be defined and controlled by its 4 basic rules or factors, viz: morphology, constraint, interaction and load.
Rather than utilising the standard empirical study design, this project used a conceptual research strategy to make a limited number of observations on the mechanics of the wrist, and then propose a theory of how the wrist may work. An important early observation was the apparent isometric connection between various regions in the carpus, which underpins the proposed theory of the Stable Central Column of Carpal mechanics.
This theory defines a stable central column and this has been applied to address the pathological disruptions within the carpus. Past repairs have been largely unsuccessful in predictably restoring mechanics of the wrist. The paper published by Drs Sandow and Fisher (Anatomical Volar and Dorsal Reconstruction (ANAFAB) for Scapho-lunate dissociation in Journal of Hand Surgery (European) (Sandow and Fisher 2019)) represents the culmination of over 20 years work to create a process of reverse engineering, using quantitative 3D analysis, to better characterise the normal wrist biomechanics and then extrapolate this to the delivery of a successful reconstructive solution to address wrist dysfunction.
The journey to identify the critical biomechanical restraints of the wrist, by using a reverse engineering technology and then identifying a means of restoring them to the pathologically injured wrist, would appear to have achieved its goal, at least in one part of the wrist. In the case of scapho-lunate diastasis and collapse of the central column, applying a logic based reconstructive volar and dorsal surgical solution (ANAFAB - Sandow and Fisher 2019), carpal function has been successfully restored in the majority of this group of patients, and constitutes at the very least a proof of concept.
The application of computer based quantitative analysis appear to be able to characterise carpal biomechanics and identify therapeutic solutions for wrist dysfunction – and to this extent, explain the wrist.
Keywords: Wrist biomechanics, Rules Based Motion, Scapho-lunate instability
Subject: Medicine thesis
Thesis type: Doctor of Philosophy
Completed: 2020
School: College of Medicine and Public Health
Supervisor: Professor Ruurd L. Jaarsma