Doctor of Philosophy
Musculoskeletal Health Research
James A. Johnson
Graham JW King
Roth | McFarlane Hand and Upper Limb Centre
The wrist is one of the most commonly injured joints, and injury can have serious sequelae if pathological healing ensues. Strides have been made to understand normal and pathological wrist biomechanics using experimental approaches, which has contributed to improved patient care. The present work advances our understanding of the influence of experimental techniques and joint motion measurement techniques on in-vitro wrist biomechanical cadaveric studies, and applies the knowledge learned to a common clinical entity of scapholunate insufficiency.
First, the relative contributions of the carpal rows to wrist motion were assessed, in addition to the identification of limitations of current biomechanical testing techniques. The radiocarpal joint contributed more motion to wrist flexion, the midcarpal joint contributed more to wrist extension, while near neutral wrist position there was a relatively equal contribution from both joints. Passive motion joint simulation, forearm position, and coordinate system selection and joint congruency were all identified as areas needing investigation.
In order to assess the effect of joint coordinate system (JCS) selection on resulting wrist angle, four JCS were compared to determine JCS selection on wrist angle characterization. Subtle differences were found between JCSs, and the findings support the use of any of the analyzed methods. Additionally, to quantify joint congruency at the wrist, validation and application of a previously described a non-invasive CT-based technique to measure joint congruency at the wrist is described.
The effect of forearm orientation on wrist joint biomechanics was then evaluated. Radioscaphoid joint contact was found to be sensitive to forearm orientation and wrist angle, while radiolunate joint was not sensitive to changes in forearm orientation. Scaphoid angular rotation was found to vary with forearm position, but only at the extremes of wrist flexion-extension.
The present work advances wrist biomechanics knowledge and will help to improve the clinical management of acute and chronic wrist injuries.
Summary for Lay Audience
The wrist is a complex joint made up of eight carpal bones and an intricate network of soft tissue structures. It is one of the most commonly injured joints, and injury can have serious implications if abnormal healing occurs. Previous studies have sought to understand normal and injured wrist biomechanics using a variety of experimental methods, which has contributed to improved patient care. However, the influence of study design and experimental devices (i.e. joint motion simulators) on study results have yet to be examined. A rigorous experimental framework and an understanding of how each decision made during the development of a study is of utmost importance. The potential consequences of not understanding base assumptions when designing testing apparatus or studies may lead to biased data reporting and thus misguided data interpretation. Furthermore, highly standardized experimental designs will lead to more accurate and repeatable results. Reliable results are paramount in knowledge translation as they affect an investigator’s or clinician’s ability to trust outcomes and advance research and clinical management of wrist pathologies. The results from this body of work will help investigators gain a greater understanding of how assessment techniques and experimental design affect results and will help improve overall wrist biomechanics research.
Padmore, Clare E., "A Biomechanical Investigation into the Effect of Experimental Design on Wrist Biomechanics and Contact Mechanics" (2020). Electronic Thesis and Dissertation Repository. 7223.