Date of Award
2010
Degree Type
Thesis
Degree Name
Doctor of Philosophy
Program
Medical Biophysics
Supervisor
Dr. R. Terry Thompson
Second Advisor
Dr. Peter Canham
Third Advisor
Dr. Gary Rollman
Abstract
Epidemiological studies have demonstrated a link between repetitive work and upper extremity musculoskeletal disorders (UEMSD), but the issue of causality remains controversial. Studies have shown an association between restricted wrist range of motion (ROM) and UEMSD in computer users. These restrictions were attributed to increased antagonist muscle tension. The first objective of this thesis was to compare wrist flexion ROM in computer users with UEMSD versus asymptomatic individuals with minimal computer exposure. The UEMSD group exhibited significantly reduced wrist flexion compared to controls. Measures of flexion with a supine forearm posture reduced wrist flexion in both groups, but the reduction was approximately 100% greater in the UEMSD group. The effect of a supine forearm posture on wrist flexion is consistent with known biomechanical changes in the distal extensor carpi ulnaris tendon. We infer from these results that wrist extensor muscle tension may be elevated in UEMSD subjects compared to controls. Increased antagonist muscle tension would alter the dynamics of the wrist joint and may alter carpal kinematics. The second objective of this thesis was to compare wrist flexion ROM and carpal flexion kinematics between UEMSD and asymptomatic computer users. The UEMSD group exhibited significantly reduced wrist flexion compared to controls. In both groups, maximum active wrist flexion decreased at the supine forearm posture compared to the prone posture. However, there was no significant difference in carpal flexion kinematics between groups. Abnormalities were tentatively identified in the kinematics MRI of 7 symptomatic wrists, and subsequent clinical imaging confirmed presumably post-traumatic injuries in 3 wrists and 12 intraosseous ganglia in 3 wrists. The etiology of intraosseous ganglia is controversial, but several theories implicates chronic ligament stress. The prevalence of abnormalities in the symptomatic wrists suggests that MRI may be useful in detecting wrist abnormalities related to UEMSD symptoms. The third objective of this thesis was to compare wrist flexion range of motion and the prevalence of MRI-identified abnormalities between UEMSD and asymptomatic computer users. The UEMSD group exhibited significantly reduced dominant wrist flexion compared to controls. There was no significant loss of flexion between the prone and supine forearm postures in either group, which may be related to the frequent finding of subluxation or dislocation of the distal extensor carpi ulnaris tendon. Extraosseous ganglia were common in both symptomatic and asymptomatic wrists, and there was no significant difference in their size. Intraosseous ganglia were more frequent and significantly larger in the symptomatic wrists. The symptoms associated with intraosseous ganglia may be related to their size, and symptoms were often well-localized to the sites of the larger intraosseous ganglia. The results of this study suggest that increased antagonist muscle tension in symptomatic computer users may increase ligament stress. To the best of our knowledge this is the first MRI study comparing the prevalence of wrist abnormalities between symptomatic and asymptomatic computer users.
Recommended Citation
Burgess, Ronald A., "MRI Investigation of Computer Users With and Without Chronic Wrist Pain" (2010). Digitized Theses. 4165.
https://ir.lib.uwo.ca/digitizedtheses/4165