Electronic Thesis and Dissertation Repository


Doctor of Philosophy


Health and Rehabilitation Sciences


Dr. Joy C. MacDermid


Musculoskeletal disorders (MSDs) are injuries, damage or disorders affecting the musculoskeletal system including muscles, ligaments, nerves, tendons, bones or cartilage etc. MSDs are highly prevalent and associated with sickness absence, reduced work efficiency, job changes and earlier retirement.. They also affect daily activity and social functioning. Although many MSDs are accompanied by minor symptoms and settled spontaneously, approximately 10% of the workforce with MSDs have difficulty resuming their original work or exit the workforce permanently. Return to work after MSDs is complex, and is influenced by many factors including physical, psychological, economic and social factors.

Although there are extensive studies on the association between MSDs and work, existing research on upper limb MSDs is not sufficient to guide management of the return to work process. Moreover, there is lack of evidence on how the work environment, especially the ergonomic system affects the injured workers’ decision to return to work. In consideration of the aging workforce and resulting increasing burden of such studies are needed to guide to employers, clinicians and policymakers..

The purpose of this thesis is to better understand the work-related disability of MSDs of upper limbs and identify the factors which can be used to determine return to work. The key research objectives were: 1) To identify the prognostic factors for return to work after work-related traumatic hand injuries. This was achieved through a systematic review. 2) To evaluate the structure of a modified Organizational, Policies and Practices scale (OPP-14). Specifically, to examine the addition of 3 items on the Ergonomic Subscale in terms of internal consistency, construct validity and other psychometric characteristics by using confirmatory factor and Rasch analyses. 3) To identify the predictors of job changes in a sample of an aging population with rotator cuff syndrome during surgery wait times; and the disability progression during wait times in the same population.

From the existing literature, we found evidence that greater impairment in physical function was associated with e longer time to return to work following a work-related traumatic hand injury’ whereas common predictors of RTW including age, gender and level of education demonstrated no consistent impact on RTW. Our modified OPP-14 proved to be robust in factor structure on a sample of firefighters which we believe the scale can be used in assessing the workplace health and safety. We also found that average time to job changes for people wait for rotator cuff repair is 5.5 months. WSIB status was the only significant predictor for job changes; whereas, age had a trend of significance (P=0.06). The length of wait times had a minor impact on self-reported disabilities or muscle strength.

Our work enriches the literature of MSDs by identifying prognostic factors following hand injury, validating a better scale to measure workplace policy and safety, identifying potential prognostic factors for job changes, and evaluating the disability progression and its interaction with employment status in rotator cuff disorders.