Factors associated with thoracic spinal cord injury, lesion level and rotator cuff disorders

Background: The study was concerned with the secondary functional compromis e persons with long-term paraplegia contend with, that has been shown to be associated with wheelchair use. Of particular interest was the relationshi p between the level of thoracic spinal cord injury (SCI) and factors predis posing to rotator cuff disorders (RCD), one of the most common upper extrem ity musculoskeletal complications linked with long-term SCI. Disorders of t hese peri-articular structures have previously been associated with impaire d trunk postural control and abnormal muscle strength ratios in both able-b odied groups and in paraplegic athletes. Despite their neurologically intac t shoulder joint musculature, high-level and low-level paraplegics have dif ferent degrees of trunk and pelvic stability available to them during activ ities of daily living (ADL). This fundamental functional anatomical differe nce between high-level and low-level paraplegics had not previously been re lated to the diagnosis of RCD in a non-athletic long-term paraplegic popula tion. Methods: A descriptive cross sectional study was undertaken to demonstrate the differences in the prevalence of clinically diagnosed RCD in a high-lev el (n = 22) and a low-level (n = 20) group of persons with long-term parapl egia. Any perceived differences were then related to the functional anatomi cal variations between the two groups. Inferences were made based on factor s predisposing to RCD known to exist among both able-bodied and paraplegic athletes. The 42 subjects completed the Wheelchair User's Shoulder Pain Ind ex (WUSPI) to establish the presence or absence of shoulder pain and the Mu sculoskeletal Function Assessment (MFA) instrument to determine differences in functional ability and perceived degree of difficulty within five categ ories of ADL. Each participant underwent a clinical examination using valid ated provocative clinical tests and isometric muscle strength ratio testing . Results: There was a higher prevalence of RCD in the high-level group (P=0. 009) which correlated with decreased trunk control (P = 0.009). Differences in ability to perform functional tasks were not shown to be greater in the high-level group, although there was a higher degree of perceived difficul ty in ADL. Muscle strength imbalances between the shoulder adductors and ab ductors were shown to be greater in the high-level group. Conclusions: The results of this study suggest that the functional anatomic al differences that exist within paraplegia contribute to the propensity of high-level paraplegic persons to suffer from RCD. These findings send a cl ear message to service-providers that greater acknowledgement of the differ ences in trunk postural control specific to the level of thoracic SCI is re quired. This may have implications for the prescription of wheelchairs, ass istive devices and instruction for alternative ADL techniques to this speci fic population.