Occupational Risk Factors for Shoulder Tendon Disorders 2015 Update

Abstract

Rotator cuff (RC) injuries have been classified as intrinsic when that tendon injury results from direct tendon overload, intrinsic degeneration, or other insult. RC injury mechanisms are Case Report AbstractEvidence for work-related exposure as a cause of shoulder tendinopathy is updated. Previous studies indicated that forceful movements combined with hands above head increases the likelihood of shoulder disorders. Hands above the shoulder and arm flexion or abduction at greater than 60° combined with forceful or repetitious motions results in significantly increased occurrence of shoulder tendinopathy. Shoulder disease is multifactorial with genetics, age, and bodyweight correlated with increased occurrence though they are minor factors for young workers. Normal aging of the rotator cuff may underlie much of shoulder disease for individuals older than 60 thereby presenting a complication for the determination of work-related rotator cuff tears in this group. In contrast, there is sufficient evidence to support work-related musculoskeletal disorders of the shoulder in younger individuals who have not undergone the aging processes. Numerous reviews along with individual cross sectional and longitudinal studies conclude that shoulder tendinopathy can result from work-related exposures based on the odds and relative risks of occurrence in a working population compared to a group that has not been similarly exposed to comparable manual effort.

The Association Between Forceful Hand Exertions and Musculoskeletal Disorders of the Neck and Shoulder

“…The results of this study found that higher amounts of worker-rated peak force were associated with lower risk of neck/shoulder disorders, although confidence intervals were wide. This is inconsistent with previous findings, which found that increasing levels of force are associated with an increase in neck/shoulder disorders 11,14,18 . It is possible that the unexpected association is due to the large amount of missing data (>10%) for that exposure variable.…”

“…This is inconsistent with previous findings, which found that increasing levels of force are associated with an increase in neck/shoulder disorders. 11,14,18 It is possible that the unexpected association is due to the large amount of missing data (>10%) for that exposure variable. More importantly, this inconsistent finding highlights the limitations of simply measuring peak force, without taking into consideration the posture during that force or the amount of time or the frequency exerting the force.…”

“…Previous studies have found that forceful movements combined with hands above the shoulder level increase the risk of shoulder disorders 14 . In addition, evidence suggests a dose-response relationship.…”

“…10 Previous studies have found that forceful movements combined with hands above the shoulder level increase the risk of shoulder disorders. 14 In addition, evidence suggests a dose-response relationship. Seidler et al 15 conducted a case-control study and found a dose-response relationship between cumulative duration of work above shoulder level and symptomatic supraspinatus tendon tears confirmed radiographically.…”

Muscle fatigue response of rotator cuff muscles in different postures

“…RC muscle fatigue is the primary cause of shoulder pathologies due to its direct influence on humeral and scapular kinematics [ 16 ]. In addition, the RC muscles experience increased mechanical stress during work-related tasks at elevation angles above 60° [ 17 ]. Muscle fatigue, experienced due to repetitive activities, tends to have a cumulative trauma effect over time, resulting in musculoskeletal disorders [ 6 ].…”