Background: Joint dislocation injuries involve the complete loss of contact between the articulating surfaces of bones or internal joint prostheses, while joint subluxations involve the partial loss of contact. These injuries are associated with considerable economic costs, healthcare utilisation, and losses in occupational performance and availability. Currently, available evidence indicates military populations experience shoulder dislocations at a rate that may be 20 times higher than that reported for the general population. However, a comprehensive review of the incidence and associated occupational risk factors in tactical personnel is lacking. The identification and synthesis of evidence regarding rates of occurrence and risk factors for dislocations and subluxations in occupational settings, may provide subsequent opportunities for development of strategies to mitigate the initial injury risk (given high risks of re-dislocation once initial injury has occurred), leading to reduced on-going individual and organisational costs. Therefore, this review aimed to identify and synthesise findings from studies which have reported on the occurrence rates and risk factors of glenohumeral dislocations in tactical populations.
Method: This review was conducted according to the PRIMSA-P guidelines and registered on the Open Science Framework. PubMed, EBSCO, CINAHL and ProQuest databases were systematically searched using key terms derived from the following concepts: ‘dislocation’, ‘work’ and ‘risk’. Key findings from the included studies were extracted, including risk factors, prevalence or incidence and risk ratios (e.g., relative risk, hazard ratios, and incidence rate ratios). Each study included in the review was critically appraised to assess its methodological quality, using the Critical Appraisal Skills Programme (CASP) and AXIS toolkits.
Results: The methodological quality score of the included studies ranged from 66% to 90%. The incidence of glenohumeral dislocations ranged from 1.69 – 3.13, and 5.4 per 1,000 person-years, respectively, in active-duty military personnel, and in military cadets undergoing training. Identified risk factors for sustaining acute primary glenohumeral dislocations include Army and Marine Corps service, enlisted rank, younger age, male sex, sporting activities and military training. Regarding relative risks for shoulder dislocations associated with specific activities, it is notable the results indicated incidence rates associated with participation in military obstacle course sessions and the U.S. Army fitness test were 4 times as high and 1.4 times as high, respectively, as the incidence associated with participation in rugby, when expressed per 10,000 exposures.
Discussion: These findings demonstrate military populations are at a higher risk of glenohumeral dislocation than civilians. Further, the review showed that members of these tactical populations who are younger, and male, are at an increased risk of sustaining glenohumeral dislocations. Additionally, the evidence suggests some military activities may be particularly high-risk for shoulder dislocation events. It is also important to note, that many of the identified risk factors in this review (e.g., enlisted rank, military training, age, male sex etc.) may be proxies for the level of overall exposure to physical-based occupational tasks.
Impact: This review provides some clear insights to prevalence and incidence rates for shoulder dislocations, as well as key intrinsic and extrinsic risk factors.
Conflict of interest statement:
This research was funded by the Department of Veterans’ Affairs.