Predicting Recurrent Shoulder Instability After a First-time Traumatic Anterior Shoulder Dislocation
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The optimal management for a person following a first-time traumatic anterior shoulder dislocation (FTASD) is currently unknown. While some have advocated for immediate surgical intervention, others propose a period of conservative management. Failure rates from conservative management leading to recurrent shoulder instability episodes range from between 26 to 100%, with the wide range attributable to the heterogeneity of the population. Decisions regarding clinical management can be aided through the use of decision-making tools. This approach augments patient care to become individualised and the person with the FTASD becomes an active participant in their healthcare. The number of high quality prospective cohort studies which examine risk factors predisposing or protecting people from recurrent shoulder instability, after a FTASD is limited. The most commonly reported risk factors are age and sex. However, it is widely known that there are other risk factors which predispose a person with a FTASD to recurrent shoulder instability. These factors include pathological lesions, hypermobility, and involvement in collision sport. In order to better understand the relevant risk factors for recurrent instability following a FTASD, a literature search was conducted. As age is one of the most dominant risk factors published in the literature, and children represent differences beyond skeletal immaturity, two separate literature reviews and meta-analyses were undertaken. These publications, along with additional anecdotal risk factors identified by expert clinicians, provided the risk factors to form the basis of a decision-making tool to predict recurrent shoulder instability following a FTASD. A one-year prospective cohort study was then undertaken in a population of people with FTASD. Data regarding risk factors were collected from participants, at baseline and at 3, 6, 9 and 12 months after the FTASD. Univariate logistic regression was used to establish variables that were significant at p≤0.10. Backwards stepwise logistic regression was used to establish key variables that were statistically significant in the presence of other risk factors to develop the predictive clinical tool. These variables included the presence of a bony Bankart lesion, immobilisation status following the FTASD, aged between 16 and 25 years, kinesiophobia (TSK-11), shoulder pain and disability (SPADI), and dislocation to the dominant limb. The predictive validity and reliability of the tool was established in a second one-year prospective cohort study. Analysis of the receiver operative characteristic (ROC) curve was undertaken to correctly identify the sensitivity and specificity at various cut-points along the curve. The tool was found to have high specificity (94.7%) and a positive likelihood ratio of 7.39, but limited validity (area under the curve (AUC)=0.69) and low sensitivity (38.9%). Analysis of the secondary outcomes revealed a negative relationship between a FTASD and quality of life, kinesiophobia, shoulder pain and disability and shoulder activity level. The tool developed in this research can predict people who are not going to have recurrent shoulder instability within 12 months following a FTASD. However, clinical implementation of the tool and longer follow-up is required. Further validation of the tool in an international population and in a younger cohort is required to assess its generalisability.