Biomechanical and neuromuscular characteristics in patients with traumatic anterior shoulder instability undergoing arthroscopic Bankart repair: a clinical prospective cohort study protocol.

INTRODUCTION: Traumatic shoulder dislocation is a common shoulder injury, especially among the young and active population. More than 95% of dislocations are anterior, in which the humeral head is forced beyond the anterior glenoid rim. The injury leads to increased joint laxity and recurrence rates are high. There is evidence that the shoulder biomechanics and neuromuscular control change following dislocation, but the existing literature is scarce, and it remains to be established if and how these parameters are useful in the clinical setting. The aim of this exploratory prospective cohort study is to investigate biomechanical and neuromuscular outcomes in patients with traumatic anterior shoulder instability undergoing arthroscopic Bankart repair, to test the hypothesis that examinations of these characteristics are applicable in the clinical setting to assess shoulder instability. METHODS AND ANALYSIS: This is a prospective multicentre cohort study with repeated measures of 30 patients undergoing arthroscopic Bankart repair. With carefully selected and completely non-invasive examination methods, we will investigate biomechanical and neuromuscular outcomes in the affected shoulders once presurgically and twice post surgically at 6 and 12 months. Patients' contralateral shoulders are investigated once to establish a preinjury level. ETHICS AND DISSEMINATION: The study was approved by the Capital Region Ethics Committee (journal-no: H-21027799) and the Capital Region Knowledge Center for Data Reviews (journal-no: P-2021-842) before patient recruitment began. The study results will be published in international peer-reviewed journals, online and in other relevant media, presented at medical conventions and disseminated to clinicians and patients as appropriate. TRIAL REGISTRATION NUMBER: NCT05250388.

Anterior-posterior glenohumeral translation in shoulders with traumatic anterior instability: a systematic review of the literature.

Background: Reports of glenohumeral translation in shoulders with traumatic anterior instability have been presented. The aim of this systematic review was to investigate anterior-posterior translation in shoulders with traumatic anterior instability. Methods: This systematic review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies including patients aged ≥15 years with previous traumatic anterior shoulder dislocation or subluxation were included. The outcome was anterior-posterior glenohumeral translation. A search of PubMed, Embase, and Cochrane library was performed on July 17, 2022. Two reviewers individually screened titles and abstracts, reviewed full text, extracted data, and performed quality assessment. Results: Twenty studies (582 unstable shoulders in total) of varying quality were included. There was a lack of standardization and unity across studies. Radiography, ultrasound, computed tomography, magnetic resonance imaging, motion tracking, instrumentation, and manual testing were used to assess the glenohumeral translation. The glenohumeral translation in unstable shoulders ranged from 0.0 ± 0.8 mm to 11.6 ± 3.7 mm, as measured during various motion tasks, arm positions, and application of external force. The glenohumeral translation was larger or more anteriorly directed in unstable shoulders than in stable when contralateral healthy shoulders or a healthy control group were included in the studies. Several studies found that the humeral head was more anteriorly located on the glenoid in the unstable shoulders. Conclusion: This systematic review provides an overview of the current literature on glenohumeral translation in traumatic anterior shoulder instability. It was not able to identify a threshold for abnormal translation in unstable shoulders, due to the heterogeneity of data. The review supports that not only the range of translation but also the direction hereof as well as the location of the humeral head on the glenoid seem to be part of the pathophysiology. Technical development and increased attention to research methodology in recent years may provide more knowledge and clarity on this topic in the future.

The heel-rise work test overestimates the performed work with 21-25% after an Achilles tendon rupture.

PURPOSE: The purpose of this study was to evaluate concurrent validity of the heel-rise work test performed with use of the heel as a surrogate for the center of body mass. METHODS: The study was a validity study performed on a prospective cohort of consecutive patients. Forty-five patients were included in the study. The heel-rise work test estimates the total work performed by repeated heel-rises until fatigue. In this study, the heel-rise work was assessed by the linear encoder and a motion capture system simultaneously for validation. The linear encoder was attached to the patient's heel and reflective marker was attached to the pelvis and heel. Student's paired t-test, linear regression analysis and Bland Altman plots were used to estimate the measurement error of the linear encoder. RESULTS: The heel-rise work test overestimated the total work with 21.0% on the injured leg and 24.7% on the non-injured leg. Student's paired t-test showed no difference in measurement error between the limbs (n.s.). The linear regression analysis showed no difference in limb symmetry index between the two methods of heel-rise work estimation (a (slope) = 1.00, R = 0.94, p < 0.0001). CONCLUSION: The heel-rise work test performed using the heel as a surrogate for center of body mass overestimates the total work with 21.0-24.7% compared to a gold standard but was able to precisely detect the relative difference between the limbs. The heel marker can be considered a valid measurement device for assessing relative differences between the limbs. CLINICAL RELEVANCE: Clinical testing of injuries to the lower body using the heel-rise work test is valid when using the relative difference between the limbs. LEVEL OF EVIDENCE: I.