Background:

Shoulder dislocations are the most common joint dislocations seen in emergency departments. Most traumatic cases are anterior and cause recurrent dislocations. Management options include surgical and conservative treatments. There is a lack of evidence about which method is most effective after the first traumatic anterior shoulder dislocation (TASD).

Objectives:

To produce UK age- and sex-specific incidence rates for TASD. To assess whether or not surgery within 6 months of a first-time TASD decreases re-dislocation rates compared with no surgery. To identify clinical predictors of recurrent dislocation.

Design:

A population-based cohort study of first-time TASD patients in the UK. An initial validation study and subsequent propensity-score-matched analysis to compare re-dislocation rates between surgery and no surgery after a first-time TASD. Prediction modelling was used to identify potential predictors of recurrent dislocation.

Setting:

UK primary and secondary care data.

Participants:

Patients with a first-time TASD between 1997 and 2015.

Interventions:

Stabilisation surgery within 6 months of a first-time TASD (compared with no surgery). Stabilisation surgery within 12 months of a first-time TASD was also carried out as a sensitivity analysis.

Main outcome measure:

Re-dislocation rate up to 2 years after the first TASD.

Methods:

Eligible patients were identified from the Clinical Practice Research Datalink (CPRD) (1997–2015). Accuracy of shoulder dislocation coding was internally validated using the CPRD General Practitioner questionnaire service. UK age- and sex-specific incidence rates for TASD were externally validated against rates from the USA and Canada. A propensity-score-matched analysis using linked CPRD and Hospital Episode Statistics (HES) data compared re-dislocation rates for patients aged 16–35 years, comparing surgery with no surgery. Multivariable Cox regression models for predicting re-dislocation were developed for the surgical and non-surgical cohorts.

Results:

Shoulder dislocation was coded correctly for 89% of cases in the CPRD [95% confidence interval (CI) 83% to 95%], with a ‘primary’ dislocation confirmed for 76% of cases (95% CI 67% to 85%). Far fewer patients than expected received stabilisation surgery within 6 months of a first TASD, leading to an underpowered study. Around 20% of re-dislocation rates were observed for both surgical and non-surgical patients. The sensitivity analysis at 12 months also showed little difference in re-dislocation rates. Missing data on risk factors limited the value of the prediction modelling; however, younger age, epilepsy and sex (male) were identified as statistically significant predictors of re-dislocation.

Limitations:

Far fewer than the expected number of patients had surgery after a first-time TASD, resulting in an underpowered study. This and residual confounding from missing risk factors mean that it is not possible to draw valid conclusions.

Conclusions:

This study provides, for the first time, UK data on the age- and sex-specific incidence rates for TASD. Most TASD occurs in men, but an unexpected increased incidence was observed in women aged > 50 years. Surgery after a first-time TASD is uncommon in the NHS. Re-dislocation rates for patients receiving surgery after their first TASD are higher than previously expected; however, important residual confounding risk factors were not recorded in NHS primary and secondary care databases, thus preventing useful recommendations.

Future work:

The high incidence of TASD justifies investigation into preventative measures for young men participating in contact sports, as well as investigating the risk factors in women aged > 50 years. A randomised controlled trial would account for key confounders missing from CPRD and HES data. A national TASD registry would allow for a more relevant data capture for this patient group.

Study registration:

Independent Scientific Advisory Committee (ISAC) for the Medicines and Healthcare Products Regulatory Agency (ISAC protocol 15_0260).

Funding:

The National Institute for Health Research Health Technology Assessment programme.

Article history

The research reported in this issue of the journal was funded by the HTA programme as project number 14/160/01. The contractual start date was in January 2016. The draft report began editorial review in June 2018 and was accepted for publication in October 2018. The authors have been wholly responsible for all data collection, analysis and interpretation, and for writing up their work. The HTA editors and publisher have tried to ensure the accuracy of the authors’ report and would like to thank the reviewers for their constructive comments on the draft document. However, they do not accept liability for damages or losses arising from material published in this report.

Declared competing interests of authors

Nigel Arden has received honoraria from, held advisory board positions (which involved receipt of fees) in and received consortium research grants from Merck & Co. (Kenilworth, NJ, USA) (honorarium), Roche Holding AG (Basel, Switzerland), Novartis (Basel, Switzerland) and Bioiberica S.A. (Barcelona, Spain) (grants), Smith & Nephew plc (London, UK), NicOx S.A. (Valbonne, France), Flexion Bioventus (Bioventus LLC, Durham, NC, USA) and Freshfields Bruckhaus Deringer LLP (London, UK) (personal fees) outside the submitted work. Amar Rangan reports grants from the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) programme, Orthopaedic Research UK (London, UK), DePuy Synthes UK (Leeds, UK) and JRI Orthopaedics (Sheffield, UK) outside the submitted work. Andrew Judge is a subpanel member of the NIHR Programme Grants for Applied Research (PGfAR) programme, has received consultancy fees from Freshfields Bruckhaus Deringer LLP and has held advisory board positions (which involved receipt of fees) from Anthera Pharmaceuticals Inc. (Hayward, CA, USA). Daniel Prieto Alhambra has received grants and other support from Amgen Inc. (Thousand Oaks, CA, USA) and UCB Biopharmal Srl (Brussels, Belgium); grants from Laboratories Servier (Neuilly-sur-Seine, France), Novartis International AG (Basel, Switzerland), Astellas Pharma Inc. (Tokyo, Japan), the NIHR HTA programme and from NIHR Research for Patient Benefit (RfPB), outside the submitted work. He is also a member of the NIHR HTA Clinical Evaluation and Trials panel (from November 2017 to present) and the NIHR RfPB South-Central Regional Advisory Committee panel (from 2013 to 2017). Tim Holt is a general practitioner (GP) in London and is a GP advisor for, but not employed by, the Clinical Practice Research Datalink. Gary S Collins is a member of the HTA Commissioning Board and has received grants from the NIHR HTA programme, NIHR RfPB, NIHR Biomedical Research Centre (BRC) and British Heart Foundation outside the submitted work. Sarah E Lamb was on the HTA Additional Capacity Funding Board (2012–15), HTA End of Life Care and Add-on Studies Board (2012–15), HTA Prioritisation Group Board (2010–15), HTA Trauma Board (2013–15), HTA Clinical Trials Board (2010–15) and the HTA Funding Boards Policy Group (2010–15) within 36 months of the start of the study. Andrew Carr has received other grants from the NIHR HTA programme, the Medical Research Council and the Wellcome Trust during the conduct of this study. He is a panel member on the Medical Research Council Developmental Pathway Funding Scheme (2016–present), a theme leader for the NIHR Oxford Biomedical Research Centre (2017–present) and was the Director of the NIHR Oxford Musculoskeletal Biomedical Research Unit (2008–17). Jonathan L Rees has received other grants from the NIHR HTA and NIHR PGfAR programmes. He works within a NIHR BRC and currently holds other grants from the Royal College of Surgeons of England, the Dinwoodie Charitable Company (Macclesfield, UK), McLaren Applied Technologies (Woking, UK) and the National Joint Register (NJR). He sits on committees at the NJR, National Institute for Health and Care Excellence and the Orthopaedic Data Evaluation Panel (ODEP), advises the Medicines and Healthcare Products Regulatory Agency and is a council member of the British Elbow and Shoulder Society.