title: The True Recurrence Rate and Factors Predicting Recurrent Instability After Nonsurgical Management of Traumatic Primary Anterior Shoulder Dislocation: A Systematic Review.
abstract: To (1) define the cumulative recurrence rate after primary anterior shoulder dislocation in Level I and II comparative studies and (2) to pool risk ratios for common risk factors to provide a clinically practical hierarchy of modifiable and nonmodifiable risk factors for recurrence.
  
  
  
  Level I and II prognostic studies were identified using the electronic databases CINAHL, Embase, and MEDLINE from inception to December 2014. Included studies (n = 15) had recurrent dislocation as the main outcome, and a minimum 2-year follow-up. The cumulative odds ratio of prognostic factors was calculated where appropriate. Bias was assessed in each study using the Quality in Prognosis Studies (QUIPS) tool.
  
  
  
  The reported rate of recurrence ranged from 19% to 88% (pooled overall = 21%; pooled Level I only = 47%). The pooled time to recurrence was 10.8 months (standard deviation 0.42). Male sex (n = 6 studies) conferred a 2.68 (1.66-4.31; P < .001) and patient age <20 years (n = 4 studies) conferred a 12.76 (5.77-28.2; P < .001; vs >20 years) increased odds of recurrence. An associated greater tuberosity fracture (n = 7 studies) decreased the odds of recurrence by 3.8 times (2.94-5.00; P < .001). The quality of evidence was moderate for age, low for sex, and very low for all other prognostic variables.
  
  
  
  The pooled rate of recurrence after primary anterior shoulder instability was found to be 21% among moderate- to high-quality prognostic studies. Male sex and younger age predicted a significantly higher risk of recurrent instability (approaching 80%), whereas concurrent fracture of the greater tuberosity significantly decreased the risk of subsequent recurrent dislocation. However, considering the quality of available evidence for these predictors, there remains a clear need for further high-quality prospective studies.
  
  
  
  Level II, systematic review of Level I and II prognostic studies.
authors.affiliation: Division of Orthopaedic Surgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada; University of Toronto Orthopaedic Sports Medicine at Women's College Hospital, Toronto, Ontario, Canada.
authors.forename: David N
authors.initials: DN
authors.lastname: Wasserstein
authors.affiliation: Division of Orthopaedic Surgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada. Electronic address: ujash.sheth@mail.utoronto.ca.
authors.forename: Ujash
authors.initials: U
authors.lastname: Sheth
authors.affiliation: Vanderbilt Sports Medicine, Vanderbilt University, Nashville, Tennessee, U.S.A.
authors.forename: Kristina
authors.initials: K
authors.lastname: Colbenson
authors.affiliation: Division of Orthopaedic Surgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada; University of Toronto Orthopaedic Sports Medicine at Women's College Hospital, Toronto, Ontario, Canada.
authors.forename: Patrick D G
authors.initials: PD
authors.lastname: Henry
authors.affiliation: University of Toronto Orthopaedic Sports Medicine at Women's College Hospital, Toronto, Ontario, Canada.
authors.forename: Jaskarndip
authors.initials: J
authors.lastname: Chahal
authors.affiliation: University of Toronto Orthopaedic Sports Medicine at Women's College Hospital, Toronto, Ontario, Canada.
authors.forename: Tim
authors.initials: T
authors.lastname: Dwyer
authors.affiliation: Vanderbilt Sports Medicine, Vanderbilt University, Nashville, Tennessee, U.S.A.
authors.forename: John E
authors.initials: JE
authors.lastname: Kuhn
mesh_terms: D000367:Age Factors; D016208:Databases, Factual; D006801:Humans; D007593:Joint Instability / Q000453:epidemiology*; D016017:Odds Ratio; D011379:Prognosis; D011446:Prospective Studies; D065840:Protective Factors; D012008:Recurrence; D012307:Risk Factors; D012737:Sex Factors; D012783:Shoulder Dislocation / Q000453:epidemiology / Q000628:therapy*; D012784:Shoulder Fractures / Q000453:epidemiology*; D016896:Treatment Outcome