Meta-analysis Is Bony Morphology and Morphometry Associated With Degenerative Full-Thickness Rotator Cuff Tears? A Systematic Review and Meta-analysis Renato Andrade, B.Sc., Ana Lucinda Correia, M.D., Joni Nunes, M.D., Francisco Xará-Leite, M.D., Emilio Calvo, M.D., Ph.D., João Espregueira-Mendes, M.D., Ph.D., and Nuno Sevivas, M.D., Ph.D. Purpose: To scope the scientific literature and analyze the influence of bony risk factors for degenerative full-thickness primary rotator cuff tear. Methods: A systematic review of databases PubMed, Scopus, EMBASE, and Cochrane Library was performed up to June 30, 2018. Meta-analysis was performed with mean difference (MD) or risk ratio for degen- erative full-thickness rotator cuff injury, and when there were 3 studies for the considered potential risk factor. Methodologic quality was assessed using the Newcastle-Ottawa scale. Results: We analyzed 34 studies comprising 5,916 shoulders (3,369 shoulders with rotator cuff tear and 2,546 controls) and identified 19 potential risk factors for degen- erative full-thickness rotator cuff tears. There was moderate evidence that a higher critical shoulder angle (MD ¼ 4.41, 95% confidence interval [CI] 3.43 to 5.39), higher acromion index (MD ¼ 0.06, 95% CI 0.04 to 0.09), and lower lateral acromion angles (MD ¼7.11, 95% CI 8.32 to 5.90) were associated with degenerative full-thickness rotator cuff tears compared with controls. Moderate evidence showed that a type III acromion significantly increases the risk for full- thickness degenerative rotator cuff tear (risk ratio ¼ 2.26, 95% CI 1.38 to 3.70). Conclusion: There is moderate evi- dence that larger critical shoulder angle, higher acromion index, lower lateral acromion angles, and a type III acromion are significantly associated with degenerative full-thickness rotator cuff tears. Other potential risk factors identified showed insufficient evidence. Level of Evidence: Level IV, systematic review of level II to IV studies. See commentary on page 3316 R otator cuff tear is a common shoulder pathology in the general adult population. 1-3 The prevalence increases with age, 3-5 increasing 50% after the age of 50 years. 1 It represents one of the most common causes of shoulder pain and shoulder dysfunction 4,6 and leads to substantial economic burden with respect to health care resources. 7 The etiology and natural progression of degenerative rotator cuff disease is often recognized as multifactorial, with a strong age-dependent and intrinsic degenerative process component. 3 Because of the high socioeconomic impact and reduction in the quality of life, 8,9 identifying potential risk factors and patients at risk of developing rotator cuff tear is important to implement risk stratification strategies, individualize management, and improve treatment outcomes. Early diagnosis is challenging because a considerable proportion of rotator cuff tears remain asymptomatic. 1,10,11 Although some tears can be suc- cessfully treated conservatively, 12,13 progression of partial-to full-thickness tear ranges from 10% to 50%, 14,15 and surgical management is required in most cases. 16-18 From the Clínica do Dragão, Espregueira-Mendes Sports Centre, FIFA Medical Centre of Excellence (R.A., J.E-M., N.S.); the Faculty of Sports, University of Porto (R.A.); the Orthopaedics Department, Centro Hospitalar do Porto (F.X-L.); the Dom Henrique Research Centre (R.A., J.E-M., N.S.), Porto, Portugal; School of Medicine, Life and Health Sciences Research Institute/3B’s - PT Government Associate Laboratory, University of Minho, Campus de Gualtar (A.L.C., N.S., J.E-M.); Orthopaedics Department, Hospital de Braga (J.N.), Braga, Portugal; the Fundacion Jimenez Diaz, Universidad Autonoma de Madrid (E.C.), Madrid, Spain; and Trofa Saúde Hospital Sr Bonfim - Trofa Saúde Group (N.S.), Touguinhó, Portugal. The authors report that they have no conflicts of interest in the authorship and publication of this article. Full ICMJE author disclosure forms are available for this article online, as supplementary material. Received February 20, 2019; accepted July 3, 2019. Address correspondence to João Espregueira-Mendes, M.D., Ph.D., Clínica do Dragão, Espregueira-Mendes Sports Centre, FIFA Medical Centre of Excellence, Via Futebol Clube do Porto, F. C. Porto Stadium, Porto, Portugal. E-mail: espregueira@dhresearchcentre.com Ó 2019 by the Arthroscopy Association of North America 0749-8063/19191/$36.00 https://doi.org/10.1016/j.arthro.2019.07.005 3304 Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 35, No 12 (December), 2019: pp 3304-3315