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Orthop J Sports Med. 2020 Feb 4;8(2):2325967119894738. doi: 10.1177/2325967119894738. eCollection 2020 Feb.

The Prevalence and Clinical Implications of Comorbid Back Pain in Shoulder Instability: A Multicenter Orthopaedic Outcomes Network (MOON) Shoulder Instability Cohort Study.

Author information

Investigation performed at the University of Kentucky Department of Orthopaedic Surgery & Sports Medicine, Lexington, Kentucky, USA.



Understanding predictors of pain is critical, as recent literature shows that comorbid back pain is an independent risk factor for worse functional and patient-reported outcomes (PROs) as well as increased opioid dependence after total joint arthroplasty.


The purpose of this study was to evaluate whether comorbid back pain would be predictive of pain or self-reported instability symptoms at the time of stabilization surgery. We hypothesized that comorbid back pain will correlate with increased pain at the time of surgery as well as with worse scores on shoulder-related PRO measures.

Study Design:

Cross-sectional study; Level of evidence, 3.


As part of the Multicenter Orthopaedic Outcomes Network (MOON) Shoulder Instability cohort, patients consented to participate in pre- and intraoperative data collection. Demographic characteristics, injury history, preoperative PRO scores, and radiologic and intraoperative findings were recorded for patients undergoing surgical shoulder stabilization. Patients were also asked, whether they had any back pain.


The study cohort consisted of 1001 patients (81% male; mean age, 24.1 years). Patients with comorbid back pain (158 patients; 15.8%) were significantly older (28.1 vs 23.4 years; P < .001) and were more likely to be female (25.3% vs 17.4%; P = .02) but did not differ in terms of either preoperative imaging or intraoperative findings. Patients with self-reported back pain had significantly worse preoperative pain and shoulder-related PRO scores (American Shoulder and Elbow Surgeons score, Western Ontario Shoulder Instability Index) (P < .001), more frequent depression (22.2% vs 8.3%; P < .001), poorer mental health status (worse scores for the RAND 36-Item Health Survey Mental Component Score, Iowa Quick Screen, and Personality Assessment Screener) (P < .01), and worse preoperative expectations (P < .01).


Despite having similar physical findings, patients with comorbid back pain had more severe preoperative pain and self-reported symptoms of instability as well as more frequent depression and lower mental health scores. The combination of disproportionate shoulder pain, comorbid back pain and mental health conditions, and inferior preoperative expectations may affect not only the patient's preoperative state but also postoperative pain control and/or postoperative outcomes.


back pain; dislocation; patient-reported outcomes; shoulder; shoulder instability; shoulder instability surgery

Conflict of interest statement

One or more of the authors has declared the following potential conflict of interest or source of funding: This study was supported, in part, by research grants from the Orthopaedic Research & Education Fund. B.R.W. is a paid board member of United HealthCare and a paid consultant for ConMed Linvatec and SportsMed Innovate. B.R.W.’s institution has received educational support from ConMed, Smith & Nephew, Arthrex, and Wardlow Enterprises. K.M.B. has received consulting fees from Wright Medical, speaking fees from Wright Medical and Arthrex, and royalties from Lippincott Williams & Wilkins. J.T.B. has received consulting fees from Encore Medical, Smith & Nephew, and DJO Global; speaking fees from Smith & Nephew; and royalties from Shukla Medical. R.H.B. has received educational support from Arthrex and Elite Orthopedics, speaking fees from Arthrex and Smith & Nephew, and consulting fees from ISTO Technologies and Sanofi-Aventis. B.T.F. has received hospitality payments from Zimmer Biomet. J.A.G. has received educational support from Pinnacle, hospitality payments from Aesculap Biologics and Smith & Nephew, and consulting fees from Ossur and JRF Ortho. G.L.J. is a board member for the Musculoskeletal Transplant Foundation and has received educational support from CDC Medical. J.E.K. is a paid editor for the Journal of Shoulder and Elbow Surgery. C.B.M. has received speaking fees from Zimmer Biomet and consulting fees from Zimmer Biomet, Medacta, Stryker, Tornier, Wright Medical, and Linvatec. R.G.M. is a paid editor for the Journal of Bone and Joint Surgery and receives royalties from Springer and Demos Health. E.C.M. has received consulting fees from Zimmer Biomet; research support from Smith & Nephew, Arthrex, and DePuy; and royalties from Zimmer Biomet and Elsevier. B.S.M. has received consulting fees from Arthrex. A.J.S. has received educational support from Gemini Medical and Arthrex, honoraria from Encore Medical, and consulting fees from Medacta. M.V.S. has received educational support from Elite Orthopedics and consulting fees from Arthrex and Flexion Therapeutics. R.W.W. has received royalties from Wolters Kluwer–Lippincott Williams & Wilkins and is a team physician for the St. Louis Blues Hockey Club. A.L.Z. has received consulting fees from Stryker. C.M.H. has received research support from Zimmer Biomet, speaking fees from Pacira Pharmaceuticals, and hospitality payments from Arthrex and Tornier.

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