The influence of central pain modulation on postoperative outcomes after shoulder surgery: A systematic review

Objective: The aim of this study was to systematically review whether the altered central pain modulation has a significant influence on post-surgical outcomes in patients undergoing shoulder surgery due to musculoskeletal disorders. Methods: A systematic search of MEDLINE, PEDro, and EMBASE was conducted without time restriction, including observational prognostic studies. Quality in Prognostic Studies Tool was adopted for critical appraisal, and a qualitative synthesis was undertaken. Two authors independently performed study selection, data extraction, and risk of bias assessment; any disagreement was resolved by a third author. A review protocol is published in the PROSPERO registry (CRD42019122303). The data regarding the potential predictors and outcome measures were obtained from the studies. Results: 11 prospective cohort studies were appraised. Overall, 952 patients were included with a sample size that ranged from 20 to 314. Studies included both arthroscopy and open surgery and presented low to moderate ROB. The prognostic factors investigated were depression, psychological distress, anxiety, catastrophizing, fear avoidance beliefs, self-efficacy and quantitative sensory testing. Only avoidance behaviors and self-efficacy were significantly related to post-surgical pain and function at 12 months after surgery. Conclusion: Fear avoidance beliefs and inadequate coping strategies seem to be the most correlated factors with the worst pain and function scores. Surgeons and physical therapists should look for patients with signs of altered central pain modulation before surgery as they might be at risk of unfavorable outcome.