Risk Factors for instability and dislocation after reverse total shoulder arthroplasty: a systematic review

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering

Background:

• Reverse total shoulder arthroplasty (RToSA) use is rising, increasing revision surgeries.
• Postoperative instability is a common complication impacting RToSA outcomes.
• Identifying RToSA instability risk factors and mechanisms is crucial for improving patient care.

Purpose of the Study:

• To identify risk factors for instability following RToSA.
• To evaluate the underlying mechanisms of RToSA instability.
• To inform preoperative risk assessment and surgical planning for RToSA.

Main Methods:

• Systematic literature review of PubMed and Google Scholar.
• Included MeSH terms: "shoulder replacement," "shoulder arthroplasty," "joint instability," "risk factors," "odds ratio."
• Meta-analysis of odds ratios for identified risk factors.

Main Results:

• Eleven significant risk factors identified: male sex, younger age, opioid use disorder, depressive disorder, revision surgery, nonunion, rotator cuff disease, prior subluxation, no subscapularis repair, cemented humeral stem, and expanded glenosphere (>9mm).
• Common instability mechanism: loss of compression, followed by impingement.
• Additional factors: high BMI, malunion, hypertension, electrolyte disorders, prior ipsilateral surgery, acute fractures, and glenosphere factors.

Conclusions:

• Established and novel risk factors for RToSA instability identified, including younger age, opioid use disorder, depressive disorder, nonunion, and lack of bony lateralization.
• Loss of compression is the predominant instability mechanism.
• Findings are hypothesis-generating; future research should link risk factors to mechanisms for targeted treatments and risk score development.