Instability after reverse total shoulder arthroplasty: risk factors and how to avoid them

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering

Background:

• Instability following reverse total shoulder arthroplasty (RTSA) is a recognized complication.
• Limited salvage options exist for RTSA instability, necessitating research into risk factors and effective treatments.

Purpose of the Study:

• To determine the incidence, predisposing factors, and treatment outcomes of RTSA instability.
• To risk-stratify patients and identify reliable treatment methods for RTSA instability.

Main Methods:

• Retrospective review of 103 RTSAs performed between 2008 and 2017 by a single surgeon using a consistent technique.
• Identification of post-operative dislocations or symptoms of instability.

Main Results:

• Six patients (5.8%) experienced dislocations after RTSA (3 primary, 3 revision).
• Higher BMI and revision surgery were associated with increased instability risk.
• RTSA for severe proximal humerus fractures showed the highest risk (approx. 25% recurrent dislocation).
• All dislocations required surgical intervention; closed reduction was unsuccessful in the clinic.

Conclusions:

• While uncommon, RTSA dislocation risk is elevated in specific patient groups.
• Consideration of larger glenospheres and increased lateral offset may mitigate instability.
• Peri-glenoid release and optimal soft tissue tension are crucial for RTSA stability.