Which rTSA Patients Have the Greatest Risk for Dislocation?

Can we identify which patients are most likely to experience a dislocation after reverse shoulder arthroplasty (rTSA)?

Dislocation is a rare but challenging complication with rTSA. Parsons and colleagues analyzed over 10,000 rTSA cases to identify risk factors and assess the impact of multiple risk factors on the occurrence of this difficult complication. They wanted to give surgeons a way to preoperatively identify which patients are at the greatest risk of this complication so they could perform mitigating measures from the onset.

• A relatively rare complication: 1.4% of 10,023 primary rTSA patients experienced a dislocation using the Equinoxe^® Reverse Shoulder System rTSA prosthesis.
• Accumulating risk factors: The dislocation rate increased with the presence of additional risk factors. Zero risk factors = 0.5%, 1 risk factor = 0.9%, 2 risk factors = 1.0%, 3 risk factors = 1.6%, 4 risk factors = 2.7%, 5 risk factors = 5.3%, and 6 risk factors = 7.3% dislocation rate.
• High-risk patient: Males, patients younger than 67 at surgery and those with a BMI over 31 were found to be most at risk, patients with larger diameter glenospheres (>40 mm) and lateralized offset glenospheres.
• Low-risk patient: Females, patients with subscapularis repair, older than 67 years at surgery, osteoarthritis diagnosis, no history of previous shoulder surgery, and those receiving a standard offset glenosphere had the lowest risk for dislocation.

Dislocation risk after rTSA is multifactorial, with risk increasing based on the number of multiple risk factors. Preoperative knowledge of patients with high-risk combinations can help surgeons better counsel patients and adjust their surgical plans to maximize stability.

These findings are limited by the retrospective nature of the analysis, with limited generalizability due to the use of only one specific rTSA prosthesis design.