Pitfalls of revision reverse replacement part I: dealing with instability and glenoid bone loss

Reliable and reproducible functional outcomes contributed to expanding indications for reverse shoulder arthroplasty (RSA) beyond its original scope to more complex cases. Consequently, complications have also increased dramatically, with an overall complication rate of 24%. Revision RSA has twice as frequent complications as primary RSA. Instability and glenoid bone loss are some of the most common postoperative complications of RSA. These are devastating complications that result in disability, and revision RSA is highly problematic because of bone loss on both humerus and glenoid, poor soft tissue quality, dysfunctional deltoid, absent subscapularis and teres minor, heterotopic ossification, and extreme fibrosis with high risk of iatrogenic nerve injuries. Dealing with failed RSA requires a comprehensive and individualized analysis of each patient with an effort to identify the mechanism of failure and potential risk factors. The purpose of this article was to review the most recent literature about instability after RSA and glenoid bone loss on revision RSA, pointing out risk factors and mechanisms of failure, in an effort to guide treatment based on the best evidence available.