Instability failure in total shoulder arthroplasty

Glenohumeral instability is the second most common complication of shoulder arthroplasty, occurring in 4.9% of cases. Instability following arthroplasty is best classified based on its direction. The unconstrained shoulder arthroplasty can be unstable superiorly, anteriorly, inferiorly, and posteriorly. The causes and incidences of each direction are unique and individualized. The goal of this paper is to identify the cause of different types of total shoulder arthroplasty instability and discuss techniques to avoid such complications.