What is the primary purpose of TSA stems in shoulder arthroplasty?

The primary purpose of TSA stems in shoulder arthroplasty is to achieve ingrowth or on-growth for bone. This function is essential for the long-term stability and integration of the implant within the patient's anatomy. The stem is designed to facilitate bony integration, allowing for the natural bone to grow into the surface of the implant. This biological fixation enhances the stability of the implant, reduces the risk of loosening, and contributes to the overall longevity of the shoulder prosthesis.

In contrast, while providing immediate mobility, minimizing post-operative pain, and simplifying the surgical procedure are also important considerations in shoulder arthroplasty, they are not the primary functions of the stems themselves. The stems serve a biomechanical role rather than directly influencing mobility or pain relief; those aspects are more related to the overall design of the implant system, surgical technique, and post-operative rehabilitation protocols.