Prostheses for reverse total shoulder arthroplasty.

INTRODUCTION: Historically, patients with rotator cuff arthropathy had limited reconstructive options. The early generations of reverse total shoulder arthroplasty (rTSA) designs had increased failure rates due to loosening of glenoid baseplates secondary to excessive torques. In 1985, Paul Grammont introduced a prosthetic design changing the center of rotation that addressed this major complication. The Grammont principles remain the foundation of modern reverse total shoulder prostheses, although the original design has undergone several adaptations. We reviewed here the various aspects of prosthetic designs including baseplates, glenospheres, humeral components, and polyethylene bearing interfaces. AREAS COVERED: We discuss the evolution, biomechanics, prosthetic options, and future direction for rTSA. A literature search using the PubMed database including review articles, biomechanical studies, and clinical trials pertaining to rTSA prothesis and outcomes. EXPERT COMMENTARY: Despite an expansion in the understanding of the biomechanics of the rotator cuff deficient shoulder and its effect on the reverse total shoulder prostheses, Grammont principles remain the foundation of contemporary rTSA designs. Further clinical studies are needed to assess how modern prosthetic modifications effect clinical and radiographic outcomes. Additionally, implants are being used in younger individuals with expanded indications, therefore, close clinical monitoring is needed to better evaluate their prosthetic longevity.