A unique tribological inverted bearing solution for reverse shoulder arthroplasty: Vitamin E and ceramic (unique inverse pairings in rTSR)

Reverse total shoulder arthroplasty has gained popularity for various shoulder conditions and has evolved over time to accommodate for material changes and design philosophy including inverse materials. The tribological behaviour of shoulder arthroplasty has been extensively studied in relation to biological osteolysis which is a notable concern regarding component loosening. This study aims to assess the wear performance of a vitamin E-stabilised glenosphere or conventional ultra-high-molecular-weight polyethylene glenosphere whilst paired with ceramic or cobalt–chrome–molybdenum inlay in a shoulder joint wear simulator. A cumulative total of five million cycles was utilised with gravimetric and visual analysis of wear. Gravimetric wear was observed to be the lowest when a vitamin E-stabilised glenosphere was paired with a ceramic inlay – demonstrating the greatest wear resistance. Our results demonstrate that the combination of vitamin E-stabilised polyethylene glenosphere and ceramic inlay has improved wear resistance properties in load simulations when compared to other bearing surface combinations. This supports the use of the novel inverse combination in clinical practice to attain longer-term survivorship in reverse total shoulder replacements. Basic Science Study; Tribology