Macro- and Microscale Analysis of Bearing Surface Damage on Total Shoulder Replacements

Damage to bearing surfaces of total joint replacements (TJR) can have clinical consequences: wear debris generated from ultra-high molecular weight polyethylene (UHMWPE) surfaces can cause osteolysis and subsequent implant loosening [1]. Counterbearing metallic damage may significantly increase UHMWPE wear [2]. Documenting the morphology, frequency and location of bearing surface damage may provide insight into wear initiation and prevention. While scoring methodologies have been available and validated for total hip replacements (THR) and total knee replacements (TKR) [3–4], there is a paucity of validated scoring protocols for total shoulder replacements (TSR) [5]. Our previous work presented a damage scoring methodology to evaluate the severity and coverage of six damage modes on retrieved cobalt chrome (CoCr) humeral heads [6]. In this study, we adapt that protocol to include bearing surface damage on the counter-bearings (UHMWPE glenoid components). Additionally, we incorporate the results of 3D profilometry analysis of scratches in the Co-Cr humeral heads [6]. Ultimately, this macroscale and microscale analysis, combined with clinical data, for coupled TSR retrievals will provide insight on the origin, evolution and consequences of bearing damage in vivo.