Inter-population glenohumeral kinematic variation post total shoulder arthroplasty

Glenohumeral (GH) morphometry vary among populations and the current Total Shoulder Arthroplasty (TSA) implants do not incorporate these features. This study aims to determine the inter-population kinematic variation owing to morphometric changes of a GH surface using OpenSim. Three population-specific musculoskeletal models were created. These models represented average South African (SA), Chinese (CN) and Swiss (CH) populations. Post-surgical muscle moment arms were calculated for deltoid, supraspinatus and subscapularis during abduction, forward flexion and internal rotation. The average SA and the CH models exhibited similar muscle moment arms, the Swiss and the CN models showed the maximum difference in moment arm, ranging up to 11.2%. This observation correlated with the average morphometric variation, which was maximum for the SA and CN populations. From this pilot study it can be concluded that there might be a need for population-specific TSA prosthesis since the morphometric variation induces kinematic changes.