Biomechanical shoulder models can support surgical decisions for joint replacement

Complex computational shoulder models have been used to investigate and understand the biomechanics of Reverse Shoulder Arthroplasty(RSA), but despite the advancements in knowledge, impingement and limited ROM still remain a concern. To solve the problem, new technologies were introduced (e.g. Patient Specific Instrumentation-PSI) that allow surgeons achieve implantation accuracy. However, it is not clear how accuracy alone can result in better functional outcomes. There is a great potential using customized models in conjunction with accurate implantation to improve RSA. A recent cadaveric validation study showed that when a pre-operative model was used with PSIs, impingement free ROM was improved compared to traditional RSA surgery. However, the results did not match the expected model predictions because the model did not account for humeral placement or muscle tensioning. Overall biomechanical models can improve RSA, but there is a need for further model development to account for multiple factors.