Implementation of a patient specific model for the calculation of glenohumeral subluxation

Introduction: Total Shoulder Arthroplasty is a well-established surgery for restoring comfort and function to the arthritic shoulder. Among the different surgical options this procedure appears to provide the most rapid and complete reestablishment of the normal conditions. Still, there is a high failure of the implant after the surgery (5- to 10- year failure rates for is up to 10% [1]). This is mainly caused by luxation due to aseptic glenoid loosening, associated with off-center loading. Method: In this study, a new method for the prevision of subluxation after total shoulder arthroplasty is developed. The final goal of this study is to prevent and anticipate subluxation’s risks thanks to a patient-specific model for the calculation of subluxation. The model is developed based on preoperative and post-operative CT-scans of patients that already underwent the surgery at the CHUV (The Lausanne University Hospital). A comparative study between subluxation’s calculation with normal and overcorrected implant is undergone. The design of this last overcorrected implant (still not commercialized) is developed to reduce the subluxation. Results: A new end-to-end method has been developed for the measurement of subluxation. The results obtained during this first study do not confirm about the potential of this new implant, but encourage to get deeper into the model development, both for the FE-model and the implant design to find a new design able to reduce the post-operative subluxation. Conclusion: The new developed tool for the prediction of subluxation is very promising in the subluxation’s risk prevention after TSA. Still, efforts need to be done on the model’s development to obtain better results for the possible future commercialization of new overcorrected implants.