Can Subscapularis Deficiency Explain Glenoid Wear (Thus Possibly Glenohumeral Pain MSK Modelling and In-Vitro Wear Simulator Study)

Description

This presentation from the ISTA 2024 conference held in Nashville, begins with an acknowledgment of Dr. Mahmood's work, with a focus on investigating the implications of subscapularis muscle deficiency in shoulder arthroplasty. The presenter, Dr Ulrich Hansen explains that the research aims to explore whether this deficiency leads to increased wear in the shoulder joint, which is interpreted as a proxy for pain.



A key aspect of the discussion revolves around shoulder hemiarthroplasty, where the subscapularis muscle is typically cut during surgery for access to the joint. The concern is that in elderly patients, this muscle may not heal properly, resulting in dysfunction in about 67% of cases, potentially altering biomechanics and increasing pain experience.



The findings from the study indicate that when the subscapularis is removed, other muscles like the latissimus dorsi and teres minor attempted to compensate, leading to altered joint contact forces. Using a mobile simulation model, the research quantified wear on the glenoid surface under normal and subscapularis-deficient conditions over 500,000 cycles.



Results showed that shoulders with subscapularis deficiency experienced significantly greater wear initially. Interestingly, the wear patterns also showed a posterior preference, mirroring trends seen in posterior shoulder wear.



In conclusion, the study reinforces the notion that subscapularis deficiency is undesirable, advocating for muscle-sparing surgical techniques as a potential solution to mitigate wear and improve patient outcomes.

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