The Effect of Humeral Head Backside Contact on Humeral Bone Stress following Total Shoulder Arthroplasty with a Short Humeral Stem

Description

In this presentation, Amir Tavakoli discusses the impact of humeral head backside contact on bone stresses in the humerus after total shoulder arthroplasty (TSA). He introduces the concept of stress shielding, where the replacement of natural bone with a stiffer metallic implant causes the bone to become porous due to altered stress distribution. Research indicates that proximal stress shielding affects a significant percentage of TSA patients, leading to complications such as early stem loosening, especially with uncemented implants.



The objective of Tavakoli's study is to investigate how different conditions of humeral head backside contact influence humeral bone stresses and the expected bone response, with the hypothesis that full backside contact will minimize changes in bone stress. The methodology involves virtually reconstructing cadaveric humeri from CT scans and subjecting them to various loading conditions while assessing stress changes through von Mises stress comparisons between intact and reconstructed states.



Results demonstrated that the inferior contact condition resulted in the most significant changes in cortical bone stress, indicating more pronounced bone resorption than other contact conditions. Graphs illustrate these variations, showcasing that inferior contact promotes greater bone resorption potential across multiple quadrants, while superior contact contributes to more maintenance of bone volume.



The study concludes that inferior contact conditions may exacerbate stress shielding, leading to negative implications for bone integrity post-surgery. Tavakoli acknowledges his sponsors and thanks his audience for their attention.

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