Cadaveric validation of a finite element modeling approach for studying scapular notching in reverse shoulder arthroplasty.

Cadaveric experiments were undertaken to validate a finite element (FE) modeling approach for studying impingement-related scapular notching in reverse shoulder arthroplasty (RSA). The specific focus of the validation was contact at the site of impingement between the humeral polyethylene component and the inferior aspect of the scapula during an adduction motion. Lateralization of the RSA center of rotation was varied because it has been advocated clinically to reduce impingement and presumably decrease the risk of scapular notching. Tekscan sensors were utilized to directly measure contact stress at the impingement site, and FE was used to compute contact stresses. Favorable agreement was seen between physically measured and FE-computed impingement site location (within one sensing element of the Tekscan sensor) and contact loads (mean absolute difference of 14.9%). Contact stresses and contact areas were difficult to compare directly due to the disparate spatial resolutions of the Tekscan sensor and the FE model. FE-computed contact at the impingement site was highly focal, with a total contact area comparable to the area of an individual Tekscan sensing element. The good agreement between the physically measured and FE-computed contact data (i.e., contact load and location) support the use of FE modeling as a tool for computationally testing the efficacy of changing various surgical variables associated with RSA.