Characterization of In Vivo Damage on Retrieved Total Shoulder Glenoid Liners

Abstract

An attempt was made to retrieve glenoid liners from revision surgery to undertake a retrospective study to measure the resulting in vivo damage. Since the glenoid liners are circumferential, the curvature changes at every point in the component, an “assisting arm” was designed to hold the liner firmly, thus allowing accurate microscopic measurements. We characterized the damage in terms of pitting, embedded debris, complete fracture, abrasion, deformation, delamination, burnishing, grooving, and scratching that took place mutually exclusively. This study of 26 liners showed embedded debris was the most underrated damage mode found on the liners, followed by pitting and abrasion, representing 65.2% and 52.2% of the liners, respectively. The prevalence of pitting in over half the samples examined is indicative of free-radical oxidation, resulting in a decrease in physical strength from morphological changes in the microstructure. These may initiate from different pathways, however, they may interact with other processes in which other damage initiates and grows, resulting in higher damage causing premature failure due to wear. A probabilistic approach was developed to generate survival time for these liners and may provide a statistical removal time of the glenoid liners in the future.