Polyethylene Wear in Anatomic and Reversed Shoulder Prostheses

INTRODUCTION: Polyethylene wear is a recurrent problem in joint arthroplasty. In addition to permanent deformation or complete destruction of the component, small debris particles are also associated to inflammation reaction of the surrounding bone, eventually leading to the failure of the bound between the implant and the host bone, and implant loosening. In anatomic total shoulder arthroplasty, failure of the glenoid polyethylene component is the main cause of complication, often related to periprosthetic osteolysis and aseptic loosening [1]. Polyethylene wear of anatomic prostheses has been clinically observed on retrieved glenoid components. For reversed shoulder prostheses, polyethylene wear is usually related to the scapular notching. However, the surface wear of the humeral cup is still unknown. In reversed prosthesis, the glenohumeral force is lower and the contact area is higher than in anatomic prosthesis [2]. Consequently, the contact pressure should thus be much lower, but the volumetric wear might be as important in reversed prostheses as in anatomic prostheses. The goal of this study was thus to estimate the volume of polyethylene wear of a reversed prosthesis, and compare it to an anatomic prosthesis, during one year of activities of daily living (ADL).