Chapter 9 - The Clinical Performance of UHMWPE in Shoulder Replacements

Abstract

This chapter introduces alternatives to standard contemporary device designs and materials used in shoulder replacement. The shoulder is made up of a number of bones, ligaments, and muscles. The partial ball is defined by the head of the humerus and the partial socket is defined by the glenoid of the scapula form the main articulating ball and socket geometry of the joint. Along with the passive and active stability provided by the surrounding joint capsule, ligaments, and the muscles of the rotator cuff, the geometry allows the normal shoulder joint to achieve the largest range of motion of any joint in the human body. When considering the performance of ultra-high molecular weight polyethylene (UHMWPE) in shoulder replacement components, one should have a basic understanding of the anatomical and biomechanical system into which they are placed, as well as the ways that system can be compromised by disease or trauma. It is also useful to gain a historical perspective on the origins and evolution of design and technique, as well as see a number of systems currently in use. It is especially critical to also examine overall measures of replacement success, as well as specific measures of wear or damage, to directly assess the performance of UHMWPE components in particular.