12 – The Clinical Performance of UHMWPE in Elbow Replacements

Due to its important role in manipulating the hand, loss of elbow function can impair many activities of daily living leading to diminished quality of life. Although total elbow arthroplasty (TEA) has been successfully used for the treatment of relatively inactive patients with rheumatoid arthritis, implant survival has been limited when used for treatment of osteoarthritis or trauma. Like the knee, the axis of rotation of the elbow shifts in both position and orientation during flexion. This makes the use of a fixed-hinge device unacceptable for TEA. Early fixed hinge TEA systems, although inherently stabile, suffered from early loosening because of increased forces induced at the cement by this unnatural constraint. Compared to the knee, stability of the natural elbow depends to a greater degree on the conforming bony anatomy and to a lesser degree on the soft tissue structures. For this reason, it has been difficult to design a TEA system that relies purely on joint resurfacing for patients with compromised soft tissue function. As will be discussed in this chapter, modern implants are generally based on two types of designs: (1) resurfacing type implants, (2) linked hinge devices that depend on a “sloppy hinge” design to allow some degree of joint laxity. Both types of design rely on a metal on UHMWPE bearing couple for function. As TEA designs have improved, so has the survival of the devices. This has led to the usage of TEA for increased indications rather than as a salvage procedure. According to National Inpatient Survey, the number of primary TEA procedures performed has increased 2.5-fold between 1993 and 2006. However, as the longevity of TEA has increased, UHMWPE wear and osteolysis have become an increased concern. In this chapter, we will review the basic anatomy of the elbow joint, address contemporary and historic designs as well as design related issues for TEA.