Movement that occurs in the wrist joints includes abduction, flexion, and extension adduction. Unlike the hip or knee, the wrist is a complex joint that implants can mimic through careful testing of their implant designs so that they can be approved for use in clinical settings.
The articular cartilage of the joint can wear out or accumulate damage, leading to conditions such as rheumatoid arthritis, osteoarthritis, infection, and injury. Total wrist implants are used in wrist arthroplasty to create a pain-free and stable joint that has a functional movement range. Implants must be able to pass specific standards to ensure their in vitro performance can withstand kinematic and dynamic forces of regular activity. A wrist implant lasts between 10-15 years and is a non-weight bearing joint, meaning that it must be designed for the specific kinematic environment of its implantation location.
ASTM F1357 sets a guideline of the provisionary physical characteristics of total wrist replacements for manufacturers that are seeking approval for their prototype for clinical use. They are intended for use in patients with a fully matured skeletal structure. They must be fit for the imposition of dynamic loads, corrosive environments, and at bearing surfaces must attain continuous motion.
Artificial wrist prostheses have two primary components: the radial component and the distal component. The radial component is made of two pieces: a stemmed flat metal component with attachment capabilities in the bone canal and a fitted plastic cup on the metal piece, which forms a socket.