Wrist Joint Replacement
Joint replacement surgery which is performed in the wrist is less common than knee or hip replacement but it can be an option if the patient has painful arthritis that does not respond to other treatments.
The damaged parts of the wrist bones are removed and replaced with artificial components in wrist joint replacement surgery.
The wrist is a more sophisticated joint than the hip or the knee. On the hand side of the wrist, there are two rows of bones at the base of the hand. There are four bones in each row.
The bones in these rows are called the carpals. The long thin bones of the hand radiate out from one row of carpals and form the basis of the fingers and thumb.
The radius and the ulna are the two different bones of the forearm that forms a joint with the first row of carpals.
The ends of the bones are covered with an elastic tissue, called cartilage. The cartilage makes a slick surface that makes the bones to move smoothly against each other.
If the cartilage gets damaged by an injury, infection or disease then the bones themselves will rub against each other, wearing out the ends of the bones. This causes a painful, arthritic condition.
Osteoarthritis is the most common form of arthritis which results from a gradual wearing away of the cartilage covering on bones.
Rheumatoid arthritis is a chronic inflammatory disease of the joints that results in pain, stiffness and swelling. Rheumatoid arthritis generally affects several joints on both the right and left sides of the body.
Both types of arthritis may affect the strength of the fingers and hand making it difficult to grip or pinch.
The patient for wrist replacement surgery has severe arthritis but does not need to use the wrist to meet heavy demands in daily use. The main reason for having wrist replacement surgery is to relieve pain and to maintain function in the wrist and hand.
Wrist replacement surgery may help retain or recover wrist movements. It can also better the ability to perform daily living activities specially if there is arthritis in the elbow and shoulder. The worn-out ends of the bones are removed and replaced by an artificial joint (prosthesis), during any total joint replacement.
In some instances, fusing the bones of the wrist together will reduce or eliminate pain and improve grip strength. However, if the bones are fused together, the wrist will not be able to bend.
There are several different types of implants. Most have two components, one for each side of the joint. These components are made of metal. A high-quality plastic, called polyethylene is used as a spacer between the two metal components. Newer implant designs try to replicate the anatomy of the wrist.
One component is putted into the radius of the forearm. The portion of this component that faces into the wrist joint has a curve that fits a second component placed on the wrist side.
The component that puts into the hand bone (the carpal component) has a flat surface that faces the first component. It inserts into a carpal bone through one long stem and one or two shorter stems.
A plastic spacer fits between the components in the joint area. Spacers are present in different sizes so that they can match the hand. A spacer is normally flat on one side and rounded on the other. This design enables it to fit into the carpal component while it rocks on the radial component, creating a more natural wrist motion.
Wrist joint replacement can be performed as an outpatient procedure, unlike a hip or knee replacement. Wrist replacement surgery is often combined with other procedures to correct deformities or disorders in the tendons, nerves, and small joints of the fingers, and thumb.
A cut is made on the back of the wrist. The damaged ends of the lower arm bones are removed and the first row of carpal bones may also be removed.
The radial component of the prosthesis is inserted into the center of the radius bone on the outside of the lower arm. It is held in place with bone cement.
Depending on the component design, the carpal component is then inserted into the center hand bone (third metacarpal) or screwed into the remaining row of carpal bones. Bone cement can be used to grip the component in place.
The carpal bones may be linked or fused together to better secure this component. An estimated sized spacer is used between the metal components.