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The Total Truth about Total Joints
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Posted on: 02/21/2001
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Total joint replacement is very successful for most people. As a result, it has become much more common--and its drawbacks are becoming more obvious. One of the major problems with artificial joints is called creep. Creep is a gradual change in the shape of the plastic as it is pressed down. Creep tends to happen within the first 18 months of surgery.
A bigger problem is joint wear, erosion of the replacement parts that happens over the life of the joint. As the parts rub or move against each other, the joint starts to wear, causing small wear particles to build up in the joint. The wear particles are like the sawdust that results from sanding a piece of wood.
Today's replacement parts are affected by different causes of wear. Adhesion happens when the bonded surfaces get pressed together, causing one of them to loosen up. Abrasion is when the harder surface rubs the softer one like sandpaper, releasing wear particles into the joint. Fatigue is when the components get overstressed from heavy or repeated activity, contributing to wear particles and to possible failure of the artificial joint.
Some types of joint wear are unavoidable. Other types of wear happen when the parts rub and move in unintended ways. The authors highlight some of the causes of wear, including problems with anchoring the replacement joint, unusual stresses, and methods of sterilizing the components.
The authors also addressed the problem of bone loss in the bone that connects to the replacement parts. This bone loss is called bone resorption. It happens from a reaction to the small wear particles that build up. It can also happen if the artificial joint somehow allows the bone to come in contact with joint fluid.
The authors conclude that improving the durability of artificial joints requires finding ways to limit wear and the resulting wear particles. It will also require finding ways to keep joint fluid from coming into contact with the underlying bone.
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References:
Thomas P. Schmalzried, MD, and John J. Callaghan, MD. Wear in Total Hip and Knee Replacements. In The Journal of Bone and Joint Surgery. January 1999. Vol. 81-A. No. 1. Pp. 115-136.
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*Disclaimer:*The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic. |
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