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Cartilage Replacement

Is cartilage replacement possible for knee arthritis?

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Updated March 10, 2008

cartilage replacement repair

The ideal treatment for a worn out joint would be to replace the damaged cartilage.

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Many patients with knee arthritis want a solution for their problem other than artificial joint replacement surgery. Arthritis causes joint problems because of loss of cartilage within the knee. This leads to the symptoms of arthritis including:
    • inflammation,
    • swelling,
    • and pain.
These symptoms of knee arthritis tend to worsen as the arthritis progresses. Therefore, the logical conclusion would be to simply replace the worn out cartilage with new cartilage -- a cartilage replacement procedure.

Can cartilage be replaced?
Unfortunately, a cartilage replacement procedure is not as simple a task as we would hope. Cartilage cells can be cloned and reproduced in a lab. The real problem arises when we want to place those cells in a particular location, and get them to function effectively in that area. Cartilage is a complex tissue; in order for cartilage to function it must be able to withstand tremendous forces. Simply injecting cartilage into a joint would serve no useful purpose, those cells would be destroyed in a short time.

What is the problem with cartilage replacement?
The problem is that no one has been able to figure out a way for the body to accept new cartilage, and allow the cartilage to adhere to the surface of the joint. Once on the joint surface, the cartilage must be able to support the weight of the body, and glide smoothly to allow motion. Many scientists are working on ways to accomplish these goals, but there is no solution right now.

I have heard cartilage cells be grown in the lab?
Yes. There are surgical procedures that use cartilage cells that have been harvested from a patient, cloned and reproduced in a lab, and then reinserted into the patient. However, these cartilage cells can only be inserted into relatively small holes in the cartilage, not to "resurface" a worn out, arthritic joint.

There are possible solutions for patients with limited area of cartilage damage, but this is not an arthritis treatment. These cartilage replacement techniques are for patients with limited areas of cartilage damage, often caused by sports or traumatic injuries. These areas of cartilage damage have to be small, not the widespread damage seen in arthritis.

How can cartilage replacement succeed?
In order for cartilage replacement to become a reality, a few basic problems must be resolved.

  • Scaffold
    Cartilage is more than just cells. In fact, cartilage is a tissue made up mostly of non-cellular material including water, collagen, and other proteins. Injecting cartilage cells into the knee does not address the other components of cartilage that also need to be in place.

  • Adherence
    Cartilage forms a think lining on the end of the bone. Finding a way for cartilage to adhere to the bone is difficult.

  • Joint Damage
    As knee arthritis progresses, the joint becomes further damaged over time. This damage includes the formation of bone spurs, the flattening of the normally rounded ends of the bone, and changes in alignment of the joint. These changes make restoring a joint impossible even if cartilage replacement were a possibility.
Why haven't these problems been solved?
Thousands of scientists and research physicians are trying to address this problem of how to develop a cartilage replacement for knee arthritis patients. While there are surgical procedures for cartilage replacement in patients with limited areas of damage, there is no procedure for cartilage replacement in knee arthritis. There certainly has been progress, and we are closer to a solution right now than we were a few years ago, but there is no cartilage replacement procedure presently available for knee arthritis patients.

Future research is looking into solutions that involve the use of growth factors and genetic engineering to direct the body to repair cartilage. The body does a poor job of repairing cartilage damage on its own, and future research is directed at being able to manipulate the body to repair damage before arthritis destroys the joint.

Sources:

"Questions About Stem Cells" American Academy of Orthopedic Surgeons. September 2007.

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