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Joint Preservation
By Samuel D. Murray, Jr., M.D
We have all been taught the benefits of an active lifestyle since our youth. When we advance in age the consequences of repetitive, high impact exercise become painfully clear.
In the year 100 AD, Galen (respected Greek physician and philosopher) said "Athletes over indulge, live shorter and get arthritis (painful inflammation and stiffness of the joints)."
As Galen noted, our joints, particularly our knees, take a beating from many types of exercise.
While total knee replacement is a time-honored solution for loss of protective cartilage of the knee, it is not the only solution. The ends of bones that make up the joint are covered with a tough, smooth surface called articular cartilage. Articular cartilage covers the end of the femur, the top of the tibia, and the back of the patella. It serves as a shock absorber and is essentially frictionless, providing a smooth surface for the contact and movement of the bones of the knee joint. When this covering tissue is damaged by wear and tear of trauma, it does not have the capacity to heal like other tissues of the body. As a result, the bones will begin to rub against one another causing pain and stiffness of that joint. Now rather than replacing the entire knee joint, advances in biological engineering have given us some new techniques to restore this covering of the bones making up the knee joint. These techniques involve using the patient's own tissues. The various techniques used can be one of the following:
- Bone plus cartilage graft- ing.
A plug of bone and cartilage from a non-weight bearing portion of the knee joint is removed and then is "plugged" into a hole made in the damaged area. This is known as OATS or mosaicplasty.
- Autologous Chondrocyte Implantation.
This involves two separate procedures. In the first, cells are taken from a healthy area of the knee by using an arthroscope. They are then biologically treated so they will grow many new cells. In a second procedure, a patch of tissue lining the bone is harvested and sewn over the defect in the joint. The cells grown in the lab are then injected under the patch where they will eventually produce more cartilage to repair the worn out area.
- Marrow Stimulation (Microfracture).
In this technique, multiple small holes are made in the defect using an awl. A clot forms and then cartilage similar to, but not the same as the original forms. This is done through the arthroscope so it is a single surgery.
Looking to the future, we see that new technology will allow doctors to harvest cells known as mesencheymal stem cells (MSC). These cells are relatively undifferentiated and as a result have the potential to develop into several types of cells, depending on their environment and surrounding stimuli. MSCs are located in the patient's bone marrow as well as in the tissue covering the bone. The procedure to replace cartilage with MSCs is performed by the physician taking an aspiration of bone marrow then placing the cells in a gel. The gel is then inserted into the patient's cartilage defect. The MSCs then organize into the structural scaffolding normally found in cartilage and are then able to repair the problem causing lesion in the bone.
Who is a candidate for these procedures? There are several factors that have to be considered when deciding which patient will benefit from a cartilage repairing procedure. Not everyone with arthritic knees can have this done. Size and location of the defect, type(s) of previous surgery, patient's age, the cause of the arthritis and most importantly, the patient's demands and expectations all have to be entered into the decision making process before deciding if this surgery will help.
Results:
According to the literature, overall chondral resurfacing results produce around 85% successes. No matter which surgery is used to restore the worn out cartilage, problems such as unstable ligaments and malalignment (knock-knee or bowleg) have to be solved concomitantly. Rehab is also critical. Just as you would not want to walk on a freshly tilled yard when you have just planted grass seed, you want to avoid compression of the defect by now putting full weight on it for 6 - 8 weeks.
Not everyone is a candidate for restoring lost knee joint cartilage so ask you Orthopaedic Surgeon if it can help you.
For more information about cartilage replacement or other orthopedic concerns - contact Dr. Murray at Chatham Orthopaedics, 4425 Paulsen Street, Savannah, GA 31405,
(912) 355-6615
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