Guest Editor,
Clinical Assistant Professor of Orthopaedic Surgery


When a teenage athlete commiserates with his or her grandparent about their respective knee cartilage injuries, it's likely that they're talking about different structures injured in different ways.

The young athlete likely has a traumatic injury of the cartilage caused by a misstep, accident or fall. Also known as semi-lunar cartilage because of its crescent shape, this is the shock absorber between the principle bones of the knee, the femur and tibia. It is composed of fibrous, gristle-like fibro-cartilage.

The older patient, perhaps the grandparent, points out a knee problem that may also include an injury and perhaps even a fall or misstep, but the underlying problem is likely wear-and-tear "osteo-arthritis." The structure most directly involved is a different type of cartilage, "articular", lining the ends of joint surfaces of all of the bones in the joint and composed of "glass-like" cartilage. This is best suited for compression as seen in weight bearing - walking, running, standing and increased with jumping or stair climbing.

Both of these cartilaginous structures are the focus of new, exciting and promising research. The traditional conservative mechanical measures are still applicable and appropriate. These include reducing bodyweight, soft-soled shoes and cane-assisted ambulation. These have the beneficial effect of reducing joint reactive force in weight-bearing joints, thereby reducing pain and slowing progression of arthritic changes. Similarly modified activities with an aim toward reducing loading upon weight-bearing joints are beneficial.

While anti-inflammatory medications have been widely used for many years going back to and including the standard - aspirin- newer medications have shown to be better tolerated, easier to take for long periods and more effective or as effective for control of inflammation. Aspirin remains the standard against which others are compared for relief of pain. Unfortunately, more than 50% of gastrointestinal side effects including bleeding ulcers are silent, i.e., not heralded by any symptoms. Common symptoms which might occur include an upset stomach, nausea, vomiting, diarrhea, constipation, esophagitis, heartburn, or bloating. There are newer medications used specifically as "mucosal-protection" to prevent symptoms and more specifically potentially dangerous complications. A new combination medication contains non-steroidal anti-inflammatory medication (diclofenac) and a coating of the mucosal protection medication (misprostal). A newer sub-class of arthritis medication now in experiment and available in the coming year is "Cox-2 inhibitors". This type of medication is able to separate anti-inflammatory properties that work in joints from anti-prostaglandin properties which adversely affect the gastrointestinal tract. It is helpful in reducing pain, swelling, warmth and stiffness in joints without irritating side effects in the GI tract.

New treatments have emerged from basic science experiments to clinical trials to FDA-approved treatments for use in medical practice each day. Many disciplines are involved in this new hot area of research and new studies and findings are stimulating additional research. Not all injuries are appropriate for any one treatment or perhaps even for treatment at all.

Chondroprotective agents have become popular in the past few years. Chondroitin sulfate is thought to be possibly too large a molecule to be absorbed, but there is evidence that glucosamine is absorbed and shows up in joints. These structures are both components of normal articular cartilage. Injectable hyaluronic acid is available, replacing a factor also normally in health joints, and treatments of 3 to 5 injections seem to give relief perhaps by improving lubrication.

Microfracture techniques attempt to stimulate healing of surface cartilage by surgically (and most often arthroscopically) driving a surgical pick through the area of injured cartilage into the underlying bone to stimulate a healing response channeled to the surface.

New surgical techniques developed and continuing to evolve include arthroscopic treatment enhancing the treatment and understanding of meniscal tears. These triangular-shaped shock absorbers between the bones were once treated with removal much like the appendix that was discarded as a vestigial structure. As the role of meniscal cartilage has become better understood, including its protective effect for articular cartilage, efforts to preserve function led to partial removal of torn tissue-retaining as much functioning meniscus as possible. Current efforts address repair of tears, techniques to enhance healing and, when absent or severely damaged, to replace the meniscus.

Among innovations in treatment of damaged articular cartilage is Autologous Chondrocyte Injection in which a patient's own cartilage is first harvested and sent to a lab for incubation and cell growth. In a second operation, a patch of connective tissue is sewn over a defect in the normal cartilage and the newly returned incubated cells are injected beneath this patch. Early motion is encouraged but weight-bearing delayed. Results to date are promising in restoring fairly large defects.

Defects in articular cartilage can be addressed with cylindrical plugs measured to appropriate size a less critical area within the joint. This is analogous to hair-plug transfers used to treat baldness. Multiple plugs can be used to fill slightly larger areas.

Arthritis and articular injury continue to pose problems magnified by a population that wishes to remain active into middle and old age. We certainly don't have all the answers but inroads into this frontier point to progress ahead.

The advice provided on this website is intended to be general in nature and should not be relied upon for specific treatment. If you need personal medical attention please contact your physician.

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