Collagen Implants For Meniscal Regeneration

Each year, nearly one million Americans injure a meniscus in their knee. The menisci (plural of meniscus) are crescent-shaped wedges of tough, fibrous tissue that act as cushions between the ends of the femur (thighbone) and the tibia and fibula (lower leg bones). Each meniscus acts as a shock absorber and helps to protect the articular cartilage that covers the ends of the femur and tibia. The meniscus also assists in lubricating the joint and stabilizing the knee during rotation.

The meniscus can tear during sudden twisting of the knee or from blunt or repetitive forces. Injury to the meniscus can result in pain, swelling, and occasional giving way and locking of the knee. The blood supply aids in healing these injuries. The blood supply is good around the outside rim of the meniscus, which aids the healing process; however, the interior portion of the meniscus has a minimal blood supply. Because of its poor blood supply and inability to repair itself, an injury to the inner portion of the meniscus usually requires a meniscectomy, or removal of the damaged or torn part of the meniscus. Without the protection of the meniscus, the knee joint can become unstable, and the articular cartilage covering the femur and tibia may begin to deteriorate, resulting in degenerative osteoarthritis ("wear-and-tear" arthritis). If a torn meniscus is causing symptoms, it should be treated. In years past, surgeons often removed the entire meniscus. We now know that this practice can also result in osteoarthritis, so today, only the torn portion is removed.

Currently, physicians at 13 sites in the U.S., including the Hughston Clinic, are involved in a study to determine the safety and effectiveness of the collagen meniscus implant (CMI) as an alternative to removing the meniscus. The CMI is an investigational device manufactured by ReGen Biologics, Inc. (Franklin Lakes, NJ), and is only available to patients participating in the study. The CMI is made of bovine (cow) collagen and is a biocompatible (compatible with living tissue), resorbable (absorbed by living tissue) material that is arthroscopically (surgery through small incisions in the skin) sewn into the area where the meniscus tissue is missing. Once in place, the CMI provides a scaffold or bridge onto which the body's own meniscus cells can begin to migrate and form new meniscus tissue. Over time, as the regeneration takes place, the body naturally absorbs the CMI, leaving the new meniscus tissue. The CMI provides an alternative to the removal and permanent loss of meniscus tissue that occurs during a meniscectomy.

To be eligible to participate in the CMI research study you must be between 18 and 60 years of age and have had at least one but no more than three previous surgeries involving the meniscus in your knee. Candidates will be examined and evaluated by participating physicians before entering the study group.

You can find more information about the CMI research study on the ReGen website at www.regenbio.com, or call Cynthia Wolfe, clinical coordinator for the Hughston Sports Medicine Foundation, for more details at (706) 576-3333.

Ashley Holloway, M.S.
Columbus, Georgia

Further Reading:
Rodkey WG, Steadman JR, Li ST. A clinical study of collagen meniscus implants to restore the injured meniscus. Clin Orthop. 1999;365S:S281-S292.
Stone KR, Steadman JR, Rodkey WG, Li ST. Regeneration of meniscal cartilage with use of a collagen scaffold. Analysis of preliminary data. J Bone Joint Surg Am. 1997;79:1770-1777.