Meniscal Allograft

Evan Herrold
ActiveLifeNetwork
Copyright 2000

A meniscal allograft is an infrequently performed operation. The procedure is typically performed on younger patients, and is usually considered a last option to delay the onset of arthritis or the breakdown of articular cartilage in the knee. For some patients, the operation can provide excellent results. Just a year after her meniscal allograft, Jaycie Phelps, a 1996 Olympic Gold Medal gymnast, had returned to competitive gymnastics, an event that demonstrates the possibilities of the procedure.

Jaycie had sustained a complete tear of the meniscus, severely limiting her athletic ability, and completely ruling out any competitive activities. Without a healthy meniscus, Jaycie's knee joint would have likely suffered many long-term problems. Typically, the joint deteriorates and arthritis can begin to limit movement in only a few years after the injury. Since the meniscus forms a critical "shock absorber" function in the knee, any damage will immediately be recognizied as pain as the femur and tibia rub against each other.

The procedure

A meniscal allograft is a relatively new procedure. Using a process similar to grafting tissue from hearts, livers or other organs, the meniscal cartilage must be recovered from a donor and correctly preserved within 24 hours of the donor's death. The meniscal tissue is treated with antibiotics, measured and catalogued, and is then frozen using a process to preserve the structure of the proteins and tissue.

The meniscal graft is transplanted to the knee through an arthroscopic operation. The graft is shaped to fit within the patient's remaining healthy bone and cartilage, and is then fixed in place with sutures and bioabsorbable fixtures. Although the graft mimics and replaces the mechanical characteristics of the patient's own meniscus, the transplant may still be rejected during recovery.

In Jaycie's case, an osteochondral autograft transfer (OAT) was also performed to further reinforce the damaged knee. During this procedure, a composite of cartilage and underlying bone from a non-critical area of the knee is transferred to a damaged area, resurfacing part of the joint and supplementing the benefits of the meniscal autograft.

An extensive and rigorous rehabilitation regimen is required following these procedures. During the first six months after surgery, patients are restricted from running, pivoting, deep knee bends or squatting activities that may put the graft at increased risk for dislodging. The graft is monitored very closely for at least a year following surgery for both signs of rejection and to evaluate the mechanical integrity and function of the meniscus. Patients are instructed to minimize and to control unnecessary forces acting on the knee. Re-learning correct form while performing such elementary activities like walking and standing is also important to the success of the procedure.

The Prognosis

The operation has significantly altered and delayed the onset of degenerative arthritis in Jaycie's knee, and has added back to the cartilage cushion, enabling her return to some competitive gymnastic activities. Still, her knee remains susceptible to re-injury, demanding that she avoid highly strenuous impact activities.

Damage to the meniscal cartilage is the most common of knee injuries ultimately leading to arthroscopic surgical intervention. Approximately 750,000 operations are performed each year to address these injuries. Only a small segment, or about 15% of meniscal tears can be repaired; the remaining 85% requiring removal of all or part of the meniscal cartilage.

Patients with meniscal damage, like nineteen-year old Jaycie Phelps, have seen encouraging results with the innovative allograft. The procedure has seen the greatest benefits in young individuals when performed prior to development of any joint damage. At the American Society for Sports Medicine's annual meeting, Thomas Carter, MD, reported that in a study of 33 patients, 80% of meniscal allograft recipients had increased activity levels and symptomatic improvement in a 2-5 year follow up study. Still, meniscal allografts are not uniformly successful or predictable, and further research and long-term studies are necessary to gauge results of the procedure.