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Allograft transplants relieve pain and swelling in meniscus-deficient knees
The transplant procedure works best in patients who show minimal degenerative changes.
Meniscal allograft transplants have a function in treating meniscal injuries, but how substantial that purpose is has yet to be determined, according to one investigator.
“There is a role for this procedure in the treatment of the meniscus-deficient knee with symptoms of pain and swelling,” Scott A. Rodeo, MD, told Orthopedics Today. “Current data suggests that the procedure can reliably improve symptoms in such patients as long as there are not advanced degenerative changes. However, we do not have any data at this time to prove that meniscal transplantation can change the natural history of progressive degenerative change in these knees.”
Rodeo presented a review of meniscal allograft transplants, including graft size, surgical technique and current indications at the 10th Annual Insall Scott Kelly Institute Sports Medicine and Total Knee and Hip Symposium in New York.
Images: Rodeo SA |
At the Hospital for Special Surgery in New York, Rodeo and colleagues use fresh-frozen tissue for meniscus allograft transplantation. They use nonirradiated tissue unless there is an initial high bioburden, in which case, the tissue will receive low-dose gamma irradiation.
Keys to success
There are several keys to the success of this procedure. For example, it should be done before there are advanced degenerative changes in the knee, Rodeo told Orthopedics Today.
“In particular, the results are less predictable once there are changes in joint architecture (flattening of the femoral condyle) and/or full-thickness cartilage loss,” he said.
Graft size is critical to success, according to Rodeo. “It is recommended that graft size be within 5% of your native meniscus.” Rodeo suggested using plain radiographs with a magnification marker (to correct for magnification) to size the transplant. MRI is also useful in sizing grafts, he noted.
“You want to try to achieve close sizing. If anything, have a transplant that is a bit larger than you would measure for your patient,” Rodeo said during his presentation.
Surgical technique is also important, he said. “The goal here is to reproduce anatomy.”
Rodeo’s surgical technique includes an arthroscopic-assisted approach using bone plugs in 9-mm tunnels. “You want this to be a somewhat loose fit,” he said. “You don’t want to have to struggle at the back of the knee placing the bone plug into the posterior horn tunnel.” He uses ACL vector guides to drill the tunnels and place the meniscal transplant.
For the lateral meniscus, he uses a common bone slot connecting both horns.
“Basic laboratory studies demonstrate that bone fixation provides better restoration of contact mechanics compared to just using sutures at the anterior and posterior horn attachment sites,” he told Orthopedics Today.
“In fact, several studies have demonstrated that any biomechanical advantages of the transplant are generally lost without bone plug fixation of the horn attachment sites,” Rodeo said during his presentation. “That can be done with individual bone plugs at each horn or a common bone spot.”
Indications
Rodeo has four current indications for meniscus transplantation. The most common is the meniscus-deficient knee with signs of early arthrosis, compartment overload, pain and swelling. These patients should have minimal articular cartilage degeneration; the knee should be stable and have proper axial alignment. The femoral condyle should not be flattened.
The second indication is a combined meniscal transplant with a cartilage resurfacing procedure or osteotomy for patients with an absent meniscus. “I think the rationale is simply to protect your cartilage graft,” Rodeo said
The third indication is in cases of ACL reconstruction with a medial meniscus deficiency. “We know there is biomechanical interdependence between the ACL and the medial meniscus,” Rodeo said. “The medial meniscus is an important secondary restraint to anterior-tibial translation in the ACL-deficient knee.”
Because failure rates are higher in revision ACL procedures, Rodeo encouraged surgeons to consider a concomitant medial meniscus transplantation if the meniscus is absent in these cases.
“There is clinical data from Don Shelbourne demonstrating worse results with ACL reconstructions if the medial meniscus is absent. In that setting, you might consider meniscus transplantation,” he said.
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Prophylactic transplantation
The fourth indication is prophylactic transplantation. Rodeo does not recommend this procedure for asymptomatic patients with normal articular cartilage. He will consider it for patients who are minimally symptomatic with early articular cartilage degeneration. These are generally healthy patients who have undergone a lateral meniscus resection, he said.
“Changes can progress rapidly in the medial compartment,” Rodeo said. “Again the goal is to prevent the known sequelae of meniscus loss. The challenge for us is to detect early cartilage degeneration before advance changes occur.”
According to Rodeo, meniscal transplantation is contraindicated in the following cases:
- advanced arthritis;
- diffuse subchondral exposure;
- full-thickness cartilage loss;
- architectural changes (eg, condylar flattening);
- axial malalignment; and
- persistent instability.
“I think there is a role for meniscus transplantation in the treatment of post-meniscectomy pain,” Rodeo said. “The procedure offers predictable pain relief and better results if performed in patients with minimal degenerative change.”
For more information:
- Scott A. Rodeo, MD, can be reached at the Hospital for Special Surgery, 535 E. 70th Street, New York, NY 10021; 202-606-1513; e-mail: rodeos.hss.edu. He has no direct financial interest in any products or companies mentioned in this article.
Reference:
- Rodeo S. Overview of meniscal allografts. Presented at 10th annual Insall Scott Kelly Institute Sports Medicine and Total Knee & Hip Symposium. Sept. 14-16, 2007. New York.