Cadaver tissue isn’t a sure fix
Note to those who have scrambled your poor knee: Using cadaver tissue to replace that torn anterior cruciate ligament may not be the best option if you’re active.
Researchers at Mississippi Sports Medicine and Orthopedic Center followed, for a minimum of two years, 64 active patients younger than 40 who had had ACL reconstruction with a cadaver replacement ligament (an allograft). The allograft procedure is a common alternative to the autograft, in which the patient’s tissue is used.
They found that 23.4% of the patients had required a second reconstruction because of injury or graft failure or had had poor scores on a combination of orthopedic outcome tests.
In general, graft failure is estimated to occur in up to 8% of both types of reconstructions, says co-author Dr. Kurre Luber, an orthopedic surgery fellow at Mississippi Sports Medicine and Orthopaedic Center in Jackson. He reported the findings last week in Orlando at the annual meeting of the American Orthopaedic Society for Sports Medicine.
“ACL replacement using allografts has been found to be very effective,” Luber says, “but there has been research suggesting that the allograft may not be as good in young athletic people, so we wanted to look at outcome versus activity level.”
Sports that involve jumping or quick turns are common causes of tears in the ACL, one of the knee’s four major ligaments. The patients enrolled in the study were those determined to be active based on their participation in competitive and recreational sports, as well as everyday activities as measured in a questionnaire.
One explanation for the increased failure rate among active patients, Luber says, is that allografts tend to take longer than autografts to become fully integrated into the knee. It could be that younger, more active patients tend to re-injure the knee before it’s fully healed.
The surgical technique may also have affected the results, he says. All patients were treated by the same physician who used a standard technique of grafting one bundle of ligaments to the injured area. Another technique involves affixing two bundles of ligaments to the area. Of course, the big question is how the group might have compared to a matched group of patients receiving an autograft in a prospective randomized trial, says Dr. Marc Friedman, orthopedic surgeon at Southern California Orthopedic Institute, headquartered in Van Nuys. “Who knows what the failure rate would have been in the autograft group?” he says.
Friedman, who performed 68 ACL replacements last year, says he always gives patients the option of either type of surgery and outlines the pros and cons of both.
Kurre is not suggesting that knee surgeons stop doing ACL allografts, which have a number of advantages over the autograft. Allografts don’t require a second procedure to procure a replacement tendon from a surgical site in the patient’s knee area.
In addition, the allograft requires less surgical time, and patients experience faster recovery of function and less pain and swelling. One of the advantages of the autograft is that it avoids the use of foreign tissue, which in very rare cases can transmit disease.
The next step would be to compare the allograft against the autograft procedure in an active population and look at other factors that could affect the results, he says.