Popular Cadaver Grafts Dangerous for Young ACL Patients
Physicians referring active, young patients for anterior cruciate ligament (ACL) reconstruction should be aware of new data about using cadaver grafts, some Arkansas surgeons warn. Two recent studies have found that athletes age 40 and younger, who have their ACL reconstructed using cadaverous tissue, are at a significantly higher risk for graft failure than are older, less active patients.
Approximately 80,000 patients experience torn ACLs in the United States each year. A tear usually necessitates reconstruction, using either tissue from a cadaver (allograft) or tissue from the patient's own patellar-tendon bone or the hamstring tendons (autograft).
The first study, published in 2007 by researchers at the University of Kentucky, tracked 125 patients aged 19 to 69 who had the allograft reconstruction of the ACL. While 23.1 percent of the total study population required revision ACL reconstruction for graft failure and 37.7 percent required repeat surgery, the failure and repeat surgery rate for patients under age 25 was 55 percent.
A similar Mississippi Sports Medicine and Orthopaedic Center study released in July at the annual meeting of the American Orthopaedic Society for Sports Medicine (AOSSM) found a cadaver graft failure for these reconstructions in close to a quarter of patients aged 40 or under.
In a release by AOSSM, study co-author Kurre Luber, MD said that while choice of a replacement ligament remained a decision that must be made by surgeon and patient, the failure rate was alarming. The study followed 64 patients 40 and under for two years. As compared to a previous study of older patients with allografts who had a failure rate of 2.4 percent, the Mississippi study's younger patients experienced allograft failure 23.4 percent of the time.
"This study found a very high failure rate in patients 40 years and younger with high activity levels in ACL-dependent sports like tennis, basketball, soccer and downhill skiing," Kurre explained. "Certainly, it would be naïve to think that only the graft selection led to these failures, we also need to look at surgical technique (single versus double bundle). Better outcome measures also need to be developed. However, this study definitely raises questions about the validity of using cadaver tissue in this patient subgroup."
Little Rock orthopedic surgeon Eric Gordon, MD, who specializes in sports medicine, said that in the past few years allografts have become increasingly popular in the state and among orthopedists nationwide.
Although autografts using patella tendons have been the gold standard, those grafts are not without problems, including complex surgery, possible lasting knee pain and a difficult rehabilitiation. For those reasons, surgeons widely began using allografts in the late 1970s. Because the tissue has only to be defrosted, not harvested from the patient's own body, the surgery is much easier, Gordon said, taking only about half as long as an autograft reconstruction that uses the patient's patella tendon or hamstring.
Use of allografts dropped off sharply, though, with the emergence of HIV/AIDS, as the virus (and others such as hepatitis) could be transmitted via the cadaverous tissue and no tests were available to screen or treat the tissue prior to surgery. The past decade has seen a great resurgence in the use of allografts for ACL reconstruction, thanks to breakthroughs in testing and cleaning protocols for the tissue that made the surgery much safer and advances in the surgery itself.
While surgeons first used cadaver grafts for older patients who had low activity levels, study after study has shown them to be as good as or almost as good as autografts and Gordon said surgeons have been pushing those clinical indications for autografts to include younger and younger ages. Now, adolescents are frequent recipients of the cadaverous tissue.
The problem, said James C. Tucker, MD, of Arkansas Specialty Orthopedics, is that while the much-publicized overall numbers of previous studies show there to be little difference between the two types of grafts, those studies only looked at the success of the two types of grafts on patients as a whole.
"Until now, studies didn't stratify based on age and activity level. These studies are the first to examine these sub-groups. Now that we can see the data, the results are pretty dramatic," Tucker said. "The allograft is still a good option for many people and probably works fine for people who have moderate activity and are really not stressing their knee, particularly in the first year or two after surgery, but physicians should be aware that it has a very high failure rate for young patients."
That's because younger patients with ACL injuries tend to have much greater activity levels than their older counterparts, Tucker said. While a 40-something weekend warrior is likely to stress her knee once or twice a week, a high school student participating in team sports is likely to be practicing throughout the week and training at a very high intensity level.
"What we can see from these studies is that the cadaver grafts simply are not strong enough in many cases for the strain an active athlete is going to put on it," Gordon said, though he said the procedure is "very common."
Without this new information and presented with the two grafts as equal choices, patients may opt for the cadaver grafts, Gordon said. "The rehabilitation is much less painful with allografts, since you aren't harvesting tissue from elsewhere in the patient's body," he explained, "so it can be attractive to patients for that reason."
The allograft surgeries can be more affordable, as well, though Tucker cautions, that with up to a 40 percent failure rate, they aren't necessarily cost-effective.
Similarly, ACL reconstructions using allografts require a significantly longer recovery time—typically 9-12 months, Gordon said, compared to 4-6 months for autografts.
"That four-month versus nine-month recovery time can make all the difference in the world to a young athlete," Tucker said. "Say a junior in high school has an injury, keep them out nine months, you've basically ensured that they're not going to play again. It's a career-ender, before they even get started."
For young patients, the consequences of a reconstruction failure are similarly magnified. A failed reconstruction can lead to damaged cartilage and early arthritis. "They can have irreparable damage," Gordon said. "For an older person, that's bad, but it's something altogether more life-changing for a patient in their teens or twenties."
Any physician referring a young athlete for ACL reconstruction should be aware of the high failure rate for allografts in these patients, Gordon said.
"People are going to have a few questions about what's going to happen, and of course primary care physicians can defer to the surgeon, but they should know that allografts are definitely proven to fail frequently in young patients," he said. "They can help us as orthopedic surgeons on the front end by telling patients that they're probably going to need to have tissue taken from somewhere else in their body to reconstruct their ACL if they want to continue playing sports. Helping young patients understand that from the start can help us do our jobs better."