Imagine you are a high school athlete here in the Charleston area.
You land awkwardly from a jump, instantly feeling a pop and excruciating pain. Minutes later, your knee looks like a basketball, and you can barely bend it without pain. The following day, your team doctor examines your knee.
Yes, it's bad news. You have torn your ACL. Your season is over. Inevitably a myriad of questions for the surgeon race through your mind (and your parents’). How long will you be out of sports? How quickly can you have surgery? But one of the most important questions you should ask might be which graft options for an ACL reconstruction are best.
Re-injury rates for autografts and allografts
A 2012 study in The American Journal of Sports Medicine examines survivorship of autografts (using the patient’s patellar tendon or hamstring tendons) and allografts (using tissue from a donor) in ACL surgery.
The researchers studied cadets entering the U.S. Military Academy from 2007-2013 who had undergone ACL reconstruction prior to arriving. I think their findings are worthy of discussion. 120 cadets who had undergone 122 ACL surgeries were followed during their time at the Academy by the researchers. 20 ACL grafts failed (the cadet re-injured his or her ACL) at an average of 545 days after starting at the Acdemy. 10% of the females with a history of prior ACL surgery had a graft failure, 19% of males suffered a re-injury. There was no difference in failure rates or time to failure between the patellar tendon autografts and hamstring autografts.
On the other hand, the failure rates were significantly different between autografts and allografts. Cadets who had an ACL reconstruction using an allograft prior to entering the USMA were 6.7 times more likely to suffer a recurrent ACL injury compared to those who had an autograft procedure. Even more remarkable were the one- and two-year findings. One year after entering the Academy, 33% of the cadets who had an allograft ACL before entering had experienced subsequent graft failure, compared with only 2% of those who had an autograft.
At the 2-year follow-up point, more than half of those who entered the Academy with an allograft had experienced graft failure compared with only 6% of those who entered with an autograft. The researchers concluded their concerns with the cadaver grafts: “This study demonstrates that individuals entering the US Military Academy with an allograft ACL reconstruction were significantly more likely to experience clinical failure requiring revision reconstruction when compared with those entering with autologous grafts.”
Factors involved in graft selection
I present this study because I think it is important for patients to consider the graft options. There is tremendous variability among the surgeons across the U.S. and the world about a number of ACL surgical choices, including the graft selection. A number of factors can affect graft choice as well, such as the age of the patient, activity level, and whether the surgery will be a primary or revision ACL reconstruction.
Allograft usage for ACL surgery appears to be increasing. For less active patients, these grafts may be acceptable choices. This study creates concern in my mind about using them in young, active patients. Yes, the authors studied military cadets, but I would point out that cadets are essentially high-level athletes like we see in high school, college, and pro sports. Pros and cons of allografts
Choosing a graft for ACL surgery comes down to risks and benefits. Yes, there is donor site morbidity, like pain at the harvest site and early weakness from taking tissue from the patient's knee. Allografts don't have those harvest site problems, but they have increased costs and potentially slower graft incorporation times. This study appears to show that young athletes need to consider much higher failure rates if they choose to use an allograft. If you are preparing for ACL surgery, talk to your orthopaedic surgeon about the risks and benefits of all the different option and make the decision that fits your needs.