When faced with ACL surgery choices, there are two types of common ACL grafts available, but is there a difference? When an ACL is reconstructed using a tendon from another human, this is called an allograft. When the ACL is reconstructed using a tendon from your own body, this is called an autograft. But the differences don’t stop at the source of harvest; based on a long-term study of ACL allografts versus autografts, allografts have three times the failure rate!
With surgeons racking up about 250,000–300,000 ACL surgeries a year, and the average cost for an ACL surgery in the U.S. running from just under $20,000 to about $50,000, we need to explore the importance of graft choice more in depth; however, first you need to understand what an ACL tear is and what type you have and make sure ACL surgery itself is the right choice.
The Types of ACL Tears
The ACL is a major stabilizing ligament of the knee, and a surgical replacement is never like the original equipment. ACL tears are common in sports, such as football, soccer, and volleyball, that put a lot of pressure on the knees. There are three very different types of tears, and yet most patients only hear of two.
- Partial ACL tear—These ACL tears don’t require surgery, and in our experience, they can be easily fixed with a simple injection under x-ray guidance.
- Complete retracted tear—In these tears the ligament has snapped back like a rubber band. Most patients believe that when they see the phrase “complete tear” on their MRI reports, they have this kind of tear, yet unless you also see the word “retracted,” you don’t have this kind of tear. While complete retracted tears are likely to require surgery, be sure your tear is retracted; if there’s even a small bit of fiber remaining, repairs may be possible without surgery. Also MRIs can be misleading; this patient’s MRI showed a grade-3 complete ACL tear, but we discovered that the fibers of her knee were mostly intact.
- Complete nonretracted tear—On the MRI these tears look like the fibers are torn all the way through the ligament, but there’s still something holding the ligaments together because it hasn’t snapped back. We see lots of these ACL tears and have fixed many through injection without the need for surgery.
So how do you find out what type of ACL tear you have? Check your MRI report for the word “retracted.” If you don’t see it, your ACL tear may be easily fixed without surgery using the Regenexx-ACL procedure. Also, don’t be dismayed if you don’t see the term “nonretracted” as radiologists only sometimes use the term.
Once you know what type of ACL tear you have, it’s time to decide if surgery is the right choice.
ACL Surgery Choices: Is ACL Surgery the Right Choice?
During surgery the natural ligament is torn out, and the graft tendon is inserted into tunnels that have been drilled into the bone. No matter which graft is used, one of the big problems with the surgery in general is that the graft tendon is inserted at a much steeper angle than the original ACL.
Most patients don’t realize that there can be quite a few problems with the surgically replaced ACLs. First, for example, with an autograft, the muscle the tendon graft is taken from never fully recovers its strength. Second, the operated knee never regains its normal position sense to guide normal landing. Finally, few patients ever return back to their prior levels of sports, and two-thirds of young ACL surgery patients will have arthritis by the time they’re 30. In addition, the new surgically installed ACL ligament has no ability to sense stretch, so the knee loses proprioception, or sense of position. As a result, we often recommend to our patients that they consider newer precise biologic injection options, like stem cells, before considering a surgical ACL replacement.
However, let’s say you’ve made the decision and feel confident ACL surgery is right for you. Now you need to consider your graft choice: allograft or autograft.
The Two Grafts: Allograft vs. Autograft
An allograft for an ACL surgery comes from a human cadaver donor, typically from a tissue bank. Donor tendons that are commonly used include the patellar and the Achilles tendons. An autograft for an ACL surgery is harvested directly from your own body. Tendons that are commonly used include the hamstrings and patellar tendons.
A study presented at the American Academy of Orthopaedic Surgeons Annual Meeting put its hat in the ring to answer the question of whether an allograft or autograft ACL was better.
The researchers looked at 100 surgeries in young patients (ages 26–28) using either a tibialis posterior allograft or a hamstring autograft from the patient. The grafts were fresh frozen, and the patients were randomized (meaning the surgeons didn’t pick who got which ACL type). The allograft group failed at three times the rate of the autograft hamstrings-tendon group, which was different from other less-well-designed studies that had shown they were the same.
Why did they see this poor showing for allografts? First, while surgeons have thought for years that recipients of ACL allografts don’t reject the ligament or tendon, there could be some minor rejection of the foreign tissue. Second, and perhaps more likely, the preparation of the graft could be causing the difference. For example, allografts are often irradiated to kill any possible communicable diseases from the donor. A recent study showed a higher failure rate in allograft ACLs that were irradiated versus those that were not.
While an ACL autograft appears to have a lower chance of failure than the ACL allograft, there’s still the fact to consider that the strength of the muscle the graft was harvested from never fully recovers.
The upshot? While an autograft may be the better of the ACL surgery choices, it is still not the ideal choice, and other options should be explored, especially if you have only a partial or complete nonretracted ACL tear. You may be able to avoid the surgery altogether by using your own stem cells precisely injected into the ACL tear. However, if your tear is beyond that scope, use your own hamstrings tendon for now to replace the ligament, as nobody wants to undergo a big surgery with big downtime and not give that new ACL its best shot at thriving!