ACL reconstruction and graft maturation
- Q: Talk about the different types of ACL injuries and how that determines the course of action for repair.
- Adam Anz, M.D.: With an ACL injury, there are a number of different grafts that can be used to reconstruct an ACL. As we look back through the history of ACL reconstruction, we initially started with your body's own inner third of your patellar tendon. Then we started looking at other grafts like your hamstring tendons, your quad tendon, and we also started looking at other tendons such as cadaver grafts. We typically call a cadaver graft an ‘allograft.’ Allografts really sprang up in the 1990’s and had some good initial thoughts around it. As we looked at some of the outcome studies in the 2000’s, we found that there was likely a higher failure rate of allografts, especially in younger people than compared to autografts. This is likely related to your body's ligamentization process – and that big word just means, a tendon graft turning into a new ligament. That process is variable, and it's dependent upon things that we can’t always quantify like your immune system or your system within your body that interprets change. We think that the immune system may be the reason that allografts may have a higher failure rate in younger individuals – because your immune system may see that as foreign and won’t incorporate robustly. Allograft to me is something that I sometimes have to use for multi-ligament knee injuries or when people tear their ACL, PCL and the MCL all at one time, because we don't have enough graft to go around and we have to use allograft. But when it's just an ACL reconstruction, I avoid allograft because to me it's a variable – the variable of your immune system as well as the variable of how it's going to respond to that graft makes me nervous. For that reason, I always choose autograft if I can.
- Q: Talk about the difference between an autograft and an allograft.
- Adam Anz, M.D.: Choosing a graft for a patient is really dependent upon the individuality of the patient. Whether it be age, what sport they prefer and also what job they perform as well. For instance, with a patellar tendon graft, which is from the front of the knee and the central third of the patellar tendon, if you have to do an occupation where you're on your knees for a long period of time during the day, you may have some pain in the front of your knee. For that reason in those patients, I tend to use a hamstring graft. Alternatively for the majority of my patients, I do prefer the patellar tendon graft because you take a piece of bone plug from your patella and from your tibia and we're using those bone plugs pushed into tunnels of bone so it heals quite robustly. For our younger patients though, they have open growth plates in some instances and in those instances, I tend to use it a hamstring graft or a quadriceps graft.
- Q: What can a patient expect post-operatively based on the ACL treatment?
- Adam Anz, M.D.: With ACL reconstruction, it is true that if we take autograft you do have some more pain after the surgery. That may not necessarily be a bad thing. When we go back to thinking about allograft and there are some higher failure rates in some studies in younger patients, one of the problems is they probably don't hurt in terms of that three-week, that four-week, that six-week time period, and they may go back to activities before the graft has had time to mature. So some of the discomfort that you have after surgery slows you down a little bit which is good in terms of allowing your body to heal. For instance, when we take a bone tendon bone plug, it does have some pain in the front of the knee, but that helps in terms of your recovery by giving you respect for what was done whether you like it or not. I had an allograft in a 52-year old male who was the perfect patient for an allograft and at six weeks he tore his graft because he jumped up on a chair to change a light bulb, and then jumped down and that's at a time when the graft is just not mature yet and not ready for that jumping down force. For that reason I believe autografts are the best grafts out there.
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