An Overview of Graft Selection
Dr. Hunt: Hi, I'm Dr. Stephen Hunt, sports medicine specialist here at Tri-County Orthopedics. In today's video I'm going to speak about ACL graft options.
When an athlete tears their anterior cruciate ligament, it's a very difficult time for both that athlete and their family. There are a lot of uncertainty and unknown factors about their treatment and potential surgery. I hope that through today's video you will have some information that can help you make a better decision about going forward.
When the anterior cruciate ligament is torn, it's one of the few ligaments in the human body that is not a minimal to repair, therefore, we have to use graft or scaffolds to try to reconstruct this ligament. We do this by taking tissue from either the patient or from a cadaver and reconstruct this ligament so it will provide the proper function to allow the athlete to return to such activities such as running, jumping, twisting, pivoting, cutting, which are all necessary for athletic performance.
Regardless of which graft you choose, all graft tissue requires a period of time for your body to convert it into living tissue, therefore all the grafts act as a scaffold that your body will eventually turn into living ligament tissue to allow you to return to your athletic performance.
In sports medicine, we use grafts when we do not have enough tissue to repair, or the quality of the tissue is not good enough for a repair. In general, ACL injuries are not a minimal to repair, therefore we use the graft tissue to try to restore the function of that ligament to the knee.
In general, there are two types of grafts we use for ACL construction. Autografts are when you take the tissue from the patient and use it during the reconstruction. The two main types of autografts that I perform include patellar tendon autografts and hamstring autografts.
The second options is allograph tissue, which is tissue donated from a cadaver. There are multiple varieties of allograph tissue, but all share the common theme that they are donated tissue.
For the patellar tendon graft, we make a mid line incision and we harvest a small piece of bone from the kneecap, the center 10 millimeters of the patellar tendon and a small piece of bone from the shin. We close up the gap between the two edges of the patellar tendon so the patellar tendon is still intact.
In general, the patellar tendon graft has been the gold standard graft used in ACL reconstructions. Most commonly, this is a very predictable healing because the bone plugs on each end of the graft heal within the bony tunnels must like a fracture would heal in the human body. The interference screw fixation that we use to adhere the graft into the tunnels is also one of the strongest types of fixations available. Additionally, the patellar tendon itself is very strong and does not tend to have any looseness.
In some patients they have loose ligaments in general, but the patellar tendon graft provides us that very good grafting reconstruction to restore the knee if we can fix it.
There are some disadvantages of using the patellar tendon graft. For one, it is a mid line incision, and there have been complaints of pain in the front of the knee with particular activities such as jumping, or with activities such as kneeling. Sometimes this goes away. Sometimes this can be something that persists longer than a year or two.
Also, there may be some increase in pain, again, in the short term with use of this graft, however, some people tolerate this graft exceptionally well and do not notice any increase in pain.
Lastly, there is disruption to the ability to extend the knee by taking this graft. However, with diligent work, knee extension, in most situations, comes back to completely normal.
To harvest the hamstring graft, we make a smaller incision more to the inside of the knee. Through this incision we identify two of the hamstring tendons that come from the back of the thigh around to the front part of the knee. With specialized instruments we harvest these hamstring tendons leaving the muscles intact. The hamstring is then doubled over to bring four strands of tissue that are then used as the graft, and inserted for the reconstruction.
A hamstring graft tends to lead to a smaller incision, which is a bit more cosmetically appealing for some patients. Additionally, the doubled over tendons leading to four strands is one of the strongest possible grafts we can use for an ACL reconstruction.
Lastly, there are some reports that patients have less pain in the short term, but over the long term the results can be just as good as all the other graft options.
There are some disadvantages to consider when using the hamstring graft, and these may be reasons why I suggest that you're not a strong candidate for it. For one, there was concern about the hamstring graft fixation, however, technological advancements over the past several years have provided new types of fixation that are just as strong as some of the interfering screw counterparts for the patellar tendon grafts, therefore, that is really no longer a strong concern.
It is very difficult to get the soft tissue to heal to the bone in certain situations if the fixation is not strong, and again, these new types of fixation devices have allowed us to use this graft in all situations.
Additionally, there is concern about the graft stretching out over time, and particularly in people who are known to be loose jointed. That may be a situation where if you have what we term hyper-laxity of your joints, that we would not want you to, or recommend you to use this graft for your reconstruction.
Finally, there are concerns about residual pains from the weakness of the hamstring harvest. The concern is that the function of the hamstring muscles will not return to normal, however, most literature suggests that the muscle function is restored to 85% more better versus the opposite and non-operative way, therefore, the majority of patients will not notice any weakness in their hamstring when using this graft.
An allograph tissue is tissue donated from a dead person. Essentially there are many options, from Achilles tendon, to leg tendons, to even hamstring tendons that we use. These are all treated sterilely with aseptic techniques to remove any potential contaminants.
This tissue may be fashioned into a graft that is equally strong to any of the tissue harvested from the patient.
The advantages of the allograph tissues are that there is no harvest site pain that is associated with the procedure. That is not to say that the procedure will cause no pain because of this, however, many patients who use allograph tissue have less pain in the short term for several weeks than patients who have had a hamstring or patellar tendon harvest.
Additionally, in situations like revision cases or in certain situations where they may be not great tissue for autographed use, then an allograph provides an abundance of options to try to reconstruct the ACL to optimize your outcome.
There are some disadvantages to consider when choosing to use allograph tissue. Disease transmission is one of the main concerns that many patients have about this tissue. Viruses such as HIV and Hepatitis C have a transmission rate that is reported at one to one and a half million for HIV to one in 650 to 750,000 for hepatitis C. There have been some case reports of Hepatitis C transmission, however, since they have changed screening parameters in 1992, there have been no cases of HIV transmission reported in the literature thus far.
In summary, with regard to disease transmission, it is very unlikely to have a fatal disease transmitted through allograph tissue because of the rigorous screening processes that are used by all the tissue banks in this region.
A second disadvantage of allograph tissue is that the tissue may incorporate slightly slower than autograph tissue. This is of particular concern for athletes or patients who have a certain timetable for their return to sport. For example, the young high school athlete who is in need to return to a sport within six months may want to consider use of autograph tissue because the incorporation rates are slightly quicker.
Additionally, there is some literature that suggests that if you are under the age of 25, there may be a higher re-rupture rate with the use of allograph tissue. While we don't know for certain why this occurs, it is something certainly you may want to consider if you are in that niche category.
I realize that selecting a graft for your ACL reconstruction can be an overwhelming decision. I hope that this video has educated you in terms of the pros and cons of several of the graft options out there, however, it is important to realize that all these grafts have very similar success rates and very similar complication rates. Therefore, it is important to have a discussion about your graft option with your surgeon with regard to the best choice that fits your needs.