ACL Reconstruction Surgery: Graft Options
In the majority of patients who have torn their anterior cruciate ligament (ACL), surgery is recommended. The ACL has been shown to not heal on its own nor when it is repaired (surgically sutured or re-attached). As such, surgery for an ACL tear requires that we make you a new ACL out of a graft. There are two main types of grafts: allograft - meaning a tendon graft from a cadaver/donor source and autograft – meaning a tendon from you.
Allograft Tendons
Allografts have been associated with higher re-tear rates in young, athletic individuals. However, patients with lower demands and in those over the age of 40, retear rates are similar to autografts. The benefits of using an allograft tendon are slightly less pain after surgery, since we are not harvesting a tendon from you, and a slightly shorter operative time. Neither of these benefits lead to a decrease in recovery time, but these grafts do remain a good option for some patients, and especially in the case of multiligamentous knee injury where several knee ligaments need to be reconstructed.
Autograft Tendon Choices for ACL Reconstruction
For autograft tendon choices, there exists three options: patellar tendon autograft, quadricep tendon autograft, and hamstring autograft. Most clinical and biomechanical studies show similar results with these three graft options, though some grafts are more successful in certain patient populations. A discussion with your surgical team about which graft choice is right for you based upon your age, activity level, goals, and preferences is important. Below is important information to help guide you in your decision making.
Patellar Tendon Autograft
This is the “gold-standard” for ACL reconstruction and has been used for over 40 years as a reliable, safe graft for ACL reconstruction. This involves harvesting a piece of bone from the patella (kneecap), the central 1cm of the patellar tendon, and a piece of bone from the tibia to create the new ACL. Tunnels are then drilled into the femur and tibia where the ACL anatomically attaches and the graft is brought into these tunnels to create the knee ligament.
The benefits of this graft are:
- Allows for bone to bone healing (like a fracture) where the bone block heals into the bony tunnel.
- Allows for a very reproducible size tendon to closely match the native ACL independent of patient size.
- Allows for a stiff graft with good biomechanical and clinical data.
Disadvantages of this graft:
- Larger anterior knee incision for graft harvest.
- The number one complaint is of anterior knee pain at the patellar bone block site with kneeling and sport over time. In the literature this is reported in about 10-15% of patients.
Quadriceps Tendon Autograft
The “new kid on the block” graft. The quadriceps tendon as an ACL graft has been used for quite some time, but has gained more popularity over the last 10 years as an excellent option. Newer graft harvest techniques and instrumentation has allowed for easy, safe, and reliable graft size harvesting. The quadriceps tendon is a thick, robust tendon above the patella (kneecap). The main advantage of this graft is all the benefits of size, stiffness, reliability of the patellar tendon graft with less of the anterior knee pain risk and smaller incision.
Advantages include:
- Safe, reliable harvest with reproducible and easy to choose graft sizes.
- Thick, robust graft.
- Can take with or without a bone block from the patella if desired.
- No anterior kneeling pain.
- Smaller incision than patellar tendon graft.
Disadvantages include:
- Less long term data/follow up on clinical outcomes of re-tear or failure; but 10-15+ year outcome data is growing.
Hamstring Tendon Autograft
Another popular graft choice, the hamstrings are muscles in the back of the thigh. Two of the smaller hamstring muscles, the gracilis and semitendinosus, have their tendinous attachments on the inner side of the knee, just below the joint. These tendons are often folded over themselves 4-6 times to create a graft that is 9-10mm in diameter (similar to the native ACL) and then inserted into tunnels in the femur and tibia making the new ligament. This graft has been used for decades and has a long track record of success; though more recent research shows that in younger athletes, other autograft options are superior.
Advantages include:
- Avoidance of anterior knee pain complications associated with patellar tendon.
- Smaller incision for harvest site.
Disadvantages include:
- Unreliability of graft size. Even large, muscular individuals sometimes have small hamstring tendons and this is especially common in smaller, young females. This leads to a smaller graft diameter which can result in higher retear rate or the need to supplement the graft with an allograft.
- More difficult graft harvest – sometimes the tendon can rip during harvest, leaving less tendon to work with. Sometimes this then requires use of allograft tendon as backup.
- Graft creep – or stretch over time – can cause increased laxity of the ACL graft over time.
- More recent studies are showing higher retear rates with this graft than in quad and patellar tendon grafts in the young, athletic population.
Choose the Graft that is Right for You
In summary, all 4 graft options can provide a strong, robust reconstruction that leads to an excellent recovery. All have pros and cons, and as with anything in surgery and medicine, there is no “one size fits all”. Which graft is right for you depends on a multitude of factors. Having a surgeon who is familiar with all of these techniques and adjusts them to your specific needs and preferences is important.
Hopefully this information helps guide your decision and stimulates thoughtful discussion between you and your surgical team. Ultimately, the decision is one shared between you and your surgeon to maximize your success.
