Quadriceps tendon graft in ACL reconstruction
Photo by Victor Freitas on Unsplash
The most common graft choice for an ACL reconstruction in Australia is the hamstrings tendon graft. Typically, the gracilis and semitendinosus hamstring tendons are harvested during ACL surgery and are used to form the ACL graft.
The other less common choice is using the patellar tendon. This involves harvesting the central part of the patella tendon with a bone block from the patella and tibia. The patella tendon graft is strong and has the lowest re-rupture rate. However, patients can experience post-operative anterior knee pain, difficulty kneeling and numbness adjacent to the incision. It also weakens the ability to extend or straighten the knee.
Benefits of the quadriceps tendon ACL graft
The quadriceps muscle is the main muscle in the thigh. It is formed by a group of four muscles: rectus femoris, vastus medialis, vastus lateralis and vastus intermedius. These muscles insert onto the top of the patella through the quadriceps tendon.
The quadriceps tendon is a relatively new graft choice and involves harvesting the central strip of the quadriceps muscle in the thigh. Sometimes a block of bone is also harvested from the top of the patella bone where the quadriceps tendon inserts into.
The quadriceps tendon is broad and long. The graft size can predictably be determined using sized harvesting instruments. This is in contrast to using hamstring grafts where the size can be unpredictable and smaller graft sizes may occur even in well-built patients.
The quadriceps tendon graft is commonly compared to a patellar tendon graft. The tissue within the quadriceps tendon has 20% more collagen fibrils (the scaffold of the graft) than a patellar tendon graft. As the quadriceps tendon is significantly larger than the patellar tendon, the graft harvested from it will weaken the tendon less. Another advantage of this is that patients experience less anterior knee pain. The extension strength, which is the force generated from straightening the knee, is higher in patients with a quadriceps tendon graft than in a patellar tendon graft.
If a quadriceps tendon graft is being used for ACL surgery, the harvest is taken through a small longitudinal or transverse incision above the patella. Given the minimally invasive harvesting technique, harvest site pain has been shown to be considerably less when using a quadriceps tendon graft. As the incision is higher than a patellar tendon graft, kneeling on your knees is less of an issue post-operatively. A graft diameter greater than 8mm can easily be achieved. On average, graft diameters of more than 8mm are less likely to have a re-injury in the long term.
Example of a prepared quadriceps tendon ACL graft: This graft was 8.5mm thick and 70mm long.
When I consider a quadriceps tendon graft
When the medial collateral ligament (MCL) is injured
The MCL stabilises the inner aspect of the knee. The hamstrings also act as stabilisers to the inner aspect of the knee. In the setting of having an ACL and MCL injury, I consider using a quadriceps graft so I can preserve the hamstrings. This will portend more stability and protection to the medial aspect of the knee.
Patients involved in a hamstring dominant activity/sport
The hamstring muscles are important in activities involving sprinting, jumping or kicking. If a patient participates regularly in a hamstring dominant activity, it makes sense to preserve the hamstrings and consider the quadriceps tendon as an alternative graft choice.
If you have already ruptured an ACL graft from a previous reconstruction and require revision surgery
Traditionally, revision ACL surgery is performed using a patellar tendon graft which has a few pitfalls as described above. However, there are certain situations where having bone blocks on the patella tendon graft are useful in a revision setting.
Some surgeons will use hamstrings from the uninjured knee. I do not prefer to use the same graft choice during revision surgery as the quality of the chosen graft may have led to graft failure.
The quadriceps tendon is an excellent alternative graft choice in revision ACL surgery with lower morbidity than a patella tendon graft. It also avoids a hamstring graft harvest from the uninjured side.
Summary
The quadriceps tendon ACL graft is the least used autograft choice in Australia. However, there is an abundance of clinical studies performed on this graft that shows the re-injury rate is comparable to patellar tendon and hamstrings grafts. It is certainly a viable alternative graft choice that should be considered.
Would you benefit from a quadriceps tendon ACL reconstruction?
Mr Pai has extensive experience in performing a quadriceps tendon ACL reconstruction can discuss the benefits of this in a consultation. He will discuss all graft options with you and will individualise this according to your lifestyle.
