Blog # 10 – Understanding ACL Graft Types
- Brodey Castle
- Jun 11
- 5 min read
A Guide to Anterior Cruciate Ligament Reconstruction
The anterior cruciate ligament (ACL) is one of the key stabilising ligaments of the knee and when ruptured has significant effects on stability and function.
Injuries to the ACL are split between contact and non-contact mechanisms. Non-contact injuries generally occur due to a change of direction/pivoting, where contact injuries are a result of a direct force to the knee which is often planted.
Following an ACL rupture, surgical reconstruction is often recommended to restore the stability and function of the knee. An important consideration during this process is the type of graft used for the reconstruction. In this blog, we'll explore the different types of ACL grafts, their advantages, disadvantages, and factors to consider when making this decision.
What is an ACL Graft?
An ACL graft is a piece of tissue used to replace the torn ACL during surgery. The new graft serves as a scaffold to rebuild the ligament, helping to restore stability and function to the knee.
There are several graft options available, each with its own set of pros and cons and this needs to be considered in the pre-surgical discussions. The decision about which graft to use depends on a variety of factors, including the patient's age, activity level, surgeon's preference, and the type of injury.
Types of ACL Grafts
Autografts (Own Tissue)
Autografts are the most common type of graft used in ACL reconstruction.
With an autograft, the surgeon takes tissue from the patient's own body.
The three primary types of autografts used for ACL reconstruction are:
Patellar Tendon Autograft (Bone-Patellar Tendon-Bone or BPTB):
The patellar tendon connects the kneecap (patella) to the shinbone (tibia) and is one of the main graft choices used for patients. This type of graft involves removing a portion of the patellar tendon along with a small amount of bone from both the patella and tibia. The bone plugs are then used to anchor the tendon in place at the knee.
Advantages:
Strong fixation due to the bone plugs, which help with early graft healing.
Good evidence of success, particularly in high-demand athletes.
Disadvantages:
Higher risk of anterior knee pain, particularly with activities like kneeling or squatting.
May incur longer recovery time
Potential for a more prominent scar at the donor site.
Hamstring Tendon Autograft (Semitendinosus):
The hamstring tendons are located on the back of the thigh, and a portion of these tendons can be harvested to create a graft for the ACL. Unlike the patellar tendon, this graft does not involve bone, and the tendons are typically doubled over to create the required graft thickness.
Advantages:
Less postoperative pain at the donor site (the back of the thigh).
Lower risk of anterior knee pain.
A less invasive procedure, as no bone plugs are required.
Disadvantages:
Slightly weaker initial fixation, requiring a longer recovery period for the graft to heal fully.
The hamstring strength may be temporarily affected, although most patients recover well over time with appropriate rehabilitation.
Quadriceps Tendon (QT) Graft:
This graft involves harvesting the quadriceps tendon from the front of the thigh.
The quadriceps tendon has similar characteristics to the patellar tendon but is often chosen for its strength and relatively lower risk of complications like patellar tendinopathy.
It can be a great choice for patients with prior patellar tendon injuries.
Advantages:
QT autografts are strong and stiff
Less donor sit morbidity
Less anterior knee pain in comparison to patella tendon grafts
Disadvantages:
Potential increased risk of patella fracture, especially if harvested with a bone block
Possible longer incision site
Persistent quadriceps weakness
Allografts (Donor Tissue)
Allografts involve the use of tissue taken from a deceased donor. The tissue is thoroughly screened and processed before being used in surgery. There are several types of allografts available, including:
Bone-Patellar Tendon-Bone (BPTB Allograft) and Hamstring Tendon Allograft
Similar to the autograft version, this graft uses patellar tendon tissue along with bone plugs for fixation. The main difference is that the tissue is sourced from a cadaver rather than the patient’s own body.
Advantages:
No donor site morbidity (no additional incisions or recovery from harvesting tissue).
Can be a good option for patients with multiple ACL injuries who may not have enough viable tissue left for an autograft.
Disadvantages:
Slightly higher risk of infection due to the use of cadaveric tissue.
Slower graft incorporation and healing compared to autografts.
Higher cost due to tissue processing and storage.
There is a slightly higher rate of graft failure compared to autografts in younger, more active individuals.
Additional Interventions - Lateral Extra-Articular Tenodesis (LEAT)
These days surgeons will often recommend the addition of a LEAT procedure alongside an ACL reconstruction. A LEAT procedure is used to enhance the stability of the knee by reinforcing the lateral side of the side.
It involves taking a strip of tissue from the iliotibial band (ITB) and routing it under the lateral collateral ligament (LCL), then attaching it to the femur. This procedure is aimed at addressing persistent anterolateral rotatory instability, especially in young, active individuals or those with a high risk of re-injury.
LEAT can help to:
Improve rotational stability of the knee.
Reduce the risk of ACL graft failure.
Lower graft re-rupture rates, particularly in young patients with hamstring grafts.
Provide additional protection to the ACL graft
Factors to Consider When Choosing an ACL Graft
Choosing the right ACL graft depends on several factors:
Activity Level: Active athletes may benefit more from an autograft (especially BPTB or hamstring), which typically provides stronger fixation and faster recovery. Non-athletic individuals or those looking for a less invasive option may lean towards allografts or hamstring autografts.
Age: Younger, more active individuals may do better with autografts, as these grafts tend to have a higher success rate and faster recovery. Older adults or those with multiple ACL injuries may prefer allografts, which don’t require harvesting tissue from the body.
Previous Injuries: If a patient has had prior ACL surgeries or their patellar or hamstring tendons are compromised, an allograft may be a better option.
Surgeon’s Expertise: The surgeon's experience with various graft types can heavily influence the outcome of the surgery. Some surgeons have a preference based on their training and results, so it’s important to discuss options thoroughly with the surgical team.
Recovery Time and Goals: Patients with high expectations for returning to sports or physical activities quickly may prefer autografts, which are generally more reliable in the long term, while those looking for a less invasive option might consider allografts.
Anterior Cruciate Ligament Reconstruction Rehabilitation
It is important to note that every ACL reconstruction surgery, no matter what surgery is completed, requires a comprehensive rehabilitation program to ensure best long-term outcomes and a successful return to performance.
The different types of ACL reconstruction, graph types & surgical protocols directly impact the impairments post-surgery and what the rehabilitation process will need to specifically address and manage.
Conclusion
Choosing the best ACL graft is a personal decision that involves balancing the pros and cons of each option with the patient's needs, goals, and the surgeon’s recommendation. Whether opting for an autograft or an allograft, it’s important to have a thorough discussion with your surgeon to determine the best approach for your situation. ACL reconstruction is a highly effective way to restore knee function, but the type of graft chosen plays a crucial role in the long-term success of the surgery.
Ultimately, the goal of ACL surgery is to restore your knee’s function and stability, allowing you to return to the activities you love with confidence.