Common Grafts For ACL Reconstruction
The most common grafts used to reconstruct a torn ACL are the patella tendon graft, hamstring tendon graft, or allograft tissue.
What is a Patellar Tendon Graft?
The patellar tendon is a flat, broad tendon with bone attached to both ends. The central third of the tendon can be used along with bone plugs from the patella and tibia for reconstruction of the anterior cruciate ligament (ACL).
Advantages of a Patellar Tendon Graft
This graft has a very long and successful track record. It has been considered the “gold standard” for ACL reconstruction. The advantages of this graft include excellent strength and stiffness, and ability to obtain early bone-to-bone healing of the graft due to the presence of bone plugs on each end of the graft. The bone plugs heal quickly to the surrounding bone resulting in rapid incorporation of the graft.
Patellar tendon autograft has the best long-term results in terms of stability and has been shown to have a mean strength that is approximately 168% of the normal ACL. It has been associated with anterior knee discomfort in some patients.
How Can Allograft Tissue Repair My ACL?
Allograft tissue is graft material that is taken from a deceased person. The graft is typically sterilized with radiation and is stored as frozen tissue in a tissue bank. This tissue is used to reconstruct the anterior cruciate ligament (ACL) using the same techniques used for autograft reconstruction.
Commonly used allograft tissue include patellar tendon allograft, achilles tendon allograft, and hamstring allograft. Allografts have been shown to provide good stability for ACL reconstruction. They are often used in multi-ligamentous injuries (multiple ligament injuries), revision ACL surgeries, and patients looking for a quicker recovery or less donor site pain.
Concerns with allograft have included laxity and disease transmission (which is extremely rare). Extensive testing is done on all allografts to minimize this risk of disease transmission. No tissue matching is required for allograft ACL reconstruction. The risk of failure (re-tearing of the ACL) is higher with allograft than with autograft tissue, especially in young active patients.
What is a Hamstring Graft?
The hamstring muscles are located in the back of the thigh and their function is to bend or flex the knee. The hamstring tendons connect these muscles to bone. Hamstring tendon grafts have evolved over time and have proven to provide good stability for anterior cruciate ligament (ACL) reconstruction. Typically two hamstring tendons (gracilis and semitendinosus) are used to create a four-bundled graft.
The advantages of this graft include less anterior knee pain and less postoperative stiffness. This graft has been associated with long-term laxity and hamstring weakness. The size of the graft varies from person to person depending on their anatomy.