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 Which is the Best Graft for ACL Reconstruction?

Overview

ACL Reconstruction, which is different than an ACL repair, requires removing your torn ACL and replacing it with transplanted tissue (called a graft) from somewhere else. There are two main options for grafts - autograft and allograft.

Autograft requires taking tendon from another location in your own body (termed harvesting) and moving it to replace the ACL.

Allograft, also called donor graft or cadaver graft, is tendon from someone who has donated their tissue.

I am commonly asked “what is the best ACL graft?”, “what graft do professional athletes get?.” These are great questions which we hope to answer here. In general, each graft choice has value depending on the circumstances. There are pros and cons for each option and selection of the appropriate graft should be individualized.

Autograft

Let’s begin with Autograft. The main benefit of autograft is that is is your own - - your own connective tissue and your own cells -- and therefore the safest with the fastest healing potential. The shortcomings including longer surgery time, larger incisions, and more postoperative pain. There are also concerns about persistent postoperative weakness of the muscles where the tendon has been harvested from - this is termed “donor site morbidity.” Common harvest sites include the patellar tendon, hamstring tendon and quadriceps tendon.

Patellar Tendon

The patellar tendon is the tendon in front of your knee. It attaches from the knee cap to the shin bone. It is the graft with the longest track record and is consider by many to be the “gold-standard” for ACL reconstruction. In most circumstances this is the graft recommended for professional athletes and in any young active individual.

The surgery requires taking the central third of the tendon with a small piece of bone from the knee cap and a small piece of bone from the tibia (shinbone). (See video below)

It is a strong graft with the most secure fixation, a low failure rate and a high rate of patient satisfaction.

The shortcomings of the graft are primarily related to donor site morbidity. The longer incision on the front of the knee may be cosmetically undesirable to some. There is also an increased risk of pain in the front of the knee with kneeling. This option may not be great for those with occupations that require a lot of kneeling - yoga teacher, carpenter, etc. Quadriceps weakness after surgery is also expected.

Hamstring Tendon

Hamstring tendons, tendons located in the back of your thigh, are harvested through a small incision just below the knee.

The hamstring graft, like the patellar tendon, has an excellent track record with high patient satisfaction. Since the incision is smaller it has a better cosmetic appearance and more importantly less pain in the front of the knee and less pain with kneeling.

There are also risks of using of hamstring autograft. The time it takes for the ligament to heal and mature is likely greater than with patellar tendon autograft. There is also a greater amount of graft stretching when compared to the patellar tendon. There is also weakness of the hamstring musculature in the back of the thigh after surgery.

In general, hamstring autograft is an excellent option for athletes not involved in high risk sports. It is also a desirable option for those who are concerned about the cosmetic appearance of a larger incision on the front of the knee or when the incision can impact activities of daily living.

Quadriceps Tendon

Quadriceps tendon is a relatively newer graft choice which shows promise. It has been studied less which makes it difficult to fully compare with the other options. However, recent studies have shown comparable results when compared to patellar tendon autograft. Proponents have argued that the graft more naturally mimics the anterior cruciate ligament, and that the donor site morbidity is less than with patellar tendon autograft. When compared to patellar tendon autograft there is less numbness around the incision, less kneeling pain. Potential risk factors for the quadriceps tendon graft include increased quadriceps muscle atrophy and quadriceps tendonitis.

Allograft

Allograft is tissue that has been donated, processed and sterilized and placed in secure packaging and kept protected until the time surgery.

Strengths

The strengths of allograft reconstruction include shorter surgery time, smaller incisions, easier postoperative recovery and no “donor site morbidity.” It is a very good option for individuals who participate in lower risks activities or in the older (35 - 40 years +) athletic population. There are multiple types and sizes of allografts that can be used which gives your surgeon significant flexibility. This is particularly useful in challenging cases when multiple ligaments need to be reconstructed or in revision ACL reconstruction.

Weaknesses

The weakness of allograft include the risk of slower healing of the foreign tissue (a process called incorporation). Due to this slower incorporation, there is an increased risk of graft failure compared to autograft, this is particular true in younger athletes. Multiple studies have shown a significant increase in graft failure in young patients (less than 25 years old) with allograft compared to autograft. The safety record for allograft tissue is excellent, however there is potential increased risk of infection compared to autograft reconstruction.

Situations for Allograft ACL

Allograft tendons are frequently utilized in Revision ACL Reconstruction, multi-ligament injuries - where multiple ligaments need to be repaired, and for individuals with lower demands.

Summary

In general it is safe to say that if you are young and active with high physical demands then autograft ACL is the best options. Patellar Tendon autograft is likely the best option in younger, higher demand athletes. Hamstring autograft also has high success rate but with less risk of postoperative pain due to a smaller incision and less risk of kneeling pain in the future.

Numerous studies have shown autograft has a decreased chance of failure compared to allograft in the younger patient population. How young? Many quote 25 years of age and younger as a good reference. By age 40 there is evidence that success rates of autograft and allograft are similar.