You have torn your Anterior Cruciate Ligament (ACL), saw your Physiotherapist and had imaging to confirm the tear. Now you are waiting to see your Orthopedic surgeon. If you're on the fence whether you want or need surgery to reconstruct your ACL then I recommend reading my other blog on prehab. Surgery for a torn ACL isn't always a necessity depending on your goals and function based on how you are recovering following the knee injury. Your rehab with your physio and strength and conditioning coach might be enough if you aren't competing at the highest level.
If you are set on having your ACL reconstructed then you still have to decide on the type of graft used to replace the ligament. A lot of this decision may be placed on the surgeon but asking the right questions and being informed can have an effect on your outcomes post operatively.
There are 2 main types of grafts options which include autografts and allografts.
Autografts - Are your own body's tissue that is transferred from one body part to another i.e. a tendon from your leg becoming your new knee ligament.
Allografts - Are one person's tissue that is transplanted to another person i.e. a tendon from another person's leg becoming your new knee ligament.
Allografts, in the case of ACL-Reconstruction (ACL-R), are generally tissue that are donated from a cadaver body. This can be a hamstring, patella or Achilles' tendons. They are often reserved for people over the age of 30-40 years of age and for revision surgeries (a re-tear of an ACL-R). For the most part they aren't the gold standard for ACL surgery but they do have some pros over other graft types.
Advantages:
Less pain as the tissue isn't taken from another body part
Shorter surgery and recovery as another tendon doesn't need rehab / physio
If you've had multiple tears, can be a good option
Disadvantages:
Immune system may reject the donor tissue, especially if you're under 30 years of age
Risk of infection is higher
Higher rate of re-rupture of the ACL-R compared to autografts
Under the autograft group, there are a few options to decide between.
Bone Patella Tendon Bone (BPTB) Autograft
This graft has been considered the gold standard for ACL-R for its strength. It is used a lot in young people in their 20s through to 30s and 40s. Generally the patellar tendon located below the kneecap is used from the same side the surgery is happening on.
Advantages:
Stronger fixation of the graft onto the bone to prevent stretching (laxity)
Strong and stable
Lower re-tear/rupture rate compared to other grafts
Disadvantages:
Increased generalized front knee pain
Pain with kneeling which may be long term
Stiffer, less range of motion (especially extension or straightening)
Risk of patellar fracture
Slower recovery possibly
Hamstring Tendon Autograft
Widely used graft option especially in Canada. It is what I see the most in Vancouver, BC. It can be a good option for younger teens to avoid bone and growth plate disruption. Usually the same side inner hamstring +/- the gracilis (adductor muscle) tendon are used.
Advantages:
Less front knee pain during rehab
Smaller incision
Thought to be a faster recovery as it is less stiff post operatively
Disadvantages:
Higher re-tear rates compared to BPTB grafts found in some studies
Have to rehab the hamstring simultaneously
Less knee flexion (bending) strength
Can take longer for the bone sites of fixation to heal and be stable
Possibly less stable inner knee joint due to graft harvesting location
Quadriceps Tendon Autograft
This is the "new kid on the block" of graft options. It is less common as it is relatively new therefore less studies to support it. It is thought to be a happy medium between the hamstring and BPTB graft options. More research is needed to provide a full outlook on this option.
The answer to the best graft choice for ACL surgery is, "it depends". Ultimately, the decision should be based on your own body, needs, expected outcomes and input from the surgeon. Your age, previous history of injuries including inner knee instability, requirements (such as kneeling) are all factors that can effect your choice. Fortunately you are not alone! Your physio and doctor can guide you through the options so you don't have to make the decision by yourself. If you don't have a current physio and you're in the Crosstown / Gastown neighbourhood, or anywhere near downtown Vancouver, feel free to reach out to myself!
REFERENCES:
Akhtar, M. A. et al. (2011). Revision ACL reconstruction - caused of failure and graft choices, Br J Sports Med, 45, 15-16; doi: 10.1136/bjsports-2011-090606.49\
Hutchinson Smith, A. Capin, J. J., & Zarzycki, R. (2020). Athletes with bone-patellar-tendon-bone autograft for anterior cruciate ligament reconstruction were slower to meet rehabilitation milestones and return-to-sport criteria than athletes with hamstring tendon autograft or soft tissue allograft: Secondary analysis from the ACL-SPORTS Trial, J Orthop Sports Physical Therapy, 50, 5, 259-266; doi: 10.2519/jospt.2020.9111
Svantesson, E. et al. (2018). Factors associated with additional anterior cruciate ligament reconstruction and register comparison: A systematic review on the Scandinavian knee ligament registers, Br J Sports Med, 53, 418-425; doi: 10.1136/bjsports-2017-098192
Vyas, D., Rabuck, S. J., & Harner, C. D. (2012). Allograft Anterior Cruciate Ligament Reconstruction: Indications, techniques, and outcomes, J Orthop Sports Physical Therapy, 42(3), 196-207; doi: 10.2519/jospt.2012.4083