ACL reconstruction is one of the most common arthroscopic surgeries performed in the United States, and there are many factors to consider when it comes to graft choice. Usually it starts with the surgeon you select, many surgeons have a specialty and may recommend that as the best option. Currently there are several options for graft selection and all but the synthetic grafts have shown good results. Autografts are performed by harvesting your own patellar tendon, hamstring tendon or recently the distal quad tendon and using it as the graft. Allografts are usually harvested from cadaveric tibialis anterior/posterior, Achilles, hamstring or patellar tendons.
Patellar Tendon BPTB Autografts have been thought of as the “gold standard” in regards to strength and stability. Complaints of BPTB grafts are harvest site pain, early post-op restrictions, possible chronic anterior knee pain, pain with kneeling and increased tendency for patellar tendonitis. Surgical procedure for this graft choice is executed by two horizontal incisions or one vertical incision where the middle 1/3rd of the tendon is removed. There is a very low rupture rate of the remaining 2/3rds of the patellar tendon.
Hamstring Autografts are harvested form the distal simitendenosis tendon with or without the gracilis and the incision will either be on the posterior medial knee or at the anterior superior medial tibia. There are less common reports of anterior knee pain, pain with kneeling and patellar tendonitis, cosmetically there are less incisions on the anterior knee as well. Although rare, some patients report decreased knee flexion strength and pain at the medial hamstring harvest site.
Allografts are an appealing choice primarily due to the lack of harvest site pain and cosmetics. In my experience, Allograft patients often report less post-op pain, demonstrate better gait patterns and have more ROM upon Physical Therapy evaluation, compared to patients with Autografts. However, this does not speed up the overall rehabilitation time. With Allografts there are few things to consider, possible rejection or infection of graft material and the cost of the graft can make the surgery more expensive.
Here is a look at the graft choices compared in the literature, below are a few recent studies that provide comparisons of the available ACL graft options. This is by no means a comprehensive list but these studies include a large number of subjects, so at least you can have a starting point when trying to make this important decision.
Long-Term Failure of Anterior Cruciate Ligament Reconstruction: The Journal of Arthroscopic and Related Surgery. 2013
In this Systematic Review the authors included studies regardless of graft choice performed between 1980 and 2012 and found that only 14 studies qualified for inclusion.
Results: At greater than 10 years’ follow-up, ACL rupture, regardless of graft choice, occurred in 6.2% of patients (173 out of 2,782). ACL graft clinical failure, which was defined as unacceptable laxity or overall instability of the graft at a 10 year follow-up, was 10.3% (158 out of 1,532). Cumulative failure was a combination of the traumatic rupture and clinical failure reports and was found to be 11.9% (331 out of 2,782)
Patellar Tendon BPTB Autograft vs. Patellar Tendon BPTB Allograft
Bone-Patellar Tendon-Bone Autograft vs Allograft in Outcomes of ACL Reconstruction: The American Journal of Sports Medicine. 2013
In this Meta-Analysis the authors reviewed 76 studies between 1998 and 2012 including 5,182 patients. All of the included patients received BPTB grafts the only difference was Autograft and Allograft.
Results: Autografts demonstrated a rupture rate of 4.2%, Allografts produced a rupture rate of 12.7%. Autografts were superior in knee laxity, single leg hop test and overall patient satisfaction. Allografts produced superior results in return to pre-injury activity level and had less anterior knee pain. Allograft recipients tended to be older and had a lower pre-injury activity level than those patients receiving Autografts, which explains the elevated return to pre-injury activity discrepancy.
Here is a look at two large population studies comparing Patellar Tendon Autografts and Hamstring Tendon Autografts
Patellar Tendon BPTB Autografts vs Hamstring Autografts
Increased Risk of Revision With hamstring Tendon Grafts Compared With Patellar Tendon Grafts After ACL Reconstruction: The American Journal of Sports Medicine. 2014
This study analyzied 12,643 (3,438 PT, 9,215 HS) patients from the Norwegian Cruciate Ligament Registry 2004-2012, the authors looked at revision rates at 1, 2 and 5 years post-op.
Results: Revision rates for the Patellar Tendon at 1, 2 and 5 years were, 0.3%, 0.7% and 2.1% Revision rates for the Hamstring Tendon were 1.1%, 2.8% and 5.1%
Patellar Tendon BPTB Autografts vs Hamstring Allografts
Comparison of Hamstring Tendon and Patellar Tendon Grafts in ACL Reconstruction in a Nationwide Population-Based Cohort Study: The American Journal of Sports Medicine. 2013
The authors looked at 13,647 ACL reconstructions using Patellar Tendon or Hamstring Tendon grafts from 2005 through 2011 and compared the revision rate at 1 and 5 years post-op.
Results: The Patellar Tendon group had 47 revisions out of 1,971 patients with a 1 year revision rate of 0.16% and 5 year revision rate of 3.03%. The Hamstring group had 312 revisions out of 11,676 patients with a 1 year revision rate of 0.65% and 5 year revision rate of 4.45%
In both studies, Hamstring tendon graft surgeries outnumbered the Patellar tendon grafts surgeries by a large number and in both studies the Patellar Tendon proved to have less revisions. However, in both cases there was a very low revision rate for Patellar Tendon and Hamstring grafts.
*Recent Update*
Gamma irradiation is a popular method for sterilizing a cadaveric ACL allografts, however it may also weaken the tissue which could cause higher failure rates. This is a smaller study with only 83 participants, but it may be worth considering. Selected subjects underwent ACL reconstruction by the same surgeon between 2008 and 2009 then followed identical post-op protocols. Each subject was tested for joint laxity, functional jumping and answered a subjective questionnaire periodically for 6 years.
Results: The good news there were no signifiant differences in post-op activity level and functional outcomes between groups. The bad news is that the Allografts demonstrated significant laxity and had a higher failure rate 30.2% vs 7.5% for the Autografts.
Conclusion: There are many choices for your ACL graft, and in general all of them have a low revision rate. It is important to understand the facts about each choice and match it to your personal lifestyle, activity level, goals and age. As I mentioned earlier, many surgeons have an ACL graft preference or specialty. It is always best to go with the procedure that the surgeon specializes in. So, once you figure out the graft you want to go with, do some research and find a surgeon that specializes in the graft option of your choice.
Finally, once your procedure is complete it important to find a rehabilitation facility that can help you achieve the level of activity you want return to.
Chris Butler Sports PT 