The Best Type of ACL Graft

Understand the different procedures used to repair a torn ACL.

I wish I could present a one-word article that simply said which ACL graft is best, but as with most things in the science world, the answer is more complex. Assuming everyone has a general grasp of the concept of ACL tears and their surgery, we know that to return effectively to cutting and agility sports following a tear, one must undergo surgical reconstruction to repair the ligament.

I happen to have a unique perspective of this process as I work side by side with an NFL surgeon as his Physician Extender, I run a return-to-play program for ACL athletes completing the rehabilitation process, and I train healthy athletes as a strength and performance coach, many of whom have a history of ACL tear. As such, I have the opportunity to witness every stage of the injury and see firsthand the long-term results of each procedure.

When athletes enter our office, the mechanism of injury, objective presentation in addition to a positive Lachman, pivot shift, or anterior drawer test will warrant the ordering of an MRI. The tests above all assess the ACL's ability to check anterior (forward) translation of the lower bone in the leg and valgus (knee coming in) tension at the knee. If the ACL is torn or sprained, we will see excess movement and positive tests. It is important to note, that the muscles, specifically the hamstrings, tend to guard or tighten following this injury. If this is the case, some tests may present with less movement, but it will be difficult to find a firm end feel of the ligament if torn.

MRI Results

Once suspected, an MRI is ordered to confirm the ACL tear and assess additional structures that may be torn or damaged by the injury. This is important as the specific structures involved will dictate the exact procedure. The patient is presented with this information, the procedure is discussed, and graft types are presented. The graft is the actual structure used to reconstruct the ACL and serve as your new ligament once integrated into your body.

The following graft types are currently available although you will most likely only discuss the first three:

BTB Autograft

A Bone-Tendon-Bone graft is harvested from the middle third of the patient's patella tendon, the ligament between your knee cap and the lower bone of your leg that provides the functional leverage to extend the knee when the quadriceps contract. In addition to the tendon, bone plugs at each end of the tendon are taken to serve as anchors for integration into the bone tunnel where the graft will be inserted. The term "autograft" implies that the graft is harvested from the patient's own body. This graft choice is recommended for patients under 25 years of age looking to return to pivoting and cutting sports.

Benefits include high success rate, high tensile strength and low risk of infection/failure of graft integration as the graft is coming from your own body. Drawbacks include an aesthetically visible scar on the anterior aspect of your knee and potential difficulty obtaining full knee flexion during physical therapy along with the possibility of anterior knee pain when kneeling, squatting, lunging or performing plyometrics during the remodeling (final stage) stage of the healing process. Not all patients experience this, however, and much of this has to do with individual variance and compliance during formal therapy. This is one of the two most popular grafts for the young athletic population, and it is regionally preferred in the east coast of America for no particular statistical reason, meaning most professional football players who tear their ACL on the east coast are using this graft and return with much success.

Hamstring Autograft

A hamstring autograft is also harvested from the patient's body, but this time we are using the semitendinosus and gracilis (adductor) tendons to form a double strand graft similar to the two bundles of the ACL. This must be fed through the aforementioned tunnel and anchored on the outsides of the bone with a button or internally fixed to the bone with an anchor like the Aperfix. Think of this as an expanding drywall screw (with higher success rate) that integrates with the bone. This graft is the other preferred option for patients under 25 years of age looking to return to pivoting and cutting sports. Benefits also include high success rate, high tensile strength and low risk of infection/failure of graft integration as the graft is coming from your own body. Drawbacks include potential difficulty achieving early knee extension following surgery and pain at the portal sites. Some patients tend to worry about weakness in the hamstrings following surgery as this is an important muscle in reinforcing the function of the ACL. This graft is typically seen on the west coast and Europe, with most professional soccer players successfully returning with this graft.

Hamstring Allograft

Allograft is a polite way of saying that your graft is from a cadaver. This is a favorable option for patients over 35 who are not returning to cutting and pivoting sports. Benefits here are the fact that you don't have a second surgical site where the graft must be harvested and therefore less potential pain at other sites from the portals. Potential drawbacks here include a higher risk of infection, although the process has been fine-tuned in later years and a higher rate of failure of the graft to integrate within the patient's bone.

Hybrid (HS Allograft/HS Autograft bundle)

In some situations, the surgeon will determine during the surgery that the HS Autograft is insufficient to serve as a graft and they may determine to integrate it with an HS Allograft to form a hybrid graft. This is not the first option, and now we have some combined drawbacks from both the HS Allograft and Autografts. However, this graft will be stronger than simply using an insufficient HS autograft.

Scaffold-B.E.A.R. Graft

In recent years, we've seen the advent of a new form of graft that scaffolds the two ends of a severed ACL. The Bridge-Enhanced ACL Repair is like a sponge filled with growth factors that joins the two ends, adds tension through suture and stimulates healing with the integrated growth factors. Not every ACL tear is a candidate for this procedure, but early results seem promising. With that said, they are just that—early. At this point, it is difficult to assess long-term success rates, but this could be a viable option as more surgeons adopt the procedure. Regionally, this procedure was pioneered in Massachusetts, and most surgeons outside the region are most comfortable with the first three grafts discussed.

Synthetic Graft

While some surgeons have experimented with the use of a synthetic ACL graft. The claim here is avoidance of damage to a harvest site, high availability and possibly lower cost in the long run as the graft won't have to be taken from a cadaver. With that said success rates have not proven to be optimal and there hasn't been a synthetic graft that has been able to sufficiently both integrate and provide the same level of function and force resistance as the previous grafts.

Special Considerations:

No Repair: Some patients opt to rehab an ACL sprain (if not completely torn) or tear and avoid surgery altogether. In some situations of very low-grade sprain, where stability is still sound, this may be a viable option, but the presence of instability could lead to increased stress on the other ligaments or soft tissue like the meniscus. If you are not looking to return to cutting, pivoting or jumping sports, many can live an active lifestyle including lifting, cardio and even running without complication.

ALL Reconstruction: The ALL or anterolateral ligament reconstruction is used in situations of increased laxity where a little bit more stability is needed. This occurs when the patient has congenital laxity or loose ligaments usually associated with knee genu recurvatum or hyperextension. In some situations, a patient may avoid ACL surgery earlier in life and return years later with loose ligaments in the knee after performing cutting and pivoting activities without a stable ACL. In this case, a standard ACL reconstruction may still be at risk of failure due to a lack of stability from the surrounding ligaments, and the addition of an ALL reconstruction may be warranted.

ACL Injury

Summary:

Youth Patients (Growth Plate Still Open)

Seek specialist consultation

Athletic Patients Under 25:

BTB Autograft

HS Autograft
No Repair-If sprain is low-grade and stability is present

Make final determination based on individual variation, surgeon consultation, and surgeon experience with a specific graft.

Non-athlete Patients Under 25:

BTB Autograft

HS Autograft
No Repair-If sprain is low-grade, and stability is present or if you are not performing any pivoting or cutting sports in the future

Make final determination based on individual variation, surgeon consultation, and surgeon experience with a specific graft.

All Patients between 25-35:

BTB Autograft
HS Autograft
HS Allograft
No Repair

Make final determination based on individual variation, exact age, surgeon consultation, desired activity level, and surgeon experience with a specific graft.

All Patients over 35:

HS Allograft

No Repair Make final determination based on individual variation, exact biological age, surgeon consultation, desired activity level, and surgeon experience with a specific graft. Autografts are still an option here, but most patients go with the allograft due to specific variations.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5120682/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2845120/

https://www.sportsmed.org/AOSSMIMIS/members/downloads/research/AllograftACLReconstructionSurveyReport.pdf

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3806178/

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Topics: REHAB | ACL INJURY | SURGERY | ACL TEAR