ACL Repair: Rationale and When to Consider Over Reconstruction

Abstract

Background:

Anterior cruciate ligament (ACL) restoration has been divided into repair versus reconstructive approaches. We present an ACL repair using FiberTape sutures as an internal brace and an adjustable cortical button fixation on the femur.

Indications:

ACL rupture is a condition in which restoration is essential to regaining adequate knee function. ACL repair may be indicated in patients with an acute tear (<4 weeks), Sherman classification type I or II tear, 35 years old or older, and with a mild-to-moderate activity level.

Technique Description:

ACL tightrope repair initially requires identification of the ACL tear. Following, there is femoral wall preparation and the creation of a drill tunnel in the femoral and tibial walls. FiberRing sutures are passed through the intact portion of the ACL as many times as desired. An ACL Tightrope is then fed through the FiberRing sutures. The ACL Tightrope and cortical button are passed through the femoral tunnel. FiberTape sutures are passed through a tibial tunnel to act as an internal brace. Range of motion and tension is assessed and adjusted as needed.

Results:

Patients meeting indications for ACL repair and undergoing repair via Tightrope implants may have outcomes comparable to counterparts undergoing ACL reconstruction. Patient-completed functional knee scores, such as International Knee Documentation Committee (IKDC), Knee Injury and Osteoarthritis Outcome Score (KOOS), and Lysholm, are similar between the 2 restoration techniques. However, younger patients undergoing an ACL repair appear to have a higher failure rate compared with reconstruction.

Conclusion:

ACL repair can be an adjuvant treatment option with acute femoral sided tears. Caution should be exercised when performing this procedure on younger, higher level athletes. In our technique, use of adjustable cortical button minimizes bone loss on femoral wall while providing adequate fixation.

Patient Consent Disclosure Statement:

The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

Hi, my name is Eddie Chang. I'm from Inova Health System in Fairfax, Virginia, and today we'll be talking about anterior cruciate ligament (ACL) repair, its rationale, and when to consider over reconstruction.

Here’s the overview of the talk today. We'll go over the historical literature on ACL repair. We'll then review the indications to perform the repair and talk about a recent case that was done. We'll then review the procedure in detail as well as any technical pearls. And finally, we'll review the rehabilitation protocol as well as clinical evidence on ACL repair.

Background

ACL tears have been baffling us for over the past century, and although we have been treating these injuries successfully with ACL reconstruction, a question that always comes up from my patients is why can't we repair the ligament rather than replace it? In 2013, Doctor Reider published an editorial where he argued that the Holy Grail of sports medicine would be to find a way to primarily repair an ACL tear. ⁷

ACL repairs will be performed in the early to mid-20th century, but as more and more articles were being published, it was becoming apparent that ACL repairs were not feasible in the athletic population. Doctor Feagin's article, published in 1976, probably is one of the most cited articles in discouraging ACL repair. ¹ In this study, he looked at 64 cadets undergoing repair and a 5-year follow-up, more than 50% sustained injury, and he concluded that ACL repair in its current form was not good enough. This led to many people to look for other alternatives.

Despite the negative and discouraging results, however, people continue to find interest in ACL repair. Dr. Sherman published in an article in 1990 looking at a retrospective review on his ACL repairs. ⁸ What was different in his study was that he classified his tears by how much proximal stump was remaining, and so therefore, type 1 was a complete avulsion. Type 2 had about 20% remaining on the femoral stump. Type 3 was one-third, and type 4 was a mid-substance tear. He found that tears that were located more proximally, such as type 1 injuries, had better results within an ACL repair, and he also noted that younger patients tended not to do as well.

Here is a list of factors that are believed to be important in achieving ACL healing, and I believe we've come a long way over the last 70 years. ³ First, we have transitioned from an open arthrotomy to an arthroscopic repair that I believe helps preserve the blood supply. Second, the evolution of suture and implants has now allowed us to create solid fixation of the repair at time 0, while still allowing our patients to rehabilitation early. Third, as we're now picking the right people to operate on, these will be patients with proximal tears that are on the older side with acute injuries. In regard to biological environment, I believe there's still much research needed here.

Indications

These are my current indications for performing an ACL repair. For me, these injuries should be acute within 4 weeks. I prefer to perform repairs on Sherman type 1 or 2. Generally, age over 35 years old. For higher level athletes, I will still recommend a reconstruction. And finally, I'll tell my patients, although our goal is to perform repair, I will consent them to a reconstruction in the event the tissue quality is not ideal for repair.

This is a patient of mine who I saw recently. He's a 46-year-old male who sustained a skiing injury 2 days prior to showing up into my clinic. He's a healthy male whose goal is to get back to triathlons. On examination, he had a large effusion, a 2B Lachman, as well as decreased range of motion, as this is an acute injury. We were able to get an MRI the next day. You can see on these coronal and sagittal slices that the ACL is torn at its proximal end.

These are 3 consecutive coronal oblique views of the knee. You can see clearly on these views that this is a type 1 avulsion injury.

These are the steps that I hope to demonstrate in the following video clips. I chose to omit the video of our approach, and we'll start first with the identification of the ACL and move on until final fixation.

I’m currently viewing through the anterolateral portal and manipulating the ACL stump through the anteromedial portal. As you can see here, this is clearly a type 1 avulsion injury.

Technique Description

Once we decided to proceed with the ACL repair, we first begin with our femoral wall preparation using a series of rasp, shavers and curettes. This allows us to prepare the wall and create a nice bleeding bone bed for the ACL to heal to.

Next we'll create an accessory medial portal. And through this portal we'll mark our tunnel location with a chondral pick. Following this will then perform marrow stimulation of the surrounding femoral wall. And then we'll use a 4.0-mm spade tip pin to drill our femoral tunnel, and then we'll place the passing suture through the pin and out through the femur.

With the tibial drill guide into the anteromedial portal, we'll drill into the ACL stump. We’ll then pass a nitinol wire through the cannulated drill bit, and this will be pulled out to anteromedial portal. We'll then place the scope of the anteromedial portal and then pull the femoral passage suture out through the anterolateral portal.

We’ll place the Scorpion through the anteromedial portal, and we'll use the Scorpion to pass a fiber ring suture through the stump of the ACL. This fiber ring suture is then pulled out through the accessory anteromedial portal. We'll then repeat these steps to the anteromedial portal to pass the second fiber ring suture.

Here, the tightrope has already been loaded through the first fiber ring suture. We'll then go ahead and pull the second fiber ring suture from the accessory medial portal through the anteromedial portal, and then we'll load the tight rope through the second fiber ring suture.

The passing suture is retrieved from the anterolateral portal and pulled out through the anteromedial portal. The sutures from the cortical button are then loaded through the passing suture and then pulled out the femur. We then pull on the 4 sutures to bring the cortical button into the joint, and this is passed through the femoral tunnel. Once we see the purple mark, we know that the button is about to be flipped, and then we'll pull on the fiber tape sutures to confirm that the button has flipped. We'll then pull on the white sutures at the tightrope individually, to help reduce the ACL to the femoral wall. And then we'll use a probe to confirm adequate tension.

The fiber tape sutures are then pulled out through the anterior tibial tunnel. We then load this into a 4.75-mm Swivelock anchor to complete our internal brace.

Here, I'm now putting the knee through different ranges of motion. I'm also using a probe to check the laxity of the ligament and making sure that there aren't any adjustments I need to make with regard to tension. In this case, I was satisfied with the tension on the repair and no further adjustments were needed.

The rehab protocol is similar to that of an ACL reconstruction. ⁵ I typically have them weightbearing locked straight in extension for about 2 weeks minimum. The brace can be unlocked once the quad control is adequate, generally around 2 to 4 weeks. They can then begin to wean out of the brace around 6 weeks. Jogging can start about 3 to 4 months and return back to sports is about 9 months at the earliest.

Discussion

A recent systematic review was published in 2022, looking at 9 studies with minimum 2-year follow-up. ⁹ They found an average age of 32 years and used 347 patients, and they found an overall failure rate of 10.4% with adequate functional knee scores. Another retrospective study looked at 56 patients, with half of them receiving internal bracing for ACL repair, and at 2-year minimum follow-up, they found no significant difference in International Knee Documentation Committee (IKDC) score, complication rate, or re-operation rate. ⁶

This study that was published in The American Journal of Sports Medicine (AJSM) in 2019 looked at 22 patients that underwent ACL repair with internal bracing, compared with 157 patients that received ACL reconstruction with a quad patellar bone autograph. ² The average age here was 13.9, and they found a significantly higher failure rate in patients undergoing ACL repair, with nearly 50% of them sustaining a graft failure.

However, other results are somewhat encouraging. This is a randomized controlled trial out of the Netherlands published in 2022. ⁴ Here, they compared ACL repair to reconstruction in a young active patient population. They found similar failure rates at 5 years. Despite their positive findings in ACL repair, they still had a disclaimer on performing repair in young, active patients.

Here are some tips that I learned on ACL repair. It's very important to clear off all the soft tissue along the femoral wall to maximize the ACL healing potential. I like to use a cannula in the anteromedial portal for easy passage of instruments. An accessory medial portal is helpful to park sutures that you're currently not using. And finally, I like to take advantage of the adjustable tightrope to re-tension the ACL if necessary after tibial fixation. Now, there are going to be some patients that when you get in, will have poor tissue quality and therefore it's important to consent these patients for both ACL repair and reconstruction. Finally, it's difficult to visualize the femoral button being flipped, and to avoid the button from passing through the IT band, I like to mark out the length of the femoral tunnel on the tightrope itself so when I see that mark, I know the button is about to be flipped and to go a little bit slower.

In summary, I still believe that ACL reconstruction is the gold standard. ACL repair has come a long way, but we need to be strict with our indications and really be cautious in performing these in young patients or patients that have mid-substance tears. There may be promising biological scaffolds that may help augment repair, and it's very important to continue to follow your outcomes.

Here are references and thank you for watching our video.