Hi everyone, my name is Ashley Bassett, and today I'm going to be speaking about when I consider an ACL repair and then how do I do it. These are my disclosures. So before we dive into ACL repair as it's done today, I'd like to start with a brief history lesson because I think it's important to understand the evolution of ACL surgery and why there are concerns about repair rather than reconstruction. So the first ACL repair was performed in 1895 by Dr. Mayo Robson. He was a general surgeon who described reattaching both cruciate ligaments to their femoral attachments using cat gut sutures. He did this via an open approach through a longitudinal split in the patella as shown here, which we no longer do today. Primary open repair of the ACL was refined and continued to be the surgical treatment of choice for ACL tears well into the early 1970s. This was done via an arthrotomy, suturing of the ligament and reattachment over transosseous drill holes. And while early results were promising, midterm outcomes demonstrated a high rate of failure with recurrent instability, swelling and pain in roughly 50% of patients. The other surgical approach during this era was to tighten the extra articular structures to stabilize the knee as shown here. This included the iliotibial band, hamstring and patellar tendons, capsular structures. And while these procedures were successful in the short term, results deteriorated over time and arthrofibrosis was common. Because of these lackluster results, there was a shift to ACL reconstruction in the late 1970s. This was initially performed open with grafts left in continuity, typically the medial third of the patellar tendon as shown here. Pre-patellar tendon was proposed by Dr. Frank shortly thereafter and quickly became the gold standard. And all tunnels at this time were independently drilled, attempting to anatomically recreate the native ACL as shown here. With the advent of the arthroscope in the 1970s, arthroscopically assisted ACL reconstruction was introduced in the early 1980s and was increasingly utilized. As the arthroscopic technique gained popularity, so did the trans-tibial technique, which involved drilling the femoral tunnel through the tibial tunnel. In the early 2000s, there was renewed interest in anatomic ACL reconstruction by independent drilling of the femoral and tibial tunnels. Anatomic tunnel placement has been shown to create knee kinematics closer to that of an intact knee, better restoring anterior translational as well as rotational stability. Which brings us to present day and a renewed interest in ACL repair. And if you were paying attention to my history lesson, you may be asking, why are we even talking about this? Well, the reason is because the repair technique, including the approach and the implants and the post-op rehab has changed dramatically. And that is responsible for the significantly improved outcomes that we're seeing with ACL repair today. And that's what I'm going to talk a bit about today. So why even consider a repair in the first place? Well, it's because this, the ACL reconstruction on the left side of the screen is not this, the ACL, native ACL on the right side of the screen. So this on the left is taken from the patellar tendon. This is now a piece of dead tissue. It has no blood supply. There's no nerve reinnervation of this. Each of these fibers here are all the same length. They're fixed at the femur and fixed at the tibia. When we look at the native ACL, we have at least a double bundle morphology. These are all individual fibers with individual lengths and individual functions. And at its attachment site, there's no screw holding it to bone. It transitions through a cartilage zone that has much different biomechanics than tendon to bone attachment. And all of these aspects really show how complex the ACL is. So while we're able to stabilize the knee with a reconstruction, we certainly do not come close to restoring the mechanics of the native ACL. Repair of the ACL, rather than reconstructing it, preserves the native ligament attachment sites, the multi-bundle morphology, and the proprioceptive nerve function. Loss of the native ACL is thought to alter joint mechanics and potentially lead to increased rates of osteoarthritis. So these images here show the distal femur cartilage surface after untreated ACL transection, which is shown here on the left, ACL reconstruction shown here in the middle, and an ACL that underwent a repair using a bridging scaffold in an animal model. And one year later, you can see significant cartilage disease involving the medial femoral condyle in the transection group that was untreated. We expect that, we know that that can develop, but in the reconstruction group, you also see some cartilage damage. I mean, it's very slight, but you can see it there by the arrow. When you look at the repair group, these animal models had no cartilage disease, and this is thought to support the theory that preserving the native ligament preserves the true biomechanics of the knee and may better protect against future cartilage disease. ACL repair also has the added benefit of decreased donor site morbidity because you're not taking a graft and smaller and fewer incisions, again, because you're not taking a graft. And if revision surgery is needed in the case of a subsequent ACL re-injury, that surgery is typically easier and results typically mirror that of the primary ACL reconstruction rather than a revision ACL reconstruction, which as we know, based on a lot of literature that has come out, revision ACL reconstructions has significantly inferior outcomes compared to primary ACL reconstruction. So we understand why repair is ideal. That's not really the issue. The issue is that repairs have historically done quite poorly. So why is this? Well, basic science studies have helped us clarify why this is, and to understand it, it's helpful to compare and contrast the healing response for an MCL tear to an ACL tear. So as shown here in this table, injury to both the ACL and the MCL stimulates increased growth factor synthesis. Cells in both the torn MCL and ACL are capable of migrating into the wound site. Those cells are able to proliferate and produce collagen for ligament healing, and both the MCL and the ACL bleed at the site of injury. The difference is that a clot forms at the MCL tear, serving as a biologic scaffold into which those cells migrate, proliferate, and ultimately regenerate the ligament. Conversely, though the torn ends of an ACL do bleed, and if you've ever aspirated a patient with an ACL tear, you know from that hemarthrosis that they do bleed, enzymes present in the synovial fluid do prevent the blood clot from forming. So what's changed? Well, recent advancements in the field of ACL surgery have attempted to address that issue with the development of a type one bovine collagen implant that acts as a scaffold. This scaffold has two roles. First, to protect the clot from synovial degradation, and second, to bridge the gap between the torn ends of the ACL and direct healing cells into that gap to facilitate repair. The implant is typically replaced by native cells, collagen, and blood vessels by roughly eight weeks postoperatively. We now also augment our repairs with an internal brace, which protects the healing ACL during the early phases of repair. So how are these patients doing? Well, based on the data that we have, ACL repair with the B.A.R.E. implant is not inferior to traditional ACL reconstruction with autograft. Level one studies, including the B.A.R.E. 1 and B.A.R.E. 2 trials, have demonstrated equivalent AP laxity at two years, equivalent performance on hop testing, equivalent use of narcotics post-op, and equivalent rates of return to sport at one year. Favoring ACL repair is the fact that patients just feel better faster. They have earlier resolution of symptoms, feel more confident in their knee, and they're more psychologically prepared to return to sports earlier, though it bears mentioning that clearance remains not until nine months post-operatively. Level one studies have also demonstrated superior hamstring strength in patients that underwent ACL repair compared to ACL reconstruction using hamstring autograft, which makes sense. And there's a multi-center RCT currently ongoing comparing the B.A.R.E. ACL repair to the gold standard of ACL reconstruction with B.T.B. autograft. So far, roughly 100 patients of 150 patients have been enrolled, so stay tuned for the results of that. So when do I consider an ACL repair? So I should point out that I'm almost always doing a B.A.R.E. ACL repair simply because I am concerned about all those issues highlighted by the basic science data that may compromise healing. So for me, I'm considering an ACL repair and a proximal third tear with greater than 50% stump remaining attached to the tibia. There are some surgeons out there doing mid-substance ACL repairs with this B.A.R.E. implant. I'm not just quite there yet. In terms of the stump, even more important perhaps than the amount of stump remaining attached to the tibia is the quality of the stump. So we've all seen those ACL tears. They may be proximal, but we get in there and it looks like a bomb went off in the knee. The ACL stump is in multiple different pieces. That's not amenable to repair. That's not gonna hold suture. So it has to be a good enough stump to be able to hold suture to redirect that ACL for the repair. Age. So for me, age over 18 is an indication for an ACL repair. It does bear mentioning that the ACL B.A.R.E. implant, B.A.R.E. repair implant, is FDA approved for patients 14 years of age and older. And about 40% of the B.A.R.E. ACL repairs being done across the country are in patients under the age of 18. But a recent study that came out in July of this past year did show young age as a significant risk factor for ACL repair failure. In patients under the age of 16, there was a 28% failure rate. So again, I'm just not there. A patient over the age of 18 is required for me to consider a repair. Obviously normal alignment. We know that alignment being normal is critical for good outcomes. After an ACL reconstruction, there is the same for ACL repair. So specifically posterior tibial slope, posterior medial tibial slope being heightened has been shown in that same study as an independent risk factor for ACL repair failure. And then timing. Ideally, I try to get to these within six weeks, but it's not really a hard stop. If I get in there, it's eight weeks post-injury and that stump tissue looks good, I'm not going to not do a repair simply because they've passed the six weeks. But obviously if I'm thinking about a repair, I'm trying to get there sooner rather than later. So we're going to talk a little bit about this specific case at the fellows course. So I'm just going to dive right into the surgical technique for now. So first, once I've confirmed that an ACL repair is indeed possible, the stump looks like it's amenable to repair, I insert a Benkart elevator to separate the ACL stump from any scar tissue or adhesions. Just a little pearl, don't completely separate the ACL from the PCL. The ACL tissue becomes quite wispy and starts to fall apart quickly. So I leave a partially scarred to the PCL for control. This part should only take about 15 to 20 seconds. You're just trying to make sure you have enough room to be able to pass the suture back and forth through the stump without it being caught up in that PCL tissue. Next, the ACL stump is sutured using a self-capturing suture passage device, passing the number two suture from distal to proximal about three passes per limb in alternating directions to create a Benel suture configuration. Once the stump is secured, I pull tension on the suture limbs to pull the ACL stump away from the wall. One, to make sure that I have good hold in the tissue, but two, to leave room to be able to do my notchplasty. So then I insert a 4.0 millimeter round burr and I prepare the footprint and perform a notchplasty. I do burr the entire wall unless there's some posterolateral bundle fibers remaining intact, I leave those. Notchplasty has been shown in one study to be associated with improved healing of the ACL on MRI six months after bare ACL repair. So I'm always doing a notchplasty if I'm doing a repair. I don't always do a notchplasty if I'm doing a reconstruction. Once the femoral footprint is prepared, I insert an outside in femoral ACL guide via the anterolateral portal and I place it in the anterior 25% of the femoral ACL footprint. Along the lateral aspect of the knee, I make a two centimeter incision through skin, soft tissue through the IT band to be able to reach the lateral cortex. And then I insert the bullet back down to bone. A 2.4 millimeter cannulated drill is advanced into the joint under visualization. A wire loop is then advanced down the cannulated drill, retrieved out the anterolateral portal and used to shuttle the two repair limbs, as well as one passing suture for later placement of the internal brace at the femoral tunnel. Tension applied to the repair sutures nicely redirects the ACL stump towards the footprint as you can see here. And at the lateral knee, a button that is preloaded with an internal brace suture is then loaded to the repair sutures of the lateral cortex. The internal brace limbs are then loaded to the passing suture and shuttled down the femoral tunnel out the anteromedial portal. And then pulling on those internal brace limbs really allows the button to come down nicely onto the lateral femoral cortex. And I do this under direct visualization to make sure that there's no soft tissue interposition between the button and the cortex. And then not shown here is placement of the tibial tunnel because it's quite similar to the femoral tunnel. I use an outside-in tibial tunnel guide. I use the oval guide, which helps push the ACL stump tissue posteriorly so that the cannulated drill isn't going into the stump tissue and grabbing the sutures. I then advance that same 2.4 millimeter cannulated drill into the anterior third of the tibial footprint. And again, a wire loop lasso is passed into the joint and retrieved out the anteromedial portal. So then we've done all our interarticular work. That's the last time that we'll be in the joint. So now at this point, I extend my arthrotomy to make sure my thumb can easily reach the notch. The joint is irrigated with antibiotic solution. I use vancomycin for my autograft ACL. So that's what I use here. The joint is dried and my gloves are then changed prior to handling the implant as that implant is very absorbent. So if you handle it with wet gloves, it will start to soften on you. So then the two internal brace suture limbs are passed through the central aspect of the implant using a Keith needle. Those limbs are then loaded to the wire loop and shuttled down the tibial tunnel. The implant is then hydrated with roughly 10 cc's of the patient's whole blood, taking care not to saturate the distal most aspect. So as to keep a firm edge to push against. And then the implant is advanced down the internal brace sutures and into the notch while the knee is fully extended by my assistant. The internal brace suture limbs at the tibial tunnel are then pulled taut. The joint is quickly closed to keep that implant in the notch. And then the internal brace limbs are secured to the proximal tibia with a suture anchor. And then lastly, we go back to that lateral femoral cortex and the repair sutures are tied over the button, which completes our repair. So postoperatively, patients are locked in full extension for 24 hours, absolutely no flexion for 24 hours. After 24 hours, they can start to bend the knee limited to 45 degrees for the first two weeks. They then are limited to 90 degrees for the next two weeks until the four week mark. At four weeks, patients are able to advance a range of motion as tolerated. I have a goal of 120 degrees by six weeks and full range of motion by eight weeks. Patients are partial weight bearing for four weeks using crutches after the surgery. And then they may advance to full weight bearing as tolerated and wean out off of the crutches. I start blood flow restriction therapy at two weeks. Postoperatively, in both my ACL reconstruction as well as my ACL repair patients. In both, I start running progression at three months. Return to play testing starts at six months and clearance is no earlier than nine months. Thank you.

ACL surgery

evolution

reconstruction

advancements

surgical technique