Arthroscopic repair of proximal ACL tears aims to restore native biomechanical properties
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Arthroscopic primary ACL repair has seen a resurgence of interest around the world.
Recent comparative trials indicate that ACL repair using modern-day selective approaches has comparable or better functional outcomes vs. ACL reconstruction, while failure rates are similar or slightly higher.
The resurgence of interest in ACL repair has led to the presentation of a variety of approaches to treat a proximally torn ACL, all with the common aim of restoring knee stability and kinematics while preserving the native ACL and its proprioceptive function in patients with proximal ACL tears.
With this updated technique, we want to highlight the importance considering essential anatomical and biomechanical factors when performing primary ACL repair. We present an evolved procedure, performing separate anatomical re-approximation of both bundles to their respective femoral footprints, with an additional posterolateral compression stitch. This technique increases the ligament-bone contact area and recreates the anatomic vectors of the native ligament, aiming to restore the native biomechanical properties of the knee joint. This technique has recently been published in Arthroscopy Techniques.
Source: Sebastian Rilk, MD; Gabriel C. Goodhart, BA; Robert O’Brien; Gregory DiFelice, MD
Indications
The indication for anatomic arthroscopic primary ACL repair is defined through the presence of a proximal tear (type 1 to type 2: proximal 25% of the ligament) and good to excellent tissue quality (Figure 2). Patients are preferably treated in the acute setting (less than 4 weeks), although performing primary ACL repair in chronic tears has also been effective.
No restrictions are given regarding activity level and age, although patients older than 21 years demonstrate lower reinjury rates than younger patients.
Technical guide
To start the procedure, the patient is positioned supine for standard arthroscopic ACL surgery. Anteromedial and anterolateral portals are created and a passport canula is inserted at the anteromedial portal to improve suture management. A final confirmation of the tear type and tissue quality is made by displaying the ligament arthroscopically (Figure 2) and the feasibility of the refixation is also tested by gently pulling the ligament to the native femoral footprint using an arthroscopic grasper. In the case of a chronic tear, where the ACL may be scarred to the PCL, the ACL can be gently separated using an arthroscopic scissor.
To start the repair procedure, a suture passer and a #2 repair suture (blue) are first used to stitch the anteromedial bundle. This is performed in an alternating, interlocking Bunnell-type pattern from as far distally as possible to the proximal avulsed end with three to four passes, depending on the tissue quality. The repair sutures exit on either side of the ligament proximally (Figures 3a through 3c). Each bite through the bundle is performed while while gently holding the suture tails (anteromedial portal) with gentle tension so the ligament will not splay apart.
Next, an inferior-medial portal is created to reach the femoral footprint of the ACL for the placement of the 4.75-mm Vented BioComposite SwiveLock anchors (Arthrex) at a later stage, and to dock and retract the repair sutures.
Applying the same technique as for the anteromedial bundle, the posterolateral bundle is stitched using a #2 repair suture (white-and-black striped), with usually two to three passes. In contrast to the anteromedial sutures, the posterolateral repair sutures exit proximally laterally toward the femoral wall (Figures 3d to 3f). The posterolateral suture is retrieved through the inferior-medial portal, while the suture used in the anteromedial bundle is retrieved out the anteromedial portal.
Following the suturing of both ACL bundles, the femoral notch is slightly decorticated with a shaver anteriorly to the femoral footprint (preserving the footprint) to induce bleeding. A 4.5-mm x 20-mm hole at the native posterolateral femoral footprint is drilled and tapped with the knee flexed at 115°. Next, a 4.75-mm suture anchor loaded with the posterolateral suture is inserted through the inferior-medial portal and deployed at 115° knee flexion into the femoral posterolateral footprint hole, tensioning the ACL remnant to the wall. With the knee at 90°, the same technique is repeated for the anteromedial bundle using repair sutures and another suture anchor, preloaded with a FiberTape suture (Arthrex) to serve as the suture augmentation. Once the anchors are deployed and flush with the femoral footprint, the handle is removed and the free ends of the repair suture are cut short while the core stitches from this anchor are removed.
The additional posterolateral compression stitch is performed by passing the posterolateral bundle’s core stitch from laterally to medially through the posterolateral bundle. After the core stitch has been placed from laterally to medially, a knot pusher is used to compress the ligament with three alternating half hitches from medially to laterally to its native femoral footprint to achieve maximal wall contact and reestablish the native anatomic ligament vector. The free ends of the core stitch are cut short to finish the femoral refixation (Figure 4).
To establish tibial fixation of the suture augmentation, a 2.4-mm cannulated pin is drilled from the proximal anteromedial cortex of the tibia up and exiting at the anterior one-third of the tibial ligamental insertion. An arthroscopic probe is used to apply counterpressure when drilling through the tibial insertion to stabilize the ligament. A nitinol wire lasso is passed through the pin and into the knee to shuttle the suture down through the tibia to create the suture augmentation (Figure 5a). The suture is lightly tensioned and, using another suture anchor, fixed with the knee in full extension perpendicular to the tibial cortex.
The procedure is completed after confirming the anatomic position of the ligament, testing the ligament for tension using a probe and then visualizing the ligament during range of motion to ensure there is no graft impingement (Figure 5B).
Postoperative care
A brace is indicated postoperatively and locked in extension while ambulating. This is maintained until the protective quadriceps function fully returns, at which point the brace can be unlocked for the rest of the first 4 postoperative weeks.
Full weight-bearing is possible from day 1 and range of motion exercises can be performed immediately without the use of the brace. Physical therapy is started in the first week after surgery and follows a milestone-based approach rather than a timeline-based approach.
- References:
- Ferreira A, et al. Am J Sports Med. 2022;doi:10.1177/03635465221126171.
- Ferretti A, et al. Am J Sports Med. 2023;doi:10.1177/03635465231178301.
- Li J, et al. Orthop J Sports Med. 2022;doi:10.1177/23259671221132564.
- Rilk S, et al. Arthrosc Tech. 2023;doi:10.1016/j.eats.2023.02.022.
- Rilk S, et al. J ISAKOS. 2023;doi:10.1016/j.jisako.2023.03.434.
- van der List JP, et al. Am J Orthop (Belle Mead NJ). 2016;45:E393-E405.
- van der List JP, et al. HSS J. 2017;doi:10.1007/s11420-016-9530-8.
- Vermeijden HD, et al. Arthroscopy. 2021;doi:10.1016/j.arthro.2020.11.024.
- Vermeijden HD, et al. Knee. 2020;doi:10.1016/j.knee.2020.04.001.
- Vermeijden HD, et al. Knee. 2021;doi:10.1016/j.knee.2021.01.028.
- For more information:
- Gregory S. DiFelice, MD; Gabriel C. Goodhart, BA; Robert O’Brien; and Sebastian Rilk, MD, can be reached at the department of orthopedic surgery at Hospital for Special Surgery, New York-Presbyterian and Weill Medical College of Cornell University in New York. DiFelice’s email: difeliceg@hss.edu. Goodhart’s email: goodhartg@hss.edu. O’Brien’s email: obrienro@hss.edu. Rilk’s email: rilks@hss.edu.
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