Anterior cruciate ligament revision (ACLR) surgery has myriad complexities and considerations. In an Instructional Course Lecture (ICL) titled “Optimizing Outcomes in Revision Anterior Cruciate Ligament Reconstruction Surgery” at the AAOS 2024 Annual Meeting, a panel of experts shared diagnostic tools, evaluation techniques, and surgical management tips for achieving optimal and reproducible outcomes for patients with failed ACLRs.

The ICL was moderated by Drew Lansdown, MD, FAAOS, a sports medicine specialist at the University of California, San Francisco Department of Orthopaedic Surgery. He was joined by Christina R. Allen, MD, FAAOS, chief of Yale Medicine Orthopaedics and Rehabilitation Sports Medicine; Michael J. Alaia, MD, FAAOS, codirector of sports medicine at NYU Langone Health; and Jonathan D. Hughes, MD, FAAOS, assistant professor of orthopaedic surgery and team physician at the University of Pittsburgh.

Preoptimization evaluation is critical
Dr. Lansdown opened the ICL by emphasizing the importance of completing a thorough preoperative evaluation and understanding the various factors contributing to the success or failure of ACLR. He detailed the various risk factors associated with reconstruction surgeries, including traumatic re-injury (e.g., graft rupture due to premature return to sport) and a range of technical issues (e.g., tunnel malposition, hardware failure). Traumatic injuries, comprising approximately 56 percent of cases, can present complex challenges that require meticulous evaluation and management. However, technical factors play a critical role in the success of reconstruction surgeries, as well.

According to Dr. Lansdown, understanding the patient’s history, goals, and previous treatments is essential in devising an appropriate treatment plan. Factors such as prior surgeries, graft types, and patient demographics can all contribute to the overall success of the procedure. “There’s a lot that we can gain from the radiographic evaluation,” he told attendees.

Radiographic evaluation plays a crucial role in assessing graft position, tunnel placement, and associated injuries. Advanced imaging techniques, including CT scans, can “be helpful [to] get good information about tunnel size and location,” he said. However, he noted that, in his experience, MRIs often provide “enough information to tailor the treatment plan” for the patient.

Hardware and bone-graft management
“It’s important to note there can be overlap of causes” of ACLR failure, Dr. Allen observed at the start of her section of the ICL. More than one cause can contribute to failure. Most failure modes fall into one of five categories: biological (e.g., graft choice, infection), traumatic, malalignment and arthrosis, surgical technique (e.g., hardware failure, early graft failure), and secondary constraints.

Malpositioned hardware and tunnels are a common cause of graft failure. In some cases, hardware removal and grafting of tunnels are an initial step.

Dr. Allen noted that it is crucial to obtain the old operative notes to understand how the tunnels were originally drilled—whether through the anteromedial portal, via the transtibial approach, or with two incisions with flexible reamers, as the initial operative technique can determine the appropriate approach for hardware removal and bone grafting.

“Beware of non-metal hardware,” Dr. Allen warned. “Just because you can’t see it on X-ray doesn’t mean it isn’t there.” Whether it’s PEEK or nylon implants, careful consideration must be given to removal options to avoid reamer deviation and potential complications.

Even bioabsorbable hardware can present challenges, with the tendency for reamers to bounce off during drilling. “Drill and seat tibial guide pin into the femur so that it is stabilized. This will force the reamer to stay concentric while reaming out tunnel and old hardware, and start with smallest reamer size,” she advised.

Regarding bone-tunnel grafting, Dr. Allen shared that she “will measure likely tunnel size based on preoperative X-rays (anteroposterior/anterolateral),” and “start with reamer 1 to 2 mm less than the [tunnel] diameter on the X-ray.”

Decision making regarding soft-tissue or bone–patellar tendon–bone (BPTB) revision grafts is based on tunnel size, typically with a cutoff of 10 mm for soft tissue and 13 mm for BPTB. Core allograft dowels, ranging from 10 to 16 mm, are used for bone grafting, offering predictable incorporation over 4 to 5 months. Alternatives such as iliac crest bone graft or cancellous allograft chips may also be considered, necessitating additional imaging for monitoring incorporation timelines.

Tunnel widening and real-time decision making
ACLR is “mostly about what we do with what has already been done,” Dr. Alaia noted as he detailed graft selection, tunnel-widening management, and decision making in the OR. He described that there are many “questions about why tunnels have widened that you have to think [about], because this is either a fixation issue or a biological issue, or perhaps an infectious issue.” These factors may force “substantial” choices in the OR.

Dr. Alaia dissected the factors contributing to tunnel widening, ranging from fixation issues to biological factors, such as subclinical infections. Fixation problems (e.g., suspensory fixation, cortical fixation, aperture fixation) can lead to undesirable effects within the tunnels, causing widening and compromising the stability of the reconstructed ligament. Awareness of these possibilities is important, especially when encountering patients with unusually wide tunnels, necessitating further investigation and potential revision strategies.

Strategies such as over-the-top ACLR or staged surgeries may be employed based on individual patient factors and the extent of tunnel widening. “Two-stage surgery is always better than a failed revision. Never hesitate [to choose a two-stage surgery]. It’s never the wrong decision,” Dr. Alaia advised attendees.

Regarding graft selection, compared with allograft, “Autograft is still king for [ACL] reconstruction,” Dr. Alaia remarked. He went on to say, “I like to use bone; if I can use bone in any way, shape, or form, I’m going to use it.” He cautioned against relying solely on soft-tissue healing in revision settings, further emphasizing the importance of ensuring fresh bone integration into the tunnel for optimal outcomes.

Furthermore, Dr. Alaia underscored the significance of anatomical reconstruction and meticulous surgical techniques to optimize outcomes and mitigate the risk of tunnel widening. Techniques such as sequential dilation and graft orientation adjustments can aid in achieving optimal tunnel placement and stability.

When is less more?
Dr. Hughes, the final speaker, was tasked with describing when surgeons should add more to revision ACLRs. Specifically, he spoke in depth about lateral extra-articular tenodesis (LET) and meniscus transplants.

“A lot of research has gone into exactly what constitutes the anterolateral capsule and anterior lateral ligament [ALL], and how much it has to do with rotatory needs,” he said. Studies have presented conflicting perspectives on whether the ALL primarily drives knee stability or serves as a secondary contributor. “[The ALL] does affect rotary instability,” Dr. Hughes remarked, “but the question is how much and what do we need to do about it?”

The debate often revolves around the timing of LET implementation and its impact on long-term outcomes. To address this, Dr. Hughes cited several studies that showed that LET may provide added protection to graft in the early postoperative period but has diminishing benefits over a longer-term period.

High-risk adolescent/young adult patients and elite athletes, including those with hyperlaxity, knee hyperextension, and anterior lateral capsular injury, have been identified as potential candidates for LET. Additionally, factors such as posterior tibial slope and anterior tibial translation play crucial roles in determining the suitability of LET in ACLR.

“Obviously, we all know that the meniscus is a big shock absorber. The knee contributes to low-transmission shock absorption,” Dr. Hughes said, switching gears from LET to meniscus transplants. “The other big thing with the meniscus is that it does help with rotational knee instability.” He explained that a meniscus-deficient knee can lead to increased stress on the ACL graft and potentially contribute to failure of the reconstruction.

Dr. Hughes outlined the indications for meniscus transplant and selection criteria, considering factors such as malalignment, degree of osteoarthritis, infections, knee arthrofibrosis, and patellofemoral arthritis. He briefly touched upon surgical techniques for meniscus transplant, focusing on a soft-tissue approach with slivers of bone on the roots for improved healing.

Like the panelists before him, Dr. Hughes emphasized the importance of thoroughly evaluating patients in revision settings to understand the reasons for previous surgical failures and maximize the success of subsequent surgeries. He closed the session with a few words of advice: “A CT scan can give you some valuable insight. Always obtain full understanding.”

Cailin Conner is the associate editor of AAOS Now. She can be reached at cconner@aaos.org.

References

1. Herbst E, Arilla FV, Guenther D, et al: Lateral extra-articular tenodesis has no effect in knees with isolated anterior cruciate ligament injury. Arthroscopy 2018;34(1):251-60.
2. Getgood A, Brown C, Lording T, et al: The anterolateral complex of the knee: results from the International ALC Consensus Group Meeting. Knee Surg Sports Traumatol Arthrosc 2019;27(1):166-76.
3. Chiba D, Gale T, Nishida K, et al: Lateral extra-articular tenodesis contributes little to change in vivo kinematics after anterior cruciate ligament reconstruction: a randomized controlled trial. Am J Sports Med 2021;49(7):1803-12.
4. Getgood A, Bryant DM, Litchfield R, et al: Lateral extra-articular tenodesis reduces failure of hamstring tendon autograft anterior cruciate ligament reconstruction: 2-year outcomes from the STABILITY Study randomized clinical trial. Am J Sports Med 2020;48(2):285-97.
5. MARS Group: Predictors of clinical outcome following revision anterior cruciate ligament reconstruction. J Orthop Res 2020;38(6):1191-203.