By: 3 July 2019
‘Less may be more’ when it comes to ACL repair

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Gregory S. DiFelice, MD, of the Hospital for Special Surgery, New York, NY, talks about primary ACL repair

Q: What is the latest news with primary ACL repair?

A: Well, it seems that the ice is starting to break as more and more surgeons are warming up to the idea that there may be a middle ground with regards to the treatment of ACL injuries. In other words, repairing appropriately selected tear patterns could be an effective treatment option to complement the current binary approach that includes nonoperative treatment and reconstruction as the only options. Thanks to an incredibly productive two years of research led by my research fellow, Dr Jelle van der List, we have a lot more to talk about with regards to all facets of the discussion surrounding ACL repair. After struggling to get our research even accepted to meetings, it seems as if the worldwide orthopaedic community is realising that “less may be more,” since we now have had posters, presentations, and scientific exhibits at nearly every major meeting and have published over 20 papers and book chapters. 

Q: At Arthrex, we can certainly confirm that there are many surgeons who have started to perform ACL repairs for well-selected patients. How have your results been?

A: So far, so good. The last thing in the world that I want to do for my patients is a surgery that will not be successful for them, and thus I have been tracking my results very closely. Importantly, the first cohort of 11 patients that we reported on in Arthroscopy in November 2015,[1] has passed the important five-year mark. In our first paper, 10 out of 11 patients were doing great at a minimum of two years’ follow-up and I am happy to report that at a minimum of five years’ follow-up, they continue to do so. All 10 patients that were doing well at the first follow-up continued to do even better at the five-year follow-up without significant reinjuries. The paper was recently published in Arthroscopy.[2] 

This data is critical because the research detailing the outcomes of the original cohorts of patients who underwent open ACL repair back in the day showed significant deterioration between the two- and five-year follow-ups.[3] We realized that the numbers are small, but also understand that you have to start somewhere. We are now amassing the data on a much larger cohort. We recently presented the results of my first 56 patients at both ESSKA and AOSSM, showing 90 per cent successful outcomes at an average follow-up of three years.[4] This paper has been accepted and published online.[5] Currently, I have performed more than 200 arthroscopic ACL primary repairs and to date have had 14 patients reinjure their ACL that I am aware of. I say reinjure because, aside from the patient that was reported in the first 11 patients who failed his repair at three months post-op without a significant trauma, the other patients all reinjured their repaired ACL between nine months and two years post-repair when they experienced another significant injury, usually while playing sports.

Q: Speaking in rough numbers, some may say that the failure rate is likely the same or possibly even higher than with ACL reconstruction. Why would a surgeon want to learn a new technique to repair the ligament rather than what they already know, that is, to reconstruct it? 

A: This is really the crux of the repair argument. In a nutshell, the recovery from an ACL repair surgery is dramatically quicker and easier on the patient than a reconstruction. The majority of my patients are off narcotic pain medications within one to two days postoperatively, have full ROM within seven to 10 days, and can run in a straight line at four to six weeks post-op. 

In general, their knees feel relatively normal afterwards, because they are relatively normal, except that the ACL is scarred to the femoral wall rather than having the native taken off. By repairing the native ACL there are no grafts, no tunnels, and you save the nerve endings and blood supply to the ligament. In May 2017, we published an article in The Knee to illustrate to practitioners that ACL repair patients have a much easier go of it than ACL reconstruction patients.[3] 

We compared 52 ACL primary repair patients to 90 ACL reconstruction patients for the first three months post-op. We showed that the repair patients have significantly more ROM at the first post-op visit, and achieve full ROM months faster than the reconstruction patients. In addition, it is a safe operation with very few complications and reoperations, as compared to reconstruction. We also have preliminary data regarding narcotic usage and are seeing that the repair patients are using half as many pills as the reconstruction patients. Close to 25 per cent of the repair patients use no narcotic pills at all after surgery. 

In the end, after many surgeons have adopted this approach, and hopefully improved it for that matter, I imagine that ACL repair might have the same, or a slightly higher, failure rate than ACL reconstruction, if strict patient selection criteria are applied. However, this brings up another tremendous benefit of this approach. If an ACL repair fails, then it can be easily “revised” to a reconstruction as if it was the first time, since no bridges were burned with the original procedure. In comparison, if an ACL reconstruction fails, then the “revision” can be far trickier with less predictable outcomes as we all know. 

It really comes down to the simple question: would you rather have a smaller operation with a quicker recovery and a slightly higher failure rate, or a larger operation with a much longer recovery and a slightly lower failure rate? Certainly the answer to this question will be individual to each surgeon and patient, and it will depend entirely upon the numbers. Based upon my work, with the right tear type and tissue quality, you know what my answer is. 

Q: For ACL primary repair, what are your thoughts on using InternalBrace™ ligament augmentation? The InternalBrace technique is used throughout the body for ligament repairs by augmenting with a FiberTape® suture. Does InternalBrace ligament augmentation have a role in ACL primary repair? 

A: When the InternalBrace implant first came out, I used it with my suture anchor technique. Gordon Mackay attaches it to the ACL TightRope® implant (Figure 1). I attach it to one of the upper anchors in the femur (Figure 2). It serves as a safety belt. It gives me a sense of calm when I put the InternalBrace implant in a patient, especially high-risk patients such as younger patients and patients with knee laxity. I know the InternalBrace augmentation will back me up so they don’t fail in the case of a fall. The InternalBrace implant will catch so the ACL does not take the full load. 

View Ellen Bellino’s story after ACL primary repair by Dr DiFelice at:


  1. DiFelice GS, Villegas C, Taylor S. Anterior cruciate ligament preservation: early results of a novel arthroscopic technique for suture anchor primary anterior cruciate ligament repair. Arthroscopy. 2015;31(11):2162-2171. doi:10.1016/j.arthro.2015.08.010 
  2. DiFelice GS, van der List JP. Clinical outcomes of arthroscopic primary repair of proximal anterior cruciate ligament tears are maintained at mid-term follow-up. Arthroscopy. 2018;34(4):1085-1093. doi:10.1016/j.arthro.2017.10.028 
  3. van der List JP, DiFelice GS. Role of tear location on outcomes of open primary repair of the anterior cruciate
    ligament: a systematic review of historical studies. Knee. 2017;24(5):898-908. doi:10.1016/j.knee.2017.05.009 
  4. Jonkergouw A, van der List JP, DiFelice GS. Arthroscopic primary repair of proximal anterior cruciate ligament tears: with or without additional suture augmentation? Orthop J Sports Med. 2018;6(7 suppl 4): 2325967118S00063. doi:10.1177/2325967118S00063 
  5. Jonkergouw A, van der List JP, DiFelice GS. Arthroscopic primary repair of proximal anterior cruciate ligament tears: outcomes of the first 56 consecutive patients and the role of additional internal bracing [published online January 5, 2019]. Knee Surg Sports Traumatol Arthrosc.