A Novel Arthroscopic Technique for ACL Preservation

Gregory S. DiFelice, MD


March 04, 2016

Editor's Note: Last November, the journal Arthroscopy published a promising study on a novel arthroscopic technique for suture anchor primary anterior cruciate ligament (ACL) repair.[1] The authors performed a retrospective review and early follow-up of 11 consecutive cases of ACL preservation and found that 10 of 11 patients had good subjective and clinical outcomes after ACL preservation surgery at a minimum of 2 years' and a mean of 3.5 years' follow-up, with level IV evidence. They concluded that preservation of the native ACL using their arthroscopic primary repair technique can achieve short-term clinical success in a carefully selected subset of patients with proximal avulsion-type tears and excellent tissue quality. Here, lead author Gregory S. DiFelice, MD, an orthopedic surgeon specializing in sports traumatology and joint reconstruction surgery at the Hospital for Special Surgery and New York-Presbyterian Hospital , discusses the new technique and provides historical context for its use.

How ACL Repair Fell Out of Favor

It is not easy to determine exactly why and when orthopedic surgeons completely gave up on trying to primarily repair the torn ACL, but it was some time in the early 1990s, and in hindsight, it might not have been the best decision. Multiple papers had reported unpredictable midterm results, but a careful review of the older literature through the lens of modern-day understanding reveals many flaws and biases.

For example, Feagin and colleagues'[2] 5-year follow-up study, still one of the most quoted articles on the topic, had limited follow-up, reporting on only 50% of the original cohort. Other studies were procedurally overbroad, including repair of all tear types (proximal, middle, and distal) and/or including subjects with multiple associated ligament injuries that blurred the results of ACL repairs; in one study, for example, 77% of participants had concomitant medial collateral ligament (MCL) repairs.[3] In other studies, the age groups of the participants were too broad to show the efficacy (or lack thereof) of torn ACL repair; in a 2005 study by Strand and colleagues,[4] for example, one patient was 79 years old. Finally, the combination of an open approach (arthrotomy) with postoperative long-leg cast immobilization for 6 weeks, which was the standard of care at the time, is currently well known to result in loss of range of motion and patellofemoral issues, which were common complaints of these patients.

If we focus specifically on tear type, Sherman and coworkers[5] did the first exhaustive covariate analysis in their landmark paper in 1991. Although they felt that ACL repair was not predictable enough to recommend routinely, they did find that tissue type (proximal type 1 tears) and tissue quality (excellent) were two of several variables associated with good outcomes. However, this article could have been the epitaph for the procedure. After its publication, interest in ACL repair dropped off precipitously as the attention of the surgical community turned toward investigating the addition of graft material in the knee to improve ACL clinical outcomes.

This was unfortunate, because while most of the surgical community began to favor ACL reconstruction as the standard treatment for all tears regardless of their characteristics, a study 2 years later by Genelin and colleagues[6] reported excellent midterm results on a group of 49 patients who all had proximal tears that were repaired primarily using a mini-open arthrotomy technique.

Findings in the Recent Literature

Several decades have passed since there was robust interest in primarily repairing the ACL. My team at the Hospital for Special Surgery in New York recently published a systematic review of the literature on ACL repair from 2003 to 2014 to see exactly what had been published.[7] We found a small group of long-term follow-up studies on the original historical cohorts that reported roughly 50% failure rates. In addition, 18 preclinical studies were identified. Using mostly porcine subjects, these papers largely investigated variables in bioenhanced ACL repair applied to a transection model. This impressive body of work, some of it award-winning, was largely the result of work by the lab of orthopedic surgeon Martha Murray, MD, at Boston Children's Hospital. Dr Murray's group recently began a pilot study in which this technique is being used in human subjects, and there is great anticipation regarding the results.

A New, Minimally Invasive Technique

Expanding on the work of Sherman's and Genelin's groups—while applying advances in imaging and surgical and rehabilitative techniques—allowed me to develop a new, minimally morbid arthroscopic suture anchor technique to reattach the ACL when it is proximally detached. Such patients are potentially the low-hanging fruit of the ACL-injured cohort because stability to the knee could be restored without undergoing a full reconstruction. With the application of this technique in appropriately indicated patients, we could potentially restore knee stability while avoiding the significantly more morbid reconstructive procedures. My team recently reported on the outcomes of my initial cohort of 11 patients using this technique.[1]

Excellent Clinical Outcomes

All patients in my series had MRI-diagnosed (Figure 1) and arthroscopically confirmed proximal avulsion ACL tears (Figure 2) prior to undergoing arthroscopic, suture-anchor primary ACL repair. The technique uses a self-retrieving suture passer (Figure 3) to pass high-strength, nonresorbable stitches in a locking pattern into both the anteromedial and posterolateral bundle fibers (Figure 4). The bundles are then reapposed back to the femoral origin of the native ACL using two vented, biocomposite, knotless suture anchors (Figure 5 and Figure 6).

Figure 1. MRI showing proximal ACL avulsion-type tear.

Figure 2. Arthroscopic confirmation of proximal ACL avulsion-type tear.

Figure 3. Self-retrieving suture passer being used to pass repair stitches into the ACL substance.

Figure 4. Repair stitches have been placed into both the anteromedial and posterolateral bundles of the proximally avulsed ACL.

Figure 5. Vented, biocomposite, knotless suture anchor being deployed to reapproximate the ACL fibers to their boney origin.

Figure 6. Final view of the arthroscopically, primarily repaired proximal ACL avulsion-type tear.

Postoperatively, patients were immediately allowed to bear weight and range the knee, although while they were standing, the knee was protected by a locked brace for the first month. Patients were mostly male, 37 years of age on average (age range, 17-57 years), and most had sports-related injuries. The average delay to surgery was 39 days (range, 10-93 days). Follow-up, averaging 41 months (range, 25-75 months) after surgery, was performed on 100% of patients.

In 10 of 11 patients, clinical outcomes were excellent. There was only one clinical failure. That patient felt a pop while going down stairs 3 months postoperatively, and subsequently was noted to have increased laxity on exam. He elected to live with it. The other 10 patients did well, with excellent subjective and objective clinical outcome scores (Table). Tegner Activity Level Scale scores were maintained in eight patients. In addition, KT-1000 measurements were available in eight patients and showed less than 3-mm side-to-side difference on maximum manual testing in all 10 patients who did well.

Table. Average Subjective and Objective Outcome Scores in 11 Patients (Average Status 3.5 Years Post-Arthroscopic Primary ACL Repair)

Scale Score
Tegner Lysholm Knee Scoring Scale 93.2
Modified Cincinnati Rating System Questionnaire 91.5
Single Assessment Numeric Evaluation (SANE) 91.5
International Knee Documentation Committee (IKDC) Subjective Knee Evaluation 86.4
IKDC Objective Knee Evaluation A 9/11, B 1/11, C 1/11 patients


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