ACL preservation making resurgence with advances in diagnostic imaging, all-arthroscopic surgical technology and rehabilitation approaches
By Gregory S. DiFelice, MD
My interest in ligament repair was really born of my particular clinical setting. My practice is a rather trauma-heavy sports medicine practice with a majority focus on knee and shoulder that is located in a level one trauma center. Early in my career, I found myself faced with a large burden of multiligamentous knee injuries to treat. At that time, our ability to address these injury patterns was not as developed as it is today and when I was faced with ligamentous avulsions, largely the PCL off of the femur, I would make an effort to primarily repair it. This need, when combined with my facility using the arthroscopic shoulder instrumentation, led to my first attempts at arthroscopic primary cruciate repair.
I had good clinical success whenever I attempted primary PCL repair. The knees were certainly as stable, if not more stable, than the reconstructions of the time. There were also a few ACLs that were avulsed either proximally or distally that I fixed during this time, also with good results. However, I was fully aware that the multiligamentous knee setting was not a comparable clinical scenario to an isolated ACL tear. This success was predicated on apposing a freshly avulsed ligament back into a bleeding bony bed, and to me made good biologic sense. A loose analogy could certainly be drawn to performing a rotator cuff repair, and much of the same biologic ingredients were present to predict a high likelihood of healing.
My early successes with primary cruciate repair sparked my interest in whether or not such a technique would work on isolated ACL tears, a much more common clinical problem than the multiligamentous injured knee. Open ACL preservation was the recommended treatment for an acute ACL rupture in the later 1970s and early 1980s; however, the procedure was largely abandoned due to unpredictable clinical results. A thorough review of the older literature convinced me that the conclusion to abandon this procedure was flawed, when viewed through the prism of our current knowledge base. Despite all of the limitations of these studies, it should be noted that on average, roughly 50 percent of these patients had excellent results, even to the long-term follow up. The trouble was predicting which 50 percent had excellent results. The only paper that looked at predictive variables was that of Mark Sherman et al.1 They found that it seemed to be that patients who were older than 22, who had a skiing injury and had proximal type 1 tears with excellent tissue quality, had a much higher likelihood of excellent results. This observation dovetailed nicely with my experiences repairing proximal tears in the multiligament injured knee setting.
I also did a review of the current literature over the past decade on the subject of ACL preservation. I found mostly animal studies from Martha Murray’s lab in Boston that suggested that there might be a role for a biologically augmented ACL preservation. There were also some long-term follow-up studies on the older cohorts confirming approximately 50 percent good to excellent results. Interestingly, there are no new clinical studies on humans regarding primary repair of complete ACL tears in the literature that I am aware of in the past 15 years or more. It was my review of the literature, old and new, that gave me the determination to proceed with expanding my arthroscopic cruciate preservation indications.
The perfect candidate was referred to me about six years ago. He was a 42-year-old skier who was still very active and had an acute, proximal ACL avulsion. I explained to him my experience, my reasoning, and the expected outcomes. I gave him full disclosure of the risks, the benefits and alternatives and he wanted me to proceed with attempted arthroscopic primary ACL preservation. I passed two #2 FiberWire® in a locking fashion with the older Scorpion™, passed them through drill holes and tied them over a ligament button at the lateral cortex. The patient ended up with a completely stable knee, and to this day continues to function well, without any instability symptoms.
As the years have gone by and Arthrex has continued to expand its complement of arthroscopic instrumentation, my technique has been improved and was recently described in the ACL Primary Repair Surgical Technique Guide and in the ACL Primary Repair Surgical Technique Video. My current technique involves passing a Bunnell type stitch of #2 FiberWire® using the Scorpion™ FastPass into each bundle of the avulsed ACL. These are then tensioned and fixed at their respective former origins utilizing 4.75 BioComposite™ SwiveLock®. Currently, I have performed approximately 35 arthroscopic ACL preservations for isolated tears using this technique and have had excellent results to date. As my clinical successes increased, so too did my indications and I now base the indication for surgery most heavily on tear pattern and acuity, rather than other variables.
Based on my experience, I am excited that this may be the beginning of a new step in our collective approach to ACL injury. It is my hope that this experience will bring an increased awareness that it is possible to repair certain patterns of ACL injury with a reasonable expectation of success. These tear patterns are easily identifiable on MRI and can be preserved using my technique or a modification thereof. Rather than abandon the concept of ACL preservation like in the past, I think that we can learn from the historic experience and revisit the concept with a better understanding. Perhaps we can now diagnose those patients who have an excellent chance of benefiting from ACL preservation and reserve the more invasive reconstructions for only those patients who truly need it. This is certainly an intriguing concept, and in light of the advances in diagnostic imaging, arthroscopic surgical technology and rehabilitation approaches that have come to the forefront over the past several decades, ACL preservation is a concept that is ripe for reevaluation.
1. Sherman MF, Lieber L, Bonamo JR, Podesta L, Reiter I. The long-term followup of primary anterior cruciate ligament repair. Defining a rationale for augmentation. Am J Sports Med. 1991; 19(3): 243-255.