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Is double-bundle ACL repair better?

An interview with Freddie H. Fu, MD

By Mary Ann Porucznik

Freddie H. Fu, MD, DSc(Hon), DPs(Hon) is a strong proponent of the double-bundle technique, which has been called a “gimmick” by some.

More than 100,000 anterior cruciate ligament (ACL) reconstructions are performed every year in the United States, making this one of the most commonly performed orthopaedic procedures. In most cases, surgeons use a hamstring tendon or a patellar tendon autograft/allograft to replace the ligament, which attaches proximally on the posterior aspect of the lateral femoral condyle and runs in an oblique course distally through the intercondylar notch to insert between the medial and lateral tibial spines.

“When orthopaedic surgeons began doing ACL reconstructions, it was a technically difficult procedure,” says Freddie H. Fu, MD. “But the development of arthroscopic tools and techniques enabled us to improve both our outcomes and our understanding of this complex structure.”

That understanding is still developing, in part due to ongoing research into the anatomic structure and functioning of the ACL.

“For example,” Dr. Fu continues, “I don’t ever recall being taught in medical school about the anatomy of the ACL. It turns out that the way orthopaedic surgeons have been doing ACL reconstruction all these years—although certainly with excellent outcomes for most patients—doesn’t really reflect the anatomic construction of the ACL itself.”

The ACL, he points out, is comprised of two separate functional bundles of fascicles, not a single cord. But traditional ACL reconstruction treats the ligament as though it were a single construct, replicating one of the functional bundles but not the other.

“Here’s the dilemma,” says Dr. Fu. “As our understanding of the basic science and anatomy of the ACL has increased, and as the technology has improved, orthopaedic surgeons now have the opportunity to more closely replicate the natural anatomy of the ACL. Doing it as we have been in the past is effective, but there’s room for improvement, particularly in restoring normal knee kinematics. The double-bundle technique may offer us that opportunity.”

Freddie H. Fu, MD, DSc(Hon), DPs(Hon) is a strong proponent of the double-bundle ACL reconstruction technique.

Closer to normal?

In Dr. Fu’s view, the introduction of the double-bundle ACL technique is “a new beginning for ACL surgery.” He compares the situation to the development of new techniques for total joint replacement. “Orthopaedic surgeons may approach total knee replacement for elderly, basically sedentary patients much differently than they do for young, active individuals. There is a recognition that what is an acceptable outcome in the first case may not be acceptable in the other.”

In the long run, he believes, a double-bundle technique, by more closely replicating the normal anatomy of the ACL, could improve knee kinematics, resulting in more normal functioning and reducing the incidence of degenerative arthritis.

“If you hang a door by only one hinge,” he says, “the door will hang crooked and the bottom may stick and wear unevenly. If you add a second hinge, you make the door more level and eliminate that erosion. With single-bundle repair, you have one hinge. With a double-bundle approach, you add the second hinge. We still need more clinical trials, but the theory applies.”

Short-term results seem to bear out the theory. Patients who have double-bundle ACL repair regain more range of motion (ROM) more quickly than those who have traditional ACL reconstruction, according to Dr. Fu.

Although other studies have shown no statistical difference between single-bundle and double-bundle ACL reconstruction using various measures, Dr. Fu points out that the most significant test has yet to be developed. Because a considerable number of patients continue to have persistent anteroposterior laxity and a persistent pivot shift after single-bundle ACL reconstruction, the difference between the two techniques might be found in the amount of internal tibial rotation after surgery.

“It’s hard to evaluate in three dimensions, so that will be the next challenge,” he says. “We need to develop more objective ways to evaluate rotational stability. Right now, we have no convenient, noninvasive and reliable clinical method to use.”

The surgeon’s challenge

The double-bundle ACL reconstruction technique is challenging and time-consuming, with a steep learning curve, admits Dr. Fu. “But the technique, concept and basic science evidence of double-bundle ACL surgery can also be applied when doing single-bundle ACL reconstruction,” says Dr. Fu. “It’s not a gimmick…it’s basic science applied to a complex function [of the knee].”

(For more on the technique, refer to the “Perspectives on Modern Orthopaedics” in the February issue of the Journal of the AAOS. Dr. Fu has also produced an award-winning video, Anatomic Double-Bundle ACL Reconstruction: Concepts and Surgical Techniques, which is available through the AAOS online store, www.aaos.org/products.)

But just as the double-bundle technique isn’t necessary for every patient undergoing ACL reconstruction, it’s not necessarily right for every surgeon either. Surgeons who do fewer than a dozen ACL reconstructions a year—with good results—probably should keep doing exactly what they’re doing.

“Current techniques are fine, if the main goal of surgery is to allow the patient to return to sports and activities,” says Dr. Fu. “You won’t see dramatic improvements simply by switching to the double-bundle technique. But double-bundle, because it is closer to normal anatomy, could make a difference in long-term outcomes, particularly in the development of degenerative joint disease.

“In Japan, they’ve been using this technique for about eight years,” he points out. “But here, it’s relatively new and surgeons are still measuring its value—in terms of work, time, and outcomes. It does take more time and requires more precision. I do it because I want to make it [the reconstruction] as perfect as I can. It’s not quite perfect yet, but I can try.”

Jan/Feb 2007 AAOS Now
http://www.aaos.org/news/bulletin/janfeb07/cover2.asp