To read a summary of the research conducted by Freddie H. Fu, MD, of the University of Pittsburgh, is to read a modern history of advances in techniques and concepts to repair a ruptured anterior cruciate ligament (ACL). His paper detailing the results of his three decades of research in this field is the recipient of the 2014 Kappa Delta Elizabeth Winston Lanier Award.
The work done by Dr. Fu and his team helped shape the evolution of ACL reconstruction, shifting it from a standardized technique that “neglected the anatomy of the patient” and failed to place the femoral and tibial tunnels within the native ACL insertion sites to one that more faithfully restores the natural anatomy of the ACL structure.
An ACL injury can be devastating, particularly for a young athlete, and surgical reconstruction is often required to enable a return to high-level participation in strenuous sports. Although techniques have been refined, long-term osteoarthritis (OA) remains a persistent problem.
“At this age, there are no good treatment options for this devastating disease,” Dr. Fu writes. “It is therefore important to develop new approaches to reconstruct the ACL, aiming to maintain both long-term knee health and quality of life.”
Less invasive, but flawed
Historically, ACL reconstruction was performed via an arthrotomy, with the goal being to reproduce the native (normal) anatomy of the ACL. The introduction of minimally invasive surgical techniques led to the development of arthroscopically assisted ACL reconstruction, originally with a two-incision technique, in which the femoral bone tunnel was drilled from the outside in. Over time, a one-incision technique was adopted, in which the femoral bone tunnel is drilled from the inside out, through the tibial tunnel.
“Both techniques were fast and efficient,” Dr. Fu writes. “Unfortunately, neither was consistent with respect to reproducing the native ACL anatomy.”
The major advancements made with the introduction of arthroscopic ACL surgery were partially offset by new problems, such as the loss of knee range of motion, as well as impingement of the new ACL graft. In addition, as the number of primary ACL reconstructions increased, so too did the number of failed ACL reconstructions, resulting in an increased number of revision ACL surgeries.
Hoping to improve the effectiveness of orthopaedic care that patients received for ACL injuries, Dr. Fu and colleagues established the University of Pittsburgh Anatomic ACL Reconstruction Research Group. Today, this multidisciplinary study group includes orthopaedic surgeons, engineers, basic scientists, radiologists, physical therapists, athletic trainers, residents, fellows, and students from the United States and all over the world.
One of the first things the researchers did was to review all studies that described the surgical technique for “anatomic ACL reconstruction.” They found a lack of evidence and consensus on appropriate methods for anatomic ACL reconstruction.
Extensive studies of the knee improved their understanding of ACL anatomy and function and led to the development of the double-bundle anatomic ACL reconstruction technique. In this technique, the anteromedial (AM) and posterolateral (PL) bundles are placed at their anatomic insertion sites on both the tibia and the femur through separate bone tunnels, with the goal of closely approximating the native anatomy and biomechanical function of the ACL.
Dr. Fu says that “it is now generally accepted that conventional, nonanatomic single-bundle ACL reconstruction fails to restore normal knee kinematics and leads to altered patterns of joint loading.”
Double vs. single
Noting a shortage of Level I studies on ACL reconstruction, he and his colleagues conducted a randomized clinical trial to compare the clinical outcomes of three different ACL reconstruction techniques: anatomic double-bundle, anatomic single-bundle, and conventional single-bundle reconstruction. They found that anatomic single-bundle reconstruction resulted in less anteroposterior and rotational laxity than conventional single-bundle reconstruction, and the results of the double-bundle group surpassed those of the anatomic single-bundle group for laxity. Their work subsequently received the 2013 Hughston Award for the best paper published in 2012 in the American Journal of Sports Medicine.
Recently, Dr. Fu and colleagues received a grant from the National Institute of Arthritis, Musculoskeletal, and Skin Diseases to conduct a prospective, randomized, double-blind clinical trial comparing anatomic single-bundle and anatomic double-bundle ACL reconstruction. The study aims to determine which procedure is better in terms of dynamic knee function and clinical outcomes.
“Successful completion of this study will provide evidence of the efficacy of anatomic double-bundle ACL reconstruction for restoring normal knee mechanics and improving clinical outcomes,” Dr. Fu writes. “If the results show a clear benefit of this procedure, then a sound basis will have been established for future studies to assess the benefits of anatomic double-bundle ACL reconstruction for long-term clinical outcomes and joint health.”
Dr. Fu observes that “anatomic double-bundle reconstruction has grown from a technique to a concept aiming to restore the knee’s native anatomy.” The goal, he states, is to make this concept applicable to all methods of ACL surgery. He and his colleagues have developed a flowchart to aid surgeons in the clinical decision making involved in ACL surgery. As a result of these efforts, anatomic ACL reconstruction has been defined as “the functional restoration of the ACL to its native dimensions, collagen orientation, and insertion sites.”
To clarify the roles of each element, Dr. Fu’s team developed the Anatomic ACL Reconstruction Scoring System, which was recently published in the Orthopaedic Forum of the Journal of Bone and Joint Surgery. This scoring system is expected to be used to grade ACL reconstruction procedures for individual patients, as well as for comparative evaluation of the description of surgical methods in published studies on anatomic single- and double-bundle ACL reconstruction and peer review of such papers. The system was recently tested and found to be both reliable and valid, with good internal consistency of the included items.
The need for reliable outcome measures for evaluating progress in ACL reconstruction persists, Dr. Fu states. “If we, as surgeons, want the best care for our patients, we must be critical of our own performance,” he writes. If systematic reviews and meta-analyses comparing different ACL reconstruction techniques show no difference in outcome, he asks, “Does this mean that there is no difference, or do we need to reevaluate the ability of our outcome measures to detect subtle differences in kinematics of the knee, which in the long term may be associated with the development or prevention of posttraumatic osteoarthritis?”
Dr. Fu says that in literature reports, normal and nearly normal are often combined into a single group, “implying that ‘nearly normal’ is good enough.” More precise instrumentation and testing techniques are needed for better evaluation, including imaging to detect early cartilage changes and dynamic stereo radiographs to precisely quantify in vivo knee kinematics. In an effort to make the pivot shift test more accurate, reliable, and objective, Dr. Fu and colleagues recently formed an international Pivot Shift Study Group.
Dr. Fu concludes that a paradigm shift has occurred in ACL reconstruction. Before this shift, he writes, ACL reconstruction was based on standardized techniques that neglected the individual anatomy of the patient. The body of research presented in his Kappa Delta paper has helped to define ACL anatomy, imaging, biomechanics, and knee kinematics after ACL reconstruction, “with the primary goal to improve medical care for patients.”
The work is ongoing. “It is a long and continuing journey to be anatomic,” Dr. Fu writes.
Disclosure information: Dr. Fu—Arthrocare, Stryker, SLACK Incorporated, Wolters Kluwer Health – Lippincott Williams & Wilkins; American Journal of Sports Medicine; Current Reviews in Musculoskeletal Journal; FORMOSAN Journal of Musculoskeletal Disorders; Isokinetics and Exercise Science;Journal of Dance Medicine & Science; Journal of Exercise Science & Fitness; Knee Surgery, Sports Traumatology, Arthroscopy; Open Access Journal of Sports Medicine; Orthopedics Today; Saunders/Mosby-Elsevier; Sports Exercise and Injury; International Society of Arthroscopy, Knee Surgery, and Orthopaedic Sports Medicine; Orthopaedic Research and Education Foundation; World Endoscopy Doctors Association