AMSURG partner David Lin, M.D., FAAOS, of Short Hills Surgery Center in Millburn, N.J., spoke with AMSURG about anterior cruciate ligament (ACL) reconstructions and how the procedure has evolved over the last several years. Considered one of the leaders in pediatric ACL reconstruction, Dr. Lin and his colleagues, Drs. Joshua Strassberg and Mark Rieger, have performed more procedures in these age groups than any other practice in New Jersey. Recent advancements in ACL repair have emphasized more accurately restoring the anatomic placement, structure and function of the native ligament. Most people have heard of an ACL injury, but many of us probably could not define it. Could you briefly explain it? The anterior cruciate ligament is a rope-like structure that connects the femur to the knee and is found within the knee joint. The ACL is the primary stabilizer in the knee that prevents the femur from translating too far forward on the tibia. In addition, along with other bony and soft tissues structures within the joint, it resists the two bones from pivoting or rotating around each other during physical activities. We usually think of ACL injuries only in adults. Under what circumstances would a child need ACL repair? ACL injuries in both the pediatric and adult patient populations occur in similar fashion. Trauma typically occurs from a sudden decelerating, angular and/or pivoting injury to the knee. Contrary to popular belief, these injuries are more commonly a result of non-contact mechanisms – the person suddenly plants his/her foot down on the ground, the knee angulates and the upper body twists generating forces greater than the ligament can withstand, rather than from blunt trauma, such as a tackle in football or soccer. ACL injuries are epidemic at this point. Most often, pediatric ACL injuries occur during sports, such as football, soccer, basketball, lacrosse and volleyball. Due to the extraordinary interest of youth sports, the broad acceptance of Title IX which has provided young female athletes the opportunities to participate, the high levels at which these individuals compete at every stage, and the emphasis of single sport/year round training, we are seeing an increasing number of injuries yearly. Patients attempting to continue competing after an ACL injury are at very high risk of further meniscal injuries, instability events, pain, swelling, arthritis and long term disabilities. The current standard is that any person under the age of 25 who wants to remain physically active and has symptoms of instability should have his/her ACL reconstructed. Many people assume that boys are more susceptible to ACL injury, but this is incorrect. Girls are actually more at risk for an ACL tear, in some studies up to 8 times higher. Landing patterns, muscle imbalances of the quadriceps and hamstrings, and inadequacies of core strength have been recently shown to be the main culprits affecting the sex discrepancy. In addition, anatomic variations, hormonal fluctuations and conditioning have been implicated. There is current evidence that pre-season training programs can help reduce knee injuries. Jump training protocols or plyometrics help build core muscles, emphasize lower extremity muscle balancing, and teach safer landing techniques. Hopefully, school and recreational programs will implement more focused training that will include ACL prevention education in the future. How has pediatric ACL surgery changed over the years? Conventional wisdom even as recently as 10 to 15 years ago was to have the kids wait until they were done growing before they had the surgery performed. These patients were told not to play sports or participate in gym, and were required to use knee braces and participate in rehabilitation with physical therapy. Study after study found the results of conservative treatment abysmal – the patients had more re-injuries and episodes of instability, more cartilage tears, increased pain, and most importantly, a higher rate of irreversible degeneration, arthritis and long term disability. Back then, typical ACL reconstruction techniques required placement of a tissue graft that often was placed or secured in areas of the femur and tibia that were active sites of growth in developing children, called growth plates. Due to the risk of causing harm to the child and possibly a permanent limb deformity, orthopedic surgeons shied away from offering the surgery. Presently, however, the gold standard for treatment in young patients under the age of 25 years is to offer and perform some type of ACL stabilization surgery. What time and experience has taught the medical community is that we have no good treatment for children who develop arthritis from a chronically unstable knee, but we have ways to correct deformities in case an ACL procedure causes a growth disturbance. Within the last decade or so, pediatric orthopedic surgeons have successfully developed various tools, implants, and techniques to treat kids of all ages – from toddlers to young adults. At all times, the main objectives are to stabilize the knee and return the patient back to physical activities while minimizing complications, including growth disturbances. I have treated ACL injuries in patients as young as 6 and as old as 24, and their reconstructions are completely different. Most general sports medicine doctors are not comfortable treating patients who still are growing and are not versed in the varying techniques that can be used depending on the patient’s skeletal maturation level. Recently, you have received training in new methods for ACL reconstruction. Can you share some information about this procedure? Traditionally, the ACL is reconstructed by first removing it and then replacing it with a single large tendon (e.g. patella, quadriceps or Achilles’ tendon) or a pair of thinner tendons (i.e. hamstring tendons) that are folded over and then attached to the tibia and femur via various methods in the general vicinity of the old ligament (non-anatomic). The ACL, in actuality, is comprised of two intertwined ligaments (double bundle) that react and move independently of one another as the knee is flexed and extended. Dr. Freddie Fu of the University of Pittsburgh has pioneered the research and methods of recreating the double-bundle ACL reconstruction. Unfortunately, it has a rather high learning curve. Within the last year, Smith & Nephew, an orthopedic manufacturing company, has created the N8TIVE ACL reconstruction. This product recreates the same 2-bundle model that Dr. Fu advocated, secures it in the anatomic tibial and femoral positions or “footprints,” and reproduces the relaxation and tension of the individual bundles through a range of motion. The protocol can be performed reproducibly with relatively little training by altering techniques most sports orthopedists already perform in their current practices. I traveled earlier this year to learn more about this new technique. I was so impressed that I shared my experience with my colleagues, and now our group offers this as an option for ACL repair. Outside the developers of the device, our group is the largest independent provider of this reconstruction on the East Coast. Do you suggest new techniques over traditional ACL surgery? I encourage my patients and their families to make informed decisions. During a consultation, graft choices, their respective implants, risks and benefits, and expectations are thoroughly reviewed. I still offer traditional non-anatomic ACL reconstructions using a single large tendon or smaller hamstring tendons, since they have withstood the test of time and have very good overall satisfaction rates and acceptable failure rates. On the other hand, I have had some parents insisting on new technologies after discussing potential benefits because it makes sense to them to recreate the original ACL and mimic its original position, orientation and function. Because this is so new, however, it will take more time to determine whether the long term results will prove to be significantly better in survivability, return to activities, stability and complications when compared to traditional methods. This new technology can only be used on patients that are about to complete their growth or have reached their full skeletal maturation. What do you enjoy most about working in pediatrics and sports trauma? As a youngster and in high school, I played several sports: baseball, basketball and soccer. I can relate with many of my patients in their desire to compete and return back to sports as quickly as possible following an injury. What I enjoy most about pediatric orthopedics is that every day is different for me. We treat patients from a few days old up to college students. Children come in for reasons related to congenital defects, sports injuries, fractures, growth disturbances, tumors, overuse injuries, and spine and hip issues. This makes my work exciting and challenging in that I have to stay up date with a large range of health conditions. Fortunately, the children’s ability to heal, their relative lack of multiple medical problems, and their exuberance in wanting to play, get healthy, and/or return back to their activities make it a worthwhile endeavor. How effective are ACL grafts in athletes? The greatest thing about offering ACL reconstructions in any of the pediatric/adult age groups is that we have been extremely successful in returning the vast majority of our patients to their preinjury levels of athleticism with a very low complication and rerupture rate. We have patients ending up as their team captains, obtaining college scholarships, playing on high level travel leagues and club teams, participating in gym class, or just happily returning to the playground. To think that these patients were once slated to the treatment of “just wait until you’re an adult,” is unimaginable. Dr. Lin ,of Advocare The Orthopedic Center in Cedar Knolls, N.J., is a board certified pediatric orthopedist and has a specialty interest in pediatric sports injuries – in particular, repairing meniscal injuries and ACL tears in young children and adolescents. Dr. Lin received his medical degree from the Mount Sinai School of Medicine in New York City, where he also completed his surgical internship. He completed his pediatric fellowship at the Campbell Clinic in Memphis, Tenn. Dr. Lin has been recognized as a “Top Doc” by NJ Monthly Magazine and is a strong advocate for orthopedic education. Dr. Lin has disclosed no relevant financial interest in N8tive.