Physicians who treat skeletally immature patients with anterior cruciate ligament (ACL) injuries face a variety of management challenges, particularly because many such patients still are growing and return to youth sports may increase the risk of reinjury.
Paul M. Saluan, MD, director of pediatric and adolescent sports medicine at the Cleveland Clinic and a member of the AAOS Now Editorial Board, discussed techniques and considerations for this patient population.
AAOS Now: How common are ACL injuries in children and growing adolescents?
Dr. Saluan: They’re increasingly common—the number is growing significantly. More kids play sports, with many participating year-round.
AAOS Now: What are the recommended strategies for preventing ACL tears in this population?
Dr. Saluan: There are different considerations. Young girls have up to a four- to six-times higher risk of ACL tears than boys, due to a variety of factors, including alignment, anatomy, and neuromuscular control. For example, kids whose muscles fire upon landing dampen the blow to the ACL, relieving some of the strain on the ligament. When those muscles don’t fire, the ligament is placed under maximal length or tension when landing a jump. This is worrisome because when the ligament is put under more stress, it results in failure.
As kids go through adolescence, their bodies are changing significantly, and it takes time to gather good control. In an attempt to combat this failure, we often employ risk-reduction strategies such as neuromuscular training that focuses on balance training, hip strengthening, and proper jump-landing techniques.
AAOS Now: What is the status of research into pediatric ACL tears?
Dr. Saluan: In the past, there were only single-center studies on skeletally immature ACL reconstruction because the number of these injuries at one medical center is pretty small. Now, there is collaboration among centers to collect more data in a shorter timeframe.
High-level prospective research is occurring at multiple centers studying various reconstructive techniques to determine the optimal surgical approaches. For example, the PLUTO (Pediatric ACL: Understanding Treatment Outcomes) study is evaluating the safety and comparative effectiveness of nonoperative treatment and four operative treatments, including:
transphyseal ACL reconstruction
partial transphyseal ACL reconstruction
physeal-sparing epiphyseal ACL reconstruction using the Anderson technique
physeal-sparing ACL reconstruction using the Micheli/Kocher technique in prepubescent and pubescent skeletally immature patients
This multicenter, prospective cohort study is led by Mininder Kocher, MD, MPH, of Boston Children’s Hospital, and Cleveland Clinic is one of the 11 participating centers. We’re several years into active data collection and moving along well.
AAOS Now: What are the risks of waiting until a patient reaches skeletal maturity before performing ACL reconstruction?
Dr. Saluan: In the past, we used to delay surgery because we didn’t want to affect the growth plate and cause growth disturbance. Up until 10 to 15 years ago, “benign neglect,” waiting until skeletal maturity before reconstructing the ACL, was common.
In hindsight, multiple pediatric studies have shown that, with time, even in the absence of recurrent subluxation episodes or injuries, these kids still had further joint damage. The ones who did not have their knees stabilized ended up having a higher incidence of chondral damage and/or meniscal damage. They had overall worse outcomes.
The mindset has changed. We tend to try to fix these problems surgically to help prevent further damage in the joint.
The risks still include growth disturbance and retear because these patients have a lot more exposure hours in front of them. Does the risk of having a growth plate disturbance outweigh the risk of joint damage? In my estimation, the answer is no. Because if you have a growth plate disturbance and the leg grows in an angulated fashion, that’s an extra-articular injury. The joint is still maintained if you stabilize the knee. That’s a fixable problem, whereas if the joint is destroyed, yet you leave the growth plate alone, that’s not. You can’t repair with certainty any cartilage or meniscus damage; it’s hard to salvage that joint damage. Given the risk versus benefit, it makes sense to fix these joints, stabilize them, try to minimize the growth plate risks, and move ahead.
AAOS Now: What are the best methods to assess skeletal age?
Dr. Saluan: There are many ways to assess skeletal age. Some physicians look at radiographs and assess tibial tuberosity; others look at the distal femoral physis. An older method is to obtain hand radiographs to assess bony maturity based on the Greulich & Pyle Atlas.
There are newer methods with different approaches and algorithms to determine skeletal maturity before you proceed with certain types of reconstructions. We also ask historical questions of our young female patients, particularly about the onset of menses because it indicates future growth.
AAOS Now: How critical is it to avoid the physis with tunnel and graft placement during ACL reconstruction with regard to avoiding growth arrest or deformity?
Dr. Saluan: There are different thoughts on this, depending on the patient’s skeletal maturity. If there’s less than one year of growth remaining, it’s not that critical to avoid physis. In these patients, you could potentially even put bone across the physis with a bone-patellar tendon-bone graft or fixation across the physis, because there’s not enough time for growth to result in significant deformity.
There are different thoughts on the best approach for patients with more than one year of growth remaining. Animal models have determined what would allow that growth plate to still continue growing versus what would not. The thought is that putting something solid across the physis, like fixation, will close a growth plate. On the other hand, if soft-tissue grafts are used to cross the physis with no fixation within the physis, the remaining physis can continue to grow around that.
AAOS Now: What are the general techniques described for avoiding injury to the physis during ACL reconstruction?
Dr. Saluan: There are a few different techniques. There is primary repair of the ACL. If you have a stump of the ACL that seems to be repairable and the bulk of the ACL appears to be intact, then you can attempt to suture this back, especially if there’s a bony piece associated with it. Salvaging the patient’s native ACL makes sense and is probably the best option right out of the gate.
Other options include reconstructive techniques: an extraphyseal reconstruction employing a strip of the iliotibial band. This is a modification of an older procedure that was used in all age groups. This was modified by Micheli and Kocher and studied in the youngest patients because it does not require making tunnels through the growth plates. This procedure is quite successful and is still used regularly in very young patients who have a significant amount of growth remaining.
The intra-epiphyseal technique also avoids the growth plates, but it does so not by wrapping around them but going into the epiphysis, the part of the bone distal to the growth plate and the femur and proximal to the growth plate and the tibia. Hamstring autograft tendons are used for this method; the placement of these tunnels must be very calculated, and the margin for error is slim. This was originally described by Allen F. Anderson, MD, who sadly passed away a little over a year ago, with high success rates.
Another option is the partial transphyseal technique using hamstrings autograft. This is a combination technique that involves similar femoral tunnel placement as the intra-epiphyseal technique in the femur. The tibial tunnel is transphyseal, but it’s placed in a relatively oblique fashion to avoid the tibial tuberosity apophysis. Again, if this tunnel is drilled through the tibial physis and soft tissue is placed across that physis, growth plate disturbance is not realized in most cases.
Another option is the transphyseal technique on both sides, which involves both the femoral and the tibial physes. This technique is used routinely in adults. The difference in pediatric patients is that we don’t fix the graft within the tunnel; it’s suspensory fixation on the femur and tibia, and then the soft-tissue graft is what traverses the physis, which still allows for growth. There’s some evidence that this works as well as other techniques.
One last option employs a quadriceps tendon graft. This was used years ago and is now back in vogue because of the qualities and characteristics of the quadriceps tendon and the stability it may provide postoperatively.
AAOS Now: Is there an algorithmic approach to selecting patients for one technique over another?
Dr. Saluan: There are some published approaches, but we need more evidence to clearly determine which procedures to use in different clinical scenarios, including skeletal maturity.
AAOS Now: Are there any extra-articular augmentation techniques in conjunction with intra-articular reconstruction?
Dr. Saluan: This school of thought has also been evolving recently, and there are a couple approaches worth discussing.
Everybody has focused a bit more on the anterolateral ligament (ALL) and what its potential properties would be to augment a very unstable knee. Some theorize that reconstructing the ALL along with performing an ACL reconstruction should be utilized in patients who have significant laxity on the Lachman test and a pivot clunk. However, the jury’s still out on this, and routine ALL reconstruction has not achieved widespread acceptance yet. But intuitively, the more unstable the knee, the farther you might go to restore stability. At least in the short term, this stability might protect the healing ACL. Then, ultimately, the goal is to restore normal kinematics.
Another technique is called the Lemaire technique, which is an older method. It’s an extra-articular reconstruction that helps control anterolateral and rotational stability, along with an ACL reconstruction. A 1-cm-wide band of iliotibial band fascia is harvested, maintaining its distal insertion. Then the fascia is passed under the lateral collateral ligament and attached to the lateral aspect of the femur and stitched back to itself. There’s some evidence that this affords more stability. The question is, does it help reestablish more normal kinematics?
AAOS Now: What are the most common growth disturbances after ACL reconstruction?
Dr. Saluan: Several types of growth disturbances could occur as a result of reconstruction in a skeletally immature individual.
A tibial tunnel too close to the tibial tuberosity apophysis may close that apophysis. Also, if the soft-tissue grafts that are retrieved are taken from close to the apophysis, then a recurvation deformity may result.
Another issue could be closure of the more lateral aspect of the femoral physis, which would then create more of a valgus growth disturbance of the distal femur. Leg length discrepancies may also occur as a result of injury or hypervascularity.
AAOS Now: What is the role of postoperative bracing?
Dr. Saluan: During the immediate postoperative period, a stabilizing brace may be used to help with control of the leg while the effects of a regional block linger. Once a patient can control the leg more reliably several weeks postoperatively, then he or she can discontinue that brace. Later, a functional brace may minimize hyperextension in the early phase of recovery, which might help with soft-tissue grafts. The brace is not only meant for mechanical stability, but also serves as a reminder to the patient that he or she has had a significant procedure and provides a bit of an anchor from a behavioral standpoint.
Some of us employ these braces early to decrease the possibility of graft stretching, but we need further evidence to support whom and how to brace. We should also consider what sports the patient plays because there are athletes in certain sports who really enjoy using a brace. For example, football linemen feel comfortable wearing a brace, and we use it a lot to prevent medial collateral ligament injuries. However, if a patient is a soccer forward who is looking to get a lot of rotational movement on the knee, he or she won’t generally adapt as well to functional bracing during play.
AAOS Now: What are the recommended physical therapy protocols and return-to-play guidelines in growing athletes?
Dr. Saluan: It generally takes growing athletes a bit longer than adult patients to return to full participation. Once an ACL is reconstructed in a skeletally immature individual, the person is still growing and must complete acute rehabilitation before gradually returning to sport. Possible contributing factors to the high level of recurrent injuries are not only increased exposure hours, more overall years of exposure risk, and early sports specialization, but also because these patients are going through all these bodily changes regarding adolescence and puberty as they rehabilitate.
Furthermore, we have them perform a jump-landing program to ensure they do not collapse into a valgus or valgus hyperextension position, which then increases their risk of reinjury. We work intensively on their hip abductor muscles, as well as core strength. Toward the end of their rehabilitation, we often utilize isokinetic testing and hop testing to compare the affected and unaffected limbs.
Kerri Fitzgerald is the managing editor of AAOS Now. She can be reached at email@example.com.
- Kocher MS, Garg S, Micheli LJ: Physeal sparing reconstruction of the anterior cruciate ligament in skeletally immature prepubescent children and adolescents. J Bone Joint Surg Am 2005;87:2371-9.