February 14, 2019
10 min read

Management of ACL tears in pediatric patients

Question: Should conservative treatment and rehabilitation be offered to pediatric patients with a torn ACL or should these tears all be fixed regardless of skeletal age?

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Trial of rehabilitation may help identify patients who would benefit from reconstruction

When parents are faced with a decision regarding the optimal treatment for their child with an ACL injury, they commonly ask, “If this was your child, what would you do?” For most, the answer is easy. We want the best surgeon to decide the best treatment that has the best outcome and the least probability of a complication. Interestingly, the paucity of high-level evidence in this area does not support the general consensus of pediatric sports medicine experts. The pendulum continues to swing as historical dogma in the treatment of pediatric ACL injuries was to delay until skeletal maturity. However, recent advances in techniques have suggested a safe alternative is early surgical treatment of ACL injuries.

Much early literature on this topic emphasizes the importance of early, and not delayed surgical treatment of pediatric ACL injuries to avoid further meniscal or chondral damage, knee instability or compromised knee function. However, that literature is either retrospective or does not emphasize modern rehabilitation techniques. Thus, it introduces significant selection bias into the reported cohorts. Furthermore, the available literature does not adequately assess and reflect the population of pediatric athletes who sustained an ACL injury and were able to return to play without operative treatment or further incident.

Henry B. Ellis Jr.
Henry B. Ellis Jr.

Lack of randomized trials

No randomized trials in the treatment of pediatric ACL injuries have been reported and, perhaps, may not be feasible. By the same token, few studies have prospectively followed pediatric ACL injuries that were treated nonoperatively. H. Moksnes and colleagues followed acute pediatric ACL injuries treated nonoperatively over a 2-year period with a specific algorithm and found the ACL reconstruction conversion rate was 21.7% and 91% of patients were able to continue to play in a pivoting sport. A relatively low number of patients — eight of 40 patients (20%) — sustained a new meniscus tear following primary non-surgical treatment for an ACL tear. As such, that study suggests that the probability of sustaining additional meniscal damage in an ACL-deficient pediatric knee may not be as substantial as previously reported.

Longitudinal prospective cohorts in surgical treatment of pediatric ACL injuries are lacking. Functional, radiographic and long-term outcomes of pediatric and adolescent ACL reconstruction remain unclear, with most of our clinical decision-making being based on studies with level 4 and 5 evidence. Furthermore, pediatric athletes who return to sports following an ACL reconstruction have a 30 to 40 times greater risk of ACL injury compared to uninjured youth athletes, and Dekker and colleagues found they may have up to a 32% incidence of secondary ACL injury. In a nutshell, surgical reconstruction of a pediatric ACL injury may not decrease the incidence of future ACL injury or instability and its menisco-protective effect is unclear.


Possible surgery-related risks

It has been argued that nonoperative treatment of an ACL injury carries a risk of future meniscal and chondral injuries. However, the risk of surgical treatment in a pediatric athlete should not be overlooked. While surgical considerations of general anesthetic risk, infection or deep vein thrombosis are rare in this age group, they warrant consideration. More significantly, arthrofibrosis that requires additional procedures can occur in up to 8.3% of these cases, according to a study by Nwachukwu and colleagues. In a meta-analysis of pediatric ACL reconstruction, Wong and colleagues reported a 4.2% incidence of growth disturbance following ACL reconstruction and about 25% of those patients required an additional surgical procedure. Future risk for the development of osteoarthritis following surgical or nonsurgical treatment of an ACL injury is reported to be no different in long-term studies.

Our understanding of the abilities of pediatric patients to develop coping skills following an ACL injury remains unclear. Neuromuscular adaptations that occur in youth athletes following the period of peak growth velocity, and possibly improve with training, may overcome the quadriceps-avoidance pattern that is commonly seen in adults who are ACL-deficient. Although this is possible, improvements in training techniques may be required for nonoperative treatment to be successful because only 37% to 50% of youth athletes with ACL deficiency in the prospective, nonoperative cohort that Moksnes and colleagues reported on in the British Journal of Sports Medicine in 2013 could return to a high level of athletic activity (ie, level-1 sports). A similar percentage of young athletes vs. adults who were copers were noted. Certainly, the overall effect of ACL deficiency in a developing athlete remains unknown.

Importance of knee stability

One important consideration in nonoperative treatment of an ACL tear in a pediatric patient is an emphasis on proper rehabilitation and confirmation of a dynamically stable knee prior to returning to a pivoting sport. This has been demonstrated in a prospective cohort of successfully treated nonoperative pediatric ACL injuries. A four-phase rehabilitation program that includes treatment of the acute injury, early strengthening, neuromuscular/proprioceptive/balance, and knee-injury prevention should be considered when a non-surgical approach is used for pediatric ACL injury.

There has been no conclusive evidence suggesting a period of nonoperative management for pediatric ACL injuries prior to the consideration of surgery has a detrimental effect. The fact that extensive information on this topic is available to the public and parents of pediatric patients may push back against a wait-and-see treatment philosophy and lead to the adoption of adult management philosophies for the pediatric ACL injury without taking into consideration the physical and psychological impact that surgical reconstruction may have on a developing athlete. These factors must be considered while keeping in mind there is currently a paucity of high-level evidence indicating the superiority of immediate operative vs. primary nonoperative rehabilitation in a child with this injury.


Although ultimate functional outcomes may remain unclear, the risk-benefit ratio — a standard we are duty-bound to follow — suggests that a trial of nonoperative treatment should be considered for an isolated, acute, pediatric ACL injury. Subjective instability following a rehabilitation program, meniscal/chondral damage or failure to return to the same level of play may be indications for the transition to surgical management. Further high-level evidence is needed for a consensus regarding optimal primary treatment of an acute, isolated pediatric ACL injury.

Disclosure: Ellis reports no relevant financial disclosures.

Reconstruction would decrease risk of meniscus tears, chondral injuries, recurrent instability

Prior to the widespread use of MRI in the 1990s, midsubstance ACL tears in children were considered to be rare. In the classic 1974 text Children’s Fractures by Rang, it was reported that “Complete ligamentous disruption occurs only after growth plate closure.” However, what was once considered rare, is now accepted to be somewhat common. The increase in ACL tears in children in last 2 decades could be attributed to a rise in early-age sports specialization, increased competitiveness, increased time spent playing organized sports, increased awareness of ACL injuries, and better diagnostic modalities, like MRI. In just a 5-year time span, the diagnosis of ACL tears increased by 18.9% in the 10-year-old to 14-year-old age group and by 17.7% in the 15-year-old to 19-year-old age group.

Shital N. Parikh
Shital N. Parikh

Frequently, ACL injuries are associated with other injuries around the knee that can affect the management, outcomes and prognosis. O’Donoghue described the terrible triad of an acute ACL tear, medial collateral ligament tear and medial meniscus tear in male patients that occurred secondary to a direct valgus force to the knee joint. Further studies recognized that female athletes were more prone to ACL tears, and these injuries were sustained from an indirect mechanism of injury. Lateral meniscus tears are more common with an acute ACL tear as the lateral tibial plateau pivots and subluxes anteriorly. Tears of the posterior horn of medial meniscus are more common in individuals with long-standing ACL tears as the medial meniscus acts as a secondary stabilizer of the knee in the absence of an ACL. Sommerfeldt and colleagues reported in a recent systematic review that with each recurrent episode of instability in an ACL-deficient knee, the rate of meniscus tears and chondral injuries increases; some of these newer tears may be irreparable, and some of the intra-articular damage to the knee may now be irreversible.


Three possible approaches

When faced with a complete ACL tear in a child, the physician has few treatment options, the first of which is to treat the child nonoperatively. This would include acute phase treatment, followed by rehabilitation and bracing, as needed. If the child fails a trial of conservative treatment, then ACL reconstruction could be performed. The second approach, as practiced by some sports surgeons who treat adults, is to treat the child nonoperatively and restrict the child’s activities until he or she reaches skeletal maturity. At maturity, an adult-type ACL reconstruction could be performed safely, obviating the risks for growth disturbances. Both of these approaches — nonoperative and delayed operative — carry the risk for continued instability episodes and progressive meniscal/chondral injury. With both approaches, the child may be restricted from participating in pivoting sports, which may be unacceptable for a young athlete. Kennedy and Fowler voiced their concern in their 1979 book, The Injured Adolescent Knee. They stated, “The adolescent knee is not immune to early degenerative changes once instability develops. Youthful enthusiasm, a tendency to minimize complaints and a natural reluctance by the surgeon to perform operative procedures on the adolescent should not stand in the way of sound surgical principles.”

The third approach to address pediatric ACL tears is to perform ACL reconstruction using physeal-respecting techniques, irrespective of patient age. Although there are risks for growth disturbances during ACL reconstruction, modern techniques have minimized these risks. The goal of the surgical approach is to allow the child to return to full activities, including pivoting sports, without the risk of future instability episodes and continued intra-articular damage to the joint. The treating surgeon should be knowledgeable and skilled enough to execute an appropriate physeal-respecting ACL reconstruction procedure based on the patient’s skeletal immaturity and remaining growth. The book, Pediatric Anterior Cruciate Ligament: Evaluation and Management Strategies, contains descriptions and illustrations of these surgical techniques and technical pearls to help avoid growth disturbances and other complications.

The recent International Olympic Committee consensus statement favored the nonoperative approach over the operative approach, unless the child has a concomitant, displaced, bucket-handle meniscus tear or an osteochondral injury. The consensus statement recommended high-quality rehabilitation for all children and adolescents with ACL tears for at least 3 to 6 months. ACL reconstruction was recommended only for those patients who continued to have instability episodes, have secondary intra-articular injuries or are unable to participate in their usual sports after undergoing rehabilitation. This approach certainly does not reflect clinical practice in the United States. The percentage of patients who are undergoing nonoperative treatment in an ongoing U.S. multicenter prospective pediatric ACL study, in which the treatment is based on physician-patient preference, is less than 2%. A recent survey of 71 pediatric orthopedic sports surgeons by Popkin and colleagues showed that for a hypothetical 8-year-old child with an ACL tear, only 3% of the surgeons would choose nonsurgical treatment.


Advantages of early reconstruction

How does one strike a balance between consensus and clinical practice? Several recommendations for nonoperative treatment for pediatric ACL tears are based on well-done prospective studies by Moksnes and colleagues from Norway. These differences in treatment philosophy may be due to cultural differences, health care system disparities, varied expectations from patients and families, demanding sports participation and medicolegal environment. The lack of prospective studies to support early ACL reconstruction in pediatric and adolescent patients does add to the controversy, but does not seem to have dictated the clinical practice. There are more than 15 observational studies that have reported the advantages of early ACL reconstruction compared to nonoperative or delayed treatment. Recent systematic reviews and a meta-analysis of these studies have summarized these advantages. The meta-analysis of 11 studies by Ramski and colleagues showed significantly decreased instability rates (75% vs. 13.6%), medial meniscus tear rates (35.4% vs. 3.9%), return to preinjury sports (0% vs. 85.7%) and significantly better IKDC scores when nonoperative/delayed operative treatment was compared with early ACL reconstruction, respectively. The nonoperative patients were 33.7-times more likely to report instability and 12-times more likely to sustain new meniscal injury. Kay and colleagues, who analyzed nine studies, reported the significantly reduced risk of medial meniscus tears and decreased rate of medial, lateral and patellofemoral compartment chondral damage in the early ACL reconstruction group.

Besides the direct consequences of ongoing intra-articular damage with recurrent instability, there are other indirect, but important, decision-making factors that favor early ACL reconstruction. This is true for many orthopedic conditions that we treat. Pediatric femoral shaft fractures in school-going children, for example, have healed well with the traditional treatment of traction and spica cast. However, elastic nailing is favored as the treatment of choice for reasons other than fracture healing. Earlier restoration of function, ease of daily care and supervision, caregiver satisfaction, less loss of time, nuances of restricted mobility and economic advantages are practical considerations that have affected the way children with femoral shaft fractures are treated. These same factors apply to pediatric patients with ACL injuries.

Downsides of delayed reconstruction

The 2013 prospective study by Moksnes and colleagues in British Journal of Sports Medicine on nonoperative treatment of ACL reconstruction in 44 children younger than 12 years old reported a 22% rate of cases requiring delayed ACL reconstruction, an 8.7% rate of new meniscus tears requiring surgery, and 38% of patients who were unable to return to their pre-injury level of sports. This was at an average 3.2 years follow-up after high-quality rehabilitation with high compliance rates. These results would likely deteriorate with longer follow-up and less compliance/monitoring with structured rehabilitation. If delayed ACL reconstruction is then required, there would be additional loss of time, besides the time lost during initial rehabilitation. An increased likelihood of new meniscal or chondral injury during nonoperative treatment would affect the long-term outcomes after ACL reconstruction as the status of meniscus and cartilage have been directly linked to development of OA. Would this be acceptable to the child and their parents? Besides these factors, economic modeling in three studies showed that ACL reconstruction is more cost-effective than nonoperative treatment; an important consideration as the U.S. health care system transitions towards value-based care.


A recent book focused on the pediatric ACL summarizes knowledge related to anatomy, epidemiology, growth estimation, rehabilitation protocols, surgical techniques, complications and preventive programs and is available to help physicians make informed treatment decisions.

Disclosure: Parikh reports no relevant financial disclosures.