Anterior Cruciate Ligament Reconstruction in Skeletally Immature Patients

Introduction

Mid-substance anterior cruciate ligament (ACL) injuries in the skeletally immature athlete are being recognized with increasing frequency. ACL injury has been reported in 10% to 65% of pediatric knee injuries with acute hemarthroses. This increased incidence is largely attributed to changes in the activity patterns of young athletes. Participation in sports is on the rise, with young athletes training year-round and specializing at earlier ages. Increased demand for peak performance at an age of major physiologic change and neuromuscular deficits may also contribute to an increase in ACL injuries in young athletes.

Ongoing debate regarding the optimal treatment for ACL injuries in children has not resulted in a clear consensus for initial nonoperative treatment or operative reconstruction. The age and relative skeletal maturity of the child influence management. Although nonoperative treatment avoids iatrogenic injury to open physes, the current literature supports the trend toward early operative treatment to restore knee stability and prevent meniscal and chondral damage that is irreversible.

The optimal surgical approach to ACL reconstruction in this age group also continues to be debated. The concern regarding iatrogenic growth disturbance in children prevents the routine use of anatomic ACL reconstruction that has proved successful in adults. The armamentarium of operative techniques for treating ACL injuries in skeletally immature patients has expanded over the past decade. Alternative surgical treatment options include primary repair, extraarticular reconstruction, and all-epiphyseal and transphyseal intraar­ticular reconstruction. Although these injuries are occurring with increasing frequency, long-term studies to help guide optimal management approach are still lacking.

Indications

Historical recommendations for nonsurgical management of ACL insufficiency in the skeletally immature patient were based primarily on the concern for complications related to physeal injury. However, the majority of active patients treated nonsurgically were unable to return to sports, developed symptomatic instability, sustained meniscal tears, and experienced long-term sequelae of articular cartilage damage. Unfortunately, the options for the young patient who develops traumatic osteoarthritis are very limited. Therefore, instability (giving-way) must be controlled. If activity modification can successfully eliminate episodes of instability, nonoperative treatment is an option. If instability persists, the permanent sequelae of nonoperative treatment are seemingly more difficult to deal with than physeal injury.

Graf and associates reported poor results at 15 months after ACL injury, with new meniscal tears and episodes of instability in seven of eight skeletally immature patients who did not undergo reconstruction. Similarly, in a series of 18 skeletally immature patients examined an average of 51 months after complete ACL tear, Mizuta and colleagues found that all patients had symptoms, 6 had meniscal tears, and 11 had developed radiographic changes. McCarroll and associates reported superior results with surgical management of complete ACL tears in prepubescent and junior high school patients compared with patients receiving conservative treatment. Of 16 prepubescent patients treated nonoperatively, 9 stopped all sports participation, 4 sustained at least one reinjury, and only 3 were able to return to sport. In their study of a separate group of 75 junior high school athletes with mid-substance tears, McCarroll and colleagues reported that 37 of 38 patients who were initially treated nonoperatively had instability and 27 (71%) developed meniscal tears. Overall, 92% (55 of 60) of those treated with reconstruction were able to return to play. Prolonged delay between injury and reconstruction has been associated with irreparable meniscal injury. Lawrence and colleagues reported on a cohort of 29 patients who underwent ACL reconstruction more than 12 weeks from the time of injury. There was a significant association between time to reconstruction and severity of both chondral lesions and medial meniscal tears. Henry and colleagues compared two treatment strategies for the management of ACL rupture in skeletally immature patients. Group 1 patients were treated at a children's hospital with physeal-sparing reconstruction. Group 2 participants underwent delayed reconstruction at an adult hospital once skeletally mature. Patients in group 2 had a higher rate of medial meniscal tears (41% vs 16%) and a higher rate of meniscectomy.

In a recent metaanalysis of nonoperative versus operative treatment, Ramski and colleagues revealed multiple trends that favored early surgical stabilization over nonoperative or delayed treatment. Patients treated nonoperatively or with delayed reconstruction experienced more instability and inability to return to previous activity levels.

Similarly, in a systematic review of 48 studies that included both surgical and conservative treatment of complete ACL tears in immature individuals, Vavken and Murray found that conservative treatment resulted in poor clinical outcomes as well as a high incidence of secondary meniscal and chondral injuries. They concluded that surgical stabilization should be considered the preferred treatment.

Contraindications

Nonoperative treatment is contraindicated in patients with giving-way episodes that produce meniscal tears or articular cartilage damage. If surgical intervention is chosen, the patellar tendon autograft should not be harvested in a skeletally immature individual, because it violates the proximal tibial apophysis and may result in tibial recurvatum. The placement of bone blocks into tunnels drilled across the femoral or tibial physis reliably causes growth arrest and must be avoided. Similarly, disruption of the periosteum surrounding a growth plate (perichondrial ring) can alter growth. In the pubescent patient in whom a final growth spurt is anticipated, a soft tissue graft can be used.

Clinical reports of growth disturbance following ACL reconstruction in the skeletally immature athlete are rare. A survey of the Herodicus Society noted 15 cases of growth disturbance. Associated risk factors included fixation hardware across the physis, large tunnels (≥12 mm), lateral extraarticular tenodesis, dissection in proximity to the perichondrial ring of LaCroix, and suturing near the tibial tubercle. Yoo and associates reported a retrospective review of 43 patients who underwent transphyseal reconstruction of the ACL using a soft tissue graft with postoperative magnetic resonance imaging (MRI) at a mean of 16 months. A focal bone bridge was observed in five patients, four involving the tibial physis and one at the femoral physis. Despite this, physeal angles did not change significantly during follow-up in either the coronal or sagittal plane. The risk of physeal arrest following trauma with fractures involving the distal femoral and proximal tibial growth plates is much higher (30%-50%). If parents are unwilling to accept the risk of growth plate injury to their child, reconstruction should be delayed until the physes are closed.

Clinical Evaluation