Complications in Pediatric Anterior Cruciate Ligament Surgery: Transphyseal in Skeletally Immature Patients

Introduction

Although once thought to be uncommon, anterior cruciate ligament (ACL) injuries are increasingly recognized in the pediatric and adolescent athletic population. In total, 12% to 36% of children and adolescents presenting with a hemarthrosis after a knee injury have evidence of an ACL injury on magnetic resonance imaging (MRI).

Studies have demonstrated that the incidence of pediatric ACL tears has increased at a significantly higher rate than that seen in adults over the last 20 years. This is likely because of a combination of factors including an increase in the number of females participating in competitive sports since the passage of Title IX in 1972, earlier single-sport specialization, increased participation in year-round sports, more intense and frequent training, and improved awareness on the part of medical professionals. One large study demonstrated that the rate of ACL tears in children and adolescents averaged 121 per 100,000 person-years. In that study, there was a 2.3% rate of annual increase in diagnosis over the study period (1994–2013). Furthermore, surgical treatment of ACL reconstruction (ACLR) in patients under 15 years of age has also increased dramatically. One large study demonstrated a 28% increase in the rate of ACLRs in patients between the ages of 10 and 14 from 2007 to 2011. Another demonstrated a 924% increase in rates of ACLR in patients under the age of 15 from 1994 to 2006. ^,

Surgeon attitudes regarding the treatment of pediatric ACL tears have changed dramatically. A recent survey of the Pediatric Research in Sports Medicine society demonstrated that only 3% of members would treat an 8-year-old child with an ACL tear nonoperatively. This shift is caused in part by the understanding that nonoperative management of children with complete ACL ruptures leads to an increased rate of secondary pathology, such as meniscal or chondral injury. In addition, there is a 50% rate of failure to return to sports in young athletes treated nonoperatively.

Despite the collective agreement that ACL tears in young athletes are best treated with surgical management, the optimal surgical technique remains controversial. The most commonly used techniques in this setting include extraphyseal reconstruction with a combined extra- and intraarticular approach using an iliotibial band autograft, all-epiphyseal reconstruction, partial or “hybrid” transphyseal reconstruction, “physeal-respecting” transphyseal reconstruction, or traditional adult-type reconstruction.

For patients who are Tanner stage I and II or patients with 2 to 3 years of growth remaining (boys younger than 13–14 years and girls younger than 12–13 years), previous studies and literature have recommended extraphyseal (iliotibial band) or all-epiphyseal techniques. ^, However, there are multiple case series which demonstrate that transphyseal ACLR can be a safe technique, even in Tanner stage I and II patients.

The “physeal-respecting” transphyseal technique is similar to the standard adult-type technique used, but there are several important differences, as outlined later ( Fig. 15.1 ). ^{, , ,} Most commonly, a 4-strand hamstring autograft is used. Quadriceps and patellar tendon autograft, as well as multiple allograft options, have also been described. ^{, ,} Graft options and potential complications are discussed in this chapter.

Intraoperative Complications

There is the potential for similar intraoperative complications as those seen in the adult population, including graft truncation during autologous hamstring harvest, patellar fracture during autologous patellar tendon or quadriceps tendon harvest, damage to the infrapatellar branch of the saphenous nerve, fixation hardware breakage or complication, posterior femoral tunnel “blowout,” inappropriate placement of graft tunnels, and failure to appropriately tension the graft.

Quadriceps autograft is being used more often because of the robust volume and reliable length of the quadriceps tendon. The graft can be harvested with or without an attached bone plug from the superior patella. As discussed subsequently, it is imperative that the surgeon not place bone blocks across the physis, to avoid tethering and subsequent growth disturbance. A potential intraoperative complication when harvesting a bone block is patella fracture. Fu et al. noted an 8.8% incidence of patella fracture following quadriceps harvest in 55 patients. It should be noted that two of the five fractures were asymptomatic and were noted on research-computed tomography at 6 months postsurgery. Lee et al. noted only three patellar fractures among 350 patients. One option to mitigate patellar fracture is to harvest a soft tissue only graft. If a bone block is used, it should be taken from the central aspect of the patella because fractures most frequently occur when the bone block is taken laterally. The depth of the cut should be less than 30% to 50% of the patellar thickness, whereas the length should be less than 50% of the patellar length. Additionally, the defect should be bone grafted with autograft when possible.

As discussed subsequently, one surgical “pearl” is avoidance of fixation hardware crossing the physis. For this reason, perhaps the most common fixation device for femoral-sided fixation is a suspensory button. A variety of options are available, including fixed-loop and adjustable-loop. As with any fixation device, there are specific potential intraoperative complications related to the use of a suspensory button fixation. Pulling too rapidly or with too much force on the leading sutures can lead to the button advancing past the iliotibial band. At a minimum, this leads to a prolonged operative time and potentially a larger skin incision. Conversely, failure to advance the button past the lateral femoral cortex can lead to the button remaining intraosseous or within the tunnel ( Fig. 15.2 ). This will ultimately lead to graft laxity and failure.

This technical complication can be avoided with careful surgical technique. The surgeon should measure the intraosseous distance, defined as the distance between the lateral femoral cortex and the aperture of the intraarticular femoral tunnel. This length can then be marked on the button-graft construct. When advancing the graft, the surgeon knows the button has advanced past the lateral cortex when this mark reaches the edge of the intrarticular femoral tunnel ( Fig. 15.2 ). There is also usually distinct tactile feedback once the button has “flipped.” Intraoperative fluoroscopy can also be used to verify the correct position of the button. Alternatively, the arthroscope can be placed into the anteromedial portal, and the button can be directly visualized as it passes the lateral cortex.