The Risk of Transphyseal Drilling in Skeletally Immature Patients With Anterior Cruciate Ligament Injury

BACKGROUND Anterior cruciate ligament reconstruction (ACLR) in skeletally immature patients can result in growth plate injury, which can cause growth disturbances. PURPOSE To evaluate radiological tibial and femoral length and axis growth disturbances as well as clinical outcomes in skeletally immature ACLR patients treated with a transphyseal drilling technique. STUDY DESIGN Cohort study; Level of evidence, 3. METHODS A total of 39 pediatric patients with ACL injury and open physes at time of surgery, as diagnosed clinically and with magnetic resonance imaging (MRI), were treated using transphyseal ACLR using hamstring graft. Mean patient age was 11.7 years (range, 9.0-14.0 years). Patients were evaluated with full extremity radiographs measuring leg length discrepancy and malalignment, as well as clinical evaluation with KT-1000 arthrometer measurements and Tegner activity scale and Knee injury and Osteoarthritis Outcome Score (KOOS) outcomes after follow-up of 68 months (range, 29-148 months). RESULTS Of the 39 initial patients, 33 were evaluated both clinically and radiographically. We found a mean femoral length shortening of 3.5 mm (P = .01) on the operated leg. Eight patients (24%) had a more than 10-mm shortening of the operated leg, whereas only 1 patient (3%) had a 10-mm shortening of the nonoperated leg. In 27 of 33 patients (82%; P < .001), the anatomic femoral axes of the operated leg were found to be more than 2° of valgus compared with the nonoperated leg. The tibial anatomic axes changed into a less pronounced varus angulation (P = .02). The femoral-tibial anatomic axes were not significantly different when comparing the 2 legs. We did not find any statistical difference in growth arrest comparing patients treated surgically at the ages of 13 to 14 years to patients younger than 13 years. Tegner and KOOS scores were significantly lower among girls compared with boys. Side-to-side KT-1000 arthrometer difference improved from 5.2 mm preoperatively to 1.6 mm at follow-up. CONCLUSION This study shows that transphyseal ACLR in children results in minor length growth disturbances in 24% of patients. The surgically induced distal femoral valgus angulation is counterbalanced by a proximal tibial varus angulation. Growth disturbance after surgery is not associated with a certain pediatric age group. Otherwise, transphyseal ACLR has satisfactory clinical outcomes, with good subjective outcomes, function level, and knee stability.