Association Between Knee Alignment and Meniscal Tear in Pediatric Patients with Anterior Cruciate Ligament Injury.

BACKGROUND The present study aimed to evaluate the association between elapsed time from anterior cruciate ligament (ACL) injury to surgical treatment and the incidence of meniscal tears in a cohort of patients ≤16 years old with varus-aligned and non-varus-aligned knees. METHODS The study cohort included 123 patients ≤16 years old who underwent primary ACL reconstruction between January 2016 and March 2020. Knee alignment was expressed as the hip-knee-ankle angle (HKAA), as measured preoperatively on an anteroposterior view of 3-dimensional computed tomography of the full length of the lower limb. Varus alignment was defined as an HKAA ≥181.0°, and non-varus alignment was defined as an HKAA <181.0°. Patients were divided into groups according to knee alignment and the elapsed time from injury to surgical treatment: early-treatment group (<60 days) and delayed-treatment group (≥60 days). RESULTS A total of 64 varus-aligned and 59 non-varus-aligned knees were identified. Among patients with varus-aligned knees, those in the delayed-treatment group showed a significantly lower rate of lateral meniscal tears (6 of 30, 20%) compared with those in the early-treatment group (17 of 34, 50%; p = 0.015). Among patients with non-varus-aligned knees, there was no significant difference in meniscal tears of any type between the early and delayed-treatment groups. Among patients without medial meniscal injury identified on initial magnetic resonance imaging, those with varus-aligned knees in the delayed-treatment group showed a significantly higher rate of medial meniscal tears at the time of the surgical procedure (8 of 20, 40%) compared with those with non-varus-aligned knees (1 of 18, 6%; p = 0.015). CONCLUSIONS Delayed ACL reconstruction in patients ≤16 years old with varus-aligned knees might be associated with an increased incidence of secondary medial meniscal tears. Accordingly, earlier ACL reconstruction in patients with varus-aligned knees should be considered. LEVEL OF EVIDENCE Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.