Paper 38: Addition of a Lateral Extra-articular Tenodesis is Associated with Lower Quadriceps Tendon Autograft MRI Signal Intensity Two Years Following Anterior Cruciate Ligament Reconstruction in Skeletally Immature Adolescents

OBJECTIVES: In recent studies, quadriceps tendon autograft (QTA) has been shown to yield promising results in the treatment of anterior cruciate ligament (ACL) ruptures in pediatric and adolescent patients. Additionally, lateral extra-articular tenodesis (LET) has been found to reduce the risk of ACL re-tear in high-risk patients when performed concomitantly with ACL reconstruction (ACLR). The purpose of this study was to evaluate graft maturity two years after ACLR by comparing magnetic resonance imaging (MRI) signal intensity ratio (SIR) of QTA in patients that underwent a primary ACL reconstruction with a concomitant LET versus patients without a concomitant LET. METHODS: After institutional review board approval, operative records of all pediatric patients ≤ 18 years old who underwent an ACLR from June 2015 to December 2021 were retrospectively reviewed. MRIs were ordered for this age cohort of patients for clinical growth plate surveillance. Patients were included if they underwent an ACLR using a QTA and had open distal femoral and proximal tibial physes. MRIs were excluded if they were external or were ordered due to a new injury. The final cohort included 28 patients: 13 without a LET (ACLR only) and 15 with a LET (ACLR+LET). Signal intensity ratio (SIR) was measured on sagittal MRI by averaging the signal at three regions of interest along the ACL graft and dividing by the signal of the insertion of the posterior cruciate ligament. Statistical analysis was performed to evaluate for differences in SIR values at 6 months, 1 year, and 2 years post-operatively in skeletally immature patients undergoing ACLR alone versus ACLR with LET. RESULTS: A total of 43 patients had an MRI at a two-year follow-up, 28 of whom were included in the study. The mean age of the complete cohort was 12.63±3.62 years (ACLR+LET: 13.96±0.91 years vs. ACLR only: 13.51±1.19 years). There were no significant differences in SIR between groups on the 6-month MRI or the 12-month MRI. However, the average SIR of the ACLR+LET group was significantly lower than the average SIR of the ACLR-only group at the two-year post-operative time point (1.398 vs. 1.916, respectively, p=0.046). CONCLUSIONS: QTA MRI signal intensity is lower two years after surgery in patients that underwent ACLR with a LET versus ACLR alone. Lower MRI signal intensity correlates with increased graft maturity and structural integrity. These findings suggest improved graft maturation, remodeling, and structural integrity with the addition of a LET to an ACLR with QTA in skeletally immature patients.