Quadriceps Tendon Autograft in Pediatric ACL Reconstruction: Graft Dimensions and Prediction of Size on Preoperative MRI

BACKGROUND: There is increased interest in quadriceps autograft anterior cruciate ligament (ACL) reconstruction in the pediatric population. PURPOSE: To evaluate children and adolescents who underwent ACL reconstruction using a quadriceps autograft to determine the properties of the harvested graft and to assess the value of demographic, anthropometric, and magnetic resonance imaging (MRI) measurements in predicting the graft size preoperatively. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A retrospective database search was performed from January 2018 through October 2020 for patients undergoing ACL reconstruction. Patients <18 years old at the time of surgery in whom a quadriceps tendon autograft was used were selected. Demographic data and anthropometric measurements were recorded, and graft measurements were abstracted from the operative notes. Knee MRI scans were reviewed to measure the quadriceps tendon thickness on sagittal cuts. Graft length and diameter were then correlated with anthropometric and radiographic data. RESULTS: A total of 169 patients (98 male) were included in the final analysis, with a median age of 15 years (range, 9-17 years). A tendon length ≥65 mm was harvested in 159 (94%) patients. The final graft diameter was 8.4 ± 0.7 mm (mean ± SD; range, 7-11 mm). All patients had a graft diameter ≥7 mm, and 139 (82%) had a diameter ≥8 mm. Preconditioning decreased the graft diameter by a mean 0.67 ± 0.23 mm. Age (P = .04) and quadriceps thickness on MRI (P = .003) were significant predictors of the final graft diameter. An MRI sagittal thickness >6.7 mm was 97.4% sensitive for obtaining a graft ≥8 mm in diameter. CONCLUSION: Our findings suggest that tendon-only quadriceps autograft is a reliable graft source in pediatric ACL reconstruction, yielding a graft diameter ≥8 mm in 82% of pediatric patients. Furthermore, preoperative MRI measurements can be reliably used to predict a graft of adequate diameter in children and adolescents undergoing ACL reconstruction, with a sagittal thickness >6.7 mm being highly predictive of a final graft size ≥8 mm.