Comparison of preoperative mechanical axis alignment in pediatric and adolescent patients with anterior cruciate ligament rupture and patellofemoral instability.

Overview

abstract

BACKGROUND: The primary aim of this study was to examine mechanical axis alignment and its association with ACLR and PFI in pediatric and adolescent patients. The authors hypothesized that there would be differences in mechanical axis alignment between patients with ACLR, PFI, and a control cohort. METHODS: Patients aged 8-21 years at a single institution who sustained an ACLR or PFI injury and underwent operative treatment. Patients with scoliosis with a Cobb angle less than 20° served as controls (Controls). One-way ANOVA was used to compare mechanical axis alignment between all cohorts (ACLR, PFI, Controls), and independent samples t-tests were analyzed to compare the individual differences between the cohorts. RESULTS: Of the patients identified, 197 met final inclusion and exclusion criteria (60 ACLR, 92 PFI, 45 Controls). The mean age at time of imaging was 14.4 ± 2.2 years and 50.8 % were female. The mean mechanical axis was 0.067 ± 2.5° for the ACLR cohort, 0.937 ± 2.4° for PFI, and -0.073 ± 2.6° for the Control cohort (p = 0.032) (positive = valgus, negative = varus). The PFI cohort was in significantly more valgus than the ACL cohort (p = 0.032) and the Control cohort (p = 0.026). CONCLUSION: Mechanical axis alignment was found to be significantly different in preoperative weightbearing radiographs between patients with ACLR, PFI, and a control cohort, demonstrating that static valgus alignment may be associated with PFI in pediatric and adolescent patients, while static alignment may not be associated with ACLR. LEVEL OF EVIDENCE: Level III.