Coronal Alignment in Pediatric Patients With Discoid Lateral Meniscus
Julio Javier Masquijo, Smaran Garlapati, Keinan Agonias, Miguel Carabajal Mattar, Hunter Jones, Taylor Corbin Kot, Philip Lamar Wilson, Henry Bone EllisBackground:
Despite the established clinical significance of discoid lateral meniscus (DLM) and the impact of coronal alignment on knee health, a comprehensive understanding regarding the specific characteristics and prevalence of coronal plane alignment among pediatric patients with symptomatic DLM remains limited.
Purpose:
To describe coronal alignment parameters in patients with DLM and analyze associations of high-grade valgus or varus with radiographic imaging, magnetic resonance imaging (MRI), and descriptive factors in pediatric patients treated for symptomatic DLM.
Study Design:
Cross-sectional study; Level of evidence, 3.
Methods:
This 2-institution, institutional review board-approved retrospective study included patients ≤18 years of age with an MRI diagnosis of DLM. Full-length standing hip-to-ankle alignment radiographs were obtained for 141 patients (156 knees) with DLM between 2017 and 2024. Radiographic coronal alignment was classified into mechanical zones (varus, valgus, or neutral) using the linear femoral head center to talar center assessment and categorized into 3 zones: zone 1 (±1), representing low-grade malalignment, and zones 2 and 3 (±2 and ±3), representing high-grade malalignment. The mechanical axis deviation (MAD), medial proximal tibial angle (MPTA), and lateral distal femoral angle (LDFA) were measured. MRI scans were assessed for Watanabe subtype and osteochondritis dissecans (OCD). Descriptive statistics were calculated for continuous variables, while categorical data are summarized using frequencies and percentages. Comparisons were performed using the chi-square test, Fisher exact test, and 1-way analysis of variance with application of post hoc Bonferroni correction for variable significance.
Results:
The mean age was 12.91 ± 3.24 years (range, 4-18 years), with 52.48% male patients. DLM subtypes were complete (48.08%), incomplete (44.87%), and Wrisberg (3.85%). Coronal malalignment was found in 83.33% of patients: 55.13% valgus, 28.21% varus, and 16.67% neutral. High-grade malalignment (zones ±2 and ±3) occurred in 11.53% (n = 18): 4 varus (2.56%) and 14 valgus (8.97%). OCD of the lateral femoral condyle was found in 8.33% of patients, all with valgus alignment. No statistically significant associations were found between coronal malalignment (high-grade or low-grade) and descriptive factors, co-occurring conditions, sports participation, or DLM subtypes. There were significant differences in LDFA, MPTA, and MAD across malalignment severity. High-grade valgus and varus alignments showed no significant associations with age, sex, OCD, sports participation, or Watanabe type.
Conclusion:
Coronal malalignment is prevalent in pediatric DLM, with nearly 1 in 10 patients having high-grade valgus. Routine lower limb alignment assessment is key, as early detection and correction of coronal malalignment may improve the long-term success of meniscal rim-preserving surgery (MRPS). Further investigation is warranted to evaluate alignment changes over time after MRPS.