Do Age and Weightbearing Radiographs Affect Lateral Joint Space and Fibular Height Measurements in Patients With Discoid Lateral Meniscus?

Background: Several radiographic parameters have been associated with a discoid lateral meniscus. However, limited information is available regarding the radiographic findings of a discoid meniscus in the pediatric population. Purpose: To determine the effect of age and weightbearing (WB) on radiographic parameters associated with discoid lateral menisci in pediatric patients. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: Radiographs of pediatric patients with arthroscopically confirmed lateral discoid menisci were compared with age-, side-, and sex-matched individuals with confirmed normal menisci. Radiographic parameters of lateral joint space width (LJSW) and fibular head height (FHH) were measured by 3 physicians. Results: Significant differences were found between the discoid and control groups when LJSW ( P = .002) and FHH ( P < .001) were compared. Interrater reliability was good for LJSW (intraclass correlation coefficient [ICC], 0.635) and excellent for FHH (ICC, 0.759). WB radiographs were noted to have better interrater reliability compared with non-WB radiographs for LJSW (ICC, 0.729 vs 0.514, respectively) but had reduced interrater reliability for FHH (ICC, 0.625 vs 0.868, respectively). Subgroup analysis with age stratification indicated that FHH was significantly decreased (indicative of a high fibular head) in the discoid group for all age groups ( P < .001 for <10 years and 10-14 years; P = .030 for >14 years); however, LJSW was significantly different only in patients older than 14 years. Conclusion: Increased LJSW and FHH were associated with discoid lateral menisci and showed satisfactory interrater reliability. Radiographic evaluation for potential discoid meniscus in pediatric and adolescent patients may be improved by use of fibular height to indicate the presence of a discoid lateral meniscus across age groups, while lateral joint space may be more reliable for older patients.