MRI morphometry of the popliteus tendon and lateral meniscus in an Iraqi adult cohort

PURPOSE: This study provides sex-stratified and age-related MRI normative values for the popliteus tendon thickness and lateral meniscus width in an Iraqi adult cohort. METHODS: A retrospective study performed at the Medical City Complex, a tertiary-care center in Baghdad. A total of 120 normal adult knees (61 males, 59 females; age 18-66 years) were imaged on a 1.5-Tesla scanner. The coronal fat-suppressed image was used to measure the popliteus tendon, and the axial T2-weighted image was used to measure the width of the lateral meniscus body. The Mann-Whitney U test with false discovery rate correction was used to evaluate sex differences. Associations with age were evaluated using Spearman's rank correlation. RESULTS: Popliteus tendon thickness was 3.61 ± 0.33 mm in males and 2.77 ± 0.23 mm in females (p < 0.001; r = 0.84). Lateral meniscus body width was 8.35 ± 0.47 mm and 7.48 ± 0.48 mm, respectively (p < 0.001; r = 0.69). Sex remained independently associated with both measurements after adjustment for age (Popliteus tendon 0.762 mm, 95% CI 0.677-0.847; lateral meniscus body width 0.809 mm, 0.641-0.977; both p < 0.001). Both structures declined with age (ρ = - 0.491 and - 0.353), with a steeper decline observed for the popliteus tendon (p = 0.037). CONCLUSION: Preliminary sex-stratified normative values for the popliteus tendon and lateral meniscus, obtained through MRI, are reported for an Iraqi adult cohort. Both anatomical structures exhibit significant sexual dimorphism and age-related decline, underscoring the importance of accounting for sex and age when interpreting their morphometry.