UCSF

Objectives

To assess (i) normal imaging anatomy of the popliteomeniscal fascicles, (ii) prevalence and natural evolution of popliteomeniscal fascicle tears (PMFT) in subjects with traumatic anterior cruciate ligament (ACL) tears over 2 years and (iii) compare knee cartilage degeneration in subjects with and without PMFT longitudinally.

Methods

57 subjects with ACL tears were screened for PMFT. Morphological (high-resolution 3D fast spin-echo) and compositional (T1ρ and T2 mapping) MR imaging was performed prior to and 2 years after ACL reconstruction. Differences of morphological and compositional parameters were compared between subjects with and without PMFT using logistic regression, adjusting for age, sex and BMI.

Results

In 24% (n = 14) of the subjects with ACL tear a PMFT was detected on baseline MRI. One subject with PMFT developed a meniscal tear over 2 years. Cartilage ∆T1ρ of the lateral femur increased significantly more in subjects with isolated PMFT compared to controls (mean difference, 2.0 ± 2.9 vs. -1.3 ± 1.6, p = 0.027).

Conclusion

PMFT detected by MRI are a common finding in subjects with ACL tears. Subjects with these defects showed higher compositional cartilage deterioration compared to controls, over 2 years in the lateral femoral compartment, indicating accelerated cartilage degeneration.

Key points

• Popliteomeniscal fascicle lesions are a common finding in subjects with ACL tears. • Progression to a meniscal tear over 2 years is not frequent. • Anteroinferior popliteomeniscal fascicle is injured most frequently. • Patients with popliteomeniscal fascicle lesions showed accelerated cartilage degeneration.