Meniscal ramp lesions: frequency, natural history, and the effect on knee cartilage over 2 years in subjects with anterior cruciate ligament tears.

PURPOSE: (i) To investigate the frequency and natural evolution of meniscal ramp lesions (MRLs) on MRI in subjects with acute ACL tear and (ii) to compare knee cartilage compositional degeneration between subjects with MRLs and subjects without meniscal pathology over 2 years.

MATERIALS AND METHODS: Fifty-seven subjects with ACL tears (32 females; age 32.6 ± 8.3 years; BMI 24.5 ± 3.5 kg/m2 ) from a prospective study were screened for the presence of MRLs. Morphological (high-resolution 3D fast spin-echo) and compositional (T1ρ and T2 mapping) MRI was performed prior to and 2 years after ACL reconstruction. Follow-up MR images were assessed for changes in the signal intensity of the MRLs and the presence of meniscal tears. Differences of compositional parameters were compared between subjects with MRLs and without meniscal lesions using independent samples t tests.

RESULTS: MRLs were found in 16% (9/56) of the subjects with ACL tears at baseline. Only one subject with MRLs developed a posterior horn meniscal tear over 2 years. In 12 knees, no meniscal tears were found, which were defined as controls. Most interestingly, cartilage ∆T1ρ of the medial femur and medial tibia increased significantly more in subjects with MRLs compared with controls (mean difference, MF = 6.0 ± 0.8 vs. 2.3 ± 0.6, p = 0.004, and MT = 4.4 ± 1.4 vs. 0.4 ± 0.6, p = 0.027) and medial femur ∆T2 over 2 years increased significantly more in MRL than in control knees (5.1 ± 2.5 ms vs. 2.2 ± 1.9 ms, p = 0.012).

CONCLUSION: Subjects with ACL tear presented MRLs in 16% of cases. Compared with controls without meniscal lesions, knees with MRLs demonstrated accelerated degeneration of cartilage composition in the medial knee compartment over 2 years.