Is there a good agreement between MRI readers for Thaunat's classification in arthroscopically-proven meniscal ramp lesions?

Objective: To describe and evaluate the reproducibility by MRI of an arthroscopically-based classification for meniscal ramp lesions. We hypothesize that MRI would present good interobserver and intraobserver reliability to evaluate meniscal ramp lesions. Materials and Methods: Twenty MRI of the knee with arthroscopically-proven meniscal ramp lesions were independently assessed by two skilled musculoskeletal radiologists and a third-year radiology resident. Reading was performed in a randomized and anonymous manner, in two steps, with a minimum of 1-month interval between each. Cohen's kappa coefficient statistic was used to analyze intra and interobserver reading agreement. Associate findings were also categorized. Results: From 20 subjects, 17 were male, with mean age of 35 years. MRI reading showed type IV ramp lesion as most prevalent with eight cases (37%), followed by type V – four (21%), type I – four (20%), type III – three, (16%) and type II – one (6%). Regarding ramp lesion types, intraobserver agreement was substantial for both skilled readers (Kappa = 0.72), and moderate for the less experienced reader (Kappa = 0.51); interobserver agreement was moderate. Results between most experienced readers were also analyzed in two categories: stable (types I and II) and unstable (types III, IV and V), also resulting in moderate agreement (Kappa = 0.54). Intraobserver agreement was substantial for both readers (Kappa = 0.68). The most common associate findings were joint effusion (85%), posteromedial capsular structures injury (60%), and medial meniscus extrusion (60%). Conclusion: The arthroscopy classification for meniscal ramp lesions stability adapted for MRI has good reproducibility when applied by trained musculoskeletal radiologists.