Evaluation of anterior intermeniscal ligament in discoid lateral meniscus cases and presenting the accompanying meniscal pathologies with MRI.

BACKGROUND: Although several studies were conducted to put forth the biomechanical function of anterior intermeniscal ligament (AIML) on the stability of meniscal structures, there are few data on the etiology of the early degeneration of discoid type compared to the normal shaped ones.

PURPOSE: To determine the AIML subtypes and accompanying meniscal pathologies in discoid lateral menisci (DLM) on knee MRI exams.

MATERIAL AND METHODS: Knee MRI exams of 171 individuals with DLM were reviewed. DLMs and AIMLs were typed according to Watanabe's classification and Nelson-Laprade classification, respectively. Medial and lateral menisci were evaluated for tear and menisco-capsular pathology. Pearson's correlation test was used for statistical analysis.

RESULTS: DLM was type I in 83 (48.5%) individuals and type II in 88 (51.5%) individuals. AIML was absent in 90 (52.6%) participants; type I AIML was seen in 38 out 81 (22.2%), type II in 31 out of 81(18.1%), and type III in 12 out of 81 (7%). Meniscal pathology was observed in 56 (32.7%) individuals as follows: menisco-capsular strain/separation in 25 (14.6%); medial meniscal tear in 22 (12.8%); and lateral meniscal tear in nine (5.2%); Of these 56 cases, 26 (46%) had no AIML, 15 cases (27%) had type I, nine cases (16%) had type II, and six cases (11%) had type III AIML.

CONCLUSION: No statistically significant correlation was found between the type of DLM and type of AIML ( P = 0.855), between the type of DLM and meniscal pathology ( P = 0.791), or between the type of AIML and meniscal pathology ( P = 0.282).