Prevalence and Correlation Analysis of Lateral Discoid Meniscus with Degeneration or Injury of the Meniscus and Articular Cartilage in the Entire Tibiofemoral Joint

Background The current discussion comprehensively addresses the injury and treatment of discoid meniscus (DM). However, it is important to note that an unfavorable biomechanical environment caused by DM not only leads to self-injury but also has a significant impact on adjacent structures. Therefore, the aim of this study was to investigate the relationship between DM and injuries in both the meniscus and cartilage within the total tibiofemoral joint(TJ). Methods Patients undergoing knee magnetic resonance imaging (MRI) examinations at our outpatient clinic were screened, and a total of 278 patients were enrolled in the DM group, with 279 patients in the non-discoid meniscus (NDM) group. The type of DM was classified according to the Watanabe classification, while meniscal and articular cartilage injuries were classified using the Stoller and Hepple classifications, respectively. The prevalence of DM and injuries to the meniscus and articular structures within the TJ in the general population was assessed, along with their relationship. Results The prevalence of DM was 8.5%, while the incidence of TJ injury was 10%. Notably, the DM group exhibited a significantly higher incidence of TJ injury (P <0.001). Among the cases, there were 93 patients with type I DM and 185 patients with type II DM. Specifically, the type I DM group showed a significantly higher percentage of lateral meniscus injuries (P <0.005), whereas the type II DM group demonstrated a significantly higher percentage of medial TJ injuries (P <0.005). Conclusion Discoid meniscus is associated with a higher risk of degeneration or injury to both the meniscus and articular cartilage of the tibiofemoral joint. Specifically, Type I discoid meniscus is particularly susceptible to tears, whereas Type II discoid meniscus tends to remain intact over a broader age range but is more prone to degeneration or injury of the medial meniscus and articular cartilage. Study design Retrospective study.