Discoid meniscus: An ultrastructural study with transmission electron microscopy

Background: The ultrastructure of the normal menisci has been thoroughly investigated and found to correlate with meniscal tears. Although discoid menisci are accepted to have the same composition as their normal counterparts, to our knowledge, no study in the literature has investigated this issue. Purpose: To investigate the ultrastructure of the discoid menisci and compare it with nondiscoid menisci. Study Design: Descriptive laboratory study. Methods: Meniscal biopsies were taken from 12 patients who were operated for meniscus tear and diagnosed with discoid meniscus and from 6 patients who were operated for meniscal tear and did not have a diagnosis of discoid meniscus. The samples were examined with transmission electron microscopy. Results: The study group demonstrated a decrease in the number of collagen fibers compared with the control group. Also, the homogeneous course of the collagen fibers observed in the control group was replaced by a heterogeneous course in the study group. Conclusion: The ultrastructure of the discoid meniscus is different from the normal menisci. Clinical Relevance: This difference may contribute to the vulnerability of the discoid meniscus to tears.