Thesis, COLLÉGIALITÉ

Abstract

Background: The meniscal tear is one of the most common injuries in the knee joint. In recent years, as more important to the function of the meniscus has been attached, the traditional meniscectomy has been gradually replaced by repair techniques. Regenerative medicine research in meniscus has become the current mainstream trend, but due to the heterogeneity within the meniscus, the natural healing processes are very complicated. Objective: To describe macroscopical and histological changes of the meniscus at different time points after meniscectomy. Methods: 6 young sheep and 6 old sheep were enrolled to access the effect of age on the microstructure of the meniscus. 16 sheep performed medial partial meniscectomy and anterior cruciate ligament transection (pMMx+ACLT) surgery and 4 sheep performed SHAM operation were enrolled in the study. The histological staining was visualized using a modified Pauli’s histological tissue quality score system to evaluate histological changes of the left and right medial and lateral meniscus at weeks 4, 6, and 28. Results: Young sheep had higher cellularity and quality score than old sheep (p<0.01). At weeks 4 and 6, the healed part of the left medial meniscus (LMMx) had a lower score than the remaining part (LMM) and lateral meniscus (p<0.01). At week 28, LMMx had no significant difference compared with LMM. Conclusion: After the medial partial meniscectomy and anterior cruciate ligament transection surgery, the meniscus will regenerate through fibroblasts and collagen fibers, but it cannot restore to the state before the injury. It will also cause degeneration of the ipsilateral meniscus. The findings will be helpful to meniscal regenerative treatment strategies.