How did my meniscus get damaged? Meniscus tears are associated with trauma, and young people tend to have clear trauma. Sports injuries tend to occur when the knee is flexed to extended and rotated (e.g., soccer players shoveling the ball), which is the most common mechanism for traumatic meniscus tears. Many middle-aged and elderly patients with meniscus injuries often ask, “How can I have a meniscus injury when there is no trauma to my knee? This is related to the degenerative changes that have occurred in the meniscus, just like when we wear old clothes, the degenerated meniscus is less strong and more prone to injury than the normal meniscus, especially when doing household chores, such as squatting and scrubbing floors, picking vegetables, climbing mountains, and improper exercise, which inadvertently damage the meniscus with these overflexion movements. Therefore, the elderly should avoid these actions. What is the classification of meniscus injury in MRI report? Many patients do not understand the meniscus Ⅰ, Ⅱ and Ⅲ changes (injury) in MRI report, which adds to their worries. MRI is based on the abnormal signal and morphology of the meniscus images to make the diagnosis. The normal meniscus on all MR sequences is low signal (black), with normal black triangles, smooth edges and sharp tips. Once there is high signal (white) inside the meniscus, it is a meniscal change or injury that can be seen by these patients. In contrast, abnormal meniscus morphology requires a specialist’s judgment. Simple meniscal signal changes are classified into four grades (Figure 1 schematic): Grade 0: normal meniscal fibrocartilage structure with low signal on all MR sequences (Figure 2); Grade I: spherical high signal not reaching the articular surface, meniscal degeneration, (Figure 3); Grade II: linear high signal not reaching the articular surface, extensive striated mucous-like changes, a precursor to tearing (Figure 4); Grade III: high signal reaching the articular surface, a meniscal Tear. Irregular high signal within the meniscus, with a tear adjacent to the articular rim (Figure 5). Abnormal meniscus morphology: abnormally small or ruptured meniscus, blunted meniscus triangle tip, incomplete and limited depression of meniscus articular surface, height of posterior angle of medial meniscus is smaller than anterior angle, meniscus displacement, etc. How to treat meniscus injury Meniscus injury treatment is divided into non-surgical treatment and arthroscopic surgery treatment. (a) Non-surgical treatment is suitable for patients with incomplete meniscus tears or small (5 mm), stable edge tears, and stable knee joints, and good results can be achieved with non-surgical treatment. A stable marginal meniscal tear is a vertical, longitudinal tear in which the central portion of the torn meniscus is no more than 3 mm from the edge of the intact meniscus and the length of the tear is no more than 1 cm. Incomplete tears do not usually progress to complete tears while the knee remains stable and with attention to movement patterns. Small, stable meniscal tears are likely to heal with 3 – 6 weeks of protection. Non-surgical treatment is performed with inguinal to ankle tubular casts or knee braces for 4-6 weeks. after 4-6 weeks the braking should be stopped and the muscles around the knee and hip should be strengthened with functional exercises. Patients should fully understand that some meniscal tears do not heal even after prolonged braking. If symptoms reappear after a period of non-surgical treatment, meniscectomy or repair surgery will be required. (b) Surgical treatment: total excision of the injured meniscus, partial excision of the injured meniscus, meniscal suture repair, and complete allograft meniscus transplantation. The surgical treatment of meniscus is described separately.