Often encountered patients say that the knee joint mild sprain after the lateral knee pain, sometimes also radiates to the lateral calf pain, X-ray film shows no obvious abnormalities, or knee joint degeneration, osteophytes, intercondylar spines become pointed, or the lateral knee gap slightly widened. Doctor to prescribe medicine to eat, joint cavity injection of sodium vitrate pain relief, after a period of time the pain came back, and then check the magnetic resonance, diagnosed as discoid meniscus, and discoid meniscus damage, there is a tear. Often encountered children with unexplained inability to straighten the knee joint, knee pain, may be discoid meniscus. What is discoid meniscus Discoid meniscus is a rare meniscus deformity in which the lateral meniscus is more common than the medial one, and therefore most of the pain is on the lateral side of the knee. The incidence of discoid lateral meniscus is reported to be 26% in Japanese and Korean patients and less than 1% in patients from other countries; the incidence of medial discoid meniscus is 0% to 0.3%. Why discoid meniscus is prone to injury The lateral third of the meniscus is more richly vascularized, while the middle third has only a few capillaries, and the medial side is a bloodless area. Discoid meniscus is larger than normal meniscus, the blood supply in the middle is more insufficient, naturally it is more prone to injury. Moreover, the normal meniscus has the deformation ability of curling and contracting, and can adaptively move slightly during knee flexion and extension activities, while the middle hypertrophied part of the discoid meniscus lacks the guidance of ligaments, and cannot be deformed accordingly with the movement of the femoral condyles, which leads to the concentration of stress and uneven distribution of the synovial fluid, thus inducing injuries. In addition, from a histological point of view, the discoid meniscus has lost the regular arrangement of radial and circumferential fibers of a normal meniscus, not to mention the longitudinal arrangement of fibers, and its fibers are arranged haphazardly and disorderly, and at the same time, there are many internal homogeneous collagen structures, which leads to its inability to complete the transfer and transformation of loads, and is more prone to tearing suddenly when it is subjected to loads, especially when the movement of the knee joint is not coordinated. The aging of the knee joint with increasing age will also induce discoid meniscus patients to be more prone to meniscus injuries. How to treat discoid meniscus If there is pain on the outside of the knee joint and MRI suggests discoid meniscus, it already indicates discoid meniscus injury, which requires surgical treatment, arthroscopic discoid meniscus molding, or partial resection, or subtotal resection, depending on the meniscus injury. Arthroscopic surgery is a minimally invasive surgery, discoid meniscus surgery can get out of bed and walk on the first day after surgery, after active arthroscopic postoperative rehabilitation and training, the knee can return to normal walking.