Because my main work is the minimally invasive treatment of joint diseases, I often encounter a special group of patients in my clinical work: mainly women, ranging in age from adolescents to middle-aged and elderly, from all walks of life, but all diagnosed with a disease called “discoid meniscus” by the outpatient doctor. The majority of the patients were also very vocal. Most patients say, “I’ve never been injured, I’m in an office, I don’t work very hard, and I don’t like to exercise, but why would my meniscus be damaged?” This kind of misconception often exists in the early consultation process of patients, and even affects their enthusiasm and attitude towards the treatment of the disease and the recovery of joint function. Today I will give you a brief introduction to some basic knowledge about discoid meniscus injury, and I hope it will help you. Where do disc meniscus injuries come from? In normal people, the meniscus of the knee has an “inner C and outer O” meniscus shape and is uneven in thickness. However, due to physical developmental factors, some people do not “evolve” during the meniscus growth process and maintain a “thick, large disc-like fibrocartilage disk” that remains in the embryo for the rest of the patient’s life. This condition is called “developmental disc meniscus”. Some scholars used to call it “congenital discoid meniscus”, but existing scientific studies have long proven that all people have a process of discoid to meniscus transformation during embryonic development, only that this process is interrupted in some groups. What kind of people are prone to discoid meniscus Generally speaking, the high incidence of discoid meniscus is more common in females, and the ratio of females to males can even reach 3~4:1. In most Asian races, the lateral discoid meniscus is predominant, and the medial discoid meniscus is rare. Some scholars believe that this developmental abnormality has certain matrilineal inheritance characteristics, that is, it is passed from grandmother to mother or mother’s sister, and then passed to the third generation of children, etc. In our clinical work, we have encountered cases where the son came for disc meniscus surgery first and then the mother came for treatment within a few years, as well as cases where two sisters came for treatment one after another. Some scholars believe that this developmental abnormality is not a “disease”, just as some people have one eye and others have two eyes, but a physical trait that can only be considered a disease if it is damaged, ruptured, and causes knee pain and discomfort. Specifically, the discoid meniscus injury can occur in female patients of all ages who constitute the main group of discoid meniscus injuries. The distress was particularly pronounced when the leg was fully extended. During this period, the “large disc” of fibrocartilage is often torn due to accidental falls, which also indicates that the original disc is “large and thick”. Arthroscopic meniscal molding is very effective; ② Adolescence This is a period of rapid growth in height and weight, combined with a period when children are formally very active in sports at school, and there is often a popping and pain in the knee space after physical education or field day, a twisting down the stairs, or a bike ride. This is because the disc-shaped cartilage discs have difficulty withstanding strenuous physical activity and body weight loads due to their structural strength, and therefore appear to be damaged; ③Women during pregnancy and shortly after childbirth Some women describe how they were in good health before pregnancy and childbirth, but since having children they have always had knee pain, even after taking maternity leave and going to work normally. Some patients may even think that they are not doing well in the “menstrual cycle”, but this is because there is a significant fluctuation of hormone levels in the body before and after pregnancy and childbirth, which leads to relaxation of the muscles and ligaments around the joints, coupled with a significant increase and decrease in weight, which has a greater impact on the knee joint load than the disc meniscus can withstand. The discoid meniscus has “reached its useful life or even overstayed its service life” due to years of work, life and labor, as well as occasional knee fatigue and even minor trauma. It is increasingly difficult to perform normal functions and discomfort occurs. The results of disc meniscus surgery in middle-aged people are often very limited, and the postoperative period may not meet the established goals and requirements of the patient. Many women, especially those who are poor or have a lot of housework, are not willing to go to the hospital at an early stage due to financial pressure and life pressure, and often temporarily take “oral pain medication” or “plastering” for temporary symptomatic treatment, until the ruptured meniscus has seriously affected the function of life, with walking limp, lower limb muscle atrophy, joint effusion, and even the leg cannot be straightened and bent. It is only when the ruptured meniscus has seriously affected the function of life, such as walking with a limp, muscle atrophy of the lower limbs, joint effusion, or even the leg cannot be straightened and bent that we come to the clinic. At this time, we need to face not only the meniscus rupture itself, but also the knee cartilage damage, ligament laxity, synovitis, thigh muscle atrophy and a series of other complications, many of which can not be completed through arthroscopic surgery, but can only look forward to post-operative rehabilitation exercises and self-recovery, as well as cartilage nutrition drugs. It is for this reason that arthroscopic meniscus surgery can address the continued wear and tear of the ruptured meniscus in the joint and prevent the inevitable development of severe knee osteoarthritis or even the need for an artificial knee due to the rapid increase in wear and tear of the joint, for patients who have been experiencing symptoms for more than three months or even several years. However, the above-mentioned has caused various and can only slowly recover itself, and the rehabilitation goals of the postoperative patient should not be too high. Is it necessary to do both sides of the disc meniscus? We already know that the discoid meniscus of the knee is a physical trait, just like the development of the single and double eyelids in humans, and therefore the discoid meniscus is also a pair of sexes in normal people, except that often patients come to the clinic with pain and discomfort on only one side of the knee, and if it is in the dominant limb (for example, if a left-handed person has symptoms in the left leg), it often has little to do with the presence or absence of trauma. However, if the non-dominant extremity has discomfort first, it is often caused by trauma or a minor trauma or sprain. Regardless of the cause we generally only need to consider surgery when the disc meniscus is damaged, torn and causing joint discomfort, and there are many people diagnosed with a disc meniscus who have never needed to come to the hospital in their lives. For a clearly ruptured disc meniscus, only infants and school-age children can undergo meniscoplasty, which in layman’s terms is the cutting of a large round disc of cartilage into an almost normal half-moon shaped cartilage plate. This procedure requires that the disc meniscus itself not have extensive and complex ruptures and that the cartilage fiber bundles are still flexible and viable. By the time the patient reaches adulthood, the time for this procedure is often lost and only partial or even drastic removal of the meniscus can be done, preserving less than 10-15% of the remaining cartilage plate. This is because the discoid meniscus is not only different from the normal meniscus in appearance, but also in its microstructure with different arrangement of collagen fibers, which means that it is not durable and easily damaged, and even if it is cut into a normal shape or even sutured, the remaining cartilage plate will continue to rupture and wear out, which will not help the patient recover from symptoms. However, arthroscopically we preserve as much of the fibrocartilage around the circumference of the joint capsule as possible, as well as some of the anterior and posterior angles of the meniscus. Although this preservation is risky (see later), it is worthwhile to cushion the patient’s joints, reduce friction and slow down joint aging. We try not to perform a 100% discoid meniscus resection during treatment. Common post-surgical complications and management of the disc meniscus, and how to do post-surgical rehabilitation? Different age groups, different occupational groups, and different “trauma” mechanisms can cause the disc meniscus, which itself is not of good quality, to be “overloaded” and “strike”. It is just a “strike”. Therefore, the recovery after treatment varies from person to person. Generally speaking, the most common patients with poor recovery after surgery have significant atrophy of the thigh muscles before surgery (one leg is thick and the other is thin), or have significant chondromalacia (pain, even when standing, not being able to climb or squat downstairs, not being able to walk for long periods of time), or have laxity of the anterior cruciate ligament of the knee (no strength, weakness, or even “misalignment” of the leg). There is even a sense of “misalignment”). In this case, the tendency to improve may be due to tenacious and diligent muscle exercise and ligament balancing exercises, supplemented by cartilage nutrition medication. Another common postoperative discomfort is the persistent knee “popping sound”, which occurs more frequently in some patients but is not associated with joint pain and discomfort, mainly because, as mentioned above, our principle in the surgical management of discoid meniscus injuries is to try to preserve the anterior and posterior horn cartilage, which is an important part of the stable joint structure. After all, the disc meniscus is thick and large, and the removal of some of the cartilage will cause the remaining cartilage to “wander” within the joint, which is reflected by the “popping sensation”. In a sense, this is a small “price” to pay for the knee to function more permanently and to slow down the aging of the joint. In our clinical work, we do encounter a very small number of patients, especially middle-aged and elderly female patients, who have poor post-operative recovery, and even patients who say “it’s not as good as it was before surgery”. The reason for this is not that the disc meniscus rupture was not diagnosed correctly or that the surgery should not have been done, but that the patient had too many preoperative knee function “debts”, limited effect of surgery alone, and lack of patience in postoperative rehabilitation, etc. This is also a problem that must be properly recognized by patients who are considering surgical treatment.