In orthopedic clinics, patients often ask their doctors whether they need to take “chondroprotective agents” that “can stop the pathological process of osteoarthritis”, and some patients even directly ask their doctors to prescribe “chondroprotective agents Some patients even ask their doctors to prescribe “chondroprotective agents”. So, what is a “chondroprotective agent”? Can it really improve the state of the patient’s cartilage, restore the normal biochemical environment of the joint, and repair the damaged joint cartilage? Osteoarthritis (osteoarthritis) is an age-related degenerative disease of the synovial joints, which is a local manifestation of systemic aging in the joints. Currently, the treatment of osteoarthritis includes non-pharmacological, pharmacological and surgical treatments. In addition to painkillers, another major class of drugs is glycosaminoglycans, including sodium hyaluronate, glucosamine, and chondroitin sulfate, which are three highly recognized drugs. Among them, glucosamine and chondroitin sulfate were once called “chondroprotective agents,” a phrase that disappeared in academic circles only briefly, but was widely circulated among the public, where people hoped to use these drugs to protect and even repair worn cartilage. In fact, it is very unscientific to simply call two of the glycosaminoglycan drugs, glucosamine and chondroitin sulfate, collectively “chondroprotective agents”. Although there are similarities in the chemical structure of glycosaminoglycans, the large molecular weight polymers themselves are highly variable and diverse, with differences in chemical structure and vastly different clinical effects. The presence of large amounts of glycosaminoglycans in cartilage and cartilage matrix has led to the clinical use of glucosamine and chondroitin sulfate as nutritional supplements (commonly known as “chondroprotective agents”). In fact, the therapeutic mechanism of action of glycosaminoglycans remains poorly understood, and osteoarthritis is a multi-causal, total joint disease that involves all components of the joint, not just the cartilage and subchondral bone. When abnormal mechanics are present, cartilage wear is the result of the disease rather than the cause. In this case, “cartilage protection” or “cartilage repair” is useless. Therefore, the name “chondroprotective agent” with such a narrow meaning is hardly recognized by medical doctors. To date, there is no evidence that supplements containing glucosamine and chondroitin sulfate have a therapeutic effect on osteoarthritis, and a 2010 analysis showed that the results of glucosamine differed between preparations and even between manufacturers. Many of the previous studies used a combination of the two ingredients as a therapeutic agent and found no significant therapeutic effect; the new study used “pharmaceutical grade” glucosamine as the investigational agent and found only a weak therapeutic effect of chondroitin sulfate. The 2010 European guidelines clearly state that chondroitin sulfate has no significant therapeutic effect on osteoarthritis, and in 2011 it was added that chondroitin sulfate may have a weak therapeutic effect, but this remains to be further confirmed by new studies. Although sodium hyaluronate is not described as a “chondroprotective agent,” it is indeed a large molecular weight glycosaminoglycan, like glucosamine and chondroitin sulfate, and is found in the joint fluid of both normal and osteoarthritic joints. Many studies have demonstrated the effectiveness of sodium hyaluronate in the treatment of osteoarthritis, but the downside is that it cannot be taken orally, but only as an intra-articular injection, known as viscoelastic supplementation therapy. Intra-articular injections are invasive operations and their application is somewhat limited. For example, the hip joint is located very deep and is not easily injected. Currently, sodium hyaluronate is most commonly used for knee joint injections, with relatively few applications in other joints. In clinical practice, when glucocorticoids are injected into the knee joint to treat osteoarthritis, the pain-relieving effect generally lasts only about 4 weeks and does not contribute to functional improvement. Unlike hormones, sodium hyaluronate has a slower onset of action, generally taking 2 to 3 weeks, but its efficacy can last for as long as 2 to 3 months. Intra-articular injections of sodium hyaluronate in the knee are usually given once a week for five weeks as a course of treatment. Patients are advised to use 2 courses of treatment per year, usually no more than 3 courses of treatment. The development and progression of osteoarthritis is the result of many factors, and both the complexity of the disease and the diversity of glycosaminoglycans dictate that the evaluation of therapeutic agents is a long and costly process of discovery. Therefore, in the treatment of osteoarthritis, patients should not pursue the use of so-called “chondroprotective agents” or substitute health care products for medications, but should strictly follow the will and use medications reasonably to relieve symptoms and protect joint cartilage.