Last time we talked about the treatment of early osteoarthritis, and this time we will talk about the treatment of mid-stage osteoarthritis. Let’s take the knee joint as an example. Treatment of osteoarthritis is closely related to the degree of progression of the lesion and its symptoms. Unlike early-stage lesions, mid-stage osteoarthritis often has organic changes in the joint structure. As previously mentioned, the lesions include degeneration and destruction of articular cartilage in the tibiofemoral weight-bearing area, synovial hyperplasia, joint cavity effusion, swelling and pain, osteophyte spur formation, free body formation, meniscal wear and tear, and so on. At this stage of treatment, in addition to continuing the various early treatments, arthroscopic cleanup surgery is an excellent option. Arthroscopy is a minimally invasive surgical procedure that requires only 2-3 small incisions of about 5 mm in the joint area, none of which require stitches. Patients can be on the floor within 6 hours after surgery and can be discharged home in 1-2 days. Arthroscopic treatment of mid-stage osteoarthritis has the following main advantages: 1. The joint cavity is flushed with a large amount of saline during arthroscopy, which can effectively reduce the concentration of inflammatory substances in the joint cavity and reduce chemical damage to the joint; 2. Arthroscopy can clean various structures in the joint. Cleaning up the hyperplastic synovial membrane can lead to the reduction of fluid and inflammatory substances secreted by the joint and reduce the swelling and pain of the joint; cleaning up and trimming the damaged meniscus can make the tibiofemoral joint match better and eliminate the joint pain caused by interlocking (sudden jamming) and meniscal compression; cleaning up and removing the free body can eliminate the joint interlocking caused by the free body and avoid cartilage damage; cleaning up and trimming the damaged cartilage can Cleaning and repairing damaged cartilage can slow down the degeneration and exfoliation of articular cartilage; cleaning bone spurs in the weight-bearing area can reduce physical joint wear and pain; most patients with osteoarthritis will have significant clinical improvement and relief after arthroscopic cleaning procedures. However, we should recognize that arthroscopic surgery also has its limitations. Just like an old car, it will break down after years of use, we fix it and it will run again, but how to fix it is still an old car after all, it is possible but unrealistic to expect to manage a lifetime with such a surgery.