Arthroscopy is also a type of endoscopy. However, it is fundamentally different from gastroscopy, colonoscopy, etc. Arthroscopy is an invasive procedure, although it is minimally invasive. Arthroscopy works by placing a 4mm diameter high-definition wide-angle rod-shaped optical lens into the joint (knee and shoulder joints are most commonly used) through a small skin incision and transmitting the intra-articular structures to a monitor via optical fiber, which is magnified into a high-definition image that allows the surgeon to discover diseased tissue in various areas of the joint. After an accurate diagnosis is made, the surgeon uses a variety of specially designed microscopic instruments and probes to cut, aspirate, suture, fix, and repair the diseased tissue. Most arthroscopic procedures can be performed through two small, one-stitch incisions, and recovery is rapid, allowing for immediate weight bearing and joint movement. At the same time, the accuracy of arthroscopic diagnosis and repair of intra-articular disorders is unmatched by previous incisional procedures. Arthroscopy has now become a routine orthopedic procedure in developed countries. In China, although the technology started late, it is developing rapidly, and in some high-level hospitals, the number and quality of surgeries have reached international advanced level. Arthroscopic surgery is not a panacea, he also has the corresponding indications (knee and shoulder joints as an example): 1, knee anterior cruciate ligament injury: most often seen in college and high school students, the common cause of sports injuries. The ligament injury, can not make a sharp turn, emergency stop, sudden acceleration and deceleration running, change of direction running, single-leg jump and other actions. If left untreated, secondary damage to other structures within the joint occurs in 80% of cases. In case of secondary meniscal tears, sudden interlocking sensation of the joint may occur. Arthroscopic repair of the anterior cruciate ligament can be performed with a degree of precision of a few millimeters, ensuring that the pre-injury level of motion is restored. 2, posterior cruciate ligament injury of the knee joint: common in car accident injuries, the anterior part of the knee is injured with a backward high energy external force, resulting in the rupture of this ligament. After the injury, the patient’s ability to walk up and down stairs and hills is severely impaired, and in severe cases, the joint laxity can even be detected in person. Arthroscopic posterior cruciate ligament reconstruction surgery can be called a revolutionary progress compared with the previous incision surgery. 3.Severe instability of the knee joint: caused by damage to multiple ligaments, resulting in loss of joint stability and seriously affecting joint function. Arthroscopic repair of multiple ligaments maximizes the advantages of minimally invasive technology and creates conditions for later functional recovery. 4.Knee meniscus injury: It occurs in patients under 40 years old, mostly due to torsional injury. The typical symptom is frequent sudden joint interlocking, which can often be released by the patient’s own appropriate activities. Atypical symptoms are localized pain and ringing in the joint space on one side. Damage to the meniscus should be treated promptly, as otherwise it can have an adverse and irreversible effect on the articular cartilage. Arthroscopic meniscectomy (i.e., partial resection) is the most classic arthroscopic procedure that preserves the maximum amount of healthy, intact meniscal tissue to allow it to continue to function. Removal of the diseased portion of the meniscus results in rapid improvement of pre-surgical symptoms and allows for immediate bed mobility after surgery. Meniscal tears found at an early stage can be repaired and sutured under arthroscopy, and the original function can be restored after healing. 5. Congenital discoid cartilage in children: It is a congenital meniscal deformity and is common in Asians. Typical manifestations are restricted joint extension, joint rattling, and in severe cases, joint interlocking. Atypical presentation is pain in the lateral joint space of the knee. Early detection may allow for arthroscopic plication to reshape the meniscus to the crescent shape of a normal meniscus, which is gradually shaped through future growth and development to become a normal meniscus. Untreated disc cartilage can develop severe irreparable tears and is often subjected to excisional surgery. 6. Knee cartilage defect: It occurs in patients under 40 years of age and can be due to trauma. The main manifestations are not specific and include pain, swelling and intra-articular rattling. Articular cartilage cannot be regenerated, and for limited cartilage defects, arthroscopic cartilage grafting can be performed. For acute cartilage debridement, cartilage fixation can be implemented. 7, patellofemoral joint disorders: arthroscopic stabilization of patellar dislocation and correction of ectopic patella (i.e., patella tilting outward and outward) can be performed. Shoulder joint disorders that are suitable for arthroscopic treatment are: the most common ones are frozen shoulder, which can be treated by arthroscopy to clear the scar tissue formed by frozen shoulder, which can relieve the symptoms of frozen shoulder and restore the function of shoulder joint. Shoulder impingement; rotator cuff injuries, including traumatic and degenerative injuries; and injuries to the glenoid labrum (mostly seen in patients with recurrent shoulder dislocations), etc.