The pain is characterized by medial knee pain, which is obvious when walking, and the knee starts to invert and bend. X-rays show that the medial joint space is significantly narrowed, while the lateral joint space and patellofemoral joint are normal, and the pain does not improve significantly with conservative treatment, which is very painful. Doctors would say to do artificial total knee replacement, but the condition has not yet reached this level, unfortunately. Now, there is a new method to solve this problem, which is the artificial unicondylar replacement technology, i.e., simply making a 6-8cm incision for the medial minimally invasive unicondylar treatment to repair the damaged knee surface, which can restore the function and relieve the pain. So what is minimally invasive unicondylar replacement? Here is an introduction: Minimally invasive unicondylar technique (UKA) is not a knee reconstruction technique in the traditional sense, but a knee repair technique. It is a technique that restores the joint space of the affected inter-articular compartment, fills cartilage defects in the femur and tibia, restores the shape and size of the femoral condyle, and restores the line of force in the lower extremity prior to the appearance of pathological changes. Treatment of unicompartmental knee disease by unicondylar artificial knee arthroplasty preserves bone mass and cruciate ligaments, does not affect the proprioception of the knee joint, better preserves joint function, and achieves pain relief. Indications Patients with primary medial or lateral compartment osteoarthritis of the knee joint, patients with bone ischemic necrosis, age range 40-75 years, and body mass index less than 28 (weight kg/height m2). The anterior and posterior cruciate ligaments of the knee are generally required to be intact. In those with anterior cruciate ligament injury, lateral tibial wear is required to be limited to the anterior 2/3 of the tibial plateau, with no posterior wear and no significant medial or lateral side subluxation. The range of motion of the knee should be at least 90°, within 15° of inversion-eversion deformity of the knee, within 5° of flexion contracture deformity, no previous history of knee surgery, and good soft tissue conditions. Contraindications 1. Absolute contraindications: (1) Any active infection, systemic or local; (2) Severe degeneration of both the medial and lateral knee gaps; (3) Paralysis of the main joint muscles or destruction of muscle tendons and other tissues; (4) Significant patellofemoral arthritis, patellofemoral sclerosis with loss of joint space; (5) Rheumatoid arthritis and crystal deposition disease such as gout or pseudogout. 2. Relative contraindications: (1) body mass index greater than 28; (2) heavy physical activity; (3) absence or laxity of ACL; (4) history of previous knee surgery and poor soft tissue conditions; (5) patients with osteoporosis.