The clinical diagnosis of osteoarthritis involves comprehensive history taking, physical examination, and a thorough evaluation of the condition. The first question should be about the duration and severity of the lesion. Painful symptoms are usually insidious at the start, and they tend to persist for several months before the patient sees a physician. Patients often experience discomfort from prolonged standing, walking or running, and symptoms usually resolve after rest. As the extent of the lesion increases, daily activities and sleep can be affected. In addition to pain, there is a grinding sensation and popping in the joint. Injury to the cartilage, meniscus or free bodies can cause “locking” symptoms, often affecting joint flexion and squatting activities. The medial, lateral, and anterior compartments of the knee are further identified by physical examination. Internal knee malalignment is more common than external knee malalignment, and changes in the line of force and flexion deformity of the lower extremity in the standing position often indicate severe knee involvement. Joint line gap tenderness and McMurray’s test generally elicits discomfort in the involved compartment. Most patients have stable ligaments, but it is important to rule out underlying ligament instability. Pain is predominant in the patellofemoral and tibiofemoral joints in a weight-bearing state, especially when walking, walking up and down stairs, squatting and standing, and can be sudden, tender-legged or fallen during walking. Cartilage exfoliation and subchondral bone exposure are stimulated by pressure leading to reflexive and spasmodic tension of the quadriceps muscle, and symptoms of strangulation may occur due to meniscal wear and cartilage damage. Due to cartilage wear of the patella, the subchondral bone is exposed and reflexively causes spasticity of the quadriceps muscle, so the patellar nudge activity is restricted and the patellar grind test is positive. As a result of synovial hypertrophy, congestion and edema, the synovial tissue is embedded in the joint space, and swelling, pain and functional limitation of the joint cavity may occur. In obese patients, the knee is often associated with inversion and valgus deformity and patellar subluxation, with narrowing of the joint space on the stress side in standing X-rays and sclerosis or hyperplasia of the subchondral bone. On examination, we found inversion or valgus deformity of the knee, standing flexion deformity, palpable rubbing sensation or twisting or tearing rubbing sound in knee flexion and extension, pressure pain in the joint space and patellar rim, limited patellar pushing activity, positive patellar grinding test, and positive knee floating patella test. In patients with long-term physiotherapy, the skin around the knee joint changes in color and patches, and the skin shows leopard skin-like changes. It is very difficult to get up from a squat and requires two hands on the ground for support. Imaging of the knee joint helps in clinical diagnosis and understanding to determine the extent of articular cartilage lesions. In the early stages of cartilage lesions, x-ray examinations include anterior-posterior (PA) orthopantomographs of the knee in weight-bearing position and 20°-30° radiographs of the knee in weight-bearing position in flexion. The PA flexion image clearly shows narrowing of the joint space, unequal width on both sides, sharp tibial spines, flattening of the joint edges, subchondral bone sclerosis or cystic changes, inversion or valgus deformity of the knee joint, subchondral bone sclerosis, tibial intercondylar spines, bone redundancy and narrowing of the femoral intercondylar fossa, lip-like growth of the tibiofemoral joint edges, patellofemoral joint subluxation, and bone redundancy of the upper and lower pole of the patella. The radiological features include The force lines of the tibia and femur are assessed by weight-bearing x-ray of the knee, but assessment of the mechanical axis requires a full-length x-ray of the lower extremity. Magnetic resonance imaging (MRI) is a noninvasive examination, and MRI clearly shows cartilage changes when the radiographs do not show joint space narrowing changes before, i.e., early stages of articular cartilage lesions, with proton density fat-saturated fast spin echo (PDFSE) and three-dimensional gradient echo scanning.