The clinical diagnosis can be made by examining the patient’s knee joint, for example, by examining the physiological or pathological reflexes of the knee joint. The patient is instructed to sit on the edge of the bed with the lower extremities naturally lowered and the knee joint at 90 degrees, and then the physician uses a percussion hammer to tap the patellar tendon with appropriate force. If the reflexes are hyperactive or absent, the patient has a neurological disorder. The patient’s lower extremity can also be examined for external or internal rotation deformity by taking a straight line, starting at the position of the anterior superior iliac spine, and then stretching it downward to fix it between the bunion and the second toe finger. The normal result is that the straight line should pass through the outer edge of the patella. If it appears to be inward or outward, the patient’s lower extremity is externally or internally rotated.