Medial thigh knee protrusion is associated with degenerative hyperplasia of the medial knee joint bone, injury to the medial collateral ligament of the knee, and goosefoot bursitis. Thigh knee medial protrusion is related to the following factors: 1. Degenerative hyperplasia of the medial knee joint bone: the bone hyperplasia will irritate the surrounding soft tissues, which will lead to swelling, pain, protrusion and pressure pain on the medial side of the knee. 2. Injury to the medial collateral ligament of the knee: the medial side of the knee joint may have pain, limited activity, joint laxity, instability, localized swelling is obvious in the medial side, and pressure and pain in the walking area of the medial collateral ligament. 3. Goosefoot bursitis: mainly manifested as pain in the medial side of the knee joint, localized swelling, mainly due to the bursa of the medial side of the knee after repeated small trauma and other stimuli leading to bursal oedema, hyperplasia and intracapsular effusion caused by the bursa. There may also be other reasons for the protrusion of the inner side of the thigh knee, such as bone tumors and cysts, etc. It is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, and then give targeted treatment or therapy.