A bone bulge below the knee after a fall is considered to be related to joint dislocation, patellar fracture, bursitis, tibial plateau fracture and so on. 1. Joint dislocation: Joint dislocation is mostly caused by external violence, congenital joint structure abnormality, strenuous exercise and other factors. Patients will have joint deformation, swelling or ecchymosis, and are prone to pain, limited joint movement and other symptoms, which can also be manifested as a bone bulge under the knee after a fall. 2. Patellar fracture: it is a traumatic disease, mostly caused by direct or indirect violence, usually patients will have symptoms such as swelling, pain and dysfunction of the knee joint. Therefore, part of the patient fell below the knee bone bump need to be vigilant is caused by patella fracture. 3. Bursitis: the disease can also cause some patients to fall below the knee bone bump. Bursitis is related to trauma, infection and other factors, patients mainly manifested as swelling, stiffness or pain around the joint. 4. Tibial plateau fracture: some patients need to be alert to tibial plateau fracture when they fall below the knee and have a bumpy bone. Tibial plateau fracture is mostly caused by indirect or direct violence, and the affected area is usually accompanied by swelling, pain and other uncomfortable symptoms, but also prone to limited mobility, skin bruising, foot drop and other symptoms. It is recommended that people who have fallen below the knee and have a bulging bone should consult a doctor for an examination in order to determine the cause of the fracture and then follow the doctor’s instructions for treatment.