The main difference between hip synovitis and sacroiliac arthritis is that the sites of occurrence are not exactly the same and the clinical manifestations are not exactly the same. 1. Site of occurrence: the hip joint is mainly in the top of the thigh, hip synovitis is also mainly manifested in the thigh root pain, sacroiliitis pain is mainly in the lumbosacral region. 2. Clinical manifestations: hip synovitis pain can be extended to the inner thigh and knee, can be accompanied by local skin redness and swelling, sacroiliac arthritis is mainly for the lumbosacral region of the dull pain, there will be a typical morning stiffness, that is, early in the morning stiffness, after the activities of the symptom is reduced. Hip synovitis and sacroiliac arthritis occur in different parts of the body, if any hip and lumbosacral pain occurs, and if the symptoms persist, it is recommended to consult a doctor in time for treatment.