Hip bone effusion, or hip joint effusion. Typically, only a few cases can heal on their own; most hip joint effusions do not heal on their own. Hip joint effusion is a phenomenon in which pathogenic bacteria such as Staphylococcus aureus infection, autoimmune diseases such as ankylosing spondylitis, or localized necrotizing diseases such as osteonecrosis of the femoral head invade the synovial membrane of the hip joint, causing synovial inflammation and leading to increased exudate from the hip joint cavity. Clinical manifestations may include pain in the groin area during activities, claudication, and limitation of hip joint activities. For joint cavity effusion caused by traumatic factors, the main focus is to rest and avoid inappropriate or excessive exercise; for hip joint cavity effusion caused by infectious factors, it is necessary to identify the causative organisms and use antibiotics in sufficient quantity and regularly. If the localized pus is large, surgical treatments such as incision and drainage can be taken; hip joint effusion caused by non-infectious factors should be actively treated for the primary disease. Hip joint effusion is recommended to consult a doctor in time to clarify the diagnosis and carry out targeted treatment.