Four months after hip replacement surgery, there is fluid, considering the reactive fluid or infected fluid, according to the different causes of different treatments, should be under the guidance of the doctor to choose the treatment, generally take the joint puncture suction, medication, joint lavage treatment or surgical treatment and so on. 1. Reactive effusion: Because of the implantation of the joint prosthesis, the body has a foreign body reaction to the joint prosthesis, generally take joint puncture suction or medication, such as aspirin, etc. At the same time, the patient should stop the hip joint. At the same time, the patient should stop the activities of the hip joint, which can reduce the secretion of the effusion. 2. Infectious effusion: that is, the joint is infected, and the joint needs to be irrigated. If the effect of irrigated treatment is limited, the joint prosthesis needs to be removed by surgery, and the joint prosthesis will be replaced again after the infection is controlled. If there is effusion after hip replacement surgery, the patient should actively cooperate with the doctor’s treatment and review. After the effusion has been effectively reduced, the patient can choose rehabilitation exercises, such as aerial stirrups and other movements, to prevent muscle atrophy. If you feel unwell, you should go to the hospital in time, do not use medicine or treatment by yourself.