Patients can experience hip pain after hip replacement surgery. The causes of pain after hip replacement include: 1. Postoperative infection: Infection is a serious complication after hip replacement surgery. Inflammatory factors such as irritation after infection can produce severe pain. 2.Deep vein embolism in the lower limb: it can cause clinical symptoms such as pain and swelling in the injured limb. 3, artificial prosthesis loosening: prosthesis loosening will produce mechanical stimulation to the surrounding bone tissue and soft tissue, causing pain. 4, inappropriate selection of prosthetic joint specifications: the unsuitable size of the prosthesis causes instability of the joint structure, the upper and lower part of the joint is not coordinated, and in the long term, it causes loosening of the joint; the inappropriate size of the femoral head replacement can cause wear and tear of the acetabulum until the acetabulum wears through. 5, dislocation of the hip joint. 6, ectopic ossification: ossifying myositis occurs around the hip joint after hip replacement surgery. The symptoms are mainly pain around the hip joint with no improvement in swelling; or pain and swelling reappearing 2 weeks after surgery. 7, postoperative medullary hypertension: the prosthetic stalk is too large and wide, compressing the proximal femur, making the pressure of the bone marrow cavity increase. This causes pain after surgery. 8.Stress fracture of the distal end of the prosthetic stem.