The swelling of femoral neck fracture after six months may be caused by many reasons, such as poor healing, traumatic arthritis, femoral head necrosis and so on. 1. Poor healing: femoral neck fracture is easy to cause damage to the articular cartilage and trophoblastic vessels, if the treatment is not appropriate or poor maintenance may cause delayed healing or non-healing of the affected area, resulting in swelling. 2. Traumatic arthritis: when femoral neck fracture occurs, it is easy to cause cartilage damage in the hip joint, which in turn triggers edema and inflammation of the local cartilage, resulting in fluid accumulation in the hip joint and swelling. 3. Necrosis of femoral head: Femoral neck fracture may lead to damage or interruption of the blood supply to the femoral head, thus leading to necrosis of the femoral head, which is usually visible only after a few months. If the symptoms are not relieved or there are signs of aggravation, you should consult a doctor in time and actively cooperate with the doctor’s treatment.