###Human: If problem is in hip joint then why do I have pain in the knee? ###Assistant: Hi. Hip avascular necrosis (AVN) and hip arthritis causes pain in the affected hip and also sometimes in the knees as the same nerve which supplies the hip also supplies the knee joint. It is called as obturator nerve. This nerve supplies both the joints. So if there is hip joint pain, many patients also get pain in the knee joint. But, also to be sure if nothing is wrong with the knee joint, you should take x-rays and document it. Get x-ray of the knee joint both in anteroposterior view (AP) and lateral view and then get a follow up done to confirm your problem.