Although the limb is no longer there, the nerve endings at the site of the amputation continue to send pain signals to the brain that make the brain think the limb is still there.  Sometimes, the brain memory of pain is retained and is interpreted as pain, regardless of signals from injured nerves. It's still unknown why some people develop phantom pain after an amputation while others do not. Some factors that may increase your risk of phantom pain include:

Pain before amputation. ​

     Some researchers have found that people who had pain in a limb before amputation are likely to have it afterward, especially immediately after amputation. This may be because the brain holds on to the memory of the pain and keeps sending pain signals, even after the limb is removed.Stump pain. ​

    People who have persistent stump pain usually have phantom pain, too. Stump pain can be caused by an abnormal growth on damaged nerve endings (neuroma) that often results in painful nerve activity. 

​Poor-fitting artificial limb (prosthesis).

    Talk to your doctor to be sure you're putting your artificial limb on correctly and that it fits properly. If you think your artificial limb may not fit properly, or is causing pain, talk to your doctor.