when there is no movement in the whole body below the shoulders, it is called a quadriplegia. you have not indicated as to how long ago the surgery was done. Once the compression is relieved by surgery there should be some return of movement. it is possible that the injury damaged the nerves completely and return of movement may not be likely also. you have not indicated as to whether she has any feeling on her arms trunk and legs. In the mean time, rehabilitative process has to be started for her. Rehab nursing to ensure that your sister does not develop pressure sores has to be started. physiotherapy to improve the available strengths and to initiate movement at the problems areas have to be started. she will have to be trained on how to move around in bed using the available strengths. she would need occupational therapy as well in the future. there are several examples of people who have gone through high level injuries like your sister doing several things for themselves and leading a fairly independent life in a wheelchair level. it is a long drawn process and requires a lot of effort , time and support. write to me if you have any specific questions. i would need a lot more details to help you better.