In NCIS, the character Delilah McGee uses a wheelchair after being injured in an explosion. This storyline was introduced to add emotional depth and long-term development to her character and her relationship with McGee.
In real life, however, the actress Margo Harshman does not use a wheelchair. Her condition in the show is purely fictional and part of the script. Like many TV dramas, NCIS often incorporates dramatic events to shape its characters, and this is one example of that storytelling approach.