After back surgery can you get shorter?

Sure - by not much: Sure - you can get a tiny teeny bit shorter - dependent on what surgery and who did your surgery. Discectomy removes a small portion of your inter-vertebral disc. One disc only makes up a tiny fraction of your spine (or overall height) but losing a quarter inch or so following back surgery is normal.

Not usually: Depends on the problem and surgery but would expect fusion type surgery to open up disc spaces with interbody device and preserve or increase height compression fractures in verebral bodies can make a person shorter.