Open Question: can my employer legal cut my hours at work because of a work related injury?

I recently injured my shoulder at work because a client attacked me, I turned it in to my boss and then went to the dr the next day, they dr put me on light duty for 1 week and then i was realesed to return back to work with normal hours, Now my boss has cut my hours from 39 hours to 24 hours a week, I believe she knows she cannot fire me but can she legally cut my hours like this? My shoulder has not been improving therefore now the dr wants me to have a MRI done this week because he believe there maybe some permanate damage, but im still questioning the loss of hours and if she can do that when I have a full release right now? We are taking about workman comp laws in the state of nebraska