EE was moving the control box while EE was setting up saws. EE was walking backwards, lost EE's footing and fell backwards. When EE fell the control box EE had been carrying landed on EE's hand, breaking EE's thumb. EE went to clinic, was released back to work. Went to follow up appointment Tuesday, May 28th. Has lifting restrictions of 1 lb., continues to work, no lost time.