EE WAS ASSISTING HANG MONRAIL STRUCTURE IN THE NO.3 ENTRY OF THE C-5 LONGWALL PANEL. HE WAS ATTEMPTING HOOK ONE END OF A PIECE OF STRUCTURE INTOTHE PIECE THAT HAD JUST BEEN HUNG. THE END OF TH E STRUCTURE SLIPPED OUT OF EE'S HAND & IN HIS ATTEMPT TO CATCH IT, HE STRAINED HIS LEFT SHOULDER. HE BEGAN TO MISS WORK ON 8/15/01 DUE TO PROBLEM