Employee trying to break bolt loose with wrench & bar. Wrench broke & struck shoulder. Employee had discomfort & limited mobility in arm; taken to ER. Diagnosed with contusion, no restrictions. Referred for MRI. Two follow-up appointments (09/18 and 10/01) with return to full duty/no restrictions. Seen by Ortho on 10/17. Placed on restricted duty. Only became reportable on 10/17.