EE was using 4lb hammer to make belt splice on 12/4/16,during work activities EE states they strained wrist. EE worked w/o restriction until seeking med attn on 2/28/17 becoming a RLT on 3/1/17.Cause of the incident was lack of EE concentration. PPE, mining equipment/mining systems, compliance w/ rules/regs was not a factor, miner proficiency was a factor.