Employee was tramming a supply motor around a curve, the motor derailed causing EE to bump chin on the dashboard of the motor. EE returned to work next scheduled shift and worked until pre-scheduled vacation of 8/21/2019 - 9/03/2019. This office was notified on 10/07/2019 that during this time EE had surgery on 8/21/2019 to correct TMJ, making this a reportable injury.