EMPLOYEE HAD DERAILED A MANBUS AT A TRACK SWITCH AT BREAK #31 ON THE MAINLINE. WHILE EXITING THE MANBUS HE STATED THAT HE TWISTED HIS RIGHT KNEE. HE RE RAILED THE BUS HAD PROCEDED TO THE BO BCAT. HE WENT TO LOGAN GENERAL HOSPITAL AND WAS ADVISED TO SEE A SPECIALIST.