WHILE BACKING UP PC, THE FRONT WHEEL RAN OVER A ROCK WHICH SPUN THE STEERING WHEEL. THE KNOB STRUCK THE BACK OF HIS LEFT HAND. CAUSE OF INJURY WAS ROCK LAYING ON ROADWAY. COMPLIANCE WITH RULES / REGS NOT A FACTOR, INJURY INVOLVED MINE EQUIPMENT, MINER PROFIENCY MAY BE A FACTOR, INVOLVED PROTECTIVE ITEMS RELATED TO HAND AND DEVICES ON EQUIPMENT.