EE WAS HANGING A TRUSS ON RIGHT SIDE OF 435 BOLTER. EE HUNG TRUSS, WAS GETTING DOWN, HIS LEFT FOOT SLIPPED OFF, STAB JACK RIGHT FOOT GOT CAUGHT BETWEEN EXTENDING CYLINDER & STAB JACK (LOCATION ) TWISTING EE'S RIGHT KNEE. ORTHOPEDIC SPECIALIST FOUND LEFT KNEE TIBIAL SPINE FRACTURE.