EE was reassembling an 8"" line that was plugged from a scissor lift ~10.5' off the ground. EE could not lower lift w/controls from the lift platform. Partner was trying to lower lift from ground when EE climbed down the lift, hopped to floor from bottom brace ~4 ft. up. EE contacted lift base/chassis with hip. Landed on feet (no slip) but had immediate pain in hip and back.