An employee was changing a bottom hole assembly and laying down a stabilizer and pony sub. Nearby rig hands could not get a pipe to a trowel. He saw they were in trouble with the pipe and attempted to help get the pipe to the trowel, but the driller did not land the pipe in the trowel. The pipe landed on the edge and rolled out, pinching him against a frame and stabilizer. He fractured his scapula and the spinous processes on his vertebrae.