Although I have relatives who are docs, I'm not in the medical field, so other than the obvious that bone was compressed, I couldn't answer in more technical terms than that. This was posted above:
http://codeblueblog.blogs.com/codeblueblog/2005/03/csi_medblogs_co_1.html
The reason I ask was I have a compression fracture to my T-12...I walked around with it for months..The radiologist who read my x-rays couldn't really tell when it happened or how bad it was... The L-1 compression fracture cold have come from something a simple as falling on her butt..