Whoa. Do you mean the toilet shattered and cut the patient as they fell onto the shards, or that when the toilet broke the patient fell and had joint or bruising injury?Toilets hold a surprising amount of weight. As long as it's not shoved into a small space I doubt she would really have too much trouble with it.
The problem comes when deathfats (usually because of bad knees) powerbomb the shit out of the toilet instead of slowly lowering themselves onto the seat. You can easily shatter either the toilet seat or the bowl when your ass picks up freight train momentum. Seen some pretty nasty injuries happen that way.