broken ribs. A brutal assault upon a family member recently gives me first hand knowledge that ribs can and are broken during SA. The perp while attempting to restrain, control his intended victim can easily break ribs if they place their knee upon their victim's chest while attempting to disrobe/access areas they want to get at.
Laci Peterson had broken ribs too ... wait a minute ... that was from memory ... let me verify.
ETA: fractured ribs confirmed.