don't have any research at hand, and to be honest, i doubt there is much out there.

i think lots of things that we are taught through university to be contraindications should really be regarded as precautions. still, it's probably better to teach the former to students in some ways.

the accepted medical management of rib fractures is adequate analgesia - a nerve block is usually best.

personally i would not do manual techniques over someone's rib fractures unless they had good analgesia onboard. there are usually alternatives that are just as good - ie, do you REALLY need to do manual techniques right THERE.

for one rib fracture, the patient may tolerate it, for multiple ones, who knows? you can always trial it. too much pain will possibly stop them from even taking a deep breath and surely that's more important/effective than manual techniques.