When infected with tetanus, can your bones actually break?

Yes. Though rare in this country, tetanus discriptions of the patient care from 60 years ago are quite striking. Patients were often kept in darkened rooms with minimal stimulation as a loud noise could set off a muscle spasm that was so violent it could snap bones. Whether this is more urban legend passed down to impressionable med students or not, the descriptions of my staff id guy were memorable.
"Break bone fever" . Is called that for a reason. Yes, it is possible, but usually only severe cases and debilitated persons with it. Sedation can reduce the spasms and lower risk of self-injury.