Questions like this, and others, are good to bring up in the hiring interview, but you've already started the job and have prior experience? Try checking with Human Resources and asking what their policies are. At my place of employment we have a task force on hospital violence -- is there anything similar at your hospital? It could also help to ask discretely if anyone at work has been injured in the past, and what the response was, including Workmen's Compensation.
Another good question to ask -- does the facility have a policy of prosecuting criminal assaults against staff members?
Staffing can also be a contribution to injuries. You need to have sufficient staff, and the staff you do have on the floor have to be the kind of people who are proactive in spotting potential situations where aggression can occur, and intervene beforehand. Insufficient staffing can lead to minor injuries, such as chronic back pain or lumbar area injuries.
Quite some time ago, there was an item in the news about a nurse who was severely injured by a patient at a state facility. The patient was being admitted to the hospital unit, had a record of violence. He erupted unpredictably and slammed the nurse's head into a door frame. She suffered brain damage from the injury. Afterwards, news reports indicated that a factor in the incident was insufficient staffing. What took us aback was, the staffing on the floor of that hospital unit which they did have, reported as inadequate, was more than the staffing on our own hospital unit.
The figures for injury in the mental health field are high -- mental health professionals lead the pack with a rate of 69.9 out of 1,000 (National Crime Victimization Survey (199) and The Bureau of Labor Statistics Data). The risks are high, but with good staffing and experience people, they can be minimized.