A health and safety review is underway on a high-needs mental health unit at Hillmorton Hospital after staff have been bitten, hit, and injured while restraining patients.
The review comes as the Canterbury District Health Board is planning an extension to the Assessment, Treatment and Rehabilitation Unit to make it safer.
Mental health services general manager Toni Gutschlag said since January, there had been 11 ACC workplace injury claims for staff working in the unit - one of which resulted in 61 days off work.
"We are extremely concerned about the number of people being injured at work and the injuries they are sustaining."
Gutschlag said it prompted a health and safety review of the unit, which began last week.
"We are confident this review will give more clarity to the issues and possible mitigating strategies."
The secure unit provides treatment for people with "severe behavioural disturbance" and those receiving compulsory care.
CDHB statistics show 10 of the workplace injuries were the result of "being hit, struck or bitten by a person".
The other was for a muscular strain from restraining a patient, resulting in 61 days off work.
Three staff had 10 days or less off work, and four needed between 18-35 days off. All of those were the result of "physical assaults".
Three did not need time off work.
Gutschlag said the CDHB was also planning an extension of the unit in a bid to make it safer and easier to respond to individual patient needs.
"Staff were recently able to view a cardboard mock-up of the proposed extension to the unit, which includes patient living and lounge areas. Their feedback is currently being collated," Gutschlag said.
"Our greatest priority is the well being and safety of our patients and staff."
In May, The Star reported mental health staff met with Ministry of Health officials about increased violence and overcrowding at the unit.
It came after statistics showed between January 2014 and October 2016, there were about 1000 physical assaults recorded at the unit.