More than 200 people a day have been attending North Tees Hospital's accident and emergency unit during the recent cold weather, health staff said.
The average attendance at the Stockton department at this time of year is 130 to 160 patients a day.
They said extra patients were putting pressure on their resources, staffing and budgets.
Injuries including sprained ankles, fractured hips and broken wrists have been blamed on icy roads and pathways.
North Tees Hospital accident and emergency ward manager, Stuart Harper, described the pathways as "lethal" and advised people to be careful when outside.
He said: "One person came in with two broken wrists, we then have to deal with the injury, sort out residential care and extra help - we couldn't just send them home - and that takes time.
"We've had a few fractured hips from slips, trips and falls, and those can cost the NHS up to £5,000 for the operation, and then you have to think about care and rehabilitation afterwards.
"It's very costly to the NHS as a whole, and we're really feeling the pressure here."
Stockton Council said it focussed resources on gritting the major roads and most important bus routes, as well as roads leading to outlying communities, shopping centres and industrial estates.
But a spokesperson added: "Clearly it's impossible to treat every road but, when conditions allow, we do treat other routes during the day where we can."