While the Otago District Health Board is carrying out more complicated surgery and treating more patients, it cannot meet demand for non-urgent operations.
Chief operating officer Vivian Blake said the board was " almost daily maintaining a tight line with rationing".
Surgery statistics for the past financial year show the board treated 10,671 surgical patients, 54 more than the previous year, and the complexity of the surgery had also increased by 1072 caseweights.
Caseweights show how much money, staffing and time in hospital each operation needs.
A standard hip replacement, for instance, would use four caseweights and a cataract operation 0.5.
Most patients are seen in general surgery, with numbers of patients slightly down on the previous year at 2928, but the caseweights were higher.
One fewer orthopaedic patient was seen than the previous year, at 2586, but again the caseweight figure had increased.
Slightly fewer acute operations were carried out during 2008-09 than the previous year in most of the nine specialties listed in Ministry of Health figures, but had increased in gynaecology, paediatric surgery and ophthalmology.
Elective surgery had increased in most specialties.
Decreases in neurosurgery and ophthalmology reflected staffing shortages.
This financial year the board is required to provide about 500 more operations and is required to have a mix of simple and more complex procedures.
It has contracted Mercy Hospital to carry out some ear, nose and throat surgery and has been exploring other ways of increasing the number of operations.
Mrs Blake said the hospital was doing a lot more work than it did last year when it had fewer anaesthetists, but it was very much a "moving feast" which could easily be affected if there were specialist resignations.
In the past year, various hospital departments had sent out information tightening up assessment criteria.
Some services had been receiving far more referrals for first specialist appointments than they could cope with.
In orthopaedics, for instance, the department advised recently that it receives 200 referrals a month for first specialist appointments, but has only 90 slots to fill.
This means that nearly all referrals assessed as routine are being returned to GPs.
This could include such conditions as ganglion cysts, carpal tunnel, knee and shoulder pain and bunions.
It is an issue for city and rural patients.
Central Otago Health Services nursing services manager Debi Lawry said spaces in the clinics provided by the Dunedin specialists in rural hospitals were limited and conditions which were not life-threatening but uncomfortable were referred back to GPs.
This was not ideal, but it was understood the board had to meet Ministry of Health criteria about treatment times to ensure funding.
General practitioners could get quite frustrated, but were "pretty reasonable" about the situation.
It was important that decisions were consistent and that access was fair throughout the province.
Mrs Blake said she considered the board had come a long way in recent years in regard to consistent treatment of referrals.
The same clinical priority assessment criteria would be used in Otago as in say, Nelson, she said.
GP liaison officer with the board, Dr Anne Worsnop, said several issues affected the demand for orthopaedic surgery and access to it.
These included the ageing population, the ability to perform more complex surgery which was more time consuming, a decrease in the number of shoulder surgery cases accepted by ACC, and an increase in patients' expectations.
Also, 10 years after the joint replacement initiative began, some people were now returning for second joint replacements.
