A Newcastle Herald investigation reveals wait times to get an appointment for some specialties in the Hunter public health system has reached crisis level.

A Fern Bay man, waiting to see a specialist about a knee replacement, was forced to travel to Tamworth, a 600km round trip, to see an orthopaedic specialist after waiting 18 months.

The father-of-three who used to work in construction, lost his job and faces losing his home due to the crippling wait.

"I need to get my knee fixed so I can get back to work," he said. "This has broken us financially and there is nothing I can do to fix it."

The "secret waiting list" means the official elective-surgery waiting times in the Hunter are greatly underestimated.

People must be assessed in hospital outpatient clinics before they can be put on a waiting list for surgery - meaning those who are yet to be assessed do not show up on the official elective-surgery waiting lists.

The full extent of the problem is unknown because not every patient waiting for an outpatient appointment will need surgery.

The long delay before people join more than 80,000 NSW patients officially waiting for elective surgery was uncovered by freedom-of-information documents obtained by the Newcastle Herald.

They reveal that 12,644 people were waiting to see a specialist at John Hunter Outpatient Service in 2017, this increased to 13,414 last year.

The median waits ranged from 36 days for infectious diseases, urology and vascular specialist appointments to almost five months for orthopaedics, immunology, dermatology and ear, nose and throat.

But some patients needing to see an ear, nose and throat specialist were forced to wait three years.

For orthopaedics, some patients waited more than 985 days - or 2 years and eight months - to get an appointment.

If they are assessed as needing surgery, patients then join John Hunter Hospital's official elective-surgery waiting list that had 2979 people queuing in March.

This included 2222 people who were waiting for non-urgent proceedures including cataract removal, knee and hip replacements, hernias and tonsillectomies.

Opposition health spokesman Ryan Park described the revelation of the 'secret wait lists' as appalling. Mr Park said people should not be forced to wait years to be seen by a specialist.

"These are people who are forced to wait up to three years for an appointment, then would be expected to wait again on the official surgery waiting lists," he said.

"These are the waiting lists the Minister for Health doesn't want you to know about, they are kept quiet as the government is not required to report on this data."

Greater Metropolitan Health Services executive director Karen Kelly said an increasing and ageing population, with a growing incidence of chronic disease, continued to drive referrals to specialist clinics.

"Our outpatient service is very busy and we acknowledge there are wait times for certain appointments," she said. "We are continually striving to improve outpatient services and reduce wait times."

John Hunter Hospital's 17 outpatient clinics offered 30,845 new appointments last year and 58,201 follow-up appointments.

The busiest clinic was orthopaedics that recorded 9044 new and 18,082 follow-up appointments, or 105 appointments every weekday.

This was followed by neurosuergy with 2496 new and 3965 follow-up appointments, or 24 appointments every weekday.

Ms Kelly said outpatient services had "pooled" the waiting list for orthopaedic hip and knee clinics at John Hunter and Belmont hospitals to streamline appointments.

She said the John Hunter Hospital recently recruited three additional ear nose and throat GPs so patients could be seen sooner.

"If there is a change in a patient's condition, GPs are encouraged to provide this information to the outpatient service to ensure that patients are reprioritised for an appointment," she said.

"We are committed to providing the best possible care to our community and will continue to work on improvements to ensure all patients receive the care they need."

But Newcastle GPs described the outpatient services as "overrun" by rising patient numbers, massive waiting times and doctor shortages.

Worst affected are children, the poor, the elderly, and the chronically ill, for whom outpatient clinics are the only available medical option.

A Newcastle-based GP said he regularly provided condition updates on patients and wait times did not improve.

"We have patients return time and again with increasing problems and despite making urgent referrals, they continue to wait," he said.

"The outpatinet clinics are simply overrun by demand and it's the patients who languish and suffer."

The Fern Bay man who travelled to Tamworth for an orthapaedic appointment said he was told by hospital staff the longest wait they had seen was seven years for surgery.

The man, who asked not to be identified because he was concerned about getting a job, said the system was clearly broken.

After waiting more than a year for a specialist appointment to assess his knee, the 58-year-old contacted Newcastle MP Tim Crackanthorp asking for help.

Mr Crackanthorp wrote to NSW health minister Brad Hazzard detailing the man's predicament, highlighting his worsening financial position.

In June, parliamentary secretary for health Natasha Maclaren-Jones responded to Mr Crackanthorp informing him the case had been sent for review.

"While an appointment at John Hunter Hospital can't be expedited ahead of more urgent cases, Mr Barnett [from John Hunter Outpatient Services] suggested Tamworth Hospital as an alternative option for [the patient's] appointment, as he can be assessed there much sooner," Ms Maclaren-Jones wrote.

"[The patient] has agreed to travel to Tamworth Hospital for his outpatient clinic appointment."

The man travelled to Tamworth on June 6 and said he was "slightly relieved" when the specialist said he needed a knee replacement.

"At least the process was underway and I thought I knew the path ahead, things were finally moving," he said. "I was a bit worried about having to spend 10 days in hospital in Tamworth because I know no-one there, but I figured it was my only option."

A week later the man said he received a call from the specialist's office to inform him the doctor was unable to operate because he was overweight.

"He said my BMI [body mass index] was too high and I needed to lose weight before the surgery could be done," he said. "I told him that I couldn't exercise and had put on weight because of my knee."

The man has since enrolled in a rehabilitation program to strengthen his knee and has lost four kilograms.

"I'm doing what I can and have been doing placements to retrain into other work, but I'm no closer to getting my knee fixed," he said.

"I got a letter this week for another appointment at Tamworth in December, but there is still no date for surgery and we are about to lose our home."

Mr Crackanthorp said the secret wait lists confirmed the Hunter's hospital system was in "crisis".

"It beggars belief that a patient needing to see an orthopaedic surgeon in the second largest city in NSW would have to travel hundreds of kilometres to Tamworth to see a specialist," he said.

"Doctors and nurses are working their guts out for patients, but responsibility for the collapse of the health and hospital system lies squarely at the feet of the Berejiklian government."

John Hunter Hospital's general manager Debbie Bradley said she was sorry the patient felt "our support did not meet his expectations".

Ms Bradley said she was unable to comment on individual cases without patient consent.

"In NSW, patients are scheduled for their elective surgery based on their clinical need, which is determined by their doctor," she said.

"Hunter New England Local Health District always puts patient safety first and will not undertake surgery that places a patient at unnecessary risk."

The NSW Government has committed $780 million for a major redevelopment of John Hunter Hospital to increase services. It is also investing $45 million for an extra 8000 surgeries, including ear nose and throat.