The number of surgery requests accepted by ACC in the past two years has dropped from 42,500 to 35,000, while some speciality areas have dropped by more than fifty per cent - leaving patients "in limbo", orthopaedic surgeons say.

Last year ACC denied about 30 per cent of requests for shoulder and spine surgery, and nearly 20 per cent of knee-surgery requests, The Press reported.

New Zealand Orthopaedic Association president Gary Hooper said patients denied ACC cover were being "left in limbo" because they did not meet government thresholds to receive treatment in public hospitals.

"Because of these problems with ACC, we have now created a different group of patients within New Zealand who can't get their surgery at all."

Christchurch Hospital orthopaedic surgery department clinical director John McKie said the type of patients being denied ACC were unlikely to be accepted on the six-month public waiting list for surgery - creating a public health system like "chalk and cheese".

"If you are on one side of the line and covered and accepted by ACC, you have access to a very good system of care, but if you are on the other side of that line, the service provided by the public hospital system is somewhat inferior."

ACC general manager of claims management Denise Cosgrove said the corporation was reviewing its process for surgery applications.

"We have to pick off where are the biggest areas of risk and liability," she said. "We are not saying people don't need surgery, it's just that it's not ACC's responsibility."

The Ministry of Health expected elective surgery to be provided within six months to patients with the "greatest need and ability to benefit", a Ministry of Health spokeswoman said.