A letter sent on 31 July to Western Cheshire GPs from PCT director of commissioning and health outcomes Graham Atkinson and chair of the professional executive committee John Hodgson asks GPs to refer directly to the Cheshire and Merseyside ISTC.
At present GPs in the area first have to refer orthopaedic patients to an orthopaedic triage service run by the PCT.
'The decision has been taken due to the scale of the treatment centre contract, which is currently being under-utilised,' the letter says.
'The PCT must pay for this activity whether or not it is used and, in 2007-08, the contract is worth£6.9m.'
GPs will be monitored at practice level on the number of referrals they make to the ISTC and will get a budget allocation for use of the centre as part of their indicative practice-based commissioning budget.
Western Cheshire PCT chief executive Helen Bellairs said the move was not trying to cut patient choice.
'On the contrary, we have merely stressed to GPs the importance of considering the ISTC as an option for patients. It is appropriate that we should utilise all of our contracts to ensure best value for money.'
She said use of the ISTC was shared between eight PCTs but that Western Cheshire had a 'larger than fair share of the contract'.
The centre, run by Interhealth Canada subsidiary Interhealth Care Services, is part of the government's wave one ISTC programme.
The Cheshire and Merseyside ISTC, which opened in June 2006, is worth£120m over five years. It is contracted for 5,000 operations a year.
A second Interhealth ISTC worth£26m provides orthopaedic surgery at Kidderminster Hospital.
Janet Soo-Chung, chief executive of debt-ridden North Yorkshire and York PCT, also sent a letter to GPs last week encouraging them to take 'action to fully maximise' use of a York-based ISTC run by Capio Healthcare UK. This ISTC was also procured under the wave one scheme and Capio is paid regardless of the work the centre does.
The ISTC scheme has faced criticism from the NHS after it emerged private companies running centres are paid millions of pounds for five-year contracts whether or not they carry out work.
Wave one ISTC procurement has been dogged by under-use; in 2005 HSJ revealed Greater Manchester surgical centre had lost the health economy nearly£2m in its first six months (news, page 7, 15 December 2005).