Patients having hip replacements at independent sector treatment centres are up to 20 times more likely to need repair work.

Many operations are having to be redone in NHS hospitals, at great cost and with serious staffing implications for the health service.

A study by orthopaedic surgeons in Cardiff found that of 113 hip operations on patients sent from their NHS trust to Weston-super-Mare NHS Treatment Centre between 2004 and 2006, two thirds showed clear evidence of poor surgical technique, such as poor cementing of the hip.

In the three years since the operation, 18% had undergone revision or were awaiting an operation - 20 times the 0.9% NHS-wide revision rate at three years. A study on knee operations at the unit, conducted earlier this year, recorded a tenfold increase in revision rates.

Since the ISTC programme was introduced in 2003, dozens of centres have been set up, mainly conducting orthopaedic surgery, cataracts and diagnostic screening. A total of 44 are described as NHS centres - though they are often staffed by independent sector contracts - and 23 are provided by private companies.

Leading surgeons said that this new data underlined the need for a significant overhaul of the multimillion-pound programme, which was introduced with great fanfare by the government to reduce waiting times and increase patient choice.

They said a total lack of supervision of the sector and its clinical outcomes was a dereliction of duty by the government, which had put a premium on reducing numbers rather than patient care. Early concerns about poorly vetted overseas doctors carrying out the work had not been addressed, they said.

The Cardiff study, published in the Journal of Bone and Joint Surgery, offers the most compelling evidence to date of problems with care in the sector, and the lack of proper auditing. Surgeons said that the data backed anecdotal reports from elsewhere in the country, although it was likely to be at the high end.

They said that NHS trusts were being left to manage the extra workload created.

Read more at The Times.