Clinical Associate Professor Mark Haber performed the computer-navigated total shoulder replacements on the four patients – aged 63 to 75 – at Wollongong Private Hospital on Wednesday.

He used the pioneering technology in Australia for the first time with two patients at Hurstville Private Hospital on Tuesday, and said only around 30 such procedures had been undertaken worldwide.

Prof Haber said it was exciting that computer-assisted technology was finally available for shoulder surgery, following the success of similar technological advancements for hip and knee replacements.

It enabled surgeons to insert a titanium implant into a patient’s shoulder joint with pinpoint accuracy – reducing time in the operating theatre, speeding up recovery and extending the life of the replacement.

‘’Prior to this technology we relied mainly on X-rays or CT scans and that had the ability to measure the deformity, often caused by arthritis, with incredible accuracy,’’ he said.

‘’But when we came to surgery we then had to eyeball and use our clinical judgement to correct the deformity, with an accuracy of maybe 15 degrees at best. With computer-assisted technology, we can increase our accuracy to within one millimetre and one degree.’’

Prof Haber used the analogy of a car wheel alignment to explain the importance of such precision.

‘’If the alignment is not quite right the car won’t handle quite right and will ultimately wear out prematurely,’’ he said. ‘’In the same way, if you’re able to get the alignment precisely right in surgery, the joint will handle more like a real shoulder and it will last longer.’’

Prof Haber said while most traditional shoulder replacements would need to be replaced within 10 to 15 years, this new technology would improve outcomes by up to 50 per cent.

‘’With traditional techniques a 60-year-old may need to revisit the procedure at 75,’’ he said, ‘’but it would be ideal if this technology meant a patient of that age never needed any further surgery – that it lasted for the rest of their life.’’

Prof Haber said the US computer engineers who had developed the technology were overseeing this week’s operations, to provide technical support.

‘’This technology eliminates a lot of intraoperative planning – you don’t have to plan as much during surgery as you’ve done a lot of planning prior,’’ he said.

‘’During surgery, all instruments feed back to your laptop computer which is fitted with infrared detectors which tell me exactly the angles and degrees required.’’

With shoulder replacement surgery on the rise in Australia, Prof Haber said the new technology would allow patients to get back to their normal activities – and back to work.

‘’The shoulder joint is the most problematic in the human body, and suffers more wear and tear than other joints – not just from arthritis but also because the tendons wear out,’’ Prof Haber said.

‘’The two peak groups of patients I see are younger men, often tradies, whose tendons are wearing out; and older women with arthritis.’’