IT WAS DURING a year out in Australia that medical student Brian Thornes started thinking about the direction of his career. Around 25 per cent of all patients attending the casualty ward in which Thornes worked while in Australia had an orthopaedic injury and when he returned to Ireland in 1997 he decided to pursue this specialisation.

Because of the competitive nature of the specialist registrar scheme many medical students take time out of their studies to do research or further training to improve their CVs, something Thornes also decided to do, although in a different branch of medicine to orthopaedics.

"I was six months out doing this research and within that time I started thinking about other things and came up with the tightrope concept."

The concept has been licenced to medical devices firm Arthrex and has allowed Thornes give up a career in medicine and become a full-time entrepreneur. His innovation deals with the side-effect of treatments for ankle fractures. In around 10 per cent of fractures the syndesmosis, or ligaments holding tibia and fibula together, is also damaged

"Classically when you fix this injury you would use a screw, but a screw is too rigid for that task because over time that screw will either break or loosen itself."

Also, this procedure requires two operations as the surgeon has to remove the screw six to eight weeks later, once the joint has healed.

"My thinking was: we are in the 21st century now - can we not treat it with one operation rather than two? So I thought: what were the biomechanical forces required to hold the two bones together but allow movement?"

The solution popped into his head one night as he was struggling for sleep after two strong cups of coffee.

The ankle tightrope works like a cufflink pulled tight around the ankle joint, holding the bone together but allowing a certain level of movement. It is secured using a button on either side of the ankle bones and heavy suture material like a rope or strap pulled tight between the two buttons, a minimally invasive operation.

Having made a prototype from easily-available - and cheap - materials from the hospital, he tested it in the anatomy department of Trinity College Dublin, under professor Moira O'Brien.

He then got approval from the Ethics Committee in the Midwest Regional Hospital in Limerick, where he was working, to run a clinical trial on 16 patients.

When this trial was successful Thornes suddenly became concerned someone might steal the idea as news of it emerged. At the time he had little intention of developing it as a commercial project and was still looking at the product as contributing to his medical CV.

He approached Maura O'Connell, a partner in FR Kelly and Co in Dublin, who provided him with advice on patents. He also published an article about the procedure in a medical journal.

"Once the patent was filed I then started thinking I should probably see if someone will develop it so I pitched it to the main orthopaedic companies." He chose Arthrex, who licenced the technology in 2003 for the 20-year life of the patent.

Despite the commercial success of the ankle tightrope the response from Thornes' medical colleagues was mixed. "I guess I divided the consultant orthopaedic community. Some of the guys just didn't like what I had done and took a dislike to me and some of the guys thought it was brilliant."

Because of the revenues from the tightrope he was able to retire from the medical programme, on an income he described as comparable to that of an orthopaedic surgeon, and enrolled in an MBA at Trinity 2005 before setting up his own company, State of the Art (Sota) in 2007.

Through this firm he has developed new orthopaedic products including the Xbolt for use in hip fractures and the Ojig for elbow fractures.

Thornes developed the Xbolt in much the same way as the ankle tightrope - by improving on an established practice.

The traditional method of repairing a hip facture involves using screws and a plate.

However, in around 5 per cent of cases these screws loosen, requiring the procedure to be repeated. One of the reasons the screws become loose is that osteoporotic bone is relatively soft.

Thornes says there is a huge market in treatments for hip fractures: "It is around 10 times more common than the ankle injury."

"I was chasing the market. I saw the problem and was trying to exploit it."

His solution takes its inspiration from expanding bolts he was using to fasten the TV bracket to the wall and has been patented. It is shortly due to undergo clinical trials.

Thornes has no plans to return to medicine and is developing contacts with inventors with a view to investing in other start-ups.