The team at Queen’s University has been developing the cements for a number of years and is now looking at ways of commercialising the technology with the help of medical device companies.
‘We’re pretty much happy we’ve got a range of cements to work with — now, it’s optimising that delivery phase that’s important,’ said Prof Fraser Buchanan of Queen’s, adding: ‘The next phase of the research is focusing on how you deliver the cement in a controlled way into the spine, so it goes into the places you want it and doesn’t go where you don’t want it.’
So-called ‘burst fractures’ of the vertebrae occur when the spine is subjected to considerable compression stresses, such as those incurred in a car crash or falling from a ladder.
Conventional rehabilitation relies on joining the damaged bone fragments together and stabilising the spine with the use of metal screws, rods and cages — all requiring major surgery that carries great risks.
Polymer fillers have shown some promise for hip and knee fractures; however, Buchanan said these are not suitable for the spine because they heat upon setting, which could damage delicate nervous tissue near the spine.
In 2007 the Queen’s team received a £500,000 EPSRC grant to develop alternatives with the help of computer modelling experts from Leeds University.
They came up with a range of calcium phosphate cements with similar properties to that of bone that could be injected into fractures then re-absorbed as the bone healed. The cements were subjected to numerous materials tests, including on pig bones that had been subjected to compression and fracture then injected with the cement and retested.
‘We measure the mechanical properties of the cements to get a good idea of the physical situation in the spine and what the likely loads and stresses would be. Plus we look at biological evaluation, taking bone cells and putting them on the surfaces and seeing how the cells respond to the cement,’ Buchanan said.
He cautions that clinical trials are still some way off and it will be important to demonstrate that any new technique is more effective than what exists already.
‘The surgical technique is critical to the whole thing — much more so than small changes in mechanical properties. The need for surgeons to be trained in handling a new system would be significant, as they’re used to handling an MMA [methyl methacrylate] cement that is very different.’