A simple beam of light is enough to decide whether a person has weakened bones due to osteoporosis and to measure their risk of bone fractures. Still under trial, the new test developed at the University of Limerick provides a faster, less expensive way to detect the disease, writes Dick Ahlstrom
Osteoporosis and the bone fractures that result from it are a major problem. About a quarter of Irish women will develop the disease and probably won't know they have it until they enter hospital with a broken hip, explains UL research scholar, Dr Mark Towler.
"In Ireland, bone fractures cost the exchequer around €12 million per annum excluding costs relating to physiotherapy, drugs and social welfare," he says. The comparable figure for the US is $3,000 million (€2,404) a year.
Working in UL's Materials and Surface Science Institute, Dr Towler lead a team in the development of a hand-held device that can measure the stiffness of a person's fingernails as a gauge for osteoporosis status.
His "Bone Quality Test" method and device are now being patented and he is working with UK company, Crescent Diagnostics Ltd to commercialise the research.
The project started about four years ago when Dr Towler was talking to a consultant working at the Regional Hospital in Limerick.
The clinician had remarked that many patients with osteoporosis also had soft or "floppy" fingernails.
The scientist began to investigate whether the two conditions were linked and he began developing ways to measure just how "floppy" a person's fingernails were. His first idea was based on "nanoindentation", using a probe that could determine stiffness based on how easily a nail clipping was penetrated by a probe.
"What we found with patients with osteoporosis was they had less stiff nails," says Dr Towler.
He began to refine his measuring device, changing to a much different technology based on "Raman spectroscopy".
It involves using a laser light beamed onto a surface and then the capture and analysis of the light bouncing back. Raman is widely used to analyse surfaces, from oil paintings in the Louvre to detecting hazardous chemicals, Towler explains.
"It has never been used in an application like this before," he added.
The technique is particularly useful for studying subsurface chemistry, ideal for this application given that he was trying to measure the strength of chemical bonds within the nail itself.
"Human bone is made of a protein called collagen, that provides flexibility, and a mineral called hydroxyapatite, that provides hardness. Osteoporosis causes depletion of both the collagen and the hydroxyapatite resulting in an increased likelihood of fracture," he explains.
Raman spectroscopy is used to detect the amount of disulphide bonding in the keratin in healthy fingernail. Healthy nails have plenty of sulphur-based bonding and both nail keratin and bone collagen require sulphation and disulphide bond formation for structural integrity, Towler says.
"The keratin in your fingernails is not dissimilar to the collagen in bone. You need disulphide to bond properly." If collagen was being lost due to osteoporosis, then keratin was probably being lost too, making the analysis of the nail a possible indicator for the disease.
Initial trials on 10 healthy and 10 osteoporosis patients delivered quite promising results and Towler then set up a larger trial with 200 subjects.
In this case he compared his laser-based system with the gold standard of bone density measurement in osteoporosis, the Dexa (dual X-ray absorpiometry) scan.
Again the results were very good and he also found that his new technique, which involved no more than bouncing a laser beam off a person's nail or clipping, was also quite good at predicting a person's likelihood of fracturing a bone.
Working with Crescent Diagnostics he has produced a simple to use hand-held version.
He is working with pharmaceutical companies to exploit the new test as a way to monitor drug and treatment protocols for osteoporosis patients.
He would also like to get his device into hospitals for use by clinicians carrying out initial assessments of patients.