Frequently Asked Questions
Our portable ultrasound system is effective at identifying “At Risk” people even as early as twenty years old. We recommend people have a first scan at age 30 to identify any problem. Normally a further scan at age forty is recommended, with another follow-up five years later and thereafter two-yearly. That way you can monitor your progress and offset any changes before they develop into osteoporosis. People are living longer these days, which makes bone health more important than ever.
There is no qualifying criteria for a scan and a doctor's referral is not required.
There is now a greater public awareness of osteoporosis developing among men and women. Many people have a family member with osteoporosis and have seen the devastating effects of it on them. They want to identify any risk of it developing in them early. Others have identified one or more risk factors and feel uneasy about their level of calcium intake. Medications can also have an effect on bone.
How is the measurement taken?
To take the measurement, you will need to take off your shoe and sock and sit down. The technician will apply a gel to both sides of your heel, and then position your foot in the machine. If your foot is small, a positioning insert that raises your foot will be put in the bottom of the machine. The technician will put straps around your leg to hold your heel in position. The transducers that send and receive the sound wave will then be put into contact with your heel. The measurement takes only a few minutes and you will be given a report about your bone quality, showing your risk of fracture. There is no sensation or noise associated with the measurement procedure.
How do I get my results?
A print-out and written report is generated and given directly to the patient. The print-out indicates: a T score, which is the standard deviation away from peak bone-mineral density; and a Z score, which is the standard deviation above or below the mean for age-matched controls. These T scores are comparable to spine or hip bone mineral density.
What should I do with the report?
If your results indicate average bone density, just hold on to your results for your own records, as a comparison for future scans. If your results indicate below average bone density, you may want to take your report to your next doctor’s appointment to discuss the results and to see if follow-up is necessary. If the results are in the high fracture risk range, this indicates signs of bone thinning or osteoporosis. You will be given a copy of the print-out and a letter to take to your doctor. Your doctor may recommend a lumbar and hip DEXA scan to obtain more detailed information.
Why do we measure the heel?
Ideally, the best bone site to measure is the hip where the fracture might occur. However, this is not possible using ultrasound because the fat and muscle that covers the hip bone affects the ultrasound signal. Because most of the bone in the hip, called trabecular bone, is like the heel bone (the heel bone is 95% trabecular bone), the heel was investigated as a possible measurement site. The heel is also easy to get to.
What is bone sonometry?
In the 1970s and 1980s, Bone Mineral Density (BMD) tests were developed. Dual Energy X-ray Absorptiometry (DEXA) uses radiation to determine your bone density. The spine and hip are most commonly measured but heel, wrist, or the total body may also be measured. The procedure takes up to 20 minutes, (if the spine or hip is measured) or less (if the heel or wrist is measured).
In 1992, a new bone testing method using ultrasound (sound waves) instead of x-rays was introduced. This method is referred to as bone sonometry or quantitative ultrasound.
Bone sonometry has advantages over the traditional x-ray methods for the assessment of bone. While both QUS and x-ray systems are safe and quick, QUS does not use radiation and is typically lower in cost. While x-ray methods measure the density of bone, sonometry provides information relating to the strength of bone (structure, elasticity) which is important for determining fracture risk.
How does the heel ultrasound work?
To take a measurement, the CUBA Clinical sends an ultrasonic sound wave through the heel bone. As the sound wave travels from one side to the other, the wave is changed by the internal structure and content of the bone. For example: the more complex the structure of the bone, the more the sound wave will be absorbed. Therefore, normal bone has a higher measurement than bone with osteoporosis. Likewise, the greater the connectivity in the honeycomb-like structure of the bone, the faster the sound wave will pass through it. As bone becomes osteoporotic, this honeycomb weakens and begins to fail, and the speed of the sound wave slows down. These changes in the absorption and speed of the sound wave are changed into measurements of the strength of the bone, which can be compared to reference (normal) values for your race, age, and sex.
Relationship between CUBA Clinical results and Risk of Fracture
Prospective clinical studies have demonstrated that subjects with low BMD are at higher risk of fracture. The risk of fracture increases exponentially with decreasing MBD. For example, for Hip fracture, it has been demonstrated that with a 1 SD decrease in hip BMD there is a 2-3 fold increase in the risk of hip fracture. (A 2 fold increase is often reported at a relative risk of 2).
For example, a patient with a Z score of –1SD will have twice the risk of developing a hip fracture compared to a patient with a Z score of 0.0SD. Furthermore a patient with a Z score of –3SD will be 8 times more likely to have a hip fracture.
It has also been demonstrated that a similar relationship exists between heel ultrasound and hip fracture with approximately a two fold increase in the risk of a fracture per 1 standard deviation (SD) decrease BUA.
A recent prospective study using the CUBAClinicalTM confirmed previous findings. A decrease of one SD in BUA was associated with more than a two-fold increase (2.3RR) in hip fracture and a 60% (RR1.6) increase in the risk of an fracture.
In summary, prospective studies have demonstrated the strong exponential relationship between heel ultrasound and x-ray results, and the ability of the CUBAClinicalTM to predict the risk of future fracture.
What the CUBAClinicalTM measures
The CUBAClinicalTM measures BUA (Broadband Ultrasound Attenuation).
BUA = The attenuation of the ultrasound signal as it passes through the heel
Normal bone has a higher attenuation (BUA) than osteoporotic bone. The stronger the bone the better the BUA results. The more complex the bone structure the more the sound wave is blocked.
How accurate is the CUBAClinical?
According to the F.D.A. "The McCue CUBAClinical is safe and effective as a clinical indicator of skeletal status with performance comparable to that of bone mineral density measurements [ie. DEXA and SEXA scans]. Skeletal status and relative risk of fracture can be evaluated without the need for exposure to the ionizing radiation produced by the BMD devices [ie. DEXA and SEXA]."
Broadband Ultrasound Attenuation (BUA), in vitro precision 0.44%
Broadband Ultrasound Attenuation (BUA), in vivo precision 3%
References / Prospective Study Data
Precision and Discriminatory Ability of Calcaneal Bone Assessment Technologies.
Journal of Bone and Mineral Research Vol 12, No 8, 1997.
Susan L. Greenspan et al, Beth Israel Hospital, Boston, Mass.
Ultrasound Measurements for the prediction of osteoporotic fractures in elderly people.
S. Pluijm, W. Graafmans, L. Bouter, P. Lips, EMGO Institute, Vrjie University, Amsterdam.
Maximising the cost effectiveness of BMD referral for DXA using ultrasound as a selective population pre-screen.
C.M. Langton et al, Centre for Metabolic Bone Disease, Hull, UK.