Low bone mineral density (BMD) and fractures are common in people with intellectual disabilities (ID). Reduced mobility in case of motor impairment and the use of anti-epileptic drugs contribute to the development of low BMD. Quantitative ultrasound (QUS) measurement of the heel bone is a non-invasive and radiation-free method for measuring bone status that can be used outside the hospital. QUS might be used for screening purposes to identify people with intellectual disability with poor bone status, who are in need of supplementary examination and treatment.
To investigate feasibility of QUS in this group, QUS of the heel bone was performed on-site in 151 people with ID living in residential care.
Measurements were successfully performed in at least one foot in 94.7%, were interpretable (resulting in a stiffness index) in 91.6%, and induced barely or no stress in 90.4% of the study population. Measurements generally took less than 10 min. In 93 persons bone status of both feet had been measured. The “mean percentage of the absolute difference” between outcomes of both feet was 15.5% (±15.3% SD, range 0–76.5%).
Ultrasound measurement of the heel bone is a feasible and non-stressful method for measuring bone status in people with ID. Since the mean difference between outcomes of the left and right foot were large, measurement of both feet is recommended to prevent inaccurate interpretation.
People with Intellectual Disabilities (ID) are prone to developing osteoporosis or low bone mineral density (BMD). In people with ID low BMD often develops at an earlier age than in the general population (Henderson et al., 2005 and Zacharin, 2004). Increased frequencies of low BMD are present in persons with any degree of ID (Center et al., 1998, Henderson et al., 2002, Jaffe and Timell, 2003, Jaffe et al., 2001 and King et al., 2003). In the Netherlands the prevalence of low BMD is 5.2% in males and 16.6% in women in the general population over 55 years of age (Elders et al., 2005 and Woltman and den Hoed, 2010). In comparison, the prevalence of low BMD was 20% in young adult males with mild to moderate ID (Center et al., 1998) and even 77% in children with ID and moderate to severe cerebral palsy (CP) (Henderson et al., 2002). Important determinants of low BMD in people with ID are limited ambulancy and anticonvulsant drug use (Henderson et al., 2004, Henderson et al., 2002 and Jaffe et al., 2005). Due to the increasing lifespan of people with ID (Coppus et al., 2008, Patja et al., 2000 and Strauss et al., 2007), the prevalence of low bone mineral density may increase even further in the nearby future.
A reduced BMD in combination with an increased risk of falling, e.g. due to motor or visual impairment, causes an increased fracture incidence in people with ID compared to that of the general population (Lohiya et al., 1999 and Stevenson et al., 2006). In high risk groups, such as older women and people with impaired mobility, bone status should therefore be assessed to determine fracture risk.
