The varying distribution of intra- and inter-vertebral height ratios determines the prevalence of vertebral fractures.

Credible inferences regarding the burden of vertebral fractures (VFs) cannot be made without a globally accepted quantitative definition of 'fracture'. Currently, differences in anterior, middle, or posterior vertebral heights (VHs) within a vertebra, or between adjacent vertebrae, are used to define 'fracture'. However, VH differences are essential for the construction of thoracolumbar curves, evolutionary adaptations that provide stability in bipedal stance and gait. As there is no reference standard to distinguish anatomical variation from fracture, approaches to defining a VF use a reference range of VH ratios derived in premenopausal women or derived by trimming, a method that iteratively removes the tails of a distribution of VH ratios to produce a normal distribution. From this, reference ranges of VH ratio means and standard deviations (SDs) are obtained and a nominal deviation of 15% or more, or 3 SD or more is regarded as a 'fracture'. We measured VHs by quantitative vertebral morphometry (QVM) and bone mineral density (BMD) by dual energy X-ray absorptiometry in 697 Lebanese women (age 20-89 years) to compare the prevalence of VF ascertained by published methods and a new method that uses the premenopausal range (without trimming) and requires two VH abnormalities. VF prevalence using published methods reached 60% to 70% in pre- and post-menopausal women, and in women with normal or high BMD because VH ratios were not normally distributed and cut-offs used to define VF fracture fell within the observed distribution of the data. The new method resulted in a VF prevalence of 3.3% in younger and 14% in older women, 7% (high), 10% (middle), and 20% (low) BMD tertiles consistent with the notion that the method detected VF due to bone fragility. We suggest that using a fixed trimming method to define reference range and cut-offs or applying fixed cut-offs to identify VFs in populations, where these ratios are not normally distributed, may result in the capture of anatomical variation, not structural failure. Thus, group differences in the VF prevalence may reflect differences in methodology, not bone fragility. Improved criteria to define VF are needed before credible inferences can be made regarding the burden of VFs in women and men, and between sexes, races, countries, decades, and placebo arms of clinical trials.

Femoral neck fragility in women has its structural and biomechanical basis established by periosteal modeling during growth and endocortical remodeling during aging.

To gain insight into the growth- and age-related origins of bone fragility at the proximal femur, we analyzed structural and biomechanical data of the femoral neck from a study of postmenopausal women with hip fractures and their 47 premenopausal daughters. Results were expressed as standard deviations (SD) or Z-scores (mean +/- SEM) adjusted for age and weight, derived using a normal reference population of 262 premenopausal women and 370 postmenopausal women. Women with hip fractures had increased femoral neck (FN) periosteal and endocortical diameters (1.01 +/- 0.26 SD and 1.18 +/- 0.25 SD, respectively). Cortical thickness was reduced by 0.96 +/- 0.1 SD and volumetric bone mineral density (vBMD) was reduced by 1.2 +/- 0.1 SD). The section modulus was normal while the buckling ratio was increased by 1.59 +/- 0.17 SD). Their daughters had increased FN diameter by about one half that of their mothers (0.48 +/- 0.16 SD), while endocortical diameter was increased by only one third (0.44 +/- 0.13 SD). Cortical thickness and vBMD were not reduced, the section modulus was increased (0.48 +/- 0.13 SD) while the buckling ratio was normal. We infer that the larger femoral neck size in women with hip fractures is growth-related; the wider endocortical cavity and thinner cortex is the result of excessive age-related endocortical bone resorption producing a thin cortex in a larger bone predisposing to structural failure by local buckling. The structural basis of bone fragility has some features originating during growth and others during aging.

Reproducibility of heel ultrasound measurement in prepubescent children: lack of influence of ethnicity, sex, or body size.

OBJECTIVE: There is a growing demand for assessment of bone status in children. Among the techniques currently available, quantitative ultrasound measurement is attractive because of its lower cost, portability, and safety. However, factors influencing its reproducibility in children remain an issue. This study was designed to evaluate the effects of ethnicity, sex, and body size on the short-term reproducibility of heel ultrasound measurement in children. METHODS: We studied 59 prepubescent children, 36 white (23 girls and 13 boys) and 23 black (9 girls and 14 boys), 5 to 12 years of age. On the same day, each child underwent triplicate measurement with an ultrasonometer and was repositioned after each measurement. RESULTS: The precision error of the stiffness index expressed as a percentage of the coefficient of variation was generally good. There was no difference between ethnicity or sex. Respectively, the average values were 3.81% and 3.86% in white girls and boys and 3.64% and 3.51% in black girls and boys. Height, weight, and body mass index were not found to affect this reproducibility. CONCLUSIONS: These data support the reliability and usefulness of ultrasound for assessment of pediatric bone status.

Epidemiology of hip and wrist fractures in Cameroon, Africa.

Osteoporosis and fragility fractures are believed to be uncommon in Africa. To reevaluate this notion, we documented all patients aged 35 years and older admitted to the two main urban hospitals in Cameroon following a diagnosis of fracture during 2 years. Among 513 patients sustaining fractures (192 women, 321 men), 13.5% of all fractures in women occurred at the hip (n=26), 4.7% at the forearm (n=9), and 81.8% (n=157) at other sites (mainly tibia and femoral shaft). In men, the corresponding figures were 9% (n=29), 1.9% (n=6), and 89.1% (n=286). Of the hip and wrist fractures occurring in women, 80.0% were low energy trauma fractures due to falls, 8.6% were high-energy trauma fractures (road accidents), and 11.4% were undefined. In men, the corresponding figures were 42.9%, 34.3%, and 22.9%. Using the 1997 estimates of the population, the annual incidence rates of low-energy trauma fractures (per 100,000 persons over 35 years and above) were 4.1 in women, 2.2 in men for hip fractures, 1.2 in women, and 0.2 in men for wrist fractures. The pattern of most of the hip and wrist fractures in women is consistent with underlying bone fragility. The low incidence of fragility fractures is confirmed and is likely to be, in part, the result of reduced longevity as only 1.1% of women and 0.7% of men survive beyond 65 years of age.