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Changes in bony dimensions with age were assessed longitudinally from standardized X-ray films in 170 middle-aged Caucasian women, starting at age 40 years and with a median duration of observation of 21.125 years. Consistent with earlier work, cortical area of the metacarpals and radial shaft declined with age at rates ranging from 0.57 to 0.86%/year. As predicted, estrogen replacement therapy decreased this loss in a dose-dependent manner. Not previously reported is the fact that weight gain over the period of observation reduced upper extremity bone loss. Moreover, this protection was independent of the estrogen effect. In contrast with bone loss in the upper extremity, both femur shaft diameter and femur shaft cortical area increased significantly with age (0.23 and 0.26%/year, respectively). Estrogen replacement therapy inhibited femur shaft expansion but had no effect on femur cortical area. Weight change, however, strongly influenced gain (or loss) of femur cortical area: those in the highest weight change tertile gained 4 times as much cortical area as those in the lowest weight change tertile. VDR genotype also significantly influenced femoral shaft changes: women with the bb genotype had both greater shaft expansion and a greater increase in cortical area. The VDR effects were independent of the effects of weight change and estrogen. Femoral shaft expansion was of sufficient magnitude to suggest that the mechanical properties of the entire femur may change appreciably with age. Finally, contrary to widespread belief, there was significant, if modest, expansion at the femoral neck with age.

Vertebral fracture prevalence and severity were analyzed by sex and age in an age-stratified proportionate sample of the enumerated population of women and men 50 years of age and older in Saunders County, Nebraska. The sample consisted of 899 women and 529 men. Of these, all but 10 women and 2 men had readable lateral spine radiographs. For both sexes, fracture prevalence rises with age. Women in their fifties have 10% vertebral fracture prevalence, and women in their eighties, 45% prevalence. Men in their fifties have 29% prevalence, and men in their eighties, 39% prevalence. The rise in prevalence and total spinal deformity with age is much greater for women than for men, but the prevalence of vertebral deformity in the fifties is much greater in men than in women.

Ultrasonic measures of bone have been available for clinical research purposes for nearly 10 years, yet there still seems to be a need to compare ultrasound with the accepted gold standard of densitometry. Recently there have been published reports showing that ultrasound measures are associated with both appendicular and hip fracture, in particular after adjustment for densitometry measures. We present here a comparison between speed of sound through the patella and forearm bone densitometry, using their association with prevalent vertebral fractures in a population-based study of women and men. The prospective phase of the Saunders Bone Quality Study includes 1401 women and men who had baseline spine radiographs, patellar ultrasound, and forearm densitometry measurements. Multivariate forward logistic regression was used to determine the age-adjusted odds of vertebral fracture, the number of fractures, and the severity of these fractures, when patellar ultrasound and each of four forearm densitometry measures were entered into the model. Age is the most important factor associated with vertebral fractures, their number, and severity for women, while age is not significantly related to vertebral fractures for men. Of the bone status measures, patellar ultrasound entered the logistic regression models more consistently than any other measure except ulnar bone mineral density for women. The ultrasound measure entered every model for men. We conclude that patellar ultrasound velocity is more consistently associated with the odds of vertebral fractures than radius bone mineral content.

In order to study vertebral fractures in various study populations, we earlier prepared a database of vertebral dimensions derived from spinal radiographs of 191 normal women seen regularly over 25 years. In this report we have expanded the range of measurements to include vertebral levels T3 to L5. We report means and standard deviations on anterior and posterior heights, on wedge shape and on heights relative to adjacent vertebrae. When one or both of the latter two quantities are 'far' below the mean, a vertebra is called deformed. We also describe a more flexible way of expressing damage using the number of deformed vertebrae, the degree of deformity of individual vertebrae, or the total damage to the entire spine. In assessing damage we use criteria for deformity adjusted to the limits detected by an experienced diagnostician, replacing an earlier approach based on 95% probability limits of normal variation. The normal women from whom these variations are ascertained are a low-prevalence group with respect to vertebral deformity, with prevalence of 2.8%. When the criteria developed from these women were applied to a moderate-prevalence group (37%) the model had a sensitivity of 97%, a specificity of 89% and an accuracy of 92% as regards the identification of subjects with damaged vertebrae. When used epidemiologically for a moderate-prevalence group the model has a known overestimation of 15%. the model is compared with other schemes for identifying vertebral deformities.

Both retrospectively and prospectively designed studies consistently show low bone mass and/or bone mineral content (BMC) to be risk factor for low-trauma fractures in postmenopausal women. Along with the reports of such studies there has been concern expressed that BMC measurements overlap between fracture groups, i.e., some women with high BMC develop fractures and some women with low BMC do not. In these commonly used epidemiologic study designs, BMC does not discriminate between those who have and have not experienced the untoward event at some level of the exposure factor. The ability to discriminate is more properly determined by the sensitivity and specificity of the measured value. To contrast the concepts of risk and sensitivity, a nested case-control study was conducted within a 24-year cohort study of women at risk for osteoporosis. We found that for each 1.0 decrement of BMC z-scores, the adjusted relative risk for the prospective study design was 1.67, while the odds ratio obtained from the most recent BMC z-score measurements was 1.87. A receiver operating characteristic (ROC) curve, calculated from the nested case-control study data, showed that BMC z-scores, measured after low-trauma fracture, have both low sensitivity and low specificity to detect existing fracture status.