Melton, Joseph L.

Abstract Between 1935 and 1974, 3598 episodes of head trauma among Olmsted County, Minnesota, residents resulted in 1097 skull fractures. Of these, 53% were simple, 16% were depressed, 12% were compound, and 19% were basilar. The age- and sex-adjusted incidence of skull fractures was 44.3 per 100,000 person-years overall, was somewhat greater in the urban than in the rural areas of Olmsted County, and was relatively stable for the final 30 years of the study. Age-specific incidence rates were highest for the very young, and simple linear fractures were the predominant type of skull fracture in this age group and among the elderly. The male:female ratio of incidence rates varied from 2.1:1 to 4.5:1 depending on fracture type. Motor vehicle accidents accounted for 38% of the skull fractures and were a particularly important cause among young males. Falls accounted for 37% of the skull fractures and were the major cause of fractures in the elderly and pediatric age groups. The results of this population-based study may be helpful in formulating recommendations for the evaluation and management of head-injured patients.

Abstract Bone mass and its mineral content are under genetic control. The vitamin D receptor (VDR) gene has been shown to be a major locus for genetic effects on bone mineral density (BMD), and polymorphisms in this gene accounted for a large proportion of genetic variance in BMD in an Australian population. In this study, we investigated whether similar associations are present in a North American population. We studied 139 normal healthy women (age 53.2 ± 14.5, mean ± SD) and 43 severely osteoporotic postmenopausal women (age 65.8 ± 5.9). In the 127 of them with complete genetic studies, the distribution of genotypes, determined by polymerase chain reaction on leukocyte DNA samples, agreed closely with that in the Australian population. BMD was strongly related to age and weight, and, thus was adjusted for these parameters prior to genetic analysis. We found that age modulated the effect of VDR genotypes on femoral neck BMD (FN-BMD) (TaqI, p = 0.036;BsmI, p = 0.118; ApaI, p = 0.041) such that the effect of genotype was greatest among younger (premenopausal) women and declined with age so that there was no discernible difference by age 70. Among the younger women, a high FN-BMD was associated with the TT (or aa or bb) genotype while low FN-BMD was associated with the tt (or AA or BB) genotype. In osteoporotic women, although the difference in FN-BMD between alternate TaqI homozygotes (TT vs. tt) was 0.13 g/cm2 (or about 18%), the overall difference among the genotype groups was not significant (TaqI, p = 0.13; BsmI, p = 0.21; ApaI, p = 0.09), possibly due to the small sample of osteoporotic women. There was no relationship of VDR genotype to lumbar spine BMD. We conclude that the VDR gene modulates differences in BMD in premenopausal women. Subsequent interaction of the gene and environmental factors and the role of VDR genotypes in predisposing to osteoporosis needs further study.

Abstract Vertebral fractures are the classic hallmark of osteoporosis, yet little is known of their epidemiology. The incidence of clinically diagnosed vertebral fractures was therefore directly assessed in the predominantly white (European descent) population of Rochester, Minnesota. Altogether, 341 Rochester residents were radiologically diagnosed for the first time with one or more vertebral fractures in the 5 year study period, 1985–1989. The overall age- and sex-adjusted incidence rate was 117 per 100,000 person-years (95% CI, 105 to 130). The age-adjusted rate in women (145 per 100,000 person-years) was almost twice that in men (73 per 100,000 person-years). Of all fractures, 47 (14%) followed severe trauma, 282 (83%) followed moderate or no trauma, and 12 (3%) were pathologic. Incidence rates for fractures following moderate trauma were higher in women than in men and rose steeply with age in both genders. In contrast, fractures following severe trauma were more frequent in men, and their incidence increased less with age. These Rochester rates are greater than those previously reported from studies in Britain and Sweden but lower than the incidence rates extrapolated from a prevalence study in this population.