Citations

Abstract Measures of musculoskeletal rehabilitation play an integral part in the management of patients with increased fracture risk because of osteoporosis or extraskeletal risk factors. This article delineates current scientific evidence concerning nonpharmacologic approaches that are used in conjunction with pharmacotherapy for prevention and management of osteoporosis. Fractures caused by osteoporotic fragility may be prevented with multidisciplinary intervention programs, including education, environmental modifications, aids, and implementation of individually tailored exercise programs, which are proved to reduce falls and fall-related injuries. In addition, strengthening of the paraspinal muscles may not only maintain BMD but also reduce the risk of vertebral fractures. Given the strong interaction between osteoporosis and falls, selection of patients for prevention of fracture should be based on bone-related factors and on risk factors for falls. Rehabilitation after vertebral fracture includes proprioceptive dynamic posture training, which decreases kyphotic posturing through recruitment of back extensors and thus reduces pain, improves mobility, and leads to a better quality of life. A newly developed orthosis increases back extensor strength and decreases body sway as a risk factor for falls and fall-related fractures. Hip fractures may be prevented by hip protectors, and exercise programs can improve strength and mobility in patients with hip fracture. So far, there is no conclusive evidence that coordinated multidisciplinary inpatient rehabilitation is more effective than conventional hospital care with no rehabilitation professionals involved for older patients with hip fracture. Further studies are needed to evaluate the effect of combined bone- and fall-directed strategies in patients with osteoporosis and an increased propensity to falls.

Abstract The role of the IGFs and IGFBPs on age-related changes in BMD in adult men and women is not well understood. Studying an age-stratified community based sample of 344 men and 276 women, we found higher IGFBP-2 levels to be associated with lower BMD. IGFBP-2, which increases with age in both men and women, was the strongest, most consistent predictor of BMD among the IGF/IGFBPs studied. Introduction: Insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) are important regulators of tissue growth and metabolism, but their association with BMD in adult men and women is controversial. Materials and Methods: In an age-stratified, random sample of the community population, we examined the role of serum levels of IGF-I, IGF-II, and IGFBP-1, −2, and −3 on BMD of the proximal femur (total hip), lateral spine, midshaft, and ultradistal radius as measured by DXA. We explored the association before and after adjustment for potential confounders, including age, bioavailable estradiol and testosterone, sex hormone binding globulin (SHBG), and measures of total fat and skeletal muscle mass. Results: We studied 344 men (age, 23-90 years) and 276 women (age, 21-93 years; 166 postmenopausal) not on hormone replacement or oral contraceptives. In both men and women, IGF-I and IGFBP-3 levels fell with advancing age, whereas IGFBP-2 levels tended to rise with age. There was an inverse association of IGFBP-2 with BMD at most skeletal sites in men and both premenopausal and postmenopausal women, whereas lower IGF-I and IGFBP-3 were associated with lower BMD in men and postmenopausal women only. Lower IGF-II was associated with lower BMD in men only. There were no associations between IGFBP-1 and BMD in either sex. After adjustment for age, in most cases, we found no further associations between IGF-I, IGF-II, or IGFBP-3 and BMD. In contrast, after age adjustment, higher IGFBP-2 remained a predictor of lower BMD in men and postmenopausal women at all sites except for the lateral spine (for men: r = −0.21, −0.20, and −0.19, all p < 0.001; and for postmenopausal women: r = −0.34, −0.24, and −0.25, all p < 0.01, for the total hip, midshaft, and ultradistal radius, respectively). IGFBP-2 remained an independent negative predictor of BMD in men, postmenopausal women, and all women combined after additional adjustment for bioavailable sex steroids, but not at all sites after adjustment for SHBG and muscle mass. In premenopausal women, IGFBP-2 had similar associations as seen in postmenopausal women, but they were weaker and not statistically robust. Conclusions: Among the IGF/IGFBPs in our study, IGFBP-2 was a key negative predictor of BMD among men and women, particularly postmenopausal women. Our findings suggest a potential role of the IGF/IGFBP system in regulating bone loss in aging men and women and identify a previously under-recognized, potentially deleterious role for IGFBP-2, a known inhibitor of IGF action that increases with age in both sexes. Whether the action of the IGF/IGFBP system on bone metabolism is mediated partly through its effects on muscle mass or SHBG deserves further study.

Abstract While androgens clearly have significant skeletal effects, the paracrine mediators of androgen action on bone are at present unclear. Interleukin-6 (IL-6) is a candidate cytokine that is produced by osteoblastic lineage cells and promotes osteoclastogenesis and bone resorption. Here, we assessed constitutive as well as IL-1β– and tumor necrosis factor-α (TNF-α)–stimulated IL-6 mRNA expression by Northern analysis and protein secretion by immunoassay in a human androgen-responsive osteoblastic cell line (hFOB/AR-6) which contains ∼4000 androgen receptors (ARs)/nucleus. Treatment with 5α-dihydrotestosterone (DHT) dose-dependently inhibited constitutive and TNF-α/IL-1β–stimulated IL-6 mRNA steady-state levels in hFOB/AR-6 cells by 70–80% at 10−7 M. In addition, testosterone also suppressed TNF-α/IL-1β–stimulated IL-6 mRNA levels by 57%, while the adrenal androgen dehydroepiandrosterone had no effect. Of note, the specific AR antagonist, hydroxyflutamide, also inhibited IL-6 mRNA levels by 70%. Consistent with the Northern analyses, treatment with 5α-DHT, testosterone, and hydroxyflutamide also inhibited IL-6 protein production by 79%, 62%, and 71%, respectively (p < 0.001), while these agents had no effect on IL-6 soluble receptor levels. Finally, we demonstrated that hydroxyflutamide treatment of hFOB/AR-6 cells markedly inhibited the activation and binding of NF-κB (a known stimulator of IL-6 gene transcription) to its response element, thus providing a potential mechanism for its effect on IL-6 production by osteoblasts. These data are consistent with the hypothesis that suppression of osteoblast IL-6 production by androgens may mediate, at least in part, the antiresorptive effects of androgens on bone. Moreover, our findings also indicate that hydroxyflutamide, which is a known AR antagonist in most tissues, may function as a selective AR modulator for effects on IL-6 production by osteoblasts.

Abstract We evaluated different definitions of osteoporosis in a population-based sample of 348 men (age 22–90 years) compared with 351 women (age 21–93 years). Thirty-six men (10%) and 46 women (13%) had a history of osteoporotic fracture (hip, spine, or distal forearm due to moderate trauma at ≥ age 35). In logistic regression analysis, osteoporotic fracture risk was associated with bone mineral density (BMD) at all sites (neck, trochanter, total hip, lumbar spine, and total wrist) in both genders (p < 0.001) except spinal BMD in men. After adjusting for age, total hip BMD was the strongest predictor of fracture risk in women (odds ratio [OR] per 1 SD decline, 2.4; 95% confidence interval [CI], 1.6–3.7), while wrist BMD was best in men (OR, 1.5; 95% CI, 1.1–2.0). Among men but not women, bone mineral apparent density (BMAD) was a better predictor of fracture than BMD (wrist BMAD OR, 1.7; 95% CI, 1.3–2.3). Hip BMD/BMAD decreased linearly from age 20 years onward in both genders, while spinal BMD/BMAD declined after age 40 in women but not in men. In both genders, total wrist BMD/BMAD decreased after age 50. By World Health Organization criteria, the age-adjusted prevalence of osteoporosis at the hip, spine, or wrist was 35% among women ≥50 years of age. A similar approach (BMD > 2.5 SD below the young male mean) produced an osteoporosis prevalence rate in men ≥50 years of age of 19%. Thus, bone density predicts fracture risk in men as it does in women, and the prevalence of osteoporosis in men, using sex-specific normal values, is substantial. These observations indicate a need for better prevention and treatment strategies for men.

Abstract While severe primary hyperparathyroidism (HPT) is clearly associated with osteitis fibrosa cystica, it remains uncertain whether mild, asymptomatic primary HPT adversely affects the skeleton. Thus, we assessed the incidence of age-related fractures in a large, population-based inception cohort of 407 cases of primary HPT (93 men and 314 women) recognized during the 28-year period, 1965–1992. Fracture risk was assessed by comparing new fractures at each site to the number expected from gender- and age-specific fracture incidence rates for the general population (standardized incidence ratios, SIRs). These community patients with primary HPT mostly had mild disease (mean ± SD serum calcium, 10.9 ± 0.6 mg/dl). Altogether, 471 fractures occurred during 5766 person-years of follow-up. Overall fracture risk was significantly increased in these patients (SIR 1.3, 95% confidence interval [CI] 1.1–1.5). Primary HPT was associated with an increased risk of vertebral (SIR 3.2, 95% CI 2.5–4.0), distal forearm (SIR 2.2, 95% CI 1.6–2.9), rib (SIR 2.7, 95% CI 2.1–3.5), and pelvic fractures (SIR 2.1, 95% CI 1.1–3.5). The risk of proximal femur fractures was only marginally increased (SIR 1.4, 95% CI 1.0–2.0). By univariate analysis, increasing age and female gender were significant predictors of fracture risk, although higher serum calcium levels were also associated with increased fracture risk, and parathyroid surgery may have had a protective effect. By multivariate analysis, however, only age (relative hazard [RH] per 10-year increase, 1.6, 95% CI 1.4–1.9) and female gender (RH 2.3, 95% CI 1.2–4.1) remained significant independent predictors of fracture risk. Thus, primary HPT among unselected patients in the community is associated with a significant increase in the risk of vertebral, Colles', rib, and pelvic fractures. These data have important implications for the current trend to recommend nonsurgical management for patients with mild primary HPT.

Abstract Most estimates of osteoporosis in older U.S. adults have been based on its occurrence in white women, even though it is known to affect men and minority women. In the present study, we used dual-energy X-ray absorptiometry measurements of femoral bone mineral density (BMD) from the third National Health and Nutrition Examination Survey (NHANES III, 1988–1994) to estimate the overall scope of the disease in the older U.S. population. Specifically, we estimate prevalences of low femoral BMD in women 50 years and older and explore different approaches for defining low BMD in older men in that age range. Low BMD levels were defined in accordance with an approach proposed by an expert panel of the World Health Organization and used BMD data from 382 non-Hispanic white (NHW) men or 409 NHW women ages 20–29 years from the NHANES III dataset. For women, estimates indicate 13–18%, or 4–6 million, have osteoporosis (i.e., BMD >2.5 standard deviations [SD] below the mean of young NHW women) and 37–50%, or 13–17 million, have osteopenia (BMD between 1 and 2.5 SD below the mean of young NHW women). For men, these numbers depend on the gender of the reference group used to define cutoff values. When based on male cutoffs, 3–6% (1–2 million) of men have osteoporosis and 28–47% (8–13 million) have osteopenia; when based on female cutoffs, 1–4% (280,000–1 million) have osteoporosis and 15–33% (4–9 million) have osteopenia. Most of the older U.S. adults with low femur BMD are women, but, regardless of which cutoffs are used, the number of men is substantial.

Abstract In a population-based cross-sectional study, we examined effects of sex and age on bone microstructure at the wrist using high-resolution 3-D pQCT. Compared with women, men had thicker trabeculae in young adulthood and had less microstructural damage with aging. These findings may contribute to the virtual immunity of men to age-related increases in wrist fractures. Introduction: Although changes in bone microstructure contribute to fracture risk independently of BMD, it has not heretofore been possible to assess this noninvasively in population-based studies. Materials and Methods: We used high-resolution 3-D pQCT imaging (voxel size, 89 μm) to define, in a random sample of women (n = 324) and men (n = 278) 21–97 years of age, sex and age effects on bone microstructure at the wrist. Results: Relative to young women (age, 20–29 years), young men had greater trabecular bone volume/tissue volume (BV/TV; by 26%, p = 0.001) and trabecular thickness (TbTh; by 28%, p < 0.001) but similar values for trabecular number (TbN) and trabecular separation (TbSp). Between ages 20 and 90 years, cross-sectional decreases in BV/TV were similar in women (−27%) and in men (−26%), but whereas women had significant decreases in TbN (−13%) and increases in TbSp (+24%), these parameters had little net change over life in men (+7% and −2% for TbN and TbSp, respectively; p < 0.001 versus women). However, TbTh decreased to a greater extent in men (−24%) than in women (−18%; p = 0.010 versus men). Conclusions: Whereas decreases with age in trabecular BV/TV are similar in men and women, the structural basis for the decrease in trabecular volume is quite different between the sexes. Thus, over life, women undergo loss of trabeculae with an increase in TbSp, whereas men begin young adult life with thicker trabeculae and primarily sustain trabecular thinning with no net change in TbN or TbSp. Because decreases in TbN have been shown to have a much greater impact on bone strength compared with decreases in TbTh, these findings may help explain the lower life-long risk of fractures in men, and specifically, their virtual immunity to age-related increases in distal forearm fractures.

Abstract We updated the incidence of primary hyperparathyroidism in Rochester, Minnesota. The lower rates previously noted persisted, whereas parathyroidectomies at our institution remained high. These data suggest an etiologic factor may be responsible for the peak incidence in the 1970s. Introduction: Automated serum calcium measurements were associated with a dramatic rise in primary hyperparathyroidism in the early 1970s, but a progressive decline in the incidence thereafter was unexpected and suggested a fundamental change in the epidemiology of the disease. Our objective was to evaluate trends in the incidence of primary hyperparathyroidism since 1992. Materials and Methods: In this population-based descriptive study, Rochester, MN, residents who met defined diagnostic criteria for primary hyperparathyroidism from January 1993 through December 2001 were identified through the medical record linkage system of the Rochester Epidemiology Project and the Mayo Clinic Laboratory Information System. Changes in incidence were evaluated by Poisson regression. Results: Altogether, 136 Rochester residents (94 women and 42 men) were newly identified with primary hyperparathyroidism in 1993–2001. Their mean age was 56 years, and 93% had definite disease. The overall age- and sex-adjusted (to 2000 U.S. whites) rate during this period was 21.6 per 100,000 person-years, which was less than the annual rate of 29.1 per 100,000 observed in 1983–1992 and 82.5 per 100,000 in July 1974–1982. Although community incidence declined, the number of parathyroidectomies performed at our institution increased during the same period. Serum calcium was deleted from the automated chemistry panel in June 1996, but most subjects remained asymptomatic at diagnosis (95%) with mild hypercalcemia. The majority of subjects were observed without parathyroid surgery (75%), and there was minimal impact on patient management from the 1990 NIH consensus conference on asymptomatic primary hyperparathyroidism. Conclusions: The lower incidence of primary hyperparathyroidism noted through 1992 has persisted in our community through 2001, whereas parathyroidectomies at our institution remained high. These data suggest that some underlying etiologic factor, in addition to the introduction of automated serum calcium testing, may have been responsible for the peak incidence in the 1970s.