How Does?Bone Strength?Compare Across Sex,Site, and Ethnicity?

Background

The risk of fragility fractures in the United States is approximately 2.5 times greater among black and white women compared with their male counterparts. On average, men of both ethnicities have wider bones of greater cortical mass compared with the narrower bones of lower cortical mass among women. However, it remains uncertain whether the low cortical area observed in the long bones of women is consistent with their narrower bone diameter or if their cortical area is reduced beyond that which is expected for the sex differences in body size and external bone size.

Questions/purposes

We asked (1) do black and white women consistently have narrower bones of less strength across long bones compared with black and white men; and (2) do all long bones of black and white women have reduced cortical area compared with black and white men?

Methods

Peripheral quantitative CT was used to quantify bone strength and cross-sectional morphology from the major long bones of 125 white and 115 black adult men and women (20–35 years of age). Regression analyses were used to test for differences in bone strength and cortical area after for adjusting for either body size, bone size, or both.

Results

After adjusting bone strength for body size, regression analyses showed that black women had lower bone strength compared with black men (women: mean = 298.7–25,522 mg HA mm⁴, 95% confidence interval [CI], 270–27,692 mg HA mm⁴; men: mean = 381.6–30,945 mg HA mm⁴, 95% CI, 358.2–32,853 mg HA mm⁴; percent difference = 12%–38%, p = 0.06–0.0001). Similarly, white women also had lower bone strength compared with white men (women: mean = 229.5–22,892 mg HA mm⁴, 95% CI, 209.3–24,539 mg HA mm⁴; men: mean = 314.3–29,986 mg HA mm⁴, 95% CI, 297.3–31,331 mg HA mm⁴; percent difference = 27%–49%, p = 0.0001). All long bones of women for both ethnicities showed lower cortical area compared with men. After accounting for both body size and external bone size, black women (women: mean = 43.25–357.70 mm², 95% CI, 41.45–367.52 mm²; men: mean = 48.06–400.10 mm², 95% CI, 46.67–408.72; percent difference = 6%–25%, p = 0.02–0.0001) and white women (women: mean = 38.53–350.10 mm², 95% CI, 36.99–359.80 mm²; men: mean = 42.06–394.30 mm², 95% CI, 40.95–402.10 mm²; percent difference = 6%–22%, p = 0.02–0.0001) were shown to have lower cortical area than their male counterparts. Therefore, the long bones of women are not only more slender than those of men, but also show a reduced cortical area that is 6% to 25% greater than expected for their external size, depending on the bone being considered.

Conclusions

The long bones of females are not just a more slender version of male long bones. Women have less cortical area than expected for their body size and bone size, which in part explains their reduced bone strength when compared with the more robust bones of men.

Clinical Relevance

The outcome of this assessment may be clinically important for the development of diagnostics and treatment regimens used to combat fractures. Future work should look at how the relationship among parameters reported here translates to the more fracture-prone metaphyseal regions.     

Do Young New Zealand Pacific Island and European Children Differ in Bone Size or Bone Mineral?

Although Pacific Island adults have been shown to have larger bones and greater bone mineral density than caucasians, no previous studies have been undertaken to determine whether differences are present in prepubertal children. Forty-one Pacific Island children (both parents of Pacific Island descent) and 38 European children, aged 3 to 7 years, living in New Zealand were studied. Heights and weights were determined by simple anthropometry and body mass index (BMI, kg/m²) was calculated. Body composition, bone size, and bone mineral content (BMC, g) were measured by dual energy X-ray absorptiometry (DXA) of the total body and the non-dominant forearm. Compared to European children, in data adjusted for age and gender, Pacific Island children had significantly greater (P < 0.05) BMC in the total body (12%), the ultradistal radius (16%), and the 33% radius (8%), and also greater total body bone area (10%). Bone mineral density (BMD, g/cm²) was higher only at the ultradistal radius (11%). However, after adjustment for body weight, in particular lean mass, no differences were seen between Pacific Island and European children in any bone measure. The larger bone area and BMC of young Pacific Island children can be explained by their greater height and weight. Therefore, this study has shown that prepubertal Pacific Island children do not have greater bone size or BMC for their weight.Grant Support: Otago Medical Research Foundation.     

Does Physical Activity Level Influence Total Hip Arthroplasty Expectations,Satisfaction, and Outcomes?

BackgroundTotal hip arthroplasty (THA) patients expect pain relief and functional improvement, including return to physical activity. Our objective was to determine the impact of patients' physical activity level on preoperative expectations and postoperative satisfaction and clinical outcomes in patients undergoing THA.MethodsUsing an institutional registry of patients undergoing THA between 2007 and 2012, we retrospectively identified patients who underwent unilateral primary THA for osteoarthritis and completed a preoperative Lower Extremity Activity Scale, Hospital for Special Surgery Hip Replacement Expectations Survey, and Hip disability and Osteoarthritis Outcome Score in addition to two-year HOOS and satisfaction evaluations. Active patients (n = 1053) were matched to inactive patients (n = 1053) by age, sex, body mass index, and comorbidities. The cohorts were compared with regard to the association of expectations with Hip disability and Osteoarthritis Outcome Score and satisfaction, the change in Lower Extremity Activity Scale level from baseline to 2 years, complications, and revision surgical procedures.ResultsSignificantly more active patients (74%) expected to be “back to normal” regarding ability to exercise and participate in sports compared with inactive patients (64%, P < .001). Overall satisfaction was similar. Higher expectations with regard to exercise and sports were associated with higher HOOS sports and recreation subdomain scores in active patients. The inactive patient group improved on baseline activity level at 2 years while the active group did not.ConclusionAt 2 years after THA, active and inactive patients were similarly satisfied and achieved comparable outcomes. Inactive patients showed a greater improvement in physical activity level from preoperative baseline than active patients. Complications and revision rates were similar.Level of EvidenceIII.     

Specific Effects of γ-Linolenic,Eicosapentaenoic, and Docosahexaenoic Ethyl Esters on Bone Post-ovariectomy in Rats

Long chain polyunsaturated fatty acids (LCPUFAs) are involved in the regulation of bone metabolism. Increased dietary consumption of n-3, and possibly some n-6, LCPUFAs may limit postmenopausal bone loss. The aim of this study was to determine the effects on bone of specific fatty acids within the n-3 and n-6 LCPUFA families in ovariectomized (OVX) rats. Rats were OVX or sham-operated and fed either a control diet (OVX and sham) or a diet supplemented with 0.5 g/kg body weight/day of γ-linolenic (GLA), eicosapentaenoic (EPA), docosahexaenoic (DHA) ethyl esters or a mixture of all three (MIX) for 16 weeks. Bone mineral content (BMC), area, and density and plasma concentrations of insulin-like growth factor-I, vitamin D, selected biochemical markers of bone metabolism, and parathyroid hormone (PTH) were determined. The OVX-induced decrease in lumbar spine BMC was significantly attenuated by DHA but not by EPA or GLA supplementation or supplementation with a mixture of all three LCPUFAs. Endosteal circumferences of tibiae were significantly greater in DHA and EPA compared to OVX. Plasma C-terminal telopeptide of type I collagen and osteocalcin concentrations were not significantly different in the DHA group compared to OVX. Femur BMC decreased by a significantly greater amount in GLA than OVX, and final plasma PTH concentrations were significantly higher in GLA compared to all other groups. In conclusion, DHA ameliorated OVX-induced bone mineral loss. GLA exacerbated post-OVX bone mineral loss, possibly as a result of PTH-induced bone catabolism.     

Does Treatment Modality Have an Impact on Anemia in Patients with Chronic Renal Failure? Effect of Low‐ and High‐Flux Biocompatible Dialysis

Renal anemia significantly affects the morbidity and mortality of dialysis patients. The aim of the present study was to establish whether the severity of anemia and success of its treatment differs when using high-flux (HF) or low-flux (LF) hemodialysis. Twenty-five patients on long-term hemodialysis with a mean hematocrit (Hct) of 33%, S alb of 36 g/L, and Kt/V urea of 1.5 were divided into Groups X (n = 13) and Y (n = 12) in a prospective randomized crossover study. Group X was initially treated with LF hemodialysis to be followed by HF hemodialysis for 8 weeks each time. Group Y started with 8 week HF hemodialysis and continued, after crossover, with 8 weeks of LF hemodialysis. HF and LF hemodialysis were performed with polysulfone dialyzers F 7HPS and F60S (Fresenius Medical Care, Bad Homburg, Germany). Hct values, examined at 2 week intervals, did not differ significantly between Groups X and Y during 16 weeks of the study at any measuring interval. In another analysis, all results of HF hemodialysis (first 8 weeks of Y + second 8 weeks of X) were pooled as were all data of LF hemodialysis (first 8 weeks of X + second 8 weeks of Y). No significant relationships were noted between duration of treatment with HF hemodialysis and Hct (n = 72, rS = 0.11, p = 0.36) and between duration of LF hemodialysis and Hct (n = 74, rS = 0.02, p = 0.87) in the newly formed groups. The Hct measured during HF hemodialysis and LF hemodialysis did not differ significantly. Analysis of variance did not reveal a relationship between Hct and the HF or LF membrane. As HF and LF hemodialysis differed significantly in Kt/V urea, the variables were adjusted to identical Kt/V urea using analysis of covariance. No relationship between Hct and dialysis membrane permeability was demonstrated even in this case. Use of biocompatible LF and HF membranes in standard hemodialysis modes under conditions of adequate dose of dialysis and the time period studied did not result in different effects on anemia.     

Does a High Dietary Acid Content Cause Bone Loss,and Can Bone Loss Be Prevented With an Alkaline Diet?

A popular concept in nutrition and lay literature is that of the role of a diet high in acid or protein in the pathogenesis of osteoporosis. A diet rich in fruit and vegetable intake is thought to enhance bone health as the result of its greater potassium and lower “acidic” content than a diet rich in animal protein and sodium. Consequently, there have been a number of studies of diet manipulation to enhance potassium and “alkaline” content of the diet to improve bone density or other parameters of bone health. Although acid loading or an acidic diet featuring a high protein intake may be associated with an increase in calciuria, the evidence supporting a role of these variables in the development of osteoporosis is not consistent. Similarly, intervention studies with a more alkaline diet or use of supplements of potassium citrate or bicarbonate have not consistently shown a bone health benefit. In the elderly, inadequate protein intake is a greater problem for bone health than protein excess.     

Fracture Prospectively Recorded From Prepuberty to Young Adulthood: Are They Markers of Peak Bone Mass and Strength in Males?

Fractures are common in otherwise healthy children and adolescents. They result from trauma of varying severity. Some reflect a greater skeletal fragility. A long‐term implication of these fractures is their potentiality to predict adult bone fragility and increased risk of osteoporosis in later life. Using dual‐energy X‐ray absorptiometry (DXA), high‐resolution peripheral quantitative computed tomography (HR‐pQCT), and micro‐finite element analysis (μFEA) measurements, we previously found in 124 healthy females, followed from the age of 7.9 to 20.4 years, substantial deficits in both structural and strength components of the radius in the 42 girls who sustained a fracture during skeletal development. The objective of the current study was to assess in healthy males the relationship between fracture during development and expression of bone fragility in adulthood. A cohort of 152 boys was followed from age 7.4 ± 04 (mean ± SD) to 22.6 ± 0.7 years, ie, when peak bone mass is attained. Ninety participants (59.2%) sustained at least one fracture during growth, with highest incidence within the 10‐ to 13‐year age range. Forearm was the most frequent site of fractures. At 7.4 years, several bone DXA‐measured variables (areal bone mineral density [aBMD], bone mineral content [BMC]) were lower in the group with a positive fracture history during skeletal development compared with the non‐fractured group. In contrast, at 22.6 years, no DXA‐measured sites, including forearm, indicated a deficit in the fractured group compared with the non‐fractured group. Likewise, at 22.6 years, neither HR‐pQCT nor μFEA measurements, including distal radius, showed a structural or strength deficit in the fractured group. These results markedly contrast with a similar prospective study using the same technical and clinical design in 124 healthy girls. In conclusion, our prospective studies suggest a sex difference in the predictability of bone fragility in young adults who sustained fractures during childhood and adolescence. This difference might be related to the degree of trauma severity, usually lower in girls than in boys. © 2017 American Society for Bone and Mineral Research.     

Does Exercise Modify the Effects of Zoledronic Acid on Bone Mass,Microarchitecture, Biomechanics,and Turnover in Ovariectomized Rats?

Regular activity has effects on bone size, shape, and density, resulting in an increase in mechanical strength. The mechanism of action that underlies this improvement in bone strength is mainly linked to an increase in bone formation. Zoledronic acid (Z), in contrast, may prevent bone strength changes in ovariectomized (OVX) rodents by its potent antiresorptive effects. Based on these assumptions we hypothesized that combined effects of exercise (E) and Z may produce higher benefits on bone changes resulting from estrogen deficiency than either intervention alone. At 6 months of age, 60 female Wistar rats were OVX or sham operated (SH) and divided into five groups: SH, OVX, OVX-E, OVX-Z, and OVX-ZE. OVX rats were treated with a single IV injection of Z (20 μg/kg) or vehicle and submitted or not to treadmill exercise (15 m/min, 60 min/day, 5 days/week) for 12 weeks. Whole-body BMD and bone turnover markers were analyzed longitudinally. At sacrifice, femurs were removed. BMD by DXA, three-point bending test, and μCT were performed to study biomechanical and trabecular structure parameters, respectively. After 12 weeks, bone volume fraction decreased in OVX rats, whereas bone turnover rate, trabecular spacing, and structure model index increased compared with those in the SH group (P < 0.05). Zoledronic acid prevented the ovariectomy-induced trabecular bone loss and its subsequent trabecular microarchitectural deterioration. Treadmill exercise running was shown to preserve the bone strength and to induce bone turnover changes in favor of bone formation. However, the combined effects of zoledronic acid and running exercise applied simultaneously did not produce any synergetic or additive effects.     

Does Diet‐Induced Weight Loss Lead to Bone Loss in Overweight or Obese Adults? A Systematic Review and Meta‐Analysis of Clinical Trials

Diet‐induced weight loss has been suggested to be harmful to bone health. We conducted a systematic review and meta‐analysis (using a random‐effects model) to quantify the effect of diet‐induced weight loss on bone. We included 41 publications involving overweight or obese but otherwise healthy adults who followed a dietary weight‐loss intervention. The primary outcomes examined were changes from baseline in total hip, lumbar spine, and total body bone mineral density (BMD), as assessed by dual‐energy X‐ray absorptiometry (DXA). Secondary outcomes were markers of bone turnover. Diet‐induced weight loss was associated with significant decreases of 0.010 to 0.015 g/cm² in total hip BMD for interventions of 6, 12, or 24 (but not 3) months' duration (95% confidence intervals [CIs], –0.014 to –0.005, –0.021 to –0.008, and –0.024 to –0.000 g/cm², at 6, 12, and 24 months, respectively). There was, however, no statistically significant effect of diet‐induced weight loss on lumbar spine or whole‐body BMD for interventions of 3 to 24 months' duration, except for a significant decrease in total body BMD (–0.011 g/cm²; 95% CI, –0.018 to –0.003 g/cm²) after 6 months. Although no statistically significant changes occurred in serum concentrations of N‐terminal propeptide of type I procollagen (P1NP), interventions of 2 or 3 months in duration (but not of 6, 12, or 24 months' duration) induced significant increases in serum concentrations of osteocalcin (0.26 nmol/L; 95% CI, 0.13 to 0.39 nmol/L), C‐terminal telopeptide of type I collagen (CTX) (4.72 nmol/L; 95% CI, 2.12 to 7.30 nmol/L) or N‐terminal telopeptide of type I collagen (NTX) (3.70 nmol/L; 95% CI, 0.90 to 6.50 nmol/L bone collagen equivalents [BCEs]), indicating an early effect of diet‐induced weight loss to promote bone breakdown. These data show that in overweight and obese individuals, a single diet‐induced weight‐loss intervention induces a small decrease in total hip BMD, but not lumbar spine BMD. This decrease is small in comparison to known metabolic benefits of losing excess weight. © 2015 American Society for Bone and Mineral Research     

Vertebral Bone Mineral Density, Content and Area in 8789 Normal Women Aged 33–73 Years Who Have Never Had Hormone Replacement Therapy

The vertebral bone mineral density (BMD), bone mineral content (BMC) and bone area of the lumbar spine were measured using a bone densitometer in 8789 women aged 33–73 years who had had no previous hormone replacement therapy (HRT). The overall relationship between BMD and age was analyzed on a year-by-year basis, and comprised three separate regions that could each be described by a straight line: 33–46 years (gradient = 0.00166 g cm⁻²/year), 47–63 years (gradient = 0.0121 g cm⁻²/year) and 64–73 years (gradient = 0.0045 g cm⁻²/year). Above the age of 50 years our results were higher than the BMD in most previous reports. In those 3198 women who knew the time of their last menstrual period (mean age 49.25 years, SD 4.83) bone loss was most rapid in the first 10 menopausal years. In the whole group, the relationship between BMC and age was found to be similar to that of BMD, with three distinct regions, including a rapid drop between the ages of 47 and 63 years (gradient 0.781 g/year). Bone area showed a much more gradual (though significant) decrease with age. Based on WHO definitions and using BMD as an indicator, the percentage of women with osteoporosis varied from zero in the younger age group to about 30% of women aged over 70 years; in contrast, where BMC was used, although the trend with age had a similar shape, the percentages at each year were about half those derived from the corresponding BMD values. Osteopenia derived in the same way occurred in about 50% of women over 70 years using either BMD or BMC. The results presented here provide a reliable local reference range for lumbar spine bone densitometry measurements. They also show that for this site BMD and BMC cannot be used interchangeably to define osteoporosis. Received: 13 March 1998 / Accepted: 23 September 1998     

Coronary Artery Bypass Surgery Versus Percutaneous Coronary Artery Intervention in Patients on Chronic Hemodialysis: Does a Drug‐Eluting Stent Have an Impact on Clinical Outcome?

Abstract   Coronary revascularization methods continue to be refined, and the emergence of the drug-eluting stent (DES) has especially changed clinical practice related to ischemic heart disease. For chronic hemodialysis (HD) patients, however, the impact of DES on clinical outcome is yet to be determined. Forty-six consecutive chronic HD patients who underwent myocardial revascularization in our institute were retrospectively reviewed. Twenty-eight patients underwent coronary artery bypass surgery (CABG) and 18 patients underwent percutaneous coronary artery intervention (PCI). Patient characteristics were similar between the two groups. In the CABG group, bilateral internal thoracic artery (ITA) bypass grafting was performed in 27 patients and off-pump CABG was performed in 20 patients. In the PCI group, a DES was used in 12 patients. The number of coronary vessels treated per patient was higher in the CABG group (CABG: 4.25 ± 1.32 vs. PCI: 1.44 ± 0.78; p < 0.001). Two-year survival rates were similar between the two groups (CABG: 94.1% vs. PCI: 73.9%; p = 0.41), but major adverse cardiac event-free survival (CABG: 85.9% vs. PCI: 37.1%; p = 0.001) and angina-free survival (CABG: 84.9% vs. PCI: 28.9%; p < 0.001) rates were significantly higher in the CABG group. The one-year patency rate for the CABG grafts was 93.3% (left ITA: 100%, right ITA: 84.6%, sapenous vein: 90.9%, gastro-epiploic artery: 100%), and six-month restenosis rate for PCI was 57.1% (balloon angio-plasty: 75%, bare metal stent 40%, DES: 58.3%). Even in the era of DES, clinical results favored CABG. The difference in clinical results is due to the sustainability of successful revascularization.