Pancreas fat quantification with quantitative CT: an MRI correlation analysis.

AIM: To assess the fat content of the pancreas using quantitative computed tomography (QCT) and to correlate the results with chemical-shift-encoded magnetic resonance imaging (CSE-MRI) measurements of proton density fat fraction (PDFF). MATERIAL AND METHODS: Institutional review board approval for this research was obtained and 52 participants (25 men, 27 women; mean age 35.1 years; age range 22-50 years), who were enrolled in the Prospective Urban Rural Epidemiology (PURE) Study, underwent QCT and CSE-MRI for quantification of fat content in the pancreas. Two observers placed regions of interest (area of 100-130 mm2) in the head, body, and tail of the pancreas as closely matched as possible on the two scans. Pearson correlation and Bland-Altman analysis were performed to evaluate the correlation between the QCT and CSE-MRI measurements and the systematic difference between the two techniques. RESULTS: The QCT and CSE-MRI measurements of pancreatic fat content were well correlated (r=0.805, p<0.0001), although Bland-Altman analysis showed that the QCT measurements were systematically lower by 6.3% compared to CSE-MRI PDFF. CONCLUSION: In conclusion, the results of this study suggest good correlation between QCT and CSE-MRI measurements of pancreatic fat content. Further studies are required to improve the numerical agreement of QCT measurements with PDFF.

Optimal cut-points of visceral adipose tissue areas for cardiometabolic risk factors in a Chinese population: a cross-sectional study.

AIM: To determine the optimal cut-points of visceral adipose tissue (VAT) areas at different anatomic levels to discriminate participants with cardiometabolic risk factors in a Chinese middle-aged population. METHODS: A total of 1744 individuals who underwent regular health checks in Nanjing BENQ Medical Center from January 2013 to December 2016 were included in this cross-sectional study. VAT areas were measured by abdominal quantitative computed tomography at the L2/3 intervertebral disk and umbilicus levels. Cardiometabolic risk factors including serum triglycerides, HDL cholesterol levels, plasma glucose and blood pressure were defined using IDF 2005 criteria for metabolic syndrome. RESULTS: The cut-points for VAT area at the umbilicus level were 111 cm2 for men and 96 cm2 for women to identify people with one or more cardiometabolic risk factors. For VAT area at the L2/3 level, the optimal cut-points were 142 cm2 for men and 115 cm2 for women. A VAT area at the L2/3 level of ≥ 142 cm2 for men or 115 cm2 for women significantly increased the prevalence of hyperglycaemia [odds ratio (OR) 3.18, 95% confidence interval (CI) 2.45-4.13], hypertension (OR 2.81, 95% CI 2.27-3.49) and dyslipidaemia (OR 4.37, 95% CI 3.50-5.45) after adjusting age. CONCLUSIONS: The optimal cut-points for VAT area at the umbilicus level and L2/3 level were 111 cm2 and 142 cm2 for men and 96 cm2 and 115 cm2 for women to identify participants with one or more cardiometabolic risk factors.

Sex-related variations in cortical and trabecular bone of the femoral neck in an elderly Chinese population.

Quantitative computed tomography (QCT) was used to investigate sex-related variations in cortical and trabecular bone of the femoral neck. Cortical bone thickness of women in the superior quadrant was thinner than that of men, and the cortex in all four quadrants was negatively associated with age in women. INTRODUCTION: This cross-sectional study aimed to investigate sex-related similarities and differences in femoral neck structure in an elderly Chinese population by QCT bone investigational toolkit (BIT) analysis. METHODS: This study included 207 male (67.9 ± 7.7 years; range, 55-87 years) and 400 female subjects (68.0 ± 8.7 years; range, 55-96 years). BIT module was used to measure cortical and trabecular bone in anatomic quadrants of the femoral neck. Measurements of cortical thickness (Ct.Th), cortical vBMD (Ct.vBMD), trabecular vBMD (Tb.vBMD), and integral vBMD (It.vBMD) at the femoral neck were determined in four anatomical sectors. RESULTS: The greatest difference between sexes, after adjusting for age, height, and weight, was in Ct.Th of Quadrant Supero-anterior (SA), which was 27.4% lower in women (p<0.001). Ct.Th of Quadrant Supero-posterior (SP) was 15.1% lower in women (p = 0.027). Ct.Th and Tb.vBMD in all four quadrants appeared to be negatively associated with age in females, whereas no significant relationship was observed in males, except Ct.Th of Quadrant SP. CONCLUSIONS: The superior femoral neck geometry between males and females was significantly different, even after adjustment for body size and age, and the sub-regional cortical and trabecular bone negatively age-related changes in women indicated that women apparently have a more vulnerable geometrical outcome with age for fractures than men.

[Feasibility study of dynamic contrast enhanced magnetic resonance imaging qualitative diagnosis of musculoskeletal tumors].

OBJECTIVE: To investigate the feasibility of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) parameters in differentiating musculoskeletal tumors with different behaviours of pathological findings before therapy. METHODS: A total of 34 subjects of musculoskeletal tumors were involved in this retrospective analysis. DCE-MRI was performed using a fat-saturated 3D VIBE (volumetric interpolated breath-hold exam) imaging sequence with following parameters: FA, 10 degree; TR/TE, 5.6/2.4 ms; slice thickness, 4.0 mm with no intersection gap; field of view, 310 mm×213 mm; matrix, 256×178; voxel size, 1.2 mm×1.2 mm×4.0 mm; parallel imaging acceleration factor. The actuation time for the DCE-MRI sequence was 255 s with a temporal resolution of 5 s and 40 image volumes. Using pathological results as a gold standard, tumors were divided into benign, borderline and malignant tumors. Toft's model was used for calculation of K(trans) (volume transfer constant), Ve (extravascular extracellular space distribute volume per unit tissue volume) and Kep (microvascular permeability reflux constant). Those parameters were compared between the lesions and the control tissues using paired t tests. The one-way analysis of variance was used to assess the difference among benign, borderline and malignant tumors. P values <0.05 difference was statistically significant. RESULTS: Based on the WHO Classification of Tumours of Soft Tissue and Bone(2012) criteria, 34 patients were divided into three groups: 11 for benign tumors, 12 for borderline tumors, and 11 for malignancies. Compared with control tissues, K(trans) and Kep showed no difference, but Ve was increased in benign tumors, Kep showed no difference, but K(trans) and Ve were increased in borderline tumors,K(trans), Kep and Ve were increased in malignant tumors. K(trans) (P<0.001) and Kep (P<0.01) were significantly higher in malignant tumors than in benign and borderline tumors, but did not show any difference between benign tumors and borderline tumors. Ve was significantly higher in malignant tumors than in benign (P<0.05), but did not show any difference between malignant and borderline tumors, benign tumors and borderline tumors (P>0.05). CONCLUSION: DCE-MRI technique is useful to evaluate the pathological behaviour of musculoskeletal tumors. The quantitative analysis of DCE parameters in conjunction with conventional MR images can improve the accuracy of musculoskeletal tumor qualitative analysis.

Association of the g.19074G>A genetic variant in the osteoprotegerin gene with bone mineral density in Chinese postmenopausal women.

Primary osteoporosis is a common health problem in postmenopausal women. This study aimed to detect the association of the g.19074G>A genetic variant in the osteoprotegerin gene (OPG) with bone mineral density (BMD) and primary osteoporosis. The created restriction site-polymerase chain reaction method was used to investigate the g.19074G>A genetic variant. The BMD of the femoral neck hip, lumbar spine (L2-4), and total hip were assessed by dual-energy X-ray absorptiometry (DEXA) in 856 unrelated Chinese postmenopausal women. We found significant differences in the BMDs of the femoral neck hip, lumbar spine (L2-4), and total hip among different genotypes; individuals with the GG genotype had significantly higher BMDs than those with the GA and AA genotypes (P < 0.05). Our results indicated that the A allele was an increased risk factor for primary osteoporosis and the g.19074G>A genetic variant of the OPG gene was associated with BMD and primary osteoporosis in Chinese postmenopausal women.

[Research and progress in etiology, prevention and treatment strategies of secondary caries].

Secondary caries is one of the main reasons that affect the service life of the restoration. Compared with primary caries, secondary caries have some particularities in etiology, disease progression, clinical manifestation, clinical diagnosis, treatment and prevention. Starting from the above aspects, combined with the latest basic and clinical research on secondary caries, this paper summarizes and analyzes its pathogenesis and prevention strategies, which will lay a certain foundation for in-depth understanding of secondary caries and promoting its clinical prevention and treatment.

[Saliva microbiota and metabolite in individuals with caries or periodontitis].

Objective: To detect and analyze the characteristics of oral microbiota in species composition, function and metabolism among caries, periodontitis and oral healthy individuals, hunting for the microbiome-derived biomarkers with specificity and sensitivity to estimate the occurrence of these two diseases. Methods: Saliva samples were collected from 10 patients with high caries risk [decayed-missing-filled teeth (DMFT)≥6, HC group] in Department of Endodontics, 10 patients with periodontitis of grade Ⅱ A-Ⅲ C (PG group) in Department of Periodontology and 10 oral healthy individuals (HH group) from School of Stomatology, The Fourth Military Medical University during from March 2022 to June 2022. A baseline examination was conducted on all participants, including their oral conditions of caries and periodontal health. Metagenomic sequencing (Illumina PE150 platform) and liquid chromatography-mass spectrometry were used to detect microorganisms and their metabolites in the samples respectively. The sequencing data were analyzed to obtain the information of microbial taxonomic composition, functional genes and metabolites in each group of samples. The basic oral conditions and saliva samples of subjects in each group were evaluated and collected by the same professional endodontist. Results: There were no significant difference in baseline characteristics such as age and sex among the subjects in each group (P>0.05). DMFT in HC group (9.0±1.7) was significantly higher than that in HH group (0) and PG group (0) (F=243.00, P<0.001). Sequencing data analysis showed that the taxonomic compositions of salivary microbiota in each group were mainly Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria and Fusobacteria at the phylum level, and Streptococcus, Neisseria, Rothia, Prevotella at the genus level. Differential analysis showed that, compared with the HH group, HC group and PG group had significant differences in taxonomic composition (P<0.05), and the most significant among them was Prevotella. At the species level, Prevotella pallens was the most significant change in HC group, and Porphyromonas gingivalis in PG group. Metabolite analysis showed that there were significant differences in metabolites between HC group and PG group. The results showed that, compared with the HH group, the most significant metabolite change was 3-hydroxy-1, 5-diphenylpentan-1-one in HC group (P=0.001) and N1 acetylspermine in PG group (P=0.002) respectively. Compared with the PG group, the metabolite of HC group with the most significant difference is D-glucosamine 6-phosphate (P=0.006). The metabolism gene function analysis showed that, the enrichment of carbohydrate metabolism related genes was highest in HC group, followed with HH group, and it was lowest in PG group. In addition, compared with the HH group, the abundance of functional genes related to glucose metabolism, such as ABC transporter and phosphotransferase system, were significantly decreased in PG group (P<0.05), but significantly increased in HC group (P<0.05). Conclusions: There is a significant correlation between the alternation of carbohydrate metabolism of salivary microbiota with the occurrence of caries and periodontitis. In the future, Prevotella pallens and 3-hydroxy-1, 5-diphenylpentan-1-one may be the potential biomarkers of caries; while Porphyromonas gingivalis and N1 acetylspermine work in the predictions of periodontitis.

[Evaluation of the relationship between the attachment type of lateral pterygoid muscle and the position of temporomandibular joint disc in patients with temporomandibular joint disorders based on wireless amplified MRI detector high resolution imaging].

Objective: To explore the correlation between the attachment type of lateral pterygoid muscle (LPM) and the position of temporomandibular joint (TMJ) disc in patients with temporomandibular disorders (TMD) by using wireless amplified magnetic resonance imaging detector (WAND) coupled with conventional head and neck joint coil for high resolution imaging of TMJ. Methods: Eighty-five patients with TMD diagnosed by oral and maxillofacial surgeons of Guizhou Provincial People's Hospital from October 2019 to January 2022 were collected. A total of 160 TMJ were included. There were 16 males and 69 females, aged (32.7±14.2) years. All patients were scanned with open, closed oblique sagittal and coronal WAND coupled head and neck coils with bilateral TMJ. Based on TMJ and LPM high resolution imaging, to explore the correlation between LPM attachment types and the position of TMJ disc in TMD patients, and to evaluate the potential clinical value of LPM attachment types in TMD patients. χ2 test and Pearson correlation analysis were used to evaluate the correlation between LPM attachment type and TMJ disc location. Results: There were three types of LPM attachment: type Ⅰ in 51 cases [31.9% (51/160)], type Ⅱ in 77 cases [48.1% (77/160)] and type Ⅲ in 32 cases [20.0% (32/160)]. There was a significant correlation between the type of LPM attachment and the position of articular disc (χ2=28.20, P=0.002, r=0.776). There was no statistical significance between the type of LPM attachment and the reversible displacement of articular disc (χ2=0.24, P=0.887, r=0.825). Conclusions: There is a correlation between the attachment type of LPM and the position of the disc in TMD patients. WNAD coupled with conventional head and neck joint coil TMJ high resolution scan can provide reliable imaging evidence for TMD patients in evaluating the type of LPM attachment and the location of disc.

[A 5-year retrospective study of computer aided design and computer aided manufacturing ceramic endocrowns in endodontically treated posterior teeth].

Objective: To evaluate the clinical outcomes of computer aided design and computer aided manufacturing (CAD/CAM) ceramic endocrowns in endodontically treated posterior teeth after five years by a retrospective study. Methods: Patients who received CAD/CAM ceramic endocrowns after endodontically treatment in Department of Endodontics, School of Stomatology, The Fourth Military Medical University between January 2016 and June 2017 were invited for this clinical study. Clinical performance was evaluated in the aspect of color match, anatomic form,marginal adaptation, restoration integrity and secondary caries. Survival rate of the restorations was calculated by the use of Kaplan-Meier method. Log-rank test was applied as well for the sake of analyzing the effect of tooth position, sex and materials to the survival rate of the restorations. Results: Seventy-four patients, 25 men and 49 women with age of (38.8±10.2) years, participated in this study for a total of 101 CAD/CAM ceramic endocrowns after observation period of (62.8±12.0) months. There were 8 failed cases among 101 restorations, 5 were loss of retention, 2 were ceramic fracture and 1 was secondary caries respectively. In particular, 93% (89/96) restorations got score A on anatomic form and 95% (91/96) restorations got score A on marginal adaptation, while 38% (36/96) restorations showed the good color match compared with the abutment teeth. The estimated cumulative survival rate of CAD/CAM ceramic endocrowns in endodontically treated posterior teeth after 5 years was 93.0% (95%CI: 87.9%-98.1%). The single-factor Log-rank analysis demonstrated that there was no statistically significant difference in the survival rate of CAD/CAM ceramic endocrowns among men and women, premolars and molars, position in the dental arch, or different materials (χ²<0.01, P=0.957; χ²=0.64, P=0.422; χ²=0.69, P=0.407; χ²=0.88, P=0.349). Conclusions: Based on this clinical study, the clinical performance of CAD/CAM ceramic endocrowns in endodontically treated posterior teeth after five years is reliable, which could be a general option to restore nonvital teeth.

Changes in femoral head blood supply and vascular endothelial growth factor in rabbits with steroid-induced osteonecrosis.

The molecular aetiology of steroid-induced osteonecrosis (ON) is unclear. The aim of this study was to investigate changes in the femoral head blood supply and vascular endothelial growth factor (VEGF) protein levels following steroid-induced ON of rabbit femoral heads in the early stage of the disease, and to investigate a possible mechanism for ON. Using a classic protocol, ON was induced in 30 male 28-week old New Zealand white rabbits. An additional 15 untreated rabbits served as controls. Change of blood supply in the proximal femur was assessed by dynamic magnetic resonance imaging and microangiography. The VEGF protein and mRNA levels were assessed by immunohistochemistry and quantitative real-time polymerase chain reaction, respectively. After 6 weeks, the results indicated that VEGF protein and mRNA levels were significantly lower and femoral head blood supply had also decreased significantly in ON(+) rabbits compared with controls. The down-regulation of VEGF may play a critical role in the disease process of ON.

The regenerative effect of platelet-rich plasma on healing in large osteochondral defects.

Platelet-rich plasma (PRP), a platelet concentrate made of autogenous blood, has been used to improve bone and soft tissue defect healing in recent years. The aim of this study was to assess the effect of PRP on articular cartilage defects in a rabbit model. Forty-eight osteochondral defects created in the femoropatellar groove were (a) left untreated, (b) treated with autogenous PRP in a poly-lactic-glycolic acid (PLGA), or (c) with PLGA alone. Platelets were enriched 5.12-fold compared to normal blood in the PRP. After four and 12 weeks, the explanted tissue specimens were assessed by macroscopic examination, micro-computed tomography, and histological evaluation. Macroscopic examination, micro-computed tomography and histology of the newly formed cartilage and bone in the defect differ significantly between the PRP-treated and the untreated groups, and stimulatory effect of PRP on osteochondral formation was observed. In conclusion, PRP in PLGA improves osteochondral healing in a rabbit model.

Overexpression of miR-381-3p promotes the recovery of spinal cord injury.

OBJECTIVE: To study the effects of miR-381-3p on spinal cord injury and its underlying mechanism. MATERIALS AND METHODS: After the spinal cord injury rat model of was established, Sprague Dawley (SD) rats were randomly divided into the control group and the acute spinal cord injury (ASCI) group. Microglial BV2 cells were used as experimental cells, and the cells were divided into the control group and the lipopolysaccharide (LPS) group. The mRNA and protein expression level of miR-381-3p, IKKß, inflammatory factors, and p-p65 were detected by quantitative Reverse Transcriptase-Polymerase Chain Reaction (qRT-PCR) and Western blot, respectively. Dual-luciferase reporter gene assay and Western blot were used to detect the regulatory effect of IKKß on miR-381-3p. Changes in grip ability and rotary performance of rats in the ASCI group were evaluated after miR-381-3p overexpression in vivo. RESULTS: The expression of miR-381-3p was downregulated in rats of the ASCI group, while the expression of IKKß and p-p65 were upregulated. In vitro experiments demonstrated that LPS could inhibit the expression of miR-381-3p and promote the upregulation of IKKß and p-p65. Overexpression of miR-381-3p could inhibit the mRNA and protein expression of IKKß. The upregulated expression of IKKß, p-p65, tumor necrosis factor-alpha (TNF-α), and interleukins-1ß (IL-1ß) induced by LPS in BV2 cells were reversed by miR-381-3p mimic transfection. Besides, upregulated TNF-α and IL-1ß induced by miR-381-3p inhibitor in BV2 cells were reversed by IKKß inhibitor (BMS-345541). Results of animal experiments indicated that miR-381-3p was overexpressed in rats of the ASCI group. The protein levels of IKKß and p-p65, and the mRNA expression levels of inflammatory cytokines TNF-α and IL-1ß were remarkably decreased in the ASCI group than those of the control group. The grip ability, coordination, and anti-fatigue performance of rats in the ASCI group recovered quicker than those of the control group. CONCLUSIONS: MiR-381-3p was downregulated in ASCI rats. The overexpression of miR-381-3p could recover the motor ability of rats in the ASCI group earlier and might inhibit injury aggravation by inhibiting inflammatory responses via the IKKß-NF-κB pathway.

Differences in femoral neck structure between elderly Caucasian and Chinese populations: a cross-sectional study of Perth-Beijing cohorts.

Structural skeletal differences of the femoral neck of older Beijing-Chinese and Perth-Caucasian women were compared; adjusting for frame size-related differences, Beijing-Chinese have lower periosteal width; however, indices of internal bone distribution suggest that Beijing-Chinese may exhibit increased resistance to fracture that may relate to the reduced hip fracture incidence. INTRODUCTION: Ethnic differences in skeletal structure may relate to differences in hip fracture risk in Chinese and Caucasian populations. 2D mass, size, and structural biomechanics were compared in the two populations. METHODS: Quantitative computed tomography-derived geometric variables were compared in age-matched community-derived female populations, 196 Beijing-Chinese 76.5 ± 4.8 (mean ± SD) years and 237 Perth-Caucasians 77.1 ± 5.0 years. These included scanned area (A), periosteal width (W), bone mineral content (BMC), aBMD, bone cross-sectional area (bCSA), section modulus (Z) and buckling ratio (BR). Assumption-free measures included sigma (σ), related to the distribution of bone in the scanned image previously identified as a predictor of hip fracture, and delta (δ), the center-of-mass displacement from the geometric center. RESULTS: Compared to Beijing-Chinese, Perth-Caucasians were heavier (Beijing-Chinese 58.7 ± 11.8; Perth-Caucasians 66.1 ± 11.0 kg), taller (154.9 ± 16.7 vs 158.9 ± 6.0 cm), and had higher BMC, A, and W. After adjustment for frame size, BMC was not significantly different but W remained higher in Perth-Caucasians. Differences in variables aBMD, Z, BR, and σ favored higher resistance to failure with Beijing-Chinese before and after adjustment for frame size. δ was similar in both populations; bCSA was higher in Beijing-Chinese before adjustment for frame size but not after. CONCLUSIONS: Bone mass differences in two populations were related to frame size differences. However, femoral neck width remained smaller in Beijing-Chinese suggesting effects of local genetic and environmental factors. In Beijing-Chinese participants compared to Perth-Caucasians, internal bone distribution suggests increased resistance to deformation if exposed to same force that may, in-part, relate to reduced incidence of hip fracture in Beijing-Chinese.

Hip fracture and osteoporosis in a XIIth Dynasty female skeleton from Lisht, upper Egypt.

Osteoporosis and complications arising from loss of bone mass have been present in human populations for thousands of years. However, reports of this disease in antiquity remain uncommon. The purpose of this report is to describe an important case of osteoporosis in ancient Egypt because of its intrinsic interest and to provide perspectives on factors contributing to this condition today. The case providing the focus for this report is from Lisht, Upper Egypt and is dated to the XIIth Dynasty (1990-1786 B.C.). Methods used to characterize the pathology include gross anatomical study, radiology, and radiographic measurements. Observations, measurements, and indices all indicate osteoporosis complicated by fracture of the femoral neck and compression fractures of some vertebrae. The Lisht case adds to a small corpus of reports on osteoporosis and complicating factors of this disease in antiquity. Long-term survival of an extracapsular fracture of the femoral neck in this case is remarkable and may reflect supportive social conditions.

Prediction of vertebral and femoral strength in vitro by bone mineral density measured at different skeletal sites.

The aim of the present study was to investigate the prediction of vertebral and femoral strength in vitro by bone mineral density (BMD) measured at different skeletal sites. The third lumbar vertebral body, the right proximal femur, and the right calcaneus were removed from 38 male and 32 female cadavers (mean age 69 years, range 23-92 years). Areal BMD of all bone specimens was determined by dual-energy X-ray absorptiometry (DXA). The failure load of the vertebral body and the femur was determined by mechanical testing. Vertebral and femoral strength were both greater in males than females (p < 0.01), as was BMD at all sites (p < 0.01). Vertebral strength correlated well with vertebral BMD (r2 = 0.64) but was only moderately correlated with BMD measured at the femur (r2 = 0.36) or the calcaneus (r2 = 0.18). Femoral strength showed the highest correlations with femoral BMD (r2 = 0.88) and somewhat weaker relationships with BMD at the vertebra (r2 = 0.50) and the calcaneus (r2 = 0.54). BMD values at the vertebra, femur, and calcaneus were only moderately interrelated (r2 = 0.31-0.65), and vertebral strength correlated only modestly with the strength of the femur (r2 = 0.36). These in vitro results support the concept that optimal prediction of vertebral or femoral strength by DXA requires site-specific assessments.

Age-related (type II) femoral neck osteoporosis in men: biochemical evidence for both hypovitaminosis D- and androgen deficiency-induced bone resorption.

The problem of osteoporosis in men has recently been recognized as an important public health issue. To test the hypothesis that endocrine deficiency-mediated alterations in bone metabolism might contribute to osteoporotic fracture risk in elderly men, serum levels of 25-hydroxycholecalciferol (25(OH)D), 1,25-dihydroxycholecalciferol (1,25(OH)2D), intact parathyroid hormone (PTH), testosterone, and estradiol were measured in 40 males (mean age 73 years) who were consecutively recruited within 18 h following a fracture of the proximal femur, and in an equal number of community-living older men (mean age 72 years) who served as controls. In addition, circulating osteocalcin and urinary excretion of (deoxy)pyridinoline were determined as markers of bone formation and resorption, respectively. No differences were observed between the mean serum concentrations of osteocalcin and estradiol. Serum levels of 25(OH)D, 1,25(OH)2D, and testosterone, however, were decreased in hip fracture patients. When correcting for differences in vitamin D binding protein, differences in 1,25(OH)2D did not persist, whereas serum 25(OH)D was still significantly lower in patients than in controls (6.1 +/- 4.3 vs. 7.6 +/- 2.8, p = 0.01). Similarly, a highly significant deficit was observed in the free testosterone index, calculated from total testosterone and the level of sex hormone binding globulin (2.6 +/- 1.3 vs. 8.2 +/- 2.9, p < 0.001). Serum PTH and urinary pyridinium cross-links, however, were markedly increased in the fracture group. Moreover, in fracture patients, free 25(OH)D and free testosterone were both significant and mutually independent negative predictors of (deoxy)pyridinoline excretion. Although limited by its cross-sectional design, the present study suggests that both hypovitaminosis D and androgen deficiency may predispose to bone resorption in elderly men and in turn to remodeling imbalance and fracture risk.

Prediction of vertebral strength in vitro by spinal bone densitometry and calcaneal ultrasound.

Spinal bone mineral density (BMD) measurements and calcaneal ultrasound were compared in terms of their ability to predict the strength of the third lumbar vertebral body using specimens from 62 adult cadavers (28 females, 34 males). BMD was measured using dual X-ray absorptiometry (DXA) in both vertebra and calcaneus. Quantitative computed tomography (QCT) was used to determine trabecular BMD, cortical BMD, cortical area, and total cross-sectional area (CSA) of the vertebral body. Bone velocity (BV) and broadband ultrasonic attenuation (BUA) were measured in the right calcaneus. Vertebral strength was determined by uniaxial compressive testing. Vertebral ultimate load was best correlated with DXA-determined vertebral BMD (r2 = 0.64). Of the QCT parameters, the best correlation with strength was obtained using the product of trabecular BMD and CSA (r2 = 0.61). For vertebral ultimate stress, however, the best correlation was observed with QCT-measured trabecular BMD (r2 = 0.51); the correlation with DXA-determined BMD was slightly poorer (r2 = 0.44). Calcaneal ultrasound correlated only weakly with both ultimate load and stress with correlation coefficients (r2) of 0.10-0.17, as did calcaneal BMD (r2 = 0.18). Both spinal DXA and spinal QCT were significantly (p < 0.001) better predictors of L3 ultimate load and stress than were either calcaneal ultrasound or calcaneal DXA. Multiple regression analysis revealed that calcaneal ultrasound did not significantly improve the predictive ability of either DXA or QCT for L3 ultimate load or stress. Calcaneal DXA BMD, bone velocity, and BUA correlated well with each other (r2 = 0.67-0.76), but were only modestly correlated with the DXA and QCT measurements of the vertebra. These data indicate that spinal DXA and spinal QCT provide comparable prediction of vertebral strength, but that a substantial proportion (typically 40%) of the variability in vertebral strength is unaccounted for by BMD measurements. Ultrasonic measurements at the calcaneus are poor predictors of vertebral strength in vitro, and ultrasound does not add predictive information independently of BMD. These findings contrast with emerging clinical data, suggesting that calcaneal ultrasound may be a valuable predictor of vertebral fracture risk in vivo. A possible explanation for this apparent discrepancy between in vivo and in vitro findings could be that current clinical ultrasound measurements at the calcaneus reflect factors that are related to fracture risk but not associated with bone fragility.

Quantitative ultrasound and trabecular architecture in the human calcaneus.

Relationships between quantitative ultrasound (QUS), density (bone volume density [BV/TV]), and trabecular architecture were investigated in 69 calcaneal cancellous bone cubes. Ultrasound signal velocity, phase velocity, attenuation, and broadband ultrasonic attenuation (BUA) measurements were made along the mediolateral axis. Density and architectural parameters were measured using microcomputed tomography (microCT). Density yielded the best correlations with QUS (r2 = 73-77%). Of the individual architectural parameters, correlations with QUS were highest for the Structure Model Index (SMI), a parameter quantifying the relative proportion of rods and plates (r2 = 57-63%). After adjustment for density, significant associations with QUS remained for SMI, trabecular spacing (Tb.Sp), and trabecular number (Tb.N), although the variance in QUS attributable uniquely to individual architectural parameters was at best 4%. In multivariate regression models, combinations of density and architectural parameters explained 76-82% of the variance in QUS, representing an r2 increase of, at most, 8% compared with using density alone. However, multivariate models using combinations of architectural parameters alone (i.e., density excluded) also had a good predictive ability for QUS (r2 = 73-81%). Thus, although these data show modest but significant density-independent relationships between QUS and trabecular architecture in the human calcaneus for the first time, the causal relationships behind the variation in acoustic properties remain obscure. Given the relative weakness and complexity of the emerging associations between QUS and architecture, it is prudent to regard QUS measurements in calcaneal bone primarily as an indicator of bone density.

Assessment of the strength of proximal femur in vitro: relationship to femoral bone mineral density and femoral geometry.

Femoral neck axis length, neck width, and neck-shaft angle were measured on radiographs of right proximal femora from 64 cadavers (28 female, 36 male). Bone mineral density (BMD) was measured using dual energy X-ray absorptiometry (DXA) for various regions of interest, and quantitative computed tomography (QCT) was used to determine BMD and bone areas for cortical and trabecular bone at the trochanter and femoral neck. The strength of the femur was determined by a mechanical test simulating a fall on the greater trochanter, and the fracture type (cervical or trochanteric) was subsequently determined from radiographs. Twenty-six cervical fractures and 38 trochanteric fractures were observed, with no significant sex difference in the distribution of fracture types. Femoral strength was significantly elevated in males compared to females. DXA trochanteric BMD was more strongly (p < 0.05) correlated with femoral strength (r2 = 0.88) than were any of the other DXA BMD measurements (r2 = 0.59-0.76). In multiple regression models, a combination of different DXA BMD measurements produced only a small increase (1%) in the explained variability of femoral strength. Of the QCT measurements, trochanteric cortical area yielded the optimal correlation with femoral strength (r2 = 0.83). Weak, but significant, correlations were observed between femoral strength and cortical BMD at trochanteric (r2 = 0.28) and neck regions (r2 = 0.07). In multiple regression models, combining QCT parameters yielded, at best, an r2 of 0.87. Of the geometrical parameters, both neck axis length and neck width were significantly correlated with femoral strength (r2 = 0.24, 0.22, respectively), but no significant correlation was found between strength and the neck-shaft angle. Combining DXA trochanteric BMD with femoral neck width resulted in only a small increase in the explained variability (1%) compared to trochanteric BMD alone. The results demonstrated that DXA and QCT had a similar ability to predict femoral strength in vitro. Trochanteric BMD was the best DXA parameter, and cortical area (not cortical BMD) was the optimal QCT parameter. Geometric measurements of the proximal femur were only weakly correlated with the mechanical strength, and combinations of DXA, QCT, and geometric parameters resulted in only small increases in predictive power compared to the use of a single explanatory variable alone.

Assessment of the strength of the proximal femur in vitro: relationship with ultrasonic measurements of the calcaneus.

Matched pairs of the right proximal femur and right calcaneus were obtained from 64 cadavers (28 female, 36 male). Ultrasonic velocity and broadband ultrasonic attenuation were measured in the calcaneus using a laboratory ultrasound system. Bone mineral density (BMD) was measured at the calcaneus and at the trochanteric and neck regions of the femur using dual-energy X-ray absorptiometry. Femoral strength was determined in a mechanical test simulating a fall onto the greater trochanter. Femoral BMD was more strongly correlated with femoral strength (r2 = 0.71, 0.88 for neck BMD and trochanteric BMD, respectively) than were any of the other predictive variables investigated (p < 0.05). Calcaneal ultrasonic measurements alone produced correlations with femoral strength of r2 = 0.40-0.47, with no significant differences observed in predictive ability between the various ultrasonic parameters. In multiple regression analysis, ultrasound was, in general, not a significant additional independent predictor of femoral strength when combined with either femoral or calcaneal BMD, and combining ultrasonic parameters did not improve the ability to predict femoral strength. Calcaneal width was found to be significantly correlated with both femoral strength and femoral BMD, and this explained the slightly better correlations with femoral strength found for those ultrasonic parameters which were not effectively normalized for calcaneal width. In summary, calcaneal ultrasound did not significantly enhance the prediction of femoral strength compared to femoral BMD measurements alone. Given the substantial differences between the in vitro and in vivo situations, this finding does not necessarily contradict emerging clinical data indicating that ultrasound and BMD have comparable and independent predictive ability for hip fracture risk. Reasons for the apparent discrepancy are discussed, including the enhanced accuracy of DXA in vitro. Nevertheless, it is suggested that further fundamental investigations into the efficacy of current ultrasonic techniques are warranted.