Differences in leg bone geometry in young, old and very old women

Bone geometry is an important measure of bone strength and is known to be affected by weight-bearing and adult ageing. Engagement in weight-bearing activity decreases with age, thus in this study we compared bone geometry changes between weight-bearing (tibia) and non-weight-bearing (fibula) leg bones in three different age groups of women. Magnetic resonance images of the right leg were acquired in 9 young (20–27 years), 7 old (61–69 years) and 7 very old (71–80 years) women. Total and cortical bone volumes and medullary cavity volumes (mm³) were calculated at proximal and distal sites for both bones. Tibial cortical bone volume was significantly less at the proximal site in old (17%) and very old (24%) groups versus young subjects. Cortical bone volume in the proximal fibula was also significantly reduced in the older groups (7 and 12%), but to a substantially lesser extent than in the tibia. In contrast, distal bone geometry appeared largely to be conserved in both tibia and fibula. Proximally, medullary cavity volume was greater in the older groups in the tibia but not the fibula. Distally, the only difference found in either bone was a significantly greater fibular medullary cavity in the very old group. These findings suggest weight-bearing bones in women are more susceptible than non-weight-bearing bones to age-related changes in bone geometry likely due to decreases in weight-bearing activities. Also, weight-bearing activity appears to provide a greater osteogenic stimulus at the distal portions of the leg bones.     

The Effect of Bone Loss Pattern on the Structural Capacity of the Proximal Femur

The effect of age-related bone loss on the structural capacity of the proximal femur were investigated by Finite Element Analysis(FEA). Four bone loss patterns were considered. These were “uniform cortical bone loss“, “neck cortical bone loss“, “intertrochanteric cortical bone loss“ and “uniform trabecular bone loss“. The results show that the two “non-uniform cortical bone loss“ patterns are more dangerous than the “uniform cortical bone loss“ pattern, and that the cortical bone loss in intertrochanteric region is associated with a greater reduction in cortical failure load than the cortical bone loss in the femoral neck. The trabecular bone loss causes a limited decrease in both cortical failure and trabecular failure loads. This research should be helpful to the clinical assessment of femur fracture risk due to age-related bone loss.     

Age-related hypermineralization in the female proximal human femur.

Hip fracture incidence increases exponentially with age in virtually every human population that has been studied. In spite of this, relatively few studies have examined age-related changes in the metaphyseal cortex of the proximal femur. The present study investigates cortical aging changes in the female proximal femur, with particular reference to regions of hypermineralization. Thirty-three femora from Caucasian females were obtained at autopsy and analyzed using backscattered electron imaging. Variations in hypermineralized tissue area, cortical bone area, and porosity were quantified with standard stereological methods. Cortical width was quantified with digital calipers. Gender differences were examined by statistical comparison with previously published results. Hypermineralized tissue volume was significantly (P < 0.001) greater in elderly individuals. Hypermineralized tissue preferentially appeared near ligamentous or tendinous insertion sites, suggesting the hypermineralized tissue may be a calcified fibrocartilage. Cortical width significantly (P < 0.001) decreased with age and porosity significantly (P < 0.001) increased with age, however the changes were site-specific. The femoral neck and intertrochanteric cortices had a smaller change in cortical width and porosity with age than the diaphysis, but the femoral neck and intertrochanteric cortices had a larger increase in hypermineralized tissue. Comparison with previous data suggests that cortical aging in the proximal femur is similar between males and females and is unlikely to explain the higher incidence of fracture in females. However, the data strongly indicates that age-related changes in the femoral diaphysis cannot be directly extrapolated to either the femoral neck or intertrochanteric cortices.     

Vascularized the greater trochanter grafting treatment cysts of the femoral neck

Bone cyst is a common benign bone tumor lesion, it is characterized by a clear boundary appearing round or oval osteolytic area, cortical bone thinning, and sometimes it can be visible sclerotic margin. Limb long bone cysts occur more common shares, the current jaw bone cysts are also relatively common, and most patients are asymptomatic. Femoral neck bone cyst can lead to pain and pathologic fractures, which is one of the main reasons why patients are in treatment. Due to the lesion site and patients age specificity of femoral proximal bone cysts especially femoral neck bone cysts in young adults, treatment is necessary to completely remove the lesion to prevent cyst recurrence, but also as far as possible to restore function in patients with hip joint.     

Bone histomorphometric changes in the femoral neck of aging and ovariectomized rats

Background: This study characterizes the changes in cortical and cancellous bone and cross sectional moment of inertia of the femoral neck from aging and ovariectomized (ovx'd) rats to determine their role in the previously reported ovx-induced reduction of mechanical strength in the femoral neck. Methods: Undecalcified double-fluorescent lableled cross sections of femoral neck of 3.5-, 5.5-, 6.5-, and 8.5-month-old female rats and rats ovx'd at 3.5 months for 2, 3, and 5 months of 45 rats were studied. The estimated endocortical and trabecular surfaces, cortical and cancellous bone histomorphometry, and cortical moment of inertia were determined. Results: The femoral neck was adding cortical bone between 3.5 and 5.5 months of age by increasing cortical thickness and decreasing marrow cavity area. No change of cortical bone mass was found between 5.5 and 8.5 months and the same amount of cancellous bone was observed between 3.5 and 8.5 months of age. Ovariectomy-induced cancellous, but not cortical bone loss. The loss was due to a transient ovx-induced negative bone balance that by 5 months post-ovx produced a 42% loss in trabecular bone while the histomorphometry profiles were the same as controls. The crosssectional moment of inertia increased with age but did not differ significantly between ovx'd and controls. Conclusions: Our findings suggest that the ovx-induced cancellous bone loss could be a contributing factor to the reduced mechanical strength in the femoral neck of ovx'd rats reported previously. © 1995 Wiley-Liss, Inc.     

Decreased femoral diaphyseal mechanical strength mainly due to qualitative impairment of cortical tissue in growing rats with stress erythropoiesis

Stress erythropoiesis (SE) can be defined as a state of increased red cell production in response to an enhanced secretion of erythropoietin. Under normal conditions, erythropoiesis in the adult occurs in the erythropoietic tissue that is confined to the bone marrow within the skeleton. Hypertrophy of the erythropoietic marrow that occurs during SE must be accommodated in a larger space. The resulting expansion of the marrow space may induce bone resorption and could alter the biomechanical performance of bone. The present study was designed to estimate the effect of sustained SE on diaphyseal structure and biomechanics of rat femur by mechanically testing the diaphyseal stiffness and strength and calculating some indicators of bone material properties. Female Sprague–Dawley rats weighing 100.0 ± 5.2 g were divided in a control (C) and an experimental (E) group. E rats were biweekly injected with 60 mg/kg of phenylhydrazyne during 6 weeks to induce a haemolytic state. SE, in response to haemolysis, was estimated by reticulocyte count and erythrokinetic techniques, which were markedly increased. To assess bone mechanical properties, the right femur was tested in three-point bending test. Sections of the left femur were stained with haematoxylin–eosin. Body growth was not altered by treatment. Diaphyseal bone mass (CSA) was 13% lower in E than in C rats, while the cross-sectional bending moment of inertia (xCSMI) was significantly higher. The “load capacity” extrinsic properties of the femoral diaphysis were about 40% decreased in E rats when compared to C ones, while the bone material quality indicators (elastic modulus and yield stress of cortical bone tissue) were 54 and 38% lower, respectively. The histologic sections of E femora exhibited a marked thinning of cortical bone and the presence of woven bone in the medullary compartment. The results obtained in this study indicate that SE caused the impairment of the diaphyseal bone material properties (elastic modulus and elastic stress) but enhanced xCSMI over the control values. Neither this improvement in diaphyseal cross-sectional design nor the formation of woven bone could offset the impairment in the bone material stiffness. It is thus proposed that the biomechanical impact of SE upon the whole-bone stiffness should have been more determined by the negative effect on bone material quality than by the negative changes in the cortical area.     

Distance of walking in childhood and femoral bone density in perimenopausal women

Kuopio osteoporosis risk factor and prevention (OSTPRE) study is a population-based study from Eastern Finland. At baseline in 1989–91, bone densitometry of lumbar spine and femoral neck as assessed by DXA was carried out on women aged 48–58 (n = 3,222). In 1993, menarcheal age and health habits during adolescence were inquired from a postal inquiry. In 1996, a random sample of 254 women who had been premenopausal at baseline was interviewed over phone. They were asked how many kilometers per day they had walked to school and back, in each grade of primary school. The study sample (N = 185) was formed by excluding women with menarcheal age of >14 or <11 years. Women with any reported HRT history were also excluded. The mean age of the study sample was 50.7 (1.63) years, weight 70.8 (13.1) kg, height 161.5 (5.0) cm, and mean walking distance to and fro from the school at ages from 9 to 11 years was 2.7 (1.7) km. In regression analysis, the walking distance was associated with femoral BMD (r = 0.18, P = 0.015). After adjusting for baseline age, weight and height, this association persisted (P = 0.025). When walking distance was categorized as I = 0–0.549 km, II = 0.55–1.99 km, III = 2.0–4.99 and IV = 5.0 km and more, the respective means for femoral BMDs were 0.92, 0.97, 0.98 and 1.01 g/cm². Statistical significance persisted after adjusting for height, weight, age, grip strength, calcium intake, smoking, place of residence, use of contraceptive pills, physical load of work and baseline physical activity (P = 0.032). A 10 year follow-up revealed no changes in bone loss rate between the groups and femoral BMD benefits persisted (repeated measures analysis = NS). Walking distance was not associated with spinal bone density. Even though walking is a low impact activity, walking before menarche may have a moderate but long-lasting positive effect on femoral peak bone density. Lack of walking and similar low impact physical activities during peak growth years may have a negative effect on peak bone mass formation.     

Age‐related hypermineralization in the female proximal human femur

Hip fracture incidence increases exponentially with age in virtually every human population that has been studied. In spite of this, relatively few studies have examined age‐related changes in the metaphyseal cortex of the proximal femur. The present study investigates cortical aging changes in the female proximal femur, with particular reference to regions of hypermineralization. Thirty‐three femora from Caucasian females were obtained at autopsy and analyzed using backscattered electron imaging. Variations in hypermineralized tissue area, cortical bone area, and porosity were quantified with standard stereological methods. Cortical width was quantified with digital calipers. Gender differences were examined by statistical comparison with previously published results. Hypermineralized tissue volume was significantly (P < 0.001) greater in elderly individuals. Hypermineralized tissue preferentially appeared near ligamentous or tendinous insertion sites, suggesting the hypermineralized tissue may be a calcified fibrocartilage. Cortical width significantly (P < 0.001) decreased with age and porosity significantly (P < 0.001) increased with age, however the changes were site‐specific. The femoral neck and intertrochanteric cortices had a smaller change in cortical width and porosity with age than the diaphysis, but the femoral neck and intertrochanteric cortices had a larger increase in hypermineralized tissue. Comparison with previous data suggests that cortical aging in the proximal femur is similar between males and females and is unlikely to explain the higher incidence of fracture in females. However, the data strongly indicates that age‐related changes in the femoral diaphysis cannot be directly extrapolated to either the femoral neck or intertrochanteric cortices. Anat Rec 255:202–211, 1999. © 1999 Wiley‐Liss, Inc.     

Sensitivity of patient-specific vertebral finite element model from low dose imaging to material properties and loading conditions

Patient-specific modeling could help in predicting vertebral osteoporotic fracture. The accuracy requirement for input data available in clinical routine is related to the model sensitivity. The objective of this study is to assess the relative impact of material properties and of loading conditions on vertebral strength using a finite element model. Fourteen subject-specific vertebral finite element models were used to investigate the effect of material properties and loading conditions. A design of experiment was set to study three parameters: Young’s moduli of trabecular bone and cortico-trabecular bone (outer 3 mm of the vertebra), and load location. Cortico-trabecular bone modulus variation from 270 to 478 MPa made fracture load vary from 22 to 51%, depending on other parameters. Trabecular bone modulus variation from 115 to 258 MPa made fracture load vary from 11 to 43%. Displacing load location by 1 cm resulted in a mean decrease of 48–60% of the fracture load. Anterior bending induced strain concentration in vertebral anterior wall. Material properties of both type of bone have about the same effect. Load location is the most sensitive. Effort should be made to take into account patients’ specific load distribution regarding its sagittal balance, in addition to bone properties.     

The Effects of Interfacial Conditions and Stem Length on Potential Failure Mechanisms in the Uncemented Resurfaced Femur

It is hypothesized that changes in stem length and implant–bone interfacial conditions would affect the mechanical environment within the uncemented resurfaced femur, thereby influencing potential short- and long-term failure mechanisms. This study is aimed at investigating the influence of changes in implant–bone interfacial conditions and stem length on eventual failure, using 3D FE models integrated with bone remodeling simulations. Musculoskeletal forces corresponding to normal walking and stair climbing were used as applied loading conditions. Sliding micromotions of 26–72 μm at the implant–bone interfaces for both the stem designs suggest bone ingrowth on the coated surface of the implant was likely. The initial risk of femoral neck fracture was less for the uncemented designs as compared to the cemented designs, irrespective of interfacial conditions and variation in stem length. For the uncemented variety, shortening the stem length provided only slight advantages (5%) with regard to strain shielding and bone remodeling. However, bone resorption was considerably higher when fully bonded interfaces were simulated. It may, therefore, be concluded that cementless fixation seems to be a viable alternative to cemented fixation, provided sufficient initial fixation and secondary stability through bone ingrowth into the coated surface of the implant can be achieved.     

Nanostructure and mineral composition of trabecular bone in the lateral femoral neck: implications for bone fragility in elderly women

Despite interest in investigating age-related hip fractures, the determinants of decreased bone strength in advanced age are not clear enough. Hitherto it has been obscure how the aging process affects the femoral neck nanostructure and composition, particularly in the lateral subregion of the femoral neck, which is considered as a fracture-initiating site. The femoral bone samples used in this study were obtained at autopsy in 10 women without skeletal disease (five younger: aged 20-40 years, and five elderly: aged 73-94 years). Atomic force microscopy (AFM) was applied to explore the mineral grain size in situ in young vs. old trabecular bone samples from the lateral femoral neck. The chemical compositions of the samples were determined using inductively coupled plasma optical emission spectroscopy and direct current argon arc plasma optical emission spectrometry. Our AFM study revealed differences in trabecular bone nanostructure between young and elderly women. The mineral grain size in the trabeculae of the old women was larger than that in the young (median: 95 vs. 59nm), with a particular bimodal distribution: 45% were small grains (similar to the young) and the rest were larger. Since chemical analyses showed that levels of calcium and phosphorus were unchanged with age, our study suggests that during aging the existing bone mineral is reorganized and forms larger aggregates. Given the mechanical disadvantage of large-grained structures (decreased material strength), the observed nanostructural differences contribute to our understanding of the increased fragility of the lateral femoral neck in aged females. Moreover, increasing data on mineral grains in natural bone is essential for advancing calcium-phosphate ceramics for bone tissue replacement.     

Morphological profile of atypical femoral fractures: age‐related changes to the cross‐sectional geometry of the diaphysis

The use of bisphosphonates for osteoporosis patients has markedly decreased the incidence of femoral neck or trochanteric fractures. However, anti‐osteoporosis drugs have been reported to increase the incidence of atypical femoral fractures, which involve stress fractures in the subtrochanteric region or the proximal diaphysis. In this study, the morphological characteristics of the cortical bone in human femoral diaphysis samples were analyzed from individuals who lived before bisphosphonate drugs were available in Japan. A total of 90 right femoral bones were arbitrarily selected (46 males and 44 females) from modern Japanese skeletal specimens. Full‐length images of these femurs were acquired using a computed tomography scanner. An image processing method for binarization was used to calculate the threshold values of individual bones for determining their contours. The range between the lower end of the lesser trochanter and the adductor tubercle of each femur was divided at regular intervals to obtain 10 planes. The mean value of cortical bone thickness, periosteal border length, and the cortical cross‐sectional area was evaluated for all planes. Moreover, the ratio of the area of the cortical bone to the total area of cross‐section at the mid‐diaphysis was calculated. A comparison between males and females demonstrated that most females had lower cortical bone area ratios at the mid‐diaphysis. The femoral outer shape did not differ markedly according to age or sex; however, substantial individual differences were observed in the shape of the inner surface of the cortical bone. The cortical bone thickness and the cross‐sectional area decreased with age in the femoral diaphysis; furthermore, in females, the decrease was higher for the former than for the latter. This may be due to a compensatory increase in the circumference of the femoral diaphysis. In addition, in about half of the subjects there was a discrepancy between the region with maximal value of the cortical bone thickness and that of the total cross‐sectional area. Biological responses to mechanical stresses to the femoral diaphysis are thought not to be uniform. Bisphosphonates inhibit bone resorption and may promote non‐physiological bone remodeling. Thus, a nonhomogeneous decrease in cortical thickness may be related to the fracture occurrence in the femoral diaphysis in some cases. Thus, long‐term administration of bisphosphonates in patients with morphological vulnerability in the femoral cortical bones may increase the occurrence of atypical femoral fractures.     

Evidence of a hypermineralised calcified fibrocartilage on the human femoral neck and lesser trochanter

Femoral neck fractures are a major cause of morbidity and mortality in elderly humans. In addition to the age‐related loss of cancellous bone, changes to the microstructure and morphology of the metaphyseal cortex may be a contributing factor in osteoporotic hip fractures. Recent investigations have identified a hypermineralised tissue on the neck of the femur and trochanteric region that increases in fractional area with advancing age in both males (Boyce & Bloebaum, 1993) and females (Vajda & Bloebaum, 1999). The aim of this study was to determine if the hypermineralised tissue previously observed on the proximal femur is calcified fibrocartilage. Regional variations in the fractional area of hypermineralised tissue, cortical bone, and porosity of the cortical bone along the neck of the femur and lesser trochanter were also quantified. Comparison of back scattered electron and light microscope images of the same area show that regions of hypermineralised tissue correlate with the regions of calcified fibrocartilage from tendon and capsular insertions. The hypermineralised tissue and calcified fibrocartilage had similar morphological features such as the interdigitations of the calcified fibrocartilage into the bone, lacunar spaces, and distinctly shaped pores adjacent to the 2 tissues. Regions of the neck that did not contain insertions were covered with periosteum. There were no regional differences (P > 0.05) on the superior and inferior femoral neck in terms of the percentage area of hypermineralised calcified fibrocartilage, cortical bone, or cortical bone porosity. The lesser trochanter exhibited regional differences in the fractional area of hypermineralised calcified fibrocartilage (P = 0.007) and cortical bone (P = 0.007) but not porosity of the cortical bone (P > 0.05). The effects of calcified fibrocartilage on femoral neck periosteal expansion, repair, and mechanics are unknown, but may play a role in osteoporotic fractures and intracapsular fracture healing.     

Modelling of age-related bone loss using cross-sectional data

Background : Current applications of bone mineral density (BMD) data in age studies are not free of certain drawbacks. Since it is well established that age-related patterns of BMD changes involve three distinct periods (bone acquisition in youth, stabilization at maturity, and decrease with ageing), adjusting for age via an inappropriate mathematical function may lead to inconsistencies and wrong conclusions. Hypothesis : The piecewise model, which encompasses the above three periods, will accurately describe the BMD dependence on age. Objective : To examine age-related patterns of BMD changes using a number of possible mathematical functions and to find among them the best-fitting function. Next, to test whether the chosen function is universally applicable or if there are diverse population-specific functions. Material and methods : Thirteen ethnic samples from various regions of Europe and Asia, assigned into five ethnic-geographic groups, were examined. The total sample included 2430 males and 2515 females. Compact BMD of hand phalanges was measured by photodensitometry from plain radiographs of each individual studied. Statistical software was developed for the purposes of the present study; this software gave a maximum likelihood of the parameter estimates for various statistical models (functions). Results : In all samples of sufficient size and representative age range, a two-interval function was found as the best fitting and most parsimonious model to describe the BMD age-related changes. This two-interval function was characterized by age-related bone mass increase, positive slope &#103 1s in young age or a plateau ( &#103 1s = 0, i.e. no age-related changes) until a sex-specific age threshold, T 0, after which annual bone loss ensued with a slope coefficient &#103 2s. Threshold of BMD loss in women of different ethnic groups ranged between 37.85 and 47.77 years, and roughly coincided with perimenopausal age. In males, the age T 0 varied between 27.85 and 49.07 years. The ensuing cortical bone loss appeared to be linear in both sexes, averaging between 0.51% and 1.15% in men and between 0.74% and 1.77% per year of young age BMD value in females. Conclusions : The change of phalangeal BMD with age may be best described by a two-interval function, regardless of sex and ethnic background. However, specific parameter estimates depend both on gender and ethnic affiliation. This study has yielded a well-fitted model of BMD dependence on age suitable for further use in population studies.     

股骨颈内定位器的研究与设计

目的研发一种适用于治疗老年股骨颈骨折时打入空心加压螺钉的定位器。方法根据老年人股骨颈Ward氏三角区骨小梁稀疏、常被脂肪充填、类似＂髓腔＂的解剖特点设计一种定位器。定位器由位于头端的定位齿和位于尾部的固定柄、操作柄、从动齿、衔接器和导引器等部件构成。应用时在股骨上端外侧与股骨颈中轴线相交处的骨皮质上开一骨窗,定位器头端经此骨窗伸到Ward氏三角区内,体外操作,控制头端定位齿在股骨颈内部确定空心钉打入位置,导引器上的导引孔瞄准定位齿所确定的位置准确打入导针。结果通过旋转、撑开、合拢三个简单动作,可使头端定位齿很方便地探触到股骨颈皮质骨内侧面时钟2点、6点和10点等点位。无论头端定位齿撑开与合拢程度如何,导引器上的多个可供选择的导引孔始终都准确地瞄准定位齿所确定的位置,准确打入导针。结论本定位器结构简单、操作简便、定位准确,值得在临床上推广应用。     

Computational simulations of stress shielding and bone resorption around existing and computer-designed orthopaedic screws

Failure of an orthopaedic fixation due to stress shielding and consequent screw loosening is a major concern among surgeons: the loosened screws could not only interfere with the healing process but also endanger adjacent anatomical structures. In this study, the effect of the screw's engineering design (dimensions, profile shape and material properties) on the load sharing with adjacent bone and consequent bone resorption was tested, using a set of two-dimensional computational (finite element) models. An algorithm simulating local bone adaptation to strain energy density (SED) mechanical stimuli was developed and used to evaluate the biomechanical performances of different commercial screws. Two new designs, a ‘graded-stiffness’ composite screw, with a reduced-stiffness titanium core and outer polymeric threads, and an active-compression hollow screw that generates compressive stresses on the surrounding bone, were also evaluated. A dimensionless set of stress transfer parameters (STPs) were utilised for ranking the performances of the different screws according to the expected screw-bone load sharing and its evolution with adaptation of the surrounding tissue. The results indicated that commercial wide (6mm thread diameter) trapezoidal and rectangular screw profiles have superior biomechanical compatibility with bone (i.e. predicted to be stable after 2 years). The graded-stiffness and active-compression screws provided the best biomechanical performances: bone loading around them was predicted to decrease by no more than 15% after 3 years, compared with a decrease of 55–70% in bone loading around commercially available screws. Computer simulations of bone adaptation around orthopaedic screws are demonstrated to be effective means for objective and quantitative evaluation of the biomechanical aspects of implant-tissue compatibility.     

股方肌骨瓣治疗陈旧性青壮年股骨颈骨折

目的探讨股方肌骨瓣移植加中空钉固定治疗青壮年陈旧性股骨颈骨折临床效果。方法自2001年4月至2008年12月,采用后外侧切口,骨折切开复位,空心钉加股方肌骨瓣移植治疗青壮年股骨颈骨折39例,男24例,女15例,年龄19~41岁,平均29岁,受伤时间2~14个月,平均5.8个月,大部分病例伴有不同程度的肢体短缩及关节活动受限。结果36例随访11~86个月,平均28个月。骨折全部愈合,愈合时间5~11个月,平均8.3个月。Harris髋关节功能评分平均为90.6分。随访期间3例发生股骨头坏死,1例行关节置换。结论该手术方法疗效满意,是青壮年陈旧性股骨颈骨折的一种有效治疗方法,可以改善骨折端血运,促进骨折愈合,降低股骨头坏死率。     

股骨近端髓腔闪烁指数与股骨颈骨密度的关系

背景：髋关节成形患者具有较高的骨质疏松症患病率,骨质疏松症影响假体存活率,髓腔闪烁指数与骨密度均随年龄变化。 目的：探讨股骨近端髓腔闪烁指数与股骨颈骨密度的关系,提高对骨质疏松症的关注。 方法：回顾性研究57例髋关节成形患者的骨盆X射线正位片的股骨近端髓腔闪烁指数和股骨颈骨密度,探讨二者的相关性。 结果与结论：57例髋关节成形患者的股骨近端髓腔闪烁指数为1.8-4.8(3.1±0.7);髓腔闪烁指数< 3者23例,髓腔闪烁指数为3-4.7者33例,髓腔闪烁指数> 4.7者1例。年龄对髓腔类型有影响,> 60岁组烟囱型髓腔显著性多于≤ 60岁组,髓腔闪烁指数≥ 3组的骨密度显著高于髓腔闪烁指数< 3组。随着年龄增高,股骨颈骨密度降低,> 60岁组患者的股骨颈骨密度为(0.590±0.092) g/cm2,显著低于≤ 60岁组患者的股骨颈骨密度(0.751±0.235) g/cm2(P =0.000),比较发现随骨密度降低,髓腔闪烁指数均值变小。因此股骨颈骨密度与髓腔闪烁指数显著相关。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

Information processing limitations with aging in the visual scaling of isometric force

The experiment examined if age-related increases in force variability were due to decreases in visual acuity and/or visual-motor information processing deficits. Visual information scale was manipulated over a 250-fold range as young (20–29 years old) and old (60–79 years old) participants produced isometric force output to a visually presented target. Older adults were found to have a very small decrement in visual acuity, but there was no relation between visual acuity and force variability. Force variability exhibited a U-shaped trend as a function of visual information scale. Young adults had less relative variability and higher visual information transfer than the oldest old and these age differences increased with visual information scale. It is concluded that the age-related declines in visual-motor information processing influence changes in neuromuscular function and the emergent differences in force variability at the behavioral level.     

Reduced aminergic synthesis in the hypothalamus of the infertile,genetically diabetic (C57BL/KsJ-db/db) male mouse

Summary Diabetes mellitus is commonly associated with reproductive neuroendocrinopathy in both humans and animal models for the disease. Diabetes-associated reproductive failure in the male is a result of multilevel dysfunction within the hypothalamo-pituitary-testicular axis. In view of the known effects of diabetes on hypothalamic gonadotropin-releasing hormone (GnRH) and gonadotropins in chemically-induced animal models for diabetes, we examined hypothalamic aminergic activities (important to the regulation of GnRH release), circulating gonadotropin levels and testicular morphology in the infertile, genetically diabetic (C57BL/KsJ-db/db) male mouse. Groups of 2–5 month old (average age: 3.4 months) and 6–11 month old (average age: 8.8 months) diabetic mice were compared with age-matched non-diabetic (C57BL/KsL-+/?) male mice. Diabetic mice in both age groups were markedly obese and hyperglycemic. Hypothalamic serotonin synthesis was inhibited in the preoptic area-anterior hypothalamus (POA-AH) in both 2–5 month old and 6–11 month old diabetic mice as well as in the mediobasal hypothalamus-median eminence (MBH-ME) of 6–11 month old diabetic mice. Catecholamine synthesis (norepinephrine and dopamine) was reduced in the POA-AH of 2–5 month old diabetic mice and in the MBH-ME of 6–11 month old mice. These aminergic changes were associated in 2–5 month old diabetic mice with reduced circulating levels of LH and in 6–11 month old diabetic mice, of both LH and FSH. In 6–11 month old diabetic mice, testes were characterized by a thickened tunica albuginea, numerous Sertoli cells and the near absence of any spermatogenic cells. The epididymis from these diabetic mice was devoid of spermatozoa. In considering the central role played by these hypothalamic amine systems in regulating GnRH release and thus reproductive function, these results suggest, at least in part, an explanation for the infertility associated with the genetically diabetic male mouse.