A silk-based high impact composite for the core decompression of the femoral head.

Core decompression of the femoral head is a recommended head-conserving strategy for early-stage osteonecrosis of the femoral head. However, no ideal filling material has been found so far. In this study, we fabricated a "solid core-porous coating" composite scaffold, which is a silk fibroin/hydroxypropyl methylcellulose (SF/HPMC) scaffold, by a "two-step" process. The solid core scaffold possesses a sufficient compression modulus (860 MPa) for support, while the porous coating scaffold with controllable pore size and porosity provides a suitable microenvironment for the osteoblast cell to adhere and proliferate. Moreover, the porous coating scaffold was mineralized by adding different contents of hydroxyapatite crystal to further enhance its osteoinductivity, according to the simulated body fluid (SBF) biomineralization assay. To demonstrate the biocompatibility and osteoinductivity of such composite scaffolds, a series of in vitro experiments were performed, indicating the MC3T3-E1 pre-osteoblast cells grew and differentiated well on the mineralized porous coating scaffolds. The mechanical testing results also proved that the mechanical property of the solid core scaffold varied (230-1600 MPa) with different solid contents of SF/HPMC, as expected. Furthermore, the rabbit femoral head core decompression model was adopted and confirmed the excellent mechanical performance of the solid core scaffolds, as well as the satisfied osteoinductivity of the porous coating scaffold, by inserting the composite scaffolds into the bone tunnel in vivo. All of the preliminary results implied that the novel biodegradable composite scaffold has an outstanding prospective for the clinical use of core decompression of the femoral head.

Wear particles induce a new macrophage phenotype with the potential to accelerate material corrosion within total hip replacement interfaces.

Evidence that macrophages can play a role in accelerating corrosion in CoCrMo alloy in total hip replacement (THR) interfaces leads to questions regarding the underlying cellular mechanisms and immunological responses. Hence, we evaluated the role of macrophages in corrosion processes using the cell culture supernatant from different conditions and the effect of wear particles on macrophage dynamics. Monocytes were exposed to CoCrMo wear particles and their effect on macrophage differentiation was investigated by comparisons with M1 and M2 macrophage differentiation. Corrosion associated macrophages (MCA macrophages) exhibited upregulation of TNF-α, iNOS, STAT-6, and PPARG and down-regulation of CD86 and ARG, when compared to M1 and M2 macrophages. MCA cells also secreted higher levels of IL-8, IL-1ß, IL-6, IL-10, TNF-α, and IL-12p70 than M1 macrophages and/or M2 macrophages. Our findings revealed variation in macrophage phenotype (MCA) induced by CoCrMo wear particles in generating a chemical environment that induces cell-accelerated corrosion of CoCrMo alloy at THR modular interfaces. STATEMENT OF SIGNIFICANCE: Fretting wear and corrosion within the implant's modular taper junction are prominent causes of implant failure, as they promote the release of corrosion products and subsequent development of adverse local tissue reactions. Being a multifactorial process, several in vitro models have been developed to recreate the in vivo corrosion process, often summarized as mechanically-assisted crevice corrosion. Considering the excellent corrosion properties of CoCrMo alloy, the severity of chemically-generated damage observed at the modular interface has been surprising and poorly understood. The aim of the current study is to provide a better understanding of macrophages and their plasticity at the THR taper interface when they encounter wear debris from CoCrMo alloy. This is a preliminary study along the path towards determining the mechanism(s) of CAC.

Micro-finite-element method to assess elastic properties of trabecular bone at micro- and macroscopic level.

OBJECTIVE OF THE STUDY: The objective of the present study is to assess the mechanical behavior of trabecular bone based on microCT imaging and micro-finite-element analysis. In this way two methods are detailed: (i) direct determination of macroscopic elastic property of trabecular bone; (ii) inverse approach to assess mechanical properties of trabecular bone tissue. PATIENTS: Thirty-five females and seven males (forty-two subjects) mean aged (±SD) 80±11.7 years from hospitals of Assistance publique-Hôpitaux de Paris (AP-HP) diagnosed with osteoporosis following a femoral neck fracture due to a fall from standing were included in this study. MATERIALS AND METHODS: Fractured heads were collected during hip replacement surgery. Standardized bone cores were removed from the femoral head's equator by a trephine in a water bath. MicroCT images acquisition and analysis were performed with CTan® software and bone volume fraction was then determined. Micro-finite-element simulations were per-formed using Abaqus 6.9-2® software in order to determine the macroscopic mechanical behaviour of the trabecular bone. After microCT acquisition, a longitudinal compression test was performed and the experimental macroscopic Young's Modulus was extracted. An inverse approach based on the whole trabecular bone's mechanical response and micro-finite-element analysis was performed to determine microscopic mechanical properties of trabecular bone. RESULTS: In the present study, elasticity of the tissue was shown to be similar to that of healthy tissue but with a lower yield stress. CONCLUSION: Classical histomorphometric analysis form microCT imaging associated with an inverse micro-finite-element method allowed to assess microscopic mechanical trabecular bone parameters.

Successful disinfection of femoral head bone graft using high hydrostatic pressure.

The current standard for sterilization of potentially infected bone graft by gamma irradiation and thermal or chemical inactivation potentially deteriorates the biomechanical properties of the graft. We performed an in vitro experiment to evaluate the use of high hydrostatic pressure (HHP); which is widely used as a disinfection process in the food processing industry, to sterilize bone grafts. Four femoral heads were divided into five parts each, of which 16 were contaminated (in duplicate) with 105-107 CFU/ml of Staphylococcus epidermidis, Bacillus cereus, or Pseudomonas aeruginosa or Candida albicans, respectively. Of each duplicate, one sample was untreated and stored similarly as the treated sample. The remaining four parts were included as sterile control and non-infected control. The 16 parts underwent HHP at the high-pressure value of 600 MPa. After HHP, serial dilutions were made and cultured on selective media and into enrichment media to recover low amounts of microorganism and spores. Three additional complete femoral heads were treated with 0, 300 and 600 MPa HHP respectively for histological evaluation. None of the negative-control bone fragments contained microorganisms. The measured colony counts in the positive-control samples correlated excellent with the expected colony count. None of the HHP treated bone fragments grew on culture plates or enrichment media. Histological examination of three untreated femoral heads showed that the bone structure remained unchanged after HHP. Sterilizing bone grafts by high hydrostatic pressure was successful and is a promising technique with the possible advantage of retaining biomechanical properties of bone tissue.

Avascular Necrosis of Femoral Head: A Metabolomic, Biophysical, Biochemical, Electron Microscopic and Histopathological Characterization.

Avascular necrosis of the femur head (AVNFH) is a debilitating disease caused due to the use of alcohol, steroids, following trauma or unclear (idiopathic) etiology, affecting mostly the middle aged population. Clinically AVNFH is associated with impaired blood supply to the femoral head resulting in bone necrosis and collapse. Although Homocysteine (HC) has been implicated in AVNFH, levels of homocysteine and its associated pathway metabolites have not been characterized. We demonstrate elevated levels of homocysteine and concomitantly reduced levels of vitamins B6 and B12, in plasma of AVNFH patients. AVNFH patients also had elevated blood levels of sodium and creatinine, and reduced levels of random glucose and haemoglobin. Biophysical and ultrastructural analysis of AVNFH bone revealed increased remodelling and reduced bone mineral density portrayed by increased carbonate to phosphate ratio and decreased Phosphate to amide ratio together with disrupted trabeculae, loss of osteocytes, presence of calcified marrow, and elevated expression of osteocalcin in the osteoblasts localized in necrotic regions. Taken together, our studies for the first time characterize the metabolomic, pathophysiological and morphometric changes associated with AVNFH providing insights for development of new markers and therapeutic strategies for this debilitating disorder.

Microstructure and Nanomechanical Properties of Single Trabecular Bone in Different Regions of Osteonecrosis of the Femoral Head.

This study aimed to compare the microstructure and nanomechanical properties of single trabecular bone in different regions of osteonecrosis of the femoral head. Osteonecrotic femoral heads were taken from 20 patients undergoing total hip arthroplasties between 2011 and 2014. Following incision, resin was embedded and polished, and divided into four regions according to the type of pathologic change; i.e., subchondral bone, and necrotic, sclerotic, and healthy regions. Indents from a single trabecular bone of each region were randomly selected to undergo nanoindentation. The results are (1) The elastic modulus and degree of hardness were significantly elevated in the sclerotic region, but there were no differences in necrotic and subchondral bone regions compared with healthy regions. (2) The elastic modulus and hardness of the single trabecular bone were significantly greater in central versus edge regions (for all regions). The conclusions are (1) The mechanical properties of single bone trabeculae were not markedly altered in the necrotic region. (2) The elastic modulus and degree of hardness increased significantly between the edge and central regions, regardless of whether the bone was normal or osteonecrotic.

Organ-to-Cell-Scale Health Assessment Using Geographical Information System Approaches with Multibeam Scanning Electron Microscopy.

This study combines novel multibeam electron microscopy with a geographical information system approach to create a first, seamless, navigable anatomic map of the human hip and its cellular inhabitants. Using spatial information acquired by localizing relevant map landmarks (e.g. cells, blood vessels), network modeling will enable disease epidemiology studies in populations of cells inhabiting tissues and organs.

Effect of treatment with simvastatin on bone microarchitecture of the femoral head in an osteoporosis animal model.

The objective of this study was to evaluate the microarchitecture and trabecular bone strength at the distal region of the femur, and its biomechanical properties with simvastatin administration with two different doses in ovariectomized (OVX) rats. Ninety rats were divided into six groups to evaluate treatment with the simvastatin drug (n = 15): SH (Sham surgery), SH-5 (5 mg simvastatin), SH-20 (20 mg simvastatin), OVX, OVX-5, and OVX-20. Euthanasia was performed at three different times, five animals per period: 7, 14, and 28 days. The effectiveness of the treatments was evaluated by mechanical testing and histomorphometric analysis of the femurs. The results of analysis by the linear model of mixed effects showed 20 mg of simvastatin results in increased trabecular bone after 14 days (P = 0.039) of ingestion in ovariectomized animals. However, ingestion of 5 mg of simvastatin is able to sensitize the trabecular bone only at 28 days (P = 0.005) of ingestion. In the mechanical tests stiffness improves within 28 days (P = 0.003). Regarding maximum strength, no statistical differences were observed. According to these results, it can be concluded that for a decrease in oral intake, longer treatment times are required. Microsc. Res. Tech. 79:684-690, 2016. © 2016 Wiley Periodicals, Inc.

The Role of (99m)Tc-Annexin V Apoptosis Scintigraphy in Visualizing Early Stage Glucocorticoid-Induced Femoral Head Osteonecrosis in the Rabbit.

OBJECTIVE: To validate the ability of (99m)Tc-Annexin V to visualize early stage of glucocorticoid-induced femoral head necrosis by comparing with (99m)Tc-MDP bone scanning. METHODS: Femoral head necrosis was induced in adult New Zealand white rabbits by intramuscular injection of methylprednisolone. (99m)Tc-Annexin scintigraphy and (99m)Tc-MDP scans were performed before and 5, 6, and 8 weeks after methylprednisolone administration. Rabbits were sacrificed at various time points and conducted for TUNEL and H&E staining. RESULTS: All methylprednisolone treated animals developed femoral head necrosis; at 8 weeks postinjection, destruction of bone structure was evident in H&E staining, and apoptosis was confirmed by the TUNEL assay. This was matched by (99m)Tc-Annexin V images, which showed a significant increase in signal over baseline. Serial (99m)Tc-Annexin V scans revealed that increased (99m)Tc-Annexin V uptake could be observed in 5 weeks. In contrast, there was no effect on (99m)Tc-MDP signal until 8 weeks. The TUNEL assay revealed that bone cell apoptosis occurred at 5 weeks. CONCLUSION: (99m)Tc-Annexin V is superior to (99m)Tc-MDP for the early detection of glucocorticoid-induced femoral head necrosis in the rabbit and may be a better strategy for the early detection of glucocorticoid-induced femoral head necrosis in patients.

Comparison of microstructural and mechanical properties of trabeculae in femoral head from osteoporosis patients with and without cartilage lesions: a case-control study.

BACKGROUND: Degeneration of cartilage will change load distribution, affecting bone remodeling progress and trabecular structure and strength. However, in human primary osteoporosis, whether cartilage lesions would also affect properties beneath trabecular bone remains unknown. In this study, we explored the differences in local trabecular properties between osteoporosis patients with and without cartilage lesions. METHODS: Eighteen pairs of femoral heads with and without cartilage lesions in a weight-bearing area were collected from senile femoral neck fracture patients. The Mankin score and glycosaminoglycan (GAG) content were used to evaluate the severity of the cartilage lesions. Micro-CT and compression tests were used to obtain structural and mechanical characteristics of each trabecular column. Multivariate linear regression was performed to evaluate the association between mechanical parameters and the degree of cartilage lesion. RESULTS: In osteoporosis patients with cartilage lesions, the bone volume fraction (BV/TV) and trabecular thickness (Tb.Th) of the trabecular column were significantly higher than that of osteoporotic control patients (all P < 0.05), while the Young's modulus was lower (P = 0.024). Multivariable linear regression indicated that in both groups, bone mineral density (BMD) significantly correlated with Young's modulus (all P < 0.05). While in patients with cartilage lesion, GAG content was also correlated with Young's modulus (standardized coefficient 0.443, P < 0.01). CONCLUSIONS: Osteoporosis patients with cartilage lesions exhibited a weaker mechanical property of trabeculae. The intimate association of cartilage lesions and impairment of trabecular mechanical properties indicate that cartilage and trabeculae belong to an interdependent functional unit. Previously proposed adaptive mechanisms in osteoarthritis might also be applicable to the progression of osteoporosis.

Osseointegration of fiber-reinforced composite implants: histological and ultrastructural observations.

OBJECTIVES: The aim of this study was to evaluate the bone tissue response to fiber-reinforced composite (FRC) in comparison with titanium (Ti) implants after 12 weeks of implantation in cancellous bone using histomorphometric and ultrastructural analysis. MATERIALS AND METHODS: Thirty grit-blasted cylindrical FRC implants with BisGMA-TEGDMA polymer matrix were fabricated and divided into three groups: (1) 60s light-cured FRC (FRC-L group), (2) 24h polymerized FRC (FRC group), and (3) bioactive glass FRC (FRC-BAG group). Titanium implants were used as a control group. The surface analyses were performed with scanning electron microscopy and 3D SEM. The bone-implant contact (BIC) and bone area (BA) were determined using histomorphometry and SEM. Transmission electron microscopy (TEM) was performed on Focused Ion Beam prepared samples of the intact bone-implant interface. RESULTS: The FRC, FRC-BAG and Ti implants were integrated into host bone. In contrast, FRC-L implants had a consistent fibrous capsule around the circumference of the entire implant separating the implant from direct bone contact. The highest values of BIC were obtained with FRC-BAG (58±11%) and Ti implants (54±13%), followed by FRC implants (48±10%), but no significant differences in BIC or BA were observed (p=0.07, p=0.06, respectively). TEM images showed a direct contact between nanocrystalline hydroxyapatite of bone and both FRC and FRC-BAG surfaces. CONCLUSION: Fiber-reinforced composite implants are capable of establishing a close bone contact comparable with the osseointegration of titanium implants having similar surface roughness.

Seven day insertion rest in whole body vibration improves multi-level bone quality in tail suspension rats.

OBJECTIVE: This study aimed to investigate the effects of low-magnitude, high-frequency vibration with rest days on bone quality at multiple levels. METHODS: Forty-nine three-month-old male Wistar rats were randomly divided into seven groups, namely, vibrational loading for X day followed by X day rest (VLXR, X = 1, 3, 5, 7), vibrational loading every day (VLNR), tail suspension (SPD), and baseline control (BCL). One week after tail suspension, rats were loaded by vibrational loading (35 Hz, 0.25 g, 15 min/day) except SPD and BCL. Fluorescence markers were used in all rats. Eight weeks later, femora were harvested to investigate macromechanical properties, and micro-computed tomography scanning and fluorescence test were used to evaluate microarchitecture and bone growth rate. Atomic force microscopy analyses and nanoindentation test were used to analyze the nanostructure and mechanical properties of bone material, respectively. Inductively coupled plasma optical emission spectroscopy was used for quantitative chemical analyses. RESULTS: Microarchitecture, mineral apposition rate and bone formation rate and macromechanical properties were improved in VL7R. Grain size and roughness were significantly different among all groups. No statistical difference was found for the mechanical properties of the bone material, and the chemical composition of all groups was almost similar. CONCLUSIONS: Low-magnitude, high-frequency vibration with rest days altered bone microarchitecture and macro-biomechanical properties, and VL7R was more efficacious in improving bone loss caused by mechanical disuse, which provided theoretical basis and explored the mechanisms of vibration for improving bone quality in clinics.

Subchondral insufficiency fracture of the femoral head after internal fixation for femoral neck fracture: histopathological investigation.

Late segmental collapse after internal fixation for femoral neck fracture is the phenomenon observed in post-traumatic osteonecrosis of the femoral head (ON), which has generally been reported to occur over a year or more after internal fixation. Subchondral insufficiency fracture of the femoral head (SIF) has also been recognized to cause femoral head collapse, however, only two cases of SIF after internal fixation for femoral neck fracture have been reported. We report a case with femoral head collapse observed 5 months after internal fixation for femoral neck fracture, which was histopathologically diagnosed as SIF. Clinically, differentiating SIF from ON is important because some cases of SIF have been reported to heal without surgical treatments. The timing of femoral head collapse after femoral neck fracture may be different between SIF and post-traumatic ON.

The therapeutic effect of negative pressure in treating femoral head necrosis in rabbits.

Because negative pressure can stimulate vascular proliferation, improve blood circulation and promote osteogenic differentiation of bone marrow stromal cells, we investigated the therapeutic effect of negative pressure on femoral head necrosis (FHN) in a rabbit model. Animals were divided into four groups (n = 60/group): [1] model control, [2] core decompression, [3] negative pressure and [4] normal control groups. Histological investigation revealed that at 4 and 8 weeks postoperatively, improvements were observed in trabecular bone shape, empty lacunae and numbers of bone marrow hematopoietic cells and fat cells in the negative pressure group compared to the core decompression group. At week 8, there were no significant differences between the negative pressure and normal control groups. Immunohistochemistry staining revealed higher expression of vascular endothelial growth factor (VEGF) and bone morphogenetic protein-2 (BMP-2) in the femoral heads in the negative pressure group compared with the core decompression group. Transmission electron microscopy revealed that cell organelles were further developed in the negative pressure group compared with the core decompression group. Microvascular ink staining revealed an increased number of bone marrow ink-stained blood vessels, a thicker vascular lumen and increased microvascular density in the negative pressure group relative to the core decompression group. Real-time polymerase chain reaction revealed that expression levels of both VEGF and BMP-2 were higher in the negative pressure group compared with the core decompression group. In summary, negative pressure has a therapeutic effect on FHN. This effect is superior to core decompression, indicating that negative pressure is a potentially valuable method for treating early FHN.

The effects of damage accumulation on the tensile strength and toughness of compact bovine bone.

Damage accumulation in compact bovine femur subjected to uniaxial tensile loading was examined by strong light illumination effects of microcracking. Imaging was done using a high-speed camera capturing image at 200 to 1500FPS. The tensile tests were performed in a multipurpose tensile testing system with cross-head speeds ranging from 0.5 to 10mm/min which leads to strain rates of 0.0001 to 0.0012s(-1) (physiologically relevant to walking and running Hansen et al., 2008). The post-failure images were then examined in a scanning electron microscopy (SEM) and effects of microstructure, strain rate, and orientation were evaluated. Correlation of the high-speed images with stress-strain curves indicated that optically visible microcracks were most likely initiated at yielding, and the specimens with dispersed microcracks exhibited a higher energy-absorption capacity compared to the specimens with coalesced local cracks. It was found that damage accumulation negatively correlates to strain rate and that transverse specimens exhibited a different failure pattern compared to the longitudinal specimens. Strain hardening and softening were found in the longitudinal and transverse specimens respectively. The microcracking in the transverse specimens instantly increased to peak after yielding compared to the gradual growth until failure in the longitudinal specimens. The average Young's modulus (21.5GPa) and ultimate stress (93.5MPa) of the specimens loaded in the longitudinal direction were more than twice that of the specimens (10.9GPa and 36.2MPa respectively) loaded in the transverse direction. The current technique has shown potential in relating damage accumulation real time in bone samples subjected to tensile loading condition. This information will be helpful in relating the role of micro damage accumulation in initiating failure and/or remodeling in bone.

Microcrack density and nanomechanical properties in the subchondral region of the immature piglet femoral head following ischemic osteonecrosis.

Development of a subchondral fracture is one of the earliest signs of structural failure of the immature femoral head following ischemic osteonecrosis, and this eventually leads to a flattening deformity of the femoral head. The mechanical and mineralization changes in the femoral head preceding subchondral fracture have not been elucidated. We hypothesized that ischemic osteonecrosis leads to early material and mechanical alterations in the bone of the subchondral region. The purpose of this investigation was to assess the bone of the subchondral region for changes in the histology of bone cells, microcrack density, mineral content, and nanoindentation properties at an early stage of ischemic osteonecrosis in a piglet model. This large animal model has been shown to develop a subchondral fracture and femoral head deformity resembling juvenile femoral head osteonecrosis. The unoperated, left femoral head of each piglet (n=8) was used as a normal control, while the right side had a surgical ischemia induced by disrupting the femoral neck vessels with a ligature. Hematoxylin and eosin (H&E) staining and TUNEL assay were performed on femoral heads from 3 piglets. Quantitative backscattered electron imaging, nanoindentation, and microcrack assessments were performed on the subchondral region of both control and ischemic femoral heads from 5 piglets. H&E staining and TUNEL assay showed extensive cell death and an absence of osteoblasts in the ischemic side compared to the normal control. Microcrack density in the ischemic side (3.2±0.79 cracks/mm(2)) was significantly higher compared to the normal side (0.27±0.27 cracks/mm(2)) in the subchondral region (p<0.05). The weighted mean of the weight percent distribution of calcium (CaMean) also was significantly higher in the ischemic subchondral region (p<0.05). Furthermore, the nanoindentation modulus within localized areas of subchondral bone was significantly increased in the ischemic side (16.8±2.7GPa) compared to the normal control (13.3±3.2GPa) (p<0.05). Taken together, these results support the hypothesis that the nanoindentation modulus of the subchondral trabecular bone is increased in the early stage of ischemic osteonecrosis of the immature femoral head and makes it more susceptible to microcrack formation. We postulate that continued loading of the hip joint when there is a lack of bone cells to repair the microcracks due to ischemic osteonecrosis leads to microcrack accumulation and subsequent subchondral fracture.

Difference in subchondral cancellous bone between postmenopausal women with hip osteoarthritis and osteoporotic fracture: implication for fatigue microdamage, bone microarchitecture, and biomechanical properties.

OBJECTIVE: Osteoarthritis (OA) and osteoporosis (OP) of the hip rarely occur in the same patient. The purpose of this study was to determine whether this difference might be attributable to the different quantity and quality of subchondral cancellous bone in the two conditions. METHODS: Subchondral cancellous bone from the femoral head was obtained at the time of hip arthroplasty from 60 postmenopausal women, 30 with OA and 30 with OP. In each group, 10 specimens were subjected to compressive fatigue loading and 20 were left nonloaded. Specimens were examined by compressive mechanical testing, micro-computed tomography scanning, fluorescence microscopy, and nanoindentation techniques. RESULTS: Both the ultimate stress and the elastic modulus of cancellous bone from OA patients were significantly higher than those of cancellous bone from OP patients (P < 0.05). Compared to cancellous bone from OP patients, the bone volume fraction and trabecular thickness were significantly increased, but bone matrix mineralization was significantly decreased, in cancellous bone from OA patients (P < 0.05 for each comparison). The microcrack density was significantly higher in OP cancellous bone than in OA cancellous bone (P < 0.001), irrespective of fatigue loading. In addition, fatigue loading resulted in a significant increase in microcrack density in both OA and OP cancellous bone (P < 0.001). There was no significant difference in nanoindentation elastic modulus and hardness between cancellous bone from OA and OP patients, as well as between bones with and without fatigue loading. CONCLUSION: The difference in mechanical properties between OA and OP cancellous bone is attributed to different bone mass and bone structure. OP cancellous bone is susceptible to fatigue damage due to insufficient structure. However, increased bone volume and plate-like structure provide OA cancellous bone a superior capacity to resist fatigue damage.

Variability of morphometric parameters of human trabecular tissue from coxo-arthritis and osteoporotic samples.

Morphometric and architectural bone parameters change in diseases such as osteoarthritis and osteoporosis. The mechanical strength of bone is primarily influenced by bone quantity and quality. Bone quality is defined by parameters such as trabecular thickness, trabecular separation, trabecular density and degree of anisotropy that describe the micro-architectural structure of bone. Recently, many studies have validated microtomography as a valuable investigative technique to assess bone morphometry, thanks to micro-CT non-destructive, non-invasive and reliability features, in comparison to traditional techniques such as histology. The aim of this study is the analysis by micro-computed tomography of six specimens, extracted from patients affected by osteoarthritis and osteoporosis, in order to observe the tridimensional structure and calculate several morphometric parameters.

Proximal femoral epiphysis anatomy in chilean population: orthopedic and forensic aspects / Anatomía del epífisis proximal del fémur en la población chilena. Aspectos traumatológicos y forenses

From a biomechanical standpoint, bone geometry and density are factors correlated to the bone resistance of the femur when supporting body weight, with geometric parameters like the diameter of the femoral head and neck, the length of the femoral neck, and the femoral neck angle as determinant factors in the incidence of hip fractures, which increase in frequency and seriousness in osteoporotic patients. In Chile, morphometric data that contributes to relating the anatomy of the proximal epiphysis of the femur as an associated factor in hip fractures does not exist; likewise, there are no anthropometric indexes that may contribute to the forensic sciences. The purpose of this study is to establish average measurements of the proximal epiphysis of the femur in the adult Chilean population. Descriptive Study. The proximal epiphyses of 81 dry adult femurs were analyzed (44 right and 37 left bones), measuring the following parameters: length of the femoral neck (LN), femoral neck angle (FNA), circumference of the femoral head (CH) and circumference of the femoral neck (CN). The statistical relationship between the measurements and the side of each sample was analyzed (t-test p=0.05). The average lengths were LN= 3.59cm (+/- 0.43 cm); FNA= 124.17 (+/- 6.37), CH= 14.34 cm (+/- 1.27 cm) and CN= 9.7 cm (+/- 0.87 cm). No significant differences between the left and right sides were found. Average numbers were obtained for the anatomy of the proximal femoral epiphysis from a sample in the Chilean population. With the data obtained, we propose to carry out anatomo-clinical, epidemiologic and forensic studies in this population.

Desde un punto de vista biomecánico, la geometría y la densidad ósea son factores correlacionados con la resistencia del hueso del fémur al apoyar el peso corporal, con los parámetros geométricos, como el diámetro de la cabeza femoral y el cuello, la longitud del cuello del fémur, y el ángulo del cuello femoral factores determinantes en la incidencia de fracturas de cadera, que aumentan en frecuencia y gravedad en los pacientes con osteoporosis. En Chile, no existen datos morfométricos que relacionen la anatomía de la epífisis proximal del fémur como un factor asociado a las fracturas de cadera ni índices antropométricos que pueden contribuir a las ciencias forenses. El propósito de este estudio es establecer las medidas promedio de la epífisis proximal de fémur en población adulta chilena. Estudio Descriptivo. Se analizaron la epífisis proximal de 81 fémures adultos secos (44 derechos y 37 izquierdos), midiendo los siguientes parámetros: longitud del cuello femoral (LC) , ángulo cérvico-diafisiario femoral (ACD), circunferencia de la cabeza femoral (CCa) y circunferencia del cuello femoral (CCu). Se analizó la relación estadística de las medidas con el lado de cada muestra (test Chi cuadrado p:0,05) Las longitudes promedios fueron LC: 3,59 cm (+/- 0,43 cm); ACD: 124,17 (+/- 6,37 cm); CCa: 14,34 cm (+/- 1,27 cm) y CCu: 9,7 cm (+/- 0,87 cm). No se encontraron diferencias significativas entre el lado derecho e izquierdo. Los resultados proponen la necesidad de realizar estudios anatomo-clínicos y epidemiológicos actualizados en población chilena donde la geometría de la epífisis proximal del fémur se incluya dentro del análisis.

Human bone material characterization: integrated imaging surface investigation of male fragility fractures.

UNLABELLED: The interrelation of calcium and phosphorus was evaluated as a function of bone material quality in femoral heads from male fragility fracture patients via surface analytical imaging as well as scanning microscopy techniques. A link between fragility fractures and increased calcium to phosphorus ratio was observed despite normal mineralization density distribution. INTRODUCTION: Bone fragility in men has been recently recognized as a public health issue, but little attention has been devoted to bone material quality and the possible efficacy in fracture risk prevention. Clinical routine fracture risk estimations do not consider the quality of the mineralized matrix and the critical role played by the different chemical components that are present. This study uses a combination of different imaging and analytical techniques to gain insights into both the spatial distribution and the relationship of phosphorus and calcium in bone. METHODS: X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry imaging techniques were used to investigate the relationship between calcium and phosphorus in un-embedded human femoral head specimens from fragility fracture patients and non-fracture age-matched controls. The inclusion of the bone mineral density distribution via backscattered scanning electron microscopy provides information about the mineralization status between the groups. RESULTS: A link between fragility fracture and increased calcium and decreased phosphorus in the femoral head was observed despite normal mineralization density distribution. Results exhibited significantly increased calcium to phosphorus ratio in the fragility fracture group, whereas the non-fracture control group ratio was in agreement with the literature value of 1.66 M ratio in mature bone. CONCLUSIONS: Our results highlight the potential importance of the relationship between calcium and phosphorus, especially in areas of new bone formation, when estimating fracture risk of the femoral head. The determination of calcium and phosphorus fractions in bone mineral density measurements may hold the key to better fracture risk assessment as well as more targeted therapies.