Bone Volume Measurements Research Articles

AML Cells Alter Bone Homeostasis By Promoting the Formation of Immature Bone and Resorption of Mature Bone That Supports Leukemia Progression

Background: Genetic alterations in the osteoprogenitor cells has been shown to induce acute myeloid leukemia (AML) in several mouse models. Moreover, we have recently reported that AML cells induce osteogenic differentiation in mesenchymal stromal cells (MSC) to gain growth advantage in the bone marrow (BM; Battula et al., JCI Insight, 2017). However, the effect of AML cells on bone homeostasis/turnover and its impact on AML progression is unknown. Here, we hypothesize that AML cells expand osteoprogenitor cells and alter the balance between bone formation and resorption. Methods: To investigate the effect of AML cells on osteoprogenitor cells and mature osteoblasts, we used triple transgenic reporter mice with the genotype Osx-CreERt2;Ocn-GFP;ROSA-tdTomato. Murine AML cells with MLL-ENL translocation were implanted into these transgenic mice, and Osteoprogenitor (Osx+) cells and mature osteoblasts (Ocn+) in femurs were measured by confocal microscopy. To investigate the effect of human AML cells on bone composition, patient-derived xenograft (PDX) cells were implanted into non-obese diabetic scid interleukin-2Rγnull (NSG) mice and bone histomorphometry was performed using H&E and Goldner's trichrome staining. Computed tomography (micro-CT) was used to measure bone volume (BV) and mineral density (BMD) in mice. Tartrate-resistant acidic phosphatase (TRAP) staining was performed to measure osteoclast number/activation. Finally, bone density on the vertebral bone (T12) was measured in 263 de-novo AML patients and 23 normal individuals by CT imaging. Results: In transgenic mice implanted with syngenic AML cells, we found a 3-4 fold increase in Osterix+, but not Osteocalcin+ cells, suggesting AML cells expand osteoprogenitor cells in the BM during short term exposure (2-3 weeks). To investigate the effects of AML on bone during a long term exposure, we implanted 10 different AML-PDX models in NSG mice (3 mice per model) and analyzed femurs by micro-CT and bone histomorphometry analysis. Interestingly, we observed a dramatic increase in new web-like medullary bone formation in 5/10 of the PDX models tested. Moreover, higher bone volume is associated with less aggressive PDX models (which takes 4-6 months to reach 90% circulating leukemia), but not aggressive PDX models (only 4-8 weeks to reach 90% circulating cells). These findings were also confirmed by micro-CT of mouse femurs. Interestingly, in some PDX models, CT images revealed large cavities in cortical bones close to epiphysis and metaphysis areas in the femur and tibia of mice with AML suggesting bone resorption. To validate bone resorption, we performed TRAP staining and found a significant increase in osteoclast activity on the endosteal surface and massive bone resorption in AML bone compared to normal bone. These data indicate high bone turnover in mice with AML compared to control mice. Next, we measured bone densities in AML patients and normal individuals by chest CT imaging. We found bone densities were gradually decrease with age in both healthy individuals and AML patients. However, compared to healthy individuals, bone densities are significantly higher in majority of AML patients (~70%) (p<0.01). Interestingly, survival analysis revealed that higher bone density is associated with good prognosis in AML patients (p<0.01), suggesting high bone turnover alters patient outcomes. Conclusion: Our data suggest that AML cells expand osteoprogenitor-rich niche and alter BM microenvironment by high bone turnover. New bone induction by less aggressive AML-PDX models coupled with AML patient CT data suggests that high bone density and volume are associated with favorable prognostic factors in AML. Mechanisms underlying this observation are under investigation. Disclosures Andreeff: Amgen: Research Funding; Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees. Konopleva:Ablynx: Research Funding; AstraZeneca: Research Funding; Kisoji: Consultancy; Ascentage: Research Funding; Stemline Therapeutics: Consultancy, Research Funding; AbbVie: Consultancy, Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Rafael Pharmaceutical: Research Funding; Amgen: Consultancy; Agios: Research Funding; Sanofi: Research Funding; Cellectis: Research Funding; Calithera: Research Funding; Forty-Seven: Consultancy, Research Funding; Eli Lilly: Research Funding; Genentech: Consultancy, Research Funding; F. Hoffmann La-Roche: Consultancy, Research Funding. Battula:Leukemia Lymphoma Society: Research Funding; Tolero Pharmaceuticals: Research Funding; Golfers Against Cancer: Research Funding.

Mechanical resonator to measure magnetic susceptibility of structurally intact bone

Magnetic susceptibility of structurally intact bone may play a role in low frequency (below 10 kHz), low field (below 10 mT amplitude) pulsed electromagnetic field (LF PEMF) treatment of fracture non-unions and an adjunct to cervical fusion surgery, approved by the U.S Food and Drug Administration (FDA). The aim of this study was to determine if a difference in PEMF treatment results in measurable differences in the bone magnetic susceptibility using a model of structurally intact rat vertebrae. We measured bone volume magnetic susceptibility by a custom built mechanical resonator comprising a diametrically-polarized NdFeB permanent dipole magnet cylinder (25.4 × 25.4 mm, height by diameter) rotated about its axis by a stepper motor at even intervals from 53 to 63 RPM, acting as a source of a local, oscillating magnetic field (mean field of 95 mT, gradient of 12 T/m) on an intact laboratory rat lumbar vertebrae (n = 21, from tissue repository from past studies on LF PEMF treatment in vivo) suspended 26.0 mm from magnet axis on a thin line of 80 mm nominal length forming a pendulum of nominal eigenfrequency of 100 Hz. The vertebra motion was captured by a video camera and the geometrical center of its 2D image motion was analyzed by ImagePro® and MATLAB® routines. The amplitude of bone oscillations (at twice the angular frequency of the rotating magnet) showed a characteristic pattern of resonance with the magnet rotational frequency. The amplitude maximum agreed with that calculated from a model of forced, damped harmonic oscillator and the diamagnetic tension force acting on bone. The calculated mean volume magnetic susceptibility (SI) of -was on the order of magnitude of literature value (|χ|≈10-5). The results point to the bone site-specific aspect of LF PEMF therapy and provide experimental and theoretical basis for a novel, rational method of designing next generation of effective LF PEMF therapies.

Relating mechanical properties of vertebral trabecular bones to osteoporosis

Osteoporosis is an osteometabolic disease, which promotes structural degradation of bone tissue and reduction of mineral density. We reported here a mechanical resistance assay from normal, osteopenic and osteoporotic trabecular vertebral bones of human cadavers. We performed a compressed test on ninety samples, evaluating Young’s modulus and X-ray microtomography to measure bone volume fraction and trabecular thickness. This experimental data are employed for computing the orthotropic macroscopic behavior of vertebral trabecular bones using known analytical formulae that were obtained by Galka et al. (Arch Mech 51: 335-355, 1999) via an asymptotic homogenization model. A geometrical model with a periodic orthogonal plate-like structure is applied. The properties of the bone-trabecular mass are considered linear, homogeneous and orthotropic. Average values for all technical or engineering elastic properties are computed for three important regions of the trabecular bones corresponding to thirty individuals classified as normal, osteopenic or osteoporotic by calcaneus ultrassometry. This study could be useful for a better understanding of the elastic behavior of trabecular bones in human vertebral bodies, allowing an estimation of bone answer under stress in different directions and the risk of fracture associated with osteoporosis.HighlightsDescribing the elastic behavior of trabecular bones in human vertebral bodies at the micro and macroscopic.Allow a better estimation of the stress in different directions and risk of fracture associated with osteoporosis.Model request a very low computational cost.Offer a better understand the global effective coefficients of samples of trabecular bone, from the model of a periodic unit cell, in the format orthogonal plate-like structure with homogeneous bone mass.

Histologic and Biomechanical Evaluation of Osseointegrated Miniscrew Implants Treated with Ozone Therapy and Photobiomodulation at Different Loading Times

The aim of this study was to evaluate how continuous heavy orthopedic forces affect the stability of sandblasted, large-grit, acid-etched (SLA)-surfaced miniscrew implants and surrounding bone tissue healing at three different loading periods with treatment of photobiomodulation and ozone therapy. Miniscrew implants were applied on the tibias of 9-month-old rabbits (n = 18). The animals were randomly divided into three groups: control, photobiomodulation, and ozone therapy. In all groups, miniscrew implants were loaded with 500 gf at 0, 4, and 8 weeks, respectively (G1, G2, and G3). Several biomechanical and histologic analyses were performed in different centers to measure the implant stability quotient level, bone volume, and bone-to-implant contact. According to the results of the Infinite Focus Microscopy, the ozone therapy group revealed significantly higher scores than the control group and photobiomodulation group at the 4-week loading time, whereas the photobiomodulation and ozone therapy groups revealed significantly higher scores than the control group at the 8-week loading time in terms of bone volume measurements in mm3 (P < .05). According to the histologic analysis, the ozone therapy and photobiomodulation groups revealed significantly higher scores than the control group at the 4-week loading time, whereas the photobiomodulation group showed the highest scores among the 8-week loading groups (P < .05). This is the first study in the literature that reveals a better osseointegration process in miniscrew implants when treated with photobiomodulation and ozone therapy compared with control groups. Although the photobiomodulation and ozone therapy groups did not reveal significantly higher scores in immediately loaded miniscrew implants (G1), these treatments were significantly more effective when loaded after 4 or 8 weeks of osseointegration (G2 and G3). SLA-surfaced miniscrew implants are successful in the orthopedic forces (500 gf) and can be removed without complications.

Quantitative Evaluation of Bone Microstructure using High-Resolution Extremity Cone-Beam CT with a CMOS Detector.

A high-resolution cone-beam CT (CBCT) system for extremity imaging has been developed using a custom complementary metal-oxide-semiconductor (CMOS) x-ray detector. The system has spatial resolution capability beyond that of recently introduced clinical orthopedic CBCT. We evaluate performance of this new scanner in quantifying trabecular microstructure in subchondral bone of the knee. The high-resolution scanner uses the same mechanical platform as the commercially available Carestream OnSight 3D extremity CBCT, but replaces the conventional amorphous silicon flat-panel detector (a-Si:H FPD with 0.137 mm pixels and a ~0.7 mm thick scintillator) with a Dalsa Xineos3030 CMOS detector (0.1 mm pixels and a custom 0.4 mm scintillator). The CMOS system demonstrates ~40% improved spatial resolution (FWHM of a ~0.1 mm tungsten wire) and ~4× faster scan time than FPD-based extremity CBCT (FPD-CBCT). To investigate potential benefits of this enhanced spatial resolution in quantitative assessment of bone microstructure, 26 trabecular core samples were obtained from four cadaveric tibias and imaged using FPD-CBCT (75 μm voxels), CMOS-CBCT (75 μm voxels), and reference micro-CT (μCT, 15 μm voxels). CBCT bone segmentations were obtained using local Bernsen's thresholding combined with global histogram-based pre-thresholding; μCT segmentation involved Otsu's method. Measurements of trabecular thickness (Tb.Th), spacing (Tb.Sp), number (Tb.N) and bone volume (BV/TV) were performed in registered regions of interest in the segmented CBCT and μCT reconstructions. CMOS-CBCT achieved noticeably improved delineation of trabecular detail compared to FPD-CBCT. Correlations with reference μCT for metrics of bone microstructure were better for CMOS-CBCT than FPD-CBCT, in particular for Tb.Th (increase in Pearson correlation from 0.84 with FPD-CBCT to 0.96 with CMOS-CBCT) and Tb.Sp (increase from 0.80 to 0.85). This improved quantitative performance of CMOS-CBCT is accompanied by a reduction in scan time, from ~60 sec for a clinical high resolution protocol on FPD-CBCT to ~17 sec for CMOS-CBCT. The CMOS-based extremity CBCT prototype achieves improved performance in quantification of bone microstructure, while retaining other diagnostic capabilities of its FPD-based precursor, including weight-bearing imaging. The new system offers a promising platform for quantitative imaging of skeletal health in osteoporosis and osteoarthritis.

Bone Marrow Transplantation for Treatment of the Col1a2+/G610C Osteogenesis Imperfecta Mouse Model.

Bone marrow transplantation (BMT) of healthy donor cells has been postulated as a strategy for treating osteogenesis imperfecta (OI) and other bone fragility disorders. The effect of engraftment by tail vein injection and/or marrow ablation by 6Gy whole body irradiation were tested in Col1a2+/G610C (OI) mice as a model of mild-moderate OI. Dual-emission X-ray absorptiometry, microCT, and 4-point bending were used to measure bone volume (BV), bone mineral density (BMD), and biomechanical strength. BV, BMD, and mechanical strength were reduced in OI mice compared to wild type (WT) controls. BMT with and without irradiation yielded no difference in BV and BMD outcomes for both OI and WT mice, at 3weeks. Transplantation of OI cells into OI mice to test for paracrine effects of BMT also showed no difference with non-transplanted OI mice. In a parallel cell tracking study, donor marrow was taken from transgenic mice constitutively expressing tdTomato and transplanted into WT mice. Lineage tracking demonstrated that irradiation considerably enhanced engraftment of tdTomato+ cells. However, tdTomato+ cells predominantly expressed TRAP and not AP, indicating engrafted donor cells were chiefly from the hematopoietic lineages. These data show that whole marrow transplantation fails to rescue the bone phenotype of Col1a2+/G610C (OI) mice and that osteopoietic engraftment is not significantly enhanced by irradiation. These findings are highly relevant to modern approaches focused on the gene repair of patient cells ex vivo and their subsequent reintroduction into the osteopoietic compartment via the circulation.

Microstructural volumetric analysis of lateral ridge augmentation using differently conditioned tooth roots.

Previous research revealed that autogenous tooth roots may be biologically equivalent to conventional bone grafts for lateral ridge augmentation. However, these analyses were limited to two dimensions, whereas healing is a volumetric process. The present study aimed at volumetrically assessing the microstructure following lateral ridge augmentation using extracted tooth roots. The roots of differently conditioned maxillary premolars (i.e., healthy: PM-C; endodontically treated: PM-E; ligature-induced periodontitis: PM-P) and retromolar cortical autogenous bone (AB) blocks were used for lateral ridge augmentation at chronic-type defects in the lower quadrants of n = 16 foxhounds. At 12weeks, titanium implants were inserted and left to heal for another 3weeks. Tissue biopsies were scanned using microcomputed tomography (μCT), and volumes of interest were separated at the buccal and oral aspects to measure bone volume per tissue volume (BV/TV), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), and connectivity density (Conn.D). All groups investigated revealed comparable BV/TV, Tb.Th, Tb.Sp, and Conn.D values at either the augmented buccal or pristine oral aspects, respectively. A gradual but heterogeneous replacement of grafts was observed in all groups, but residual PM fragments were particularly noted in PM-C and PM-P groups. Differently conditioned PM and AB grafts were associated with a comparable bone microstructure within the grafted area. The duration of replacement resorption may vary considerably among the subjects. Autogenous tooth roots may serve as potential alternative to AB for localized alveolar ridge augmentation.

Influence on interradicular bone volume of Invisalign treatment for adult crowding with interproximal enamel reduction: a retrospective three-dimensional cone-beam computed tomography study

BackgroundThe aim of this study was to use three-dimensional datasets to identify associations between treatment for adult crowding, using Invisalign aligner and interproximal enamel reduction (IER), and changes in the volume of interradicular bone.MethodsA total of 60 cone-beam computed tomography (CBCT) scans from 30 adult patients (28 women, two men; 30 CBCTs pre-treatment, 30 post-treatment) were examined retrospectively in order to measure bone volume three-dimensionally. The patients’ average age was 36.03 ± 9.7 years. The interradicular bone volume was measured with OsiriX at four levels in the anterior tooth areas of the maxilla and mandible. Differences in bone between T0 and T1 were analyzed with IBM SPSS 21.0 using the Wilcoxon test for paired samples.ResultsOverall, a slight increase in the quantity of bone was found (0.12 ± 0.73 mm). There was a highly significant increase in bone in the mandible (0.40 ± 0.62 mm; P < 0.001), while in the maxilla there was a slight loss of bone, which was highly significant in the apical third (− 0.16 ± 0.77 mm; P = 0.001).ConclusionsOverall, treatment for adult crowding using an aligner and IER appears to have a positive effect on interradicular bone volume, particularly in patients with severe grades of the condition (periodontally high-risk dentition). This effect is apparently independent of IER. This is extremely important with regard to the treatment outcome, since IER and root proximity have been matters of debate in the literature and teeth should remain firmly embedded in their alveolar sockets.

CSA-90 Promotes Bone Formation and Mitigates Methicillin-resistant Staphylococcus aureus Infection in a Rat Open Fracture Model.

Infection of open fractures remains a significant cause of morbidity and mortality to patients worldwide. Early administration of prophylactic antibiotics is known to improve outcomes; however, increasing concern regarding antimicrobial resistance makes finding new compounds for use in such cases a pressing area for further research. CSA-90, a synthetic peptidomimetic compound, has previously demonstrated promising antimicrobial action against Staphylococcus aureus in rat open fractures. However, its efficacy against antibiotic-resistant microorganisms, its potential as a therapeutic agent in addition to its prophylactic effects, and its proosteogenic properties all require further investigation. (1) Does prophylactic treatment with CSA-90 reduce infection rates in a rat open fracture model inoculated with S aureus, methicillin-resistant S aureus (MRSA), and methicillin-resistant Staphylococcus epidermidis (MRSE) as measured by survival, radiographic union, and deep tissue swab cultures? (2) Does CSA-90 reduce infection rates when administered later in the management of an open fracture as measured by survival, radiographic union, and deep tissue swab cultures? (3) Does CSA-90 demonstrate a synergistic proosteogenic effect with bone morphogenetic protein 2 (BMP-2) in a noninfected rat ectopic bone formation assay as assessed by micro-CT bone volume measurement? (4) Can CSA-90 elute and retain its antimicrobial efficacy in vitro when delivered using clinically relevant agents measured using a Kirby-Bauer disc diffusion assay? All in vivo studies were approved by the local animal ethics committee. In the open fracture studies, 12-week-old male Wistar rats underwent open midshaft femoral fractures stabilized with a 1.1-mm Kirschner wire and 10 µg BMP-2 ± 500 µg CSA-90 was applied to the fracture site using a collagen sponge along with 1 x 10 colony-forming units of bacteria (S aureus/MRSA/MRSE; n = 10 per group). In the delayed treatment study, débridement and treatment with 500 µg CSA-90 were performed at Day 1 and Day 5 after injury and bacterial insult (S aureus). All animals were reviewed daily for signs of local infection and/or sepsis. An independent, blinded veterinarian reviewed twice-weekly radiographs, and rats showing osteolysis and/or declining overall health were culled at his instruction. The primary outcome of both fracture studies was fracture infection, incorporating survival, radiographic union, and deep tissue swab cultures. For the ectopic bone formation assay, 0 to 10 µg BMP-2 and 0 to 500 µg CSA-90 were delivered on a collagen sponge into bilateral quadriceps muscle pouches of 8-week-old rats (n = 10 per group). Micro-CT quantification of bone volume and descriptive histologic analysis were performed for all in vivo studies. Modified Kirby-Bauer disc diffusion assays were used to quantify antimicrobial activity in vitro using four different delivery methods, including bone cement. Infection was observed in none of the MRSA inoculated open fractures treated with CSA-90 with 10 of 10 deep tissue swab cultures negative at the time of cull. Median survival was 43 days (range, 11-43 days) in the treated group versus 11 days (range, 8-11 days) in the untreated MRSA inoculated group (p < 0.001). However, delayed débridement and treatment of open fractures with CSA-90 at either Day 1 or Day 5 did not prevent infection, resulting in early culls by Day 21 with positive swab cultures (10 of 10 for each time point). Maximal ectopic bone formation was achieved with 500 μg CSA-90 and 10 μg BMP-2 (mean volume, 9.58 mm; SD, 7.83), creating larger bone nodules than formed with 250 μg CSA-90 and 10 μg BMP-2 (mean volume, 1.7 mm; SD, 1.07; p < 0.001). Disc diffusion assays showed that CSA-90 could successfully elute from four potential delivery agents including calcium sulphate (mean zone of inhibition, 11.35 mm; SD, 0.957) and bone cement (mean, 4.67 mm; SD, 0.516). CSA-90 shows antimicrobial action against antibiotic-resistant Staphylococcal strains in vitro and in an in vivo model of open fracture infection. The antimicrobial properties of CSA-90 combined with further evidence of its proosteogenic potential make it a promising compound to develop further for orthopaedic applications.

Impact of Bone Volume Upon Condylar Activity in Patients With Unilateral Condylar Hyperplasia

Unilateral condylar hyperplasia or hyperactivity (UCH) is a bone overgrowth disorder affecting the mandible. The purpose of this study was to determine the relations among age, condylar bone structure, condylar bone volume, and condylar bone activity on single-photon emission computed tomographic (SPECT) scans in patients with UCH. This study included 20 patients with a clinical presentation of progressive mandibular asymmetry and a positive bone SPECT scan. A bone SPECT-derived standardized uptake value (bSUV) for the condylar region was determined. All patients underwent condylectomy to arrest further progression of the disease. The resected condyles were scanned with a micro-computed tomographic scanner (18-μm resolution). Bone architectural parameters were calculated with routine morphometric software. The mean bSUV of the condyle on the affected side was 15.32 (standard deviation [SD], 8.98) compared with 9.85 (SD, 4.40) on the nonaffected side (P=.0007). For trabecular bone structure, there was a nonsignificant correlation between the SUV of the affected condyle and the measured bone volume fraction (r=0.13; P=.58) and trabecular thickness (r=0.03; P=.90). No meaningful relation was found between condylar bone volume fraction and condylar activity on bone scan; therefore, the impact of bone volume fraction on the results of bone scans is limited. The measured condylar activity on SPECT scan seems to be primarily a reflection of the remodeling rate of bone.

Comparison of Bone Volume Measurements Using Conventional Single and Dual Energy Computed Tomography

Comparison of Bone Volume Measurements Using Conventional Single and Dual Energy Computed Tomography

Relationships between age and microarchitectural descriptors of iliac trabecular bone determined by microCT

Estimation of age at death is a major issue in anthropology. The main anthropological histological methods propose studying the architecture of cortical bone. In bone histomorphometry, researches on metabolic bone diseases have provided normative tables for trabecular bone volume (BV/TV) according to age and gender of individuals on trans-iliac bone biopsies. We have used microCT, a non-destructive tool for measuring bone volume and trabecular descriptors to compare the French tables to a series of forensic anthropological population and if the two iliac bones could be used interchangeably. Coxal bone of a personal forensic collection whose age and gender were known (DNA identification) were used. Bone samples, centered on the same area than bone biopsy. MicroCT (pixel size: 36μm) was used to measure BV/TV and morphometric trabecular parameters of microarchitecture. An adjusted Z-score was calculated for BV/TV to compare with normative tables and a right/left comparison of trabecular parameters was provided. Twenty-seven iliac bones, which 20 forming 10 complete pelvises, aged between 24 and 73y.o. (average of 47.7 y.o.) were used. All adjusted Z-score were within normal values. There was a strong positive correlation between right and left sides for Tb.Th, Tb.N and Tb.Sp, but an insignificant correlation was obtained for BV/TV. Normative tables between age and BV/TV are valid and therefore usable in anthropology. They may represent an alternative to determine the age at death. Nevertheless, it requires a precise technique that could be a drawback in current practice.

Human Adipose-Derived Mesenchymal Stem Cells for Osseous Rehabilitation of Induced Osteoradionecrosis: A Rodent Model.

Objective Human adipose-derived mesenchymal stem cells (ADSCs) were used to rehabilitate bone damaged by osteoradionecrosis (ORN) in an established animal model. Study Design Prospective animal study. Setting Academic department laboratory. Subjects and Methods After institutional review board and Institutional Animal Care and Use Committee approval, 24 athymic nude rats were divided into 5 groups: 4 groups irradiated (20 Gy) by brachytherapy catheter placed at the left hemimandible and 1 mock irradiation control (n = 4). For all groups, ORN was initiated by extraction of the central molar 1 week later. After 28 days, animals (n = 5/group) received injection at the extraction site with saline (SAL), ADSCs, platelet-rich plasma and collagen (PRP/COL), or ADSCs + PRP/COL. Rats were sacrificed 28 days later and their mandibles harvested for histopathology analysis (osteoblasts, osteoclasts, and fibrosis) and bone volume measurement using 3-dimensional micro-computed tomography. Results All but 1 rat survived the experiment period (23/24). Radiographic and histological analysis revealed 60% bone loss in the SAL group compared with the nonirradiated control. Injection of ADSCs increased jaw region bone volume by up to 36% ( P < .01). All experimental groups (ADSC, PRP/COL, and ADSC + PRP/COL) showed dramatically decreased osteoclast counts ( P < .001) while injection of PRP/COL with or without ADSCs increased osteoblasts. Increased fibrosis was observed after ADSC injection ( P < .05). Conclusion The application of human ADSCs to an induced mandibular osteoradionecrosis model in athymic rats results in increased deposition or preservation of bone, demonstrated both histologically and radiographically. This offers an encouraging possible treatment option for translational research in this difficult disease.

Bone-Level Changes Around Delayed Dental Implants in Previous Large Bone Defects Filled with Reactive Soft Tissue After Extraction: A Cone Beam Computed Tomography Study.

The objective of this study was to evaluate new bone regeneration around delayed implants positioned in large bone defects, filled with reactive soft tissue, using cone beam computed tomography (CBCT) at a follow-up of 3 years. Patients presented large bone defects after tooth extraction. Reactive soft tissue was left in the defects, and no grafts were used. CBCT scans were performed before tooth extraction and upon implant placement (at 3 months after extraction), and bone volume measurements were then evaluated 3 years after implant placement. Three months after extraction, CBCT revealed a bone volume gain both for single-rooted and multirooted sites: an overall mean bone level of 8.34 ± 3.18 mm was calculated, and implants were placed. At the 3-year follow-up, CBCT revealed bone maintenance, with mean levels of 10.47 ± 3.68 mm. Statistically significant differences were not observed between 3-month and 3-year bone levels, both for maxillary or mandibular defects and for sites (single-rooted or multirooted teeth). CT scans presented a successful outcome of delayed implants placed in large bone defects at the 3-year follow-up.

Focal osteoporosis defects play a key role in hip fracture

BackgroundHip fractures are mainly caused by accidental falls and trips, which magnify forces in well-defined areas of the proximal femur. Unfortunately, the same areas are at risk of rapid bone loss with ageing, since they are relatively stress-shielded during walking and sitting. Focal osteoporosis in those areas may contribute to fracture, and targeted 3D measurements might enhance hip fracture prediction. In the FEMCO case-control clinical study, Cortical Bone Mapping (CBM) was applied to clinical computed tomography (CT) scans to define 3D cortical and trabecular bone defects in patients with acute hip fracture compared to controls. Direct measurements of trabecular bone volume were then made in biopsies of target regions removed at operation. MethodsThe sample consisted of CT scans from 313 female and 40 male volunteers (158 with proximal femoral fracture, 145 age-matched controls and 50 fallers without hip fracture). Detailed Cortical Bone Maps (c.5580 measurement points on the unfractured hip) were created before registering each hip to an average femur shape to facilitate statistical parametric mapping (SPM). Areas where cortical and trabecular bone differed from controls were visualised in 3D for location, magnitude and statistical significance. Measures from the novel regions created by the SPM process were then tested for their ability to classify fracture versus control by comparison with traditional CT measures of areal Bone Mineral Density (aBMD). In women we used the surgical classification of fracture location (‘femoral neck’ or ‘trochanteric’) to discover whether focal osteoporosis was specific to fracture type. To explore whether the focal areas were osteoporotic by histological criteria, we used micro CT to measure trabecular bone parameters in targeted biopsies taken from the femoral heads of 14 cases. ResultsHip fracture patients had distinct patterns of focal osteoporosis that determined fracture type, and CBM measures classified fracture type better than aBMD parameters. CBM measures however improved only minimally on aBMD for predicting any hip fracture and depended on the inclusion of trabecular bone measures alongside cortical regions. Focal osteoporosis was confirmed on biopsy as reduced sub-cortical trabecular bone volume. ConclusionUsing 3D imaging methods and targeted bone biopsy, we discovered focal osteoporosis affecting trabecular and cortical bone of the proximal femur, among men and women with hip fracture.

Delayed Implants Outcome in Maxillary Molar Region.

The aim of the present study was to assess bone volume changes in maxillary molar regions after delayed implants placement. Patients presented large bone defects after tooth extractions. Reactive soft tissue was left into the defects. No grafts were used. Cone beam computed tomography (CBCT) scans were performed before tooth extractions, at implant placement (at 3 months from extraction) and 3 years after implant placement, bone volume measurements were assessed. Bucco-lingual width showed a statistically significant decrease (p = .013) at implant placement, 3 months after extraction. Moreover, a statistically significant increase (p < .01) was measured 3 years after implant placement. No statistically significant differences (p > .05) were found between baseline values (before extraction) and at 3 years from implant placement. Vertical dimension showed no statistically significant differences (p > .05) at implant placement, 3 months after extraction. Statistically significant differences (p < .0001) were found between baseline values (before extraction) and at 3 months from implant placement as well as between implant placement values and 3 years later. CT scans presented successful outcome of delayed implants placed in large bone defects at 3-year follow-up.

Estrogen promotes spontaneous repair of osteochondral defect via inhibition of osteoclast activity

Objective To investigate the role of estrogen in spontaneous repair of osteochondral defect, so as to provide guidance for the application of estrogen in tissue engineering. Methods Seventy-two healthy adult female SD rats (4-month-old) were assigned to negative control group (group A, n=24), ovariectomized group (group B, n=24) and ovariectomized + estrogen treatment group (group C, n=24) according to the random number table. Rats in group C were intraperitoneally injected 0.1 mg/kg estradiol benzoate once per week after operation. An osteochondral defect model (diameter: 2 mm, height: 1.5 mm) was established in femoral trochlea of rats 4 weeks after operation. At 2, 10 and 20 weeks after the modeling, 8 rats from each group were sacrificed. Femoral condyles were collected to measure bone volume fraction(BVF), number of bone trabeculae(Tb.N), trabecular thickness(Tb.Th)and trabecular spacing(Tb.Sp)in the osteochondral defect area by micro-CT scanning. Morphological changes were observed by HE staining, histomorphological changes and cartilage regeneration by safranine O- fast green staining, osteoclast count by tartrate-resistant acid phosphatase (TRAP) staining, distribution of matrix metalloproteinase-9 (MMP-9) by immunohistochemistry and expressions of osteoprotegerin (OPG), receptor activator of nuclear factor-κB ligand (RANKL) and MMP-9 by real-time-PCR. Results Compared to group B, increased BVF and Tb.N and decreased Tb.Sp were observed in groups A and C at each time point. More bone matrix formations were observed in groups A and C than in group B at 2 weeks, cysts (also known as cystic cavities) in regenerated subchondral bone and cracks in subchondral bone plate were observed in group B at 10 and 20 weeks, and proliferation of osteoclasts was active within lesions in group B at 10 and 20 weeks. Compared to group B, lowered levels of RANKL and MMP-9 (P<0.05) and significantly increased level of OPG (P<0.01) were observed in groups A and C at each time point, and osteoclast count in groups A and C was lowered at 10 and 20 weeks (P<0.05). No regeneration of cartilage layer was observed in all groups. Conclusions Excessive proliferation of osteoclasts results in formation of cystic cavities and cracks. Estrogen improves the speed and quality of bone repair by regulating activities of osteoblasts and osteoclasts, so it can be used to treat osteochondral defect in tissue engineering. Key words: Estrogens; Osteoclasts; Cysts; Osteochondral defect

WE‐AB‐207A‐01: BEST IN PHYSICS (IMAGING): High‐Resolution Cone‐Beam CT of the Extremities and Cancellous Bone Architecture with a CMOS Detector

Purpose:Extremity cone‐beam CT (CBCT) with an amorphous silicon (aSi) flat‐panel detector (FPD) provides low‐dose volumetric imaging with high spatial resolution. We investigate the performance of the newer complementary metal‐oxide semiconductor (CMOS) detectors to enhance resolution of extremities CBCT to ∼0.1 mm, enabling morphological analysis of trabecular bone. Quantitative in‐vivo imaging of bone microarchitecture could present an important advance for osteoporosis and osteoarthritis diagnosis and therapy assessment.Methods:Cascaded systems models of CMOS‐ and FPD‐based extremities CBCT were implemented. Performance was compared for a range of pixel sizes (0.05–0.4 mm), focal spot sizes (0.3–0.6 FS), and x‐ray techniques (0.05–0.8 mAs/projection) using detectability of high‐, low‐, and all‐frequency tasks for a nonprewhitening observer. Test‐bench implementation of CMOS‐based extremity CBCT involved a Teledyne DALSA Xineos3030HR detector with 0.099 mm pixels and a compact rotating anode x‐ray source with 0.3 FS (IMD RTM37). Metrics of bone morphology obtained using CMOS‐based CBCT were compared in cadaveric specimens to FPD‐based system using a Varian PaxScan4030 (0.194 mm pixels).Results:Finer pixel size and reduced electronic noise for CMOS (136 e compared to 2000 e for FPD) resulted in ∼1.9× increase in detectability for high‐frequency tasks and ∼1.1× increase for all‐frequency tasks. Incorporation of the new x‐ray source with reduced focal spot size (0.3 FS vs. 0.5 FS used on current extremities CBCT) improved detectability for CMOS‐based CBCT by ∼1.7× for high‐frequency tasks. Compared to FPD CBCT, the CMOS detector yielded improved agreement with micro‐CT in measurements of trabecular thickness (∼1.7× reduction in relative error), bone volume (∼1.5× reduction), and trabecular spacing (∼3.5× reduction).Conclusion:Imaging performance modelling and experimentation indicate substantial improvements for high‐frequency imaging tasks through adoption of the CMOS detector and small FS x‐ray source, motivating the use of these components in a new system for quantitative in‐vivo imaging of trabecular bone.Financial Support: US NIH grant R01EB018896. Qian Cao is a Howard Hughes Medical Institute International Student Research Fellow.Disclosures: W Zbijewski, J Siewerdsen and A Sisniega receive research funding from Carestream Health.

Novel Lesions of Bones and Joints Associated with Chikungunya Virus Infection in Two Mouse Models of Disease: New Insights into Disease Pathogenesis.

Chikungunya virus is an arbovirus spread predominantly by Aedes aegypti and Ae. albopictus mosquitoes, and causes debilitating arthralgia and arthritis. While these are common manifestations during acute infection and it has been suggested they can recur in patients chronically, gaps in knowledge regarding the pathogenesis still exist. Two established mouse models were utilized (adult IRF 3/7 -/- -/- and wild-type C57BL/6J mice) to evaluate disease manifestations in bones and joints at various timepoints. Novel lesions in C57BL/6J mice consisted of periostitis (91%) and foci of cartilage of necrosis (50% of mice at 21 DPI). Additionally, at 21 DPI, 50% and 75% of mice exhibited periosteal bone proliferation affecting the metatarsal bones, apparent via histology and μCT, respectively. μCT analysis did not reveal any alterations in trabecular bone volume measurements in C57BL/6J mice. Novel lesions demonstrated in IRF 3/7 -/- -/- mice at 5 DPI included focal regions of cartilage necrosis (20%), periosteal necrosis (66%), and multifocal ischemic bone marrow necrosis (100%). Contralateral feet in 100% of mice of both strains had similar, though milder lesions. Additionally, comparison of control IRF 3/7 -/- -/- and wild-type C57BL/6J mice demonstrated differences in cortical bone. These experiments demonstrate novel manifestations of disease similar to those occurring in humans, adding insight into disease pathogenesis, and representing new potential targets for therapeutic interventions. Additionally, results demonstrate the utility of μCT in studies of bone and joint pathology and illustrate differences in bone dynamics between mouse strains.

Sex determination from carpal bone volumes: A Multi Detector Computed Tomography (MDCT) study in a Malaysian population.

The use of Multi Detector Computed Tomography (MDCT) volume measurements of bones for sex determination allows fragile, fragmented human remains to be assessed without compromising the specimen. We set out to assess the ability of MDCT carpal bone volume measurement in determining sex in a Malaysian population. 52 healthy volunteers were scanned in a 16-slice MDCT, and the volume of 104 sets of carpal bones was measured using a Syngo workstation (Both CT and workstation-Siemens Healthcare, Erlangen, Germany). Male carpal bones were of higher volume compared to the female carpal bones (p<0.001). Area under the curve (AUC) assessment of responder-operator characteristics curves showed that the trapezium bone was best able to predict sex with an AUC of 0.986. At a trapezium bone volume of ⩾1.94cm(3), there was a 93.5% probability that the subject was male. Binary logistic regression analysis found that the highest accuracy was derived using the pisiform, trapezium and capitate bones. There was a strong relationship between sex prediction and grouping of the carpal bone volumes (Nagelkerke R(2)=0.923) with an overall prediction accuracy of 97%. All 8 carpal bones exhibit sexual dimorphism to varying degrees. A binary regression analysis combining the 5 carpal bones with the highest predictive values for sex produces an accurate predictive model.