Cortical hypertrophy in intramuscular hemangioma mimicking bone tumor.

Although hemangiomas are the most common soft tissue tumors, intramuscular hemangiomas account for only 0.8% of all vascular tumors. These lesions are rarely located adjacent to the bone and cause changes in the adjacent bone. They are often mistakenly diagnosed as bone tumors. In this study, a case of a 19-year-old male patient with intramuscular hemangioma causing cortical thickening was reported.

The comparison of visibility of the maxillary sinus septa between cone-beam computed tomography scans and panoramic radiograph images as dependent on the cortical bone thickness: a retrospective comparative study.

PURPOSE: To analyze the visibility of the maxillary sinus septa (MSS) in panoramic radiography (PR) versus cone beam computed tomography (CBCT) and to investigate whether the buccal cortical bone thickness (BT) or the septa dimensions influence their visibility. METHODS: Corresponding PR and CBCT images of 355 patients were selected and examined for MSS visibility. The septa dimensions (width, height, depth) and the BT were measured. Results were analysed statistically. RESULTS: Comparing the corresponding regions on CBCT and PR, 170 MSS were identified; however, only 106 of these were also visible using PR. The MSS visibility was significantly higher on CBCT versus PR images (P1: p = 0.039, P2: p = 0.015, M1: p = 0.041, M2: p = 0.017, M3: p = 0.000), except region C (p = 0.625). Regarding the measurements of MSS dimensions, only the height in region M1 (p = 0.013) and the width in region P2 (p = 0.034) were significantly more visible on CBCT. The BT in the area of the MSS was found to have a marginal influence on its visibility on the PR images only in regions M3 and M1 (M3: p = 0.043, M1: p = 0.047). In terms of MSS visibility based on the dimensions, significance was found for all three influencing variables only in region P2 (width; p = 0.041, height; p = 0.001, depth; p = 0.007). There were only isolated cases of further significance: M3 for width (p = 0.043), M2 for height (p = 0.024), and P1 for depth (p = 0.034), no further significance was noted. CONCLUSION: MSS visibility appears significantly higher on CBCT versus PR images. It is concluded that the septa dimensions and BT can influence MSS visibility on PR images just in certain regions.

The respective and dependent effects of scattering and bone matrix absorption on ultrasound attenuation in cortical bone.

Cortical bone is characterized by a dense solid matrix permeated by fluid-filled pores. Ultrasound scattering has potential for the non-invasive evaluation of changes in bone porosity. However, there is an incomplete understanding of the impact of ultrasonic absorption in the solid matrix on ultrasound scattering. In this study, maps were derived from scanning acoustic microscopy images of human femur cross-sections. Finite-difference time domain ultrasound scatter simulations were conducted on these maps. Pore density, diameter distribution of the pores, and nominal absorption values in the solid and fluid matrices were controlled. Ultrasound pulses with a central frequency of 8.2 MHz were propagated, both in through-transmission and backscattering configurations. From these data, the scattering, bone matrix absorption, and attenuation extinction lengths were calculated. The results demonstrated that as absorption in the solid matrix was varied, the scattering, absorption, and attenuation extinction lengths were significantly impacted. It was shown that for lower values of absorption in the solid matrix (less than 2 dB mm-1), attenuation due to scattering dominates, whereas at higher values of absorption (more than 2 dB mm-1), attenuation due to absorption dominates. This will impact how ultrasound attenuation and scattering parameters can be used to extract quantitative information on bone microstructure.

A numerical study of dehydration induced fracture toughness degradation in human cortical bone.

A 2D plane strain extended finite element method (XFEM) model was developed to simulate three-point bending fracture toughness tests for human bone conducted in hydrated and dehydrated conditions. Bone microstructures and crack paths observed by micro-CT imaging were simulated using an XFEM damage model. Critical damage strains for the osteons, matrix, and cement lines were deduced for both hydrated and dehydrated conditions and it was found that dehydration decreases the critical damage strains by about 50%. Subsequent parametric studies using the various microstructural models were performed to understand the impact of individual critical damage strain variations on the fracture behavior. The study revealed the significant impact of the cement line critical damage strains on the crack paths and fracture toughness during the early stages of crack growth. Furthermore, a significant sensitivity of crack growth resistance and crack paths on critical strain values of the cement lines was found to exist for the hydrated environments where a small change in critical strain values of the cement lines can alter the crack path to give a significant reduction in fracture resistance. In contrast, in the dehydrated state where toughness is low, the sensitivity to changes in critical strain values of the cement lines is low. Overall, our XFEM model was able to provide new insights into how dehydration affects the micromechanisms of fracture in bone and this approach could be further extended to study the effects of aging, disease, and medical therapies on bone fracture.

A comprehensive set of ultrashort echo time magnetic resonance imaging biomarkers to assess cortical bone health: A feasibility study at clinical field strength.

INTRODUCTION: Conventional bone imaging methods primarily use X-ray techniques to assess bone mineral density (BMD), focusing exclusively on the mineral phase. This approach lacks information about the organic phase and bone water content, resulting in an incomplete evaluation of bone health. Recent research highlights the potential of ultrashort echo time magnetic resonance imaging (UTE MRI) to measure cortical porosity and estimate BMD based on signal intensity. UTE MRI also provides insights into bone water distribution and matrix organization, enabling a comprehensive bone assessment with a single imaging technique. Our study aimed to establish quantifiable UTE MRI-based biomarkers at clinical field strength to estimate BMD and microarchitecture while quantifying bound water content and matrix organization. METHODS: Femoral bones from 11 cadaveric specimens (n = 4 males 67-92 yrs of age, n = 7 females 70-95 yrs of age) underwent dual-echo UTE MRI (3.0 T, 0.45 mm resolution) with different echo times and high resolution peripheral quantitative computed tomography (HR-pQCT) imaging (60.7 µm voxel size). Following registration, a 4.5 mm HR-pQCT region of interest was divided into four quadrants and used across the multi-modal images. Statistical analysis involved Pearson correlation between UTE MRI porosity index and a signal-intensity technique used to estimate BMD with corresponding HR-pQCT measures. UTE MRI was used to calculate T1 relaxation time and a novel bound water index (BWI), compared across subregions using repeated measures ANOVA. RESULTS: The UTE MRI-derived porosity index and signal-intensity-based estimated BMD correlated with the HR-pQCT variables (porosity: r = 0.73, p = 0.006; BMD: r = 0.79, p = 0.002). However, these correlations varied in strength when we examined each of the four quadrants (subregions, r = 0.11-0.71). T1 relaxometry and the BWI exhibited variations across the four subregions, though these differences were not statistically significant. Notably, we observed a strong negative correlation between T1 relaxation time and the BWI (r = -0.87, p = 0.0006). CONCLUSION: UTE MRI shows promise for being an innocuous method for estimating cortical porosity and BMD parameters while also giving insight into bone hydration and matrix organization. This method offers the potential to equip clinicians with a more comprehensive array of imaging biomarkers to assess bone health without the need for invasive or ionizing procedures.

Biportal endoscopic-assisted cortical bone trajectory screw placement and lumbar interbody fusion.

BACKGROUND: Endoscopically assisted screw fixation with lumbar interbody fusion is rarely performed. We succeeded in implanting the cortical bone trajectory (CBT) screws under the guidance of unilateral biportal endoscopy (UBE). METHOD: We attempted endoscopically assisted screw fixation in a patient with degenerative spondylolisthesis. Through a third portal, ipsilateral CBT screws were implanted without complications. CONCLUSIONS: We successfully performed unilateral biportal endoscopic lumbar interbody fusion (ULIF) with CBT and reversed CBT screws. Compared with percutaneous pedicle screw (PPS) placement, this procedure is a minimally invasive, endoscopic alternative that allows precise screw placement.

Evaluation of cortical bone strength using a quantitative ultrasound measurement device in dogs.

This study was performed to evaluate cortical bone strength in dogs using a quantitative ultrasound measurement device. In this study, 16 clinically healthy dogs with no lameness underwent measurement of the ultrasound propagation velocity of cortical bone (namely, speed of sound [SOS]) at the radius and tibia. Additionally, computed tomography examination with a calibration phantom was performed in 10 dogs. We calculated the bone mineral density (BMD) and Young's modulus from the computed tomography data using bone strength evaluation software. SOS, BMD, and Young's modulus were statistically compared between the radius and tibia. In addition, we examined the correlation between SOS and BMD and between SOS and Young's modulus. We also examined the correlation between SOS and age in the 13 dogs whose age was known. BMD and Young's modulus were not significantly different between the radius and tibia, but SOS was significantly different (P<0.05). Moreover, SOS and BMD showed a positive correlation in both radius and tibia. Similarly, SOS and Young's modulus showed a positive correlation. In addition, SOS and age showed a strong positive correlation (radius: r=0.77, P<0.05, tibia: r=0.83, P<0.05). Our finding that SOS of the radius and tibia cortical bone was correlated with BMD and Young's modulus indicates that quantitative ultrasound can be useful for evaluating cortical bone strength in dogs.

Ultrasound attenuation of cortical bone correlates with biomechanical, microstructural, and compositional properties.

BACKGROUND: We investigated the relationship of two commonly used quantitative ultrasound (QUS) parameters, speed of sound (SoS) and attenuation coefficient (α), with water and macromolecular contents of bovine cortical bone strips as measured with ultrashort echo time (UTE) magnetic resonance imaging (MRI). METHODS: SoS and α were measured in 36 bovine cortical bone strips utilizing a single-element transducer with nominal 5 MHz center frequency based on the time of flight principles after accommodating for reflection losses. Specimens were then scanned using UTE MRI to measure total, bound, and pore water proton density (TWPD, BWPD, and PWPD) as well as macromolecular proton fraction and macromolecular transverse relaxation time (T2-MM). Specimens were also scanned using microcomputed tomography (µCT) at 9-µm isometric voxel size to measure bone mineral density (BMD), porosity, and pore size. The elastic modulus (E) of each specimen was measured using a 4-point bending test. RESULTS: α demonstrated significant positive Spearman correlations with E (R = 0.69) and BMD (R = 0.44) while showing significant negative correlations with porosity (R = -0.41), T2-MM (R = -0.47), TWPD (R = -0.68), BWPD (R = -0.67), and PWPD (R = -0.45). CONCLUSIONS: The negative correlation between α and T2-MM is likely indicating the relationship between QUS and collagen matrix organization. The higher correlations of α with BWPD than with PWPD may indicate that water organized in finer structure (bound to matrix) provides lower acoustic impedance than water in larger pores, which is yet to be investigated thoroughly. RELEVANCE STATEMENT: This study highlights the importance of future investigations exploring the relationship between QUS measures and all major components of the bone, including the collagenous matrix and water. Investigating the full potential of QUS and its validation facilitates a more affordable and accessible tool for bone health monitoring in clinics. KEY POINTS: • Ultrasound attenuation demonstrated significant positive correlations with bone mechanics and mineral density. • Ultrasound attenuation demonstrated significant negative correlations with porosity and bone water contents. • This study highlights the importance of future investigations exploring the relationship between QUS measures and all major components of the bone.

Risk Factors for Medial Breach During Robotic-Assisted Cortical Bone Trajectory Screw Insertion.

OBJECTIVE: We describe the incidence of, and identify the risk factors for, a medial breach of the pedicle wall during robotic-assisted cortical bone trajectory (RA-CBT) screw insertion. METHODS: We analyzed a consecutive series of adult patients who underwent RA-CBT screw placement from January 2019 to July 2022. To assess the pedicle wall medial breach, postoperative computed tomography (CT) images were analyzed. Patient demographic data and screw data were compared between patients with and without a medial breach. The Hounsfield units (HUs) on the L1 midvertebral axial CT scan was used to evaluate bone quality. RESULTS: Of 784 CBT screws in 145 patients, 30 (3.8%) had a medial breach in 23 patients (15.9%). One screw was grade 2, and the others were grade 1. Patients with a medial breach had a lower HU value compared with the patients without a medial breach (123.3 vs. 150.5; P = 0.027). A medial breach was more common in the right than left side (5.5% vs. 2.0%; P = 0.014). More than one half of the screws with a medial breach were found in the upper instrumented vertebra (UIV) compared with the middle construct or lowest instrumented vertebra (6.7% vs. 1.3% vs. 2.7%; P = 0.003). Binary logistic regression showed that low HU values, right-sided screw placement, and UIV were associated with a medial breach. No patients returned to the operating room for screw malposition. No differences were found in the clinical outcomes between patients with and without a medial breach. CONCLUSIONS: The incidence of pedicle wall medial breach was 3.8% of RA-CBT screws in the postoperative CT images. A low HU value measured in the L1 axial image, right-sided screw placement, and UIV were associated with an increased risk of medial breach for RA-CBT screw placement.

Comparison of the clinical and radiographic outcomes of cortical bone trajectory and traditional trajectory pedicle screw fixation in transforaminal lumbar interbody fusion: a randomized controlled trial.

PURPOSE: To compare the clinical outcomes and radiographic outcomes of cortical bone trajectory (CBT) and traditional trajectory (TT) pedicle screw fixation in patients treated with single-level transforaminal lumbar interbody fusion (TLIF). METHODS: This trial included a total of 224 patients with lumbar spine disease who required single-level TLIF surgery. Patients were randomly assigned to the CBT and TT groups at a 1:1 ratio. Demographics and clinical and radiographic data were collected to evaluate the efficacy and safety of CBT and TT screw fixation in TLIF. RESULTS: The baseline characteristic data were similar between the CBT and TT groups. Back and leg pain for both the CBT and TT groups improved significantly from baseline to 24 months postoperatively. The CBT group experienced less pain than the TT group at one week postoperatively. The postoperative radiographic results showed that the accuracy of screw placement was significantly increased in the CBT group compared with the TT group (P < 0.05). The CBT group had a significantly lower rate of FJV than the TT group (P < 0.05). In addition, the rate of fusion and the rate of screw loosening were similar between the CBT and TT groups according to screw loosening criteria. CONCLUSION: This prospective, randomized controlled analysis suggests that clinical outcomes and radiographic characteristics, including fusion rates and caudal screw loosening rates, were comparable between CBT and TT screw fixation. Compared with the TT group, the CBT group showed advantages in the accuracy of screw placement and the FJV rate. CLINICAL TRIALS REGISTRATION: This trial has been registered at the US National Institutes of Health Clinical Trials Registry: NCT03105167.

Understanding basic multicellular unit activity in cortical bone through 3D morphological analysis: New methods to define zones of the remodeling space.

The activity of basic multicellular units (BMU) in cortical bone is classically described as a sequential order of events- resorption, reversal and formation. This simplified portrayal of the remodeling process is pervasive despite the reported variability in remodeling space morphology. These variations may reflect meaningful nuances in BMU activity but methods to quantify 3D remodeling space morphology within the context of the cellular activity are currently lacking. This study developed new techniques to define zones of BMU activity based on the 3D morphology of remodeling spaces in rabbit cortical bone and integrated morphological data with the BMU longitudinal erosion rate (LER) to elucidate the spatial-temporal coordination of BMUs and estimate mineral apposition rate (MAR). The tibiae of New Zealand white rabbits (n = 5) were imaged in vivo using synchrotron radiation and two weeks later ex vivo with desktop microCT. The in vivo and ex vivo datasets were co-registered, and 27 remodeling spaces were identified at both timepoints. A radial profile representing the 3D morphology was the platform for partitioning the remodeling spaces into resorption, reversal and formation zones. Manual, automated and semi-automated partitioning approaches were compared, and the zone-segmentations were used to calculate the length, change in radius and slope of each zone. The manual approach most accurately defined the zones of idealized remodeling spaces with known dimensions (relative error = 0.9-9.2 %) while the semi-automated method reliably defined the zones in rabbit remodeling spaces (ICC = 0.85-1.00). Combining LER and the manually derived zone dimensions indicated that a BMU passes through a cross-section in approximately 18.8 days with resorption, reversal and formation taking 4.1, 2.2, and 12.5 days, respectively. MAR estimated by the 3D analysis was not significantly different than that determined with classic histomorphometry (p = 0.48). These techniques have the potential to assess dynamic parameters of bone resorption and formation, eliminate the need for fluorochrome labeling and provide a more comprehensive perspective of the remodeling process.

Cortical bone adaptation response is region specific, but not peak load dependent: insights from µ CT image analysis and mechanostat simulations of the mouse tibia loading model.

The two major aims of the present study were: (i) quantify localised cortical bone adaptation at the surface level using contralateral endpoint imaging data and image analysis techniques, and (ii) investigate whether cortical bone adaptation responses are universal or region specific and dependent on the respective peak load. For this purpose, we re-analyse previously published µ CT data of the mouse tibia loading model that investigated bone adaptation in response to sciatic neurectomy and various peak load magnitudes (F = 0, 2, 4, 6, 8, 10, 12 N). A beam theory-based approach was developed to simulate cortical bone adaptation in different sections of the tibia, using longitudinal strains as the adaptive stimuli. We developed four mechanostat models: universal, surface-based, strain directional-based, and combined surface and strain direction-based. Rates of bone adaptation in these mechanostat models were computed using an optimisation procedure (131,606 total simulations), performed on a single load case (F = 10 N). Subsequently, the models were validated against the remaining six peak loads. Our findings indicate that local bone adaptation responses are quasi-linear and bone region specific. The mechanostat model which accounted for differences in endosteal and periosteal regions and strain directions (i.e. tensile versus compressive) produced the lowest root mean squared error between simulated and experimental data for all loads, with a combined prediction accuracy of 76.6, 55.0 and 80.7% for periosteal, endosteal, and cortical thickness measurements (in the midshaft of the tibia). The largest root mean squared errors were observed in the transitional loads, i.e. F = 2 to 6 N, where inter-animal variability was highest. Finally, while endpoint imaging studies provide great insights into organ level bone adaptation responses, the between animal and loaded versus control limb variability make simulations of local surface-based adaptation responses challenging.

Chronic kidney disease compromises structural and mechanical properties of maxillary cortical bone in a rat model.

PURPOSE: This study aimed to investigate the effects of chronic kidney disease (CKD) on the structural and mechanical properties of the maxillary and mandibular cortical bone. METHODS: The maxillary and mandibular cortical bones from CKD model rats were used in this study. CKD-induced histological, structural, and micro-mechanical alterations were assessed using histological analyses, micro-computed tomography (CT), bone mineral density (BMD) measurements, and nanoindentation tests. RESULTS: Histological analyses indicated that CKD caused an increase in the number of osteoclasts and a decrease in the number of osteocytes in the maxilla. Micro-CT analysis revealed that CKD induced a void volume/cortical volume (%) increase, which was more remarkable in the maxilla than in the mandible. CKD also significantly decreased the BMD in the maxilla. In the nanoindentation stress-strain curve, the elastic-plastic transition point and loss modulus were lower in the CKD group than that in the control group in the maxilla, suggesting that CKD increased micro fragility of the maxillary bone. CONCLUSIONS: CKD affected bone turnover in the maxillary cortical bone. Furthermore, the maxillary histological and structural properties were compromised, and micro-mechanical properties, including the elastic-plastic transition point and loss modulus, were altered by CKD.

In vivo depiction of cortical bone vascularization with ultra-high resolution-CT and deep learning algorithm reconstruction using osteoid osteoma as a model.

PURPOSE: The purpose of this study was to evaluate the ability to depict in vivo bone vascularization using ultra-high-resolution (UHR) computed tomography (CT) with deep learning reconstruction (DLR) and hybrid iterative reconstruction algorithm, compared to simulated conventional CT, using osteoid osteoma as a model. MATERIALS AND METHODS: Patients with histopathologically proven cortical osteoid osteoma who underwent UHR-CT between October 2019 and October 2022 were retrospectively included. Images were acquired with a 1024 × 1024 matrix and reconstructed with DLR and hybrid iterative reconstruction algorithm. To simulate conventional CT, images with a 512 × 512 matrix were also reconstructed. Two radiologists (R1, R2) independently evaluated the number of blood vessels entering the nidus and crossing the bone cortex, as well as vessel identification and image quality with a 5-point scale. Standard deviation (SD) of attenuation in the adjacent muscle and that of air were used as image noise and recorded. RESULTS: Thirteen patients with 13 osteoid osteomas were included. There were 11 men and two women with a mean age of 21.8 ± 9.1 (SD) years. For both readers, UHR-CT with DLR depicted more nidus vessels (11.5 ± 4.3 [SD] (R1) and 11.9 ± 4.6 [SD] (R2)) and cortical vessels (4 ± 3.8 [SD] and 4.3 ± 4.1 [SD], respectively) than UHR-CT with hybrid iterative reconstruction (10.5 ± 4.3 [SD] and 10.4 ± 4.6 [SD], and 4.1 ± 3.8 [SD] and 4.3 ± 3.8 [SD], respectively) and simulated conventional CT (5.3 ± 2.2 [SD] and 6.4 ± 2.5 [SD], 2 ± 1.2 [SD] and 2.4 ± 1.6 [SD], respectively) (P < 0.05). UHR-CT with DLR provided less image noise than simulated conventional CT and UHR-CT with hybrid iterative reconstruction (P < 0.05). UHR-CT with DLR received the greatest score and simulated conventional CT the lowest score for vessel identification and image quality. CONCLUSION: UHR-CT with DLR shows less noise than UHR-CT with hybrid iterative reconstruction and significantly improves cortical bone vascularization depiction compared to simulated conventional CT.

Simultaneous visualization of micro-damage in cortical bone, trabecular bone, and intracortical vasculature for diagnosing osteoporosis: An animal model synchrotron imaging.

Osteoporosis (OP) is difficult to diagnose through the three-dimensional visualization of micro-damage. In this study, aimed to make an objective diagnosis by visualizing micro-damage caused by OP using synchrotron radiation-based µCT (SR-µCT). Female mice (n = 12) were randomly divided into an ovariectomized group (OVX, n = 6) in which both ovaries were excised and OP occurred, and a sham-operated group (SHAM, n = 6). After six weeks, all femurs (left and right) were excised from both groups (n = 12 per group). Thereafter, femurs were randomly divided into SR-µCT (OVX group, n = 6; SHAM group, n = 6) and µCT (OVX group, n = 6; SHAM group, n = 6) groups. In the SR-µCT group, micro-damage was visualized by manually segmenting the cortical bone, trabecular bone, and intracortical vasculature using a water-shedding algorithm. In addition, trabecular bone was obtained by automatic segmentation using µCT. Cortical bone volume/total volume was greater (p = .015), and cortical thickness was greater in the SHAM group than in the OVX group (p = .007). Among the trabecular bone parameters, the bone volume/total volume (TV) in OVX was significantly lower than that in the SHAM group (p = .012). The canal volume was greater (p = .021) and lacuna volume was greater (p < .001) in the SHAM group than in the OVX group. We expect that it will be possible to analyze damage and recovery mechanisms in the field of rehabilitation. SR-µCT has been proposed as an objective method for OP diagnosis as it allows the visualization of microstructures. RESEARCH HIGHLIGHTS: Damage mechanism for diagnosis and evaluation in an osteoporosis model. Synchrotron radiation can objectively diagnose osteoporosis. Visualization is possible by segmenting microdamage caused by osteoporosis.

Cortical thickness adaptation to combined mechanical loading and parathyroid hormone treatments is site specific and synergistic in the mouse tibia model.

In this study, we aimed to quantify the localised effects of mechanical loading (ML), low (20 µg/kg/day), moderate (40 µg/kg/day) or high (80 µg/kg/day) dosages of parathyroid hormone (PTH), and combined (PTHML) treatments on cortical bone adaptation in healthy 19-week old female C57BL/6 mice. To this end, we utilise a previously reported image analysis algorithm on µCT data of the mouse tibia published by Sugiyama et al. (2008) to measure changes in cortical area, marrow cavity area and local cortical thickness measures (ΔCt.Ar, ΔMa.Ar, ΔCt.Th respectively), evaluated at two cross-sections within the mouse tibia (proximal-middle (37 %) and middle (50 %)), and are compared to a superposed summation (P + M) of individual treatments to determine the effectiveness of combining treatments in vivo. ΔCt.Ar analysis revealed a non-linear, synergistic interactions between PTH and ML in the 37 % cross-section that saturates at higher PTH dosages, whereas the 50 % cross-section experiences an approximately linear, additive adaptation response. This coincided with an increase in ΔMa.Ar (indicating resorption of the endosteal surface), which was only counteracted by combined high dose PTH with ML in the middle cross-section. Regional analysis of ΔCt.Th changes reveal localised cortical thinning in response to low dose PTH treatment in the posteromedial region of the middle cross-section, signifying that PTH does not provide a homogeneous adaptation response around the cortical perimeter. We observe a synergistic response in the proximal-middle cross-section, with regions of compressive strain experiencing the greatest adaptation response to PTHML treatments, (peak ΔCt.Th of 189.32, 213.78 and 239.30 µm for low, moderate and high PTHML groups respectively). In contrast, PTHML treatments in the middle cross-section show a similar response to the superposed P + M group, with the exception of the combined high dose PTHML treatment which shows a synergistic interaction. These analyses suggest that, in mice, adding mechanical loading to PTH treatments leads to region specific bone responses; synergism of PTHML is only achieved in some regions experiencing high loading, while other regions respond additively to this combined treatment.

Evaluation of gadolinium deposition in cortical bone using three-dimensional ultrashort echo time quantitative susceptibility mapping: A preliminary study.

The aim of the current study was to investigate the feasibility of three-dimensional ultrashort echo time quantitative susceptibility mapping (3D UTE-QSM) for the assessment of gadolinium (Gd) deposition in cortical bone. To this end, 40 tibial bovine cortical bone specimens were divided into five groups then soaked in phosphate-buffered saline (PBS) solutions with five different Gd concentrations of 0, 0.4, 0.8, 1.2, and 1.6 mmol/L for 48 h. Additionally, eight rabbits were randomly allocated into three groups, consisting of a normal-dose macrocyclic gadolinium-based contrast agent (GBCA) group (n = 3), a high-dose macrocyclic GBCA group (n = 3), and a control group (n = 2). All bovine and rabbit tibial bone samples underwent magnetic resonance imaging (MRI) on a 3-T clinical MR system. A 3D UTE-Cones sequence was utilized to acquire images with five different echo times (i.e., 0.032, 0.2, 0.4, 0.8, and 1.2 ms). The UTE images were subsequently processed with the morphology-enabled dipole inversion algorithm to yield a susceptibility map. The average susceptibility was calculated in three regions of interest in the middle of each specimen, and the Pearson's correlation between the estimated susceptibility and Gd concentration was calculated. The bone samples soaked in PBS with higher Gd concentrations exhibited elevated susceptibility values. A mean susceptibility value of -2.47 ± 0.23 ppm was observed for bovine bone soaked in regular PBS, while the mean QSM value increased to -1.75 ± 0.24 ppm for bone soaked in PBS with the highest Gd concentration of 1.6 mmol/L. A strong positive correlation was observed between Gd concentrations and QSM values. The mean susceptibility values of rabbit tibial specimens in the control group, normal-dose GBCA group, and high-dose GBCA group were -4.11 ± 1.52, -3.85 ± 1.33, and -3.39 ± 1.35 ppm, respectively. In conclusion, a significant linear correlation between Gd in cortical bone and QSM values was observed. The preliminary results suggest that 3D UTE-QSM may provide sensitive noninvasive assessment of Gd deposition in cortical bone.

The Influence of Titanium-coated Poryetheretherketone Cages in Fusion Status after Posterior Lumbar Interbody Fusion with Cortical Bone Trajectory Screw Fixation.

OBJECTIVE: Posterior lumbar interbody fusion (PLIF) with cortical bone trajectory (CBT) screw fixation (CBT-PLIF) shows potential for reducing adjacent segmental disease. Previously, our investigations revealed a relatively lower fusion rate with the use of carbon fiber-reinforced polyetheretherketone (CP) cages in CBT-PLIF compared with traditional pedicle screw fixation (PS-PLIF) using CP cages. This study aims to evaluate whether the implementation of titanium-coated polyetheretherketone (TP) cages can enhance fusion outcomes in CBT-PLIF. METHODS: A retrospective analysis was conducted on 68 consecutive patients who underwent CBT-PLIF with TP cages (TP group) and 89 patients who underwent CBT-PLIF with CP cages (CP group). Fusion status was assessed using computed tomography at 1 year postoperatively and dynamic plain radiographs at 2 years postoperatively. RESULTS: No statistically significant differences in fusion rates were observed at 1 and 2 years postoperatively between the TP group (86.8% and 89.7%, respectively) and the CP group (77.5% and 88.8%, respectively). Notably, the CP group exhibited a significant improvement in fusion rate from 1 to 2 years postoperatively (P = 0.002), while no significant improvement was observed in the TP group. CONCLUSIONS: Examination of temporal changes in fusion rates reveals that only the TP group achieved a peak fusion rate 1 year postoperatively. This implies that TP cages may enhance the fusion process even after CBT-PLIF. Nevertheless, the definitive efficacy of TP cages for CBT-PLIF remains uncertain in the context of overall fusion rates.

Characterization of rat vertebrae cortical bone microstructures using confocal Raman microscopy combined to tomography and electron microscopy.

BACKGROUND: The rat vertebrae is a good model to study bone regeneration after implantation of biomaterials used to treat bone loss, a major problem in oral and dental surgery. However, the precise characterization of bone microstructures in the rat vertebrae has not been reported. Therefore, the aim of this study was to achieve the complete analysis of such bone, at different scales, in order to have a clear model of healthy bone for comparison with regenerated bone. METHODS: In order to image the cortical bone of rat caudal vertebra, confocal Raman microscopy was combined with high resolution X-ray micro computed tomography (micro-CT), with scanning electron microscopy (SEM) using backscatter electron imaging and with more conventional histology coloration techniques. SEM and Raman microscopy were done in various regions of the cortical bone corresponding to external, middle and internal areas. The spongy bone was imaged in parallel. Micro-CT was performed on the whole vertebra to monitor the network of haversian canals in the cortical bone. Osteonic canals characteristics, and relative chemical composition were analysed in several regions of interest, in cortical and spongy bone. Five rats were included in this study. RESULTS: On micro-CT images, differences in intensity were observed in the cortical bone, substantiated by SEM. Chemical analysis with Raman spectra confirmed the difference in composition between the different regions of the cortical and spongy bone. PCA and k-mean cluster analysis separated these groups, except for the external and middle cortical bone. Peak intensity ratio confirmed these results with a CO3 to ν2 PO4 ratio significantly different for the internal cortical bone. Grayscale images stack extracted from micro-CT showed that global architecture of cortical bone was characterized by a dense and complex network of haversian osteonic canals, starting from the surface towards the vertebrae center. The mean diameter of the canals was 18.4 µm (SD 8.6 µm) and the mean length was 450 µm (SD 152 µm). Finally, Raman reconstructed images of the lamellar bone showed an enlargement of the lamellar layer width, both in circumferential lamellar bone and around haversian canals. CONCLUSIONS: Micro-CT and confocal Raman microscopy are good tools to complete classical analysis using optical and electron microscopy. The results and measurements presented in a rat model known for its small inter-individual differences provide the main characteristics of a mature bone. This study will allow the community working on this rat vertebrate model to have a set of characteristics, in particular on the structure of the haversian canals.