Cortical Bone Research Articles

A novel method to judge the safe position of C2 lamina screw with double holes.

To evaluate the feasibility of C2 laminar screw (C2LS) fixation assisted by double holes and to explore a novel method for judging its safe positioning. The Digital Imaging in Communications format data of 25 C2 vertebrae specimens were obtained by computed tomography thin-slice scanning, and the data were imported into Mimics software for three-dimensional reconstruction. The bone cortex was removed at the starting and terminal midpoints of the lamina as the observation holes. Points A, M, and P represented the three different entry points of the C2LS. Point M was designated as the central entry point, point A was 1mm from the extension surface of point M to the ventral side, and point P was 1mm from the extension surface of point M to the dorsal side. Further classified into groups A, M, and P based on the screw path correlation parameters at each entry point. The distance between holes 1 and 2 (D1 and D2) was measured at the maximum safe inclination, parallel, and maximum safe extroversion positions when the screw-insertion points of C2LS were at the center points A, M, and P, respectively. The data of D1 and D2 of the three groups (A, M, P) in different screw directions were analyzed and compared. Twenty-five specimens were measured in the parallel, maximum safe inclination, and maximum safe extroversion groups. In the parallel relationship, there were significant differences in the D1 and D2 data between the M and P groups. In the introversion relationship, there were significant differences in the D1 and D2 data between the M and P groups. In the extroversion relationship, there were significant differences in the D1 and D2 data among the A, M, and P groups, respectively. Use of the C2LS assisted by double holes was able to determine the safe position of the screw in operation. When D1 is greater than D2, the screw position can be considered relatively safe, with the intraoperative visual manifestation of a deep screw in hole 1 and a shallow screw in hole 2. If D1 is close to D2, it is necessary to ensure that the screws in both holes 1 and 2 are shallow, then the screw position is safe. If the screw in hole 1 is observed to be shallower than in hole 2 during surgery, regardless of the entry point position, there is a significant risk of ventral cortical perforation. Especially when the entry point is more anterior, even when inserting the screw parallel to the lamina, caution must be taken against the risk of ventral cortical perforation.

Effectiveness of sacroiliac screw implantation assisted by three-dimensional printed faceted honeycomb guide plate in treatment of posterior pelvic ring fracture

To investigate the effectiveness of sacroiliac screw implantation assisted by three-dimensional (3D) printed faceted honeycomb guide plate in the treatment of posterior pelvic ring fracture. The clinical data of 40 patients with posterior pelvic ring fractures treated with sacroiliac screw implantation between December 2019 and December 2022 were retrospectively analyzed. Among them, 18 cases were treated with sacroiliac screws fixation assisted by 3D printed faceted honeycomb guide plate (guide plate group), and 22 cases were treated with sacroiliac screws percutaneously fixation under fluoroscopy (conventional group). There was no significant difference in baseline data ( P>0.05) such as gender, age, time from injury to operation, and Dennis classification between the two groups. The implantation time, frequency of C-arm X-ray fluoroscopy, frequency of guide pin adjustment of each sacroiliac screw, and postoperative complications and bone healing were recorded. Majeed score was used to evaluate the functional recovery at 6 months after operation, and CT was used to observe whether the screw penetrated the bone cortex. The deviation between the virtual position and the actual position of the screw tip, the sacral foramen, and the screw entry point was measured on the sagittal CT images of the guide plate group. The number of screws implanted in S 1 and S 2 vertebral bodies was 14 and 16 respectively in the guide plate group, and 17 and 18 respectively in the conventional group. The implantation time of each sacroiliac screw, the frequency of C-arm X-ray fluoroscopy, and the frequency of guide pin adjustment in S 1, S 2, and all vertebrae in the guide plate group were significantly less than those in the conventional group ( P<0.05). Patients in both groups were followed up 8-48 months, with an average of 19.7 months. There was no incision infection, screw displacement, or internal fixation loosening in both groups. Callus growth was observed in all patients at 12 weeks after operation, and bone healing was achieved in all patients. The healing time ranged from 12 to 24 weeks, with an average of 15.7 weeks. No sacroiliac screw penetrated the bone cortex in the guide plate group; 2 patients in the conventional group had sacroiliac screws penetrating the bone cortex without damaging blood vessels or nerves. In the guide plate group, the deviation between the virtual position and the actual position of the screw tip, the sacral foramen, and the screw entry point were (2.91±1.01), (2.10±0.74), and (1.67±0.70) mm, respectively, with an average deviation of (2.19±1.22) mm. There was no significant difference in Majeed function evaluation between the two groups at 6 months after operation ( P>0.05). The application of 3D printed faceted honeycomb guide plate in sacroiliac screw implantation for posterior pelvic ring fracture can shorten the screw implantation time, reduce the frequency of fluoroscopy and guide pin adjustment, and reduce the risk of screw penetration through the bone cortex.

Residual Stress Homogenization of Hybrid Implants

Objectives: Hybrid implants commonly exhibit decreased corrosion resistance and fatigue due to differences in compressive residual stresses between the smooth and rough surfaces. The main objective of this study was to investigate the influence of an annealing heat treatment to reduce the residual stresses in hybrid implants. Methodology: Commercially pure titanium (CpTi) bars were heat-treated at 800 °C and different annealing times. Optical microscopy was used to analyze the resulting grain growth kinetics. Diffractometry was used to measure residual stress after heat treatment, corrosion resistance by open circuit potential (EOCP), corrosion potentials (ECORR), and corrosion currents (ICORR) of heat-treated samples, as well as fatigue behavior by creep testing. The von Mises distribution and the resulting microstrains in heat-treated hybrid implants and in cortical and trabecular bone were assessed by finite element analysis. The results of treated hybrid implants were compared to those of untreated hybrid implants and hybrid implants with a rough surface (shot-blasted). Results: The proposed heat treatment (800 °C for 30 min, followed by quenching in water at 20 °C) could successfully homogenize the residual stress difference between the two surfaces of the hybrid implant (−20.2 MPa). It provides better fatigue behavior and corrosion resistance (p ˂ 0.05, ANOVA). Stress distribution was significantly improved in the trabecular bone. Heat-treated hybrid implants performed worse than implants with a rough surface. Clinical significance: Annealing heat treatment can be used to improve the mechanical properties and corrosion resistance of hybrid surface implants by homogenizing residual stresses.

A systematic review and meta-analysis of the effects of probiotics on bone outcomes in rodent models.

Emerging evidence demonstrates an opportunity for using probiotics to support bone health but findings in humans are limited. This systematic review investigated if probiotic supplementation improves bone mineral density and bone structure in rodent models compared to no supplementation. Studies (n = 71) examining the effect of oral consumption of any probiotic strain on bone mineral density or bone structure in rodents were included. Meta-analyses were conducted separately by study model (intact, ovariectomized) and bone site (femur, tibia, spine) to determine the probiotic effect (standardized mean difference, SMD) on volumetric bone mineral density (vBMD), bone volume fraction (BV/TV) and cortical thickness (Ct.Th). Reasons for heterogeneity were explored (probiotic genus, sex, type of rodent). In intact rodents, probiotics resulted in greater vBMD (SMD = 0.43, 95% CI [0.13, 0.74], I2 = 3%, P<.05) and higher BV/TV (SMD = 0.63, 95% CI [0.25, 1.02], I2 = 57%, P<.05) at the femur without changes in cortical bone structure. In ovariectomized models, probiotic supplementation resulted in greater vBMD (femur: SMD = 1.28, 95% CI [1.01, 1.55], I2 = 3%, P<.05; tibia: SMD = 1.29, 95% CI [0.52, 2.05], I2 = 67%, P<.05; and spine: SMD = 1.47, 95% CI [0.97, 1.97], I2 = 26%, P<.05) as well as higher BV/TV (femur: SMD = 1.16, 95% CI [0.80, 1.52], I2 = 56%, P<.05; tibia: SMD = 2.13; 95% CI [1.09, 3.17], I2 = 79%, P<.05; spine: SMD = 2.04, 95% CI [1.17, 2.90], I2 = 76%, P<.05) and Ct.Th at the tibia (SMD = 2.35; 95% CI [0.72, 3.97], I2 = 82%, P<.05) but not at the femur versus control. The syntheses support probiotics as a strategy to improve bone outcomes in rodent models.

Bone phenotyping of murine hemochromatosis models with deficiencies of Hjv, Alk2, or Alk3: The influence of sex and the bone compartment.

Osteopenia is frequently observed in patients with iron overload, especially in those with HFE-dependent hereditary hemochromatosis (HH). Interestingly, not all mouse models of HH show bone loss, suggesting that iron overload alone may not suffice to induce bone loss. In this study, the bone phenotypes of Hjv-/- and hepatocyte-specific Alk2- and Alk3-deficient mice as additional mouse models of HH were investigated to further clarify, how high iron levels lead to bone loss and which signaling mechanisms are operational. Neither male nor female 12-week-old Hjv-/- mice had an altered trabecular or cortical bone mass or bone turnover, despite severe iron overload. Male 12-month-old Hjv-/- mice even presented with a higher femoral trabecular bone volume compared to wildtype mice. Similarly, female mice with hepatocyte-specific Alk2 or Alk3 deficiency did not show an altered bone phenotype at 3, 6, and 12 months of age. Male hepatocyte-specific Alk3-deficient mice also had a normal trabecular bone mass at all ages analyzed, despite showing increased bone resorption and decreased bone formation parameters. Interestingly, hepatocyte-specific Alk2-deficient mice showed reduced femoral trabecular bone at 6 months of age due to suppressed bone formation. Cortical thickness at the femur was reduced in both, 6-month-old male hepatocyte-specific Alk2- and Alk3-deficient mice. Raising hepatocyte-specific Alk2-deficient male mice on an iron-deficient diet rescued the bone phenotype. Taken together, despite iron overload, trabecular bone microarchitecture was not altered in mice deficient of Hjv or Alk3. Only male hepatocyte-specific Alk2-deficient mice showed site-specific lower trabecular and cortical bone mass at the femur, which was dependent on iron. Thus, bone loss does not correlate with the extent of iron overload in these mouse models, but may relate to the amount of iron-loaded macrophages, as precursors of osteoclasts, in the bone marrow.

Technical note: Effects of chemical, radiational, and thermal treatment of bone tissue on material stiffness and anisotropy.

We evaluated the effects of four treatments for pathogen inactivation in bone tissue (ethanol storage, formalin fixation, gamma irradiation, and heat treatment via autoclave) on stiffness and anisotropy values in bone samples. Cortical bone samples from the humerus of 14 bovine specimens were subjected to Knoop microindentation analysis in longitudinal and transverse planes of section and four indenter orientations within each section. From each specimen, individual samples were assigned to one of five treatment conditions: 50% ethanol-saline solution, formalin immersion, gamma irradiation, autoclave, and buffered saline (controls). Each sample was microindented 100 times and the resultant stiffness data were analyzed by a resampled factorial analysis of variance. First- and second-order interactions as well as main effects of indenter orientation, treatment, and specimen were significant for both transverse and longitudinal sections, with the sole exception that indenter orientation-treatment interaction was nonsignificant for longitudinal sections. Interaction plots reveal that thermal (autoclave) and irradiation treatments depress stiffness values the most, while patterns of indentation stiffness at different orientations are relatively unaffected. Patterns of anisotropy are relatively unaffected by preservative treatments, but elastic modulus changes are consistent and unambiguous. Formalin and ethanol treatments are most comparable to controls and represent the best preservative media for mechanical testing. These options, however, are likely to be the least effective for ensuring the inactivation or sterilization of potentially contaminated samples.

Bone microarchitecture evaluated by HR-pQCT in Chinese adolescent and pediatric patients with X-linked hypophosphatemia.

X-linked hypophosphatemia (XLH) is the most common form of heritable hypophosphatemic rickets. Previous studies have found deteriorated bone microarchitecture in the XLH adults. Detailed studies on the skeletal microarchitecture of XLH adolescent and pediatric patients are still lacking. This study aimed to evaluate bone geometry, density, microarchitecture, stiffness in XLH adolescent and pediatric patients by using high-resolution peripheral quantitative computed tomography (HR-pQCT).Method: This study utilized HR-pQCT to assess bone geometry, density, microarchitecture, and stiffness in 106 Chinese adolescent and pediatric patients with XLH. Compared with the sex- and age-matched controls, XLH patients had significantly higher trabecular area (Tb.Ar), lower total volumetric bone mineral density (Tot.vBMD), lower cortical volumetric BMD (Ct.vBMD), and lower stiffness at both the distal radius and the tibia after adjusting for height and weight. Alkaline phosphatase Z score (ALP-Z), a marker to reflect the disease activity of rickets, was negatively correlated with Ct.vBMD and cortical thickness (Ct.Th) at the distal radius, and Ct.vBMD at the distal tibia, and positively correlated with cortical porosity (Ct.Po) at the distal tibia. We developed an online calculator to estimate Tb.Ar, Ct.vBMD, and stiffness of the distal tibia of XLH adolescent and pediatric patients based on clinical general characteristic and biochemical indicators. The bone microarchitecture of XLH adolescent and pediatric patients was deteriorated, and ALP-Z was negatively correlated with the skeletal quality of XLH adolescent and pediatric patients, especially in the cortical bone. HR-pQCT parameters can be estimated using clinical characteristics and biochemical indicators, which may assist physicians to monitor the disease progression in areas without HR-pQCT access.

Comparative Study of 3D Contact Area Percentage Between Zygomatic Implant and Bone in Different Surgical Approaches: Clinical and Biomechanical Perspectives.

Zygomatic implants, either alone or in combination with dental implant placement, have emerged as a viable surgical option for elderly patients with severe bone atrophy for occlusal restoration. This study aims to examine the biomechanical impact of the three-dimensional contact area between zygomatic implants and bone on biomechanics under different surgical methods. Using Cone Beam Computed Tomography (CBCT) images from 10 patients with severe bone atrophy, we reconstructed 3D maxillary bone models and created corresponding 3D zygomatic implant models. Two distinct surgical methods (extramaxillary or intrasinus approaches) were employed based on the position and angle of the zygomatic implant for each patient. The 3D bone-to-implant contact percentage (BIC%) was calculated, and finite element analysis with nonlinear contact was conducted to assess the relationship between 3D BIC% and surrounding bone stress for both surgical methods. The 3D BIC% of extramaxillary approach (57.63%) and intrasinus approach (56.49%) for total bone (including cortical and cancellous bone) was similar (P=0.425) in zygomatic implant surgery. In contrast, the intrasinus method exhibited higher 3D BIC% in cortical bone contact (28.08%) compared to the extramaxillary approach (21.92%) (P=0.011). The correlation between 3D BIC% and high bone stress was stronger in the intrasinus approach, likely due to increased contact area in cortical bone. The intrasinus approach led to lower bone stress and a more robust correlation between bone stress and 3D BIC%, particularly in cortical bone contact. Importantly, the coverage area of cortical bone surrounding the zygomatic implant significantly influenced biomechanical performance of the zygomatic implants.

A Finite Element Analysis of Peri-implant Stresses Surrounding Zirconium and Titanium Dental Implants

ABSTRACT Introduction: Stresses tend to vary depending on the kind of implant material (titanium or zirconium) because of differences in their mechanical and physical characteristics. Objectives: The current research was done to assess the peri-implant stresses around zirconium and titanium dental implants using finite element analysis. Materials and Method: Three distinct implant configurations were used to create three-dimensional finite element models (M1, M2, and M3) using ANSYS (11.0 Version) software, a P4 CPU running at 3 GHz, and hardware with three gigabytes of RAM. These configurations are typical for zirconium and titanium implants. Under 250 N of axial force and 50 N of nonaxial load, the stress surrounding the implants was examined. Result: When compared to titanium implants, zirconium implants displayed higher strains in cancellous bone and lower stresses in cortical bone. Overall, titanium implants caused larger stresses in the bone than zirconium implants. Conclusion: Compared to titanium implants, zirconium implants resulted in reduced peri-implant stresses.

Sex hormone deficiency in male and female mice expressing the Alzheimer’s disease-associated risk-factor TREM2 R47H variant impacts the musculoskeletal system in a sex- and genotype-dependent manner

Abstract The R47H variant of the Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) is a risk factor for Alzheimer’s disease in humans and leads to lower bone mass accrual in female but not male 12-month-old mice. To determine whether, as with aging, gonadectomy results in sex-specific musculoskeletal effects, gonad removal or SHAM surgery were performed in 4-month-old TREM2R47H/+ mice and wild type (WT) male and female littermates (n = 10-12/group), with sexes analyzed separately. Body weight was lower in males, but higher in females after gonadectomy, independently of their genotype. Gonadectomy also lead to decreased BMD in males at all sites and in whole body (total) and spine in female mice for both genotypes. Total and femur BMD was lower in gonadectomized male mice 6-weeks post-surgery, independently of the genotype. On the other hand, BMD was only lower in ovariectomized WT but not TREM2R47H/+ mice in all sites measured at this time point. Bone formation and resorption markers levels were not affected by orchiectomy, whereas CTX was higher 3 weeks after surgery and P1NP showed a tendency towards lower values at the 6 weeks timepoint only in ovariectomized WT mice. μCT analyses showed no differences resulting from gonadectomy in structural parameters in femoral cortical bone for either sex, but lower tissue mineral density in males of either genotype 6 weeks post-surgery. Nevertheless, biomechanical properties were overall lower in gonadectomized males of either genotype, and only for WT ovariectomized mice. Distal femur cancellous bone structure was also affected by gonadectomy in a genotype- and sex-dependent manner, with genotype-independent changes in males, and only in WT female mice. Thus, expression of the TREM2 R47H variant minimally alters the impact of gonadectomy in the musculoskeletal system in males, whereas it partially ameliorates the consequences of ovariectomy in female mice.

Cone Beam Computed Tomography Evaluation of Socket Healing After Third Molar Germ Extraction: A Case Series Study Including Adolescents with Osteogenesis Imperfecta Type I Treated with Bisphosphonates and Healthy Age-Matched Subjects

Bisphophonates (BPs) are widely used in Osteogenesis imperfecta (OI). Cone Beam Computed Tomography (CBCT) shows clinical usefulness in evaluating impacted teeth and adjacent structure relationships, extraction socket healing, bone mineral density (BMD) and BP-related jaw osteonecrosis (BRONJ). The aim of the study was to compare alveolar sockets and the adjacent bone area before and after third molar extraction in OI type I (OI-I) adolescents treated with BPs and age-matched healthy subjects (HSs) by CBCT. Methods: Five adolescents with genetically proven OI-I treated with BPs (three males and two females, mean age: 15.2 ± 1.78 years) and four age-matched healthy subjects (two males and two females, mean age: 15.5 ± 1.29 years) were included in this study. Eight Regions of Interest (ROIs) were evaluated: between 3.7 and 3.8 (ROI-1) and 4.7 and 4.8 (ROI-2); after 3.8 (ROI-3) and 4.8 (ROI-4); alveolar sockets 3.8 (ROI-5) and 4.8 (ROI-6); left (ROI-7) and right (ROI-8) cortical bone. Results: ROIs were evaluated on both sides of the mandible for all the subjects except one OI patient in which CBCTs were performed pre- and-post third molar extraction only on the right side. CBCT was performed 12.8 ± 4.60 and 11.5 ± 2.51 days before and 8.0 ± 1.41 and 7.7 ± 0.5 months after extraction in OI-I and HSs, respectively. BPs were discontinued 62.0 ± 36.5 months before extraction. None of the OI-I adolescents developed BRONJ. Statistically significant greater values were observed in OI-I for ROI-1 and -2 (p = 0.0464), ROI-3 and -4 (p = 0.0037) and ROI-7 and -8 (p = 0.0079) after extraction. Conclusions: This descriptive study confirms that, in OI-I adolescents treated with BPs, third molar extraction is safe, and socket healing occurs properly. In addition, it demonstrates that, if the same device and imaging conditions are used and comparisons to predetermined standard values are avoided, CBCT can be used to monitor BMD changes. The significant greater BMD observed for different ROIs in OI-I could reflect the increased secondary mineralization related to the BP-dependent reduction in bone turnover.

Long-term Follow-up Study for Fractured and Non-Fractured Hand Enchondromas Treated by Sole Curettage

Background: Enchondromas are the most common primary tumors in the small tubular bones of the hand and fractures are often the result of thinned cortical bone. The main question was whether fractured enchondromas influence the long-term clinical and radiological outcome. Methods: Between 2000 and 2019, 57 patients with previously treated fractured (group I) and non-fractured (group II) hand enchondromas (34 female, 23 male, mean age was 39.4 years, ± 13.7) were evaluated for clinical and radiological treatment outcomes. SF-36 and DASH questionnaires as well as patient reported experience measures were used to assess subjective health outcomes. Subsequently, 43 patients underwent clinical and radiological follow-ups. Comparative evaluation of objective treatment outcomes in both groups was conducted in terms of hand functionality, perioperative complications, recurrence rates, and osteogenesis. Results: Almost half the patients suffered enchondromas with fractures (49.1%, n=28). Two patients received additional k-wire-stabilization due to intraoperative instability. Defect resolution could be reached in 97.7% (n=42) of all cases. No recurrence of enchondroma was observed. Groups were equal regarding radiological and clinical outcomes. The patient reported experiences were predominantly positive (86%), both cohorts had good to very good results with a DASH mean score of 4 (±6.3). The SF-36 demonstrated a return to normal quality of life in both groups. Mean follow-up time was 7.78 years (±4.8). Conclusions: Sole curettage of enchondromas yields effective outcomes with good to excellent results regardless of the presence of a fracture. Long-term radiological follow-up is not required until symptomatic recurrence. .

Multidirectional Corrective Osteotomy of the Tibial Tuberosity

This article describes the technique of a multidimensional, V-shaped, and self-centering osteotomy of the tibial tuberosity with cortical bone block support, which enables combined distoanteromedialisation of the tibial tubercule.

Kirschner wire creates more microdamage than standard or acrylic drill bits in the rabbit (Oryctolagus cuniculi) femur.

Histologically evaluate damage to rabbit femur after the creation of bicortical 1.5-mm-diameter holes using a standard surgical drill bit, an acrylic drill bit, and a Kirschner wire (K-wire). 10 femora (5 pairs) from skeletally mature female intact New Zealand white rabbits were used. The bone diaphyses were divided into 4 locations, systematically undergoing each test (surgical drill bit, acrylic drill bit, K-wire, and intact control). Four pairs were drilled using a mechanical testing machine, and 1 pair was drilled by hand. Cross-sections of the bone were stained en bloc with basic fuchsin for undecalcified histological evaluation. Damaged bone was reported as a percentage of a standardized area and categorized by location (cis- or transcortex), drill contact (entrance or exit of the cortex), and total damage (both cortices). The drilling method (hand vs mechanical testing machine) had no effect on histologic damage, so results were analyzed by combining all data. The K-wire demonstrated the greatest area of cracks/damage compared to both standard surgical and acrylic drill bits, whereas no difference in damage was noted between the 2 drill bits for all variables. The K-wire and drill bits caused microdamage; K-wire drilling created more microdamage than drill bits. The rabbit bone cortex is thin and brittle relative to dogs and cats, leading to failure during and after fracture fixation. The clinical failure of rabbit bone is at least partially caused by drill bits or K-wires causing microcracks.

Loss of Runx2 in Gli1 + Osteogenic Progenitors Prevents Bone Loss Following Ovariectomy

Abstract Osteoporosis is a metabolic bone disorder characterized by low bone mass and bone mineral density. It is the most prevalent bone disease and a common cause of fracture in aging adults. Low bone mass, as seen in osteoporosis, results from an imbalance between osteoblast and osteoclast activity. Gli1+ cells are indispensable to the maintenance of bone tissue homeostasis. These cells give rise to osteoprogenitors and are present at the osteogenic fronts of long bones in adult mice. Runx2 is a key regulator of osteogenesis and plays a crucial role in osteoblastic differentiation and maturation during development. However, its function in maintaining adult bone tissue homeostasis remains unclear. In this study, we investigated the role of Runx2 in maintaining adult bone homeostasis in the context of ovariectomy-induced estrogen deficiency, a model for postmenopausal osteoporosis. Our results show that deletion of Runx2 in the Gli1+ osteogenic progenitor population prevents loss of both cortical and trabecular bone mass and mineralization after ovariectomy. At the cellular level, loss of Runx2 leads to a decrease in osteoclast activity. Our study indicates that Runx2 is essential for maintaining adult bone tissue homeostasis by regulating osteoclast differentiation.

Automatic segmentation and visualization of cortical and marrow bone in mandibular condyle on CBCT: a preliminary exploration of clinical application.

To develop a deep learning-based automatic segmentation method for cortex and marrow in mandibular condyle on cone-beam computed tomography (CBCT) images and explore its clinical application. 825 condyles of 490 CBCT images from 3 centers of Stomatology hospitalaffliated to Zhejiang University School of Medicinewere collected. A deep learning model was developed for simultaneous segmentation of cortex and marrow in mandibular condyle. It included a region of interest extraction network and a segmentation network based on 3D U-net, with modifications made to improve the segmentation boundaries. To evaluate its clinical potential, the model's segmentation efficiency and accuracy were compared with those of both junior and senior oral and maxillofacial radiologists. Additionally, the model's ability to assist junior radiologists in diagnosis through visualization and quantitative analysis of the generated 3D model was also assessed. The Dice similarity coefficient of the deep learning model was 0.901 (cortex), 0.969 (marrow), and 0.982 (entire condyle). Hausdorff distance was 0.755mm (cortex), 0.826mm (marrow), and 0.760mm (entire condyle). The model outperformed radiologists across all segmentation metrics, completing the task in merely 15.06s. With the assistance of visualization and quantitative analysis generated from the model's segmentation, the diagnostic accuracy of junior radiologists significantly improved. The proposed deep learning-based model achieved accurate and efficient segmentation for mandibular condylar cortex and marrow. It possessed capability to generate precise 3D models, facilitating visual quantitative measurement and aiding in the diagnosis of condylar bony changes. This model holds potential for clinical applications in orthognathic surgery, orthodontic treatment, and other TMJ-related interventions.

Relationship between the microstructural energy release rate of cortical bone and age under compression condition

Most studies evaluated the energy release rate of cortical bone macrostructure under Mode I, Mode II, and mixed Mode I-II loading conditions. However, testing the macrostructural energy release rate requires an initial crack and recording the applied load and the corresponding crack length in real-time, which may introduce measurement errors and differences with the actual fracture scenarios. To further understand how the energy release rate contributed to the cortical bone fracture characteristics, this study predicted the microstructural energy release rate of cortical bone and then investigated its age-related varitions. The microstructural energy release rate of femoral cortical bone in rats from different ages was back-calculated by fitting the experimental and simulated load–displacement curves under compression load. The trends in the microstructural energy release rate were revealed, and the underlying reasons for the age-related changes were investigated by integrating the discussion on the cortical bone mechanical parameters at various levels obtained from the previous experiment. The predicted microstructural energy release rate of femoral cortical bone in the rats from 1, 3, 5, 7, 9, 11, and 15 months of age were in the range of 0.08–0.12, 0.12–0.14, 0.15–0.19, 0.25–0.28, 0.23–0.25, 0.19–0.22, and 0.13–0.16 N/mm, respectively. The statistical analyses showed the significant differences in the microstructural energy release rate at different ages. The results indicated an increasing trend followed by a decrease from 1 to 15 months of age, and the correlations between microstructural energy release rate and age were significant. The age-related variations in the microstructural energy release rate may be linked to the changes in the microarchitecture, and the fracture load is influenced by the micro-level mechanical parameters. Notably, the age-related trends in microarchitecture and energy release rate were similar. These findings were valuable for understanding the mechanism underlying the weakening mechanical properties of cortical bone microstructure with age from an energy perspective.

A novel personalized homogenous finite element model to predict the pull-out strength of cancellous bone screws

BackgroundOrthopedic surgeries often involve the insertion of bone screws for various fixation systems. The risk of postoperative screw loosening is usually assessed through experimental or finite element (FE) evaluations of the screw pull-out strength. FE simulations are based on either personalized complex but accurate heterogeneous modeling or non-personalized simple but relatively less accurate homogeneous modeling. This study aimed to develop and validate a novel personalized computed tomography (CT)-based homogeneous FE simulation approach to predict the pull-out force of cancellous bone screws.MethodsTwenty FE simulations of L1-L5 vertebral screw pull-out tests were conducted, i.e., 10 heterogeneous and 10 homogenous models. Screws were inserted into the lower-middle region of vertebrae. In our novel homogeneous model, the region around approximately twice the diameter of the screw was used as a bone material reference volume. Subsequently, the overall material property of this region was homogeneously attributed to the entire vertebra, and pull-out simulations were conducted.ResultsThe mean error of the predicted pull-out forces by our novel homogenous simulations was ~ 7.9% with respect to our heterogeneous model. When solely the cancellous bone was involved during the pull-out process (i.e., for L1, L2, and L3 vertebral bodies whose cortical bone in the inferior region is thin), the novel homogenous model yielded small mean error of < 6.0%. This error, however, increased to ~ 11% when the screw got involved to the cortical bone (for L4 and L5 vertebrae whose cortical bone in the inferior region is thick).ConclusionThe proposed personalized CT-based homogenous model was highly accurate in estimating the pull-out force especially when only the cancellous bone was involved with the screw.

Aromatase inhibitors, bone microstructure, and estimated bone strength in postmenopausal women with breast cancer: a 5-year prospective study.

Aromatase inhibitors (AIs) are the standard treatment for early breast cancer (EBC) and are typical causative agents of cancer treatment-induced bone loss. However, the effects of long-term treatment with these drugs on bone microstructure remain unclear. This prospective, single-arm observational study included postmenopausal, non-osteoporotic women with hormone receptor-positive EBC. Patients who underwent dual-energy X-ray absorptiometry (DXA), high-resolution peripheral quantitative computed tomography (HR-pQCT), and tartrate-resistant acid phosphatase-5b (TRACP-5b) or procollagen type I N-terminal propeptide levels were compared at baseline and at 60months after commencing AI treatment. Fifteen women were included in the study, with a median age of 58years and a quartile range of 56.5-62.5years. At 60months, HR-pQCT revealed that the cortical area and thickness decreased with increased cortical porosity in the cortical bone. In addition, the number of trabeculae decreased and trabecular separation increased trabecular bones decreases, and trabecular bone separation opens, resulting in a decrease in the trabecular bone volume fraction. Total bone mineral density (BMD), trabecular volumetric BMD, and cortical volumetric BMD, and estimated bone strength significantly decreased. DXA BMD values significantly decreased in the total hip and femoral neck but not the lumbar spine. TRACP-5b values after 5years of AI treatment showed a significant negative correlation with the rate of change in the total volumetric BMD in the distal tibia. Postmenopausal women who received AIs for 5years for EBC experienced significant deterioration in the bone microstructure, BMD, and estimated bone strength.

SPHENOID BONE LIGAMENTS’ ENTHESOPATHY WITH THEIR CLINICAL MANIFESTATIONS

Objective: The Cortical bone formation at enthesial sites of ligament attachments to the sphenoid bone is indeed multifactorial, involving various biological, mechanical, and biomechanical processes. The present study is aimed to observe the ossified ligaments of sphenoid bone of skull manifesting various neurological complications. Methods: An observational study conducted on sphenoid bones of 36 dried human skulls of unknown gender and age procured from the Department of Anatomy at Gautam Buddha Chikitsa Mahavidyalaya, Dehradun and People’s College of Medical Sciences and Research Centre, Bhopal. These bones were observed for enthesopathic modifications in their ligaments. Results: The present study showed ossified caroticoclinoid ligament (intra cranial ligament) predominated by 41.66% followed by pterygospinous ligament ossification (extra cranial ligament) with total 38.88% prevalence. Conclusion: Altered morphology of sphenoid bone knowledge is a must for neurosurgeons and orthopedic surgeons while operating at these sites to avoid hindrances and has scope for newer approaches for better prognosis.