Sheep Tibia Research Articles

The Effects of Putty and Granule Beta-tricalcium Phosphate on Bone Cell Histomorphometry and Ki67 Expression in Sheep Tibia

The Effects of Putty and Granule Beta-tricalcium Phosphate on Bone Cell Histomorphometry and Ki67 Expression in Sheep Tibia

Impact of Hydroxyapatite Nanoparticles, Demineralized and Decellularized Bone Matrix on Tibia Fracture Healing: A Biochemical and Histological Study in Goats

At present, using bone grafts is the most successful surgical approach for repairing deficits in the bone structure. This study investigated into how goat tibial defect fracture healing was impacted by using hydroxyapatite (HA) or demineralized and decellularized bone matrix (dDBM) xenograft. Methodology: In this study, fifteen young goats were employed. Three groups (n=5) consisting of the control group, nano-group, and xeno-group were created from the animals. Bone drill was used to remove 2 mm from the tibia of the right hind limp in all animals. The hydroxyapatite nanoparticles (HA) in the Nano-group and the xenograft demineralized and decellularized bone matrix (dDBM) (obtained from sheep tibia) in the Xeno-group were used to fill the bone defect respectively, while the bone defect in the control group remained without treatment, and the surgical site was regularly closed. Blood serum was collected at the following intervals: postoperative, 14, 42, and 64 days for detection of alkaline phosphatase (ALP) and osteocalcin (OC) levels. At 64 days after surgery, all goats were euthanized and the healing was evaluated by specimen histological observation. Results: Biochemical examination in treated groups (Nano and Xeno groups) showed a statistically significant (P < 0.05) increase in the level of ALP and OC. histopathological examination at 64 day post-operation, treated groups shows Completely grown woven bone and the fracture callus composed of mature fibro-osteoid mixture. In conclusion, We demonstrate that the healing process accelerated and the bone defect can be filled by using hydroxyapatite (HA), or dDBM, as a scaffold for the damaged tibia bone.

The Effects of Corona Stimulation on the Osseointegration of Dental Implants: An Experimental Study

Aim: Currently, one of the most promising research areas in dental implantology is the exploration of additional procedures to reduce loading time for implants and enhance osseointegration in cases of poor bone quality. Various techniques have been researched and developed for stimulating bone production, including electrical stimulation of the jawbone and surrounding tissues. However, there is limited research on the direct relationship between electrostimulation and osseointegration. This experimental study aims to investigate the effects of corona stimulation (CS) on the rate and quality of osseointegration, as well as its potential to reduce the waiting period for dental implants. Material and Method: In this experimental protocol, 32 dental implants were inserted into the tibia of four male sheep bilaterally. Implants on the right tibia of each male sheep underwent CS treatment, while the other side served as a control group without any stimulation. The animals were sacrificed on the 15th and 30th days after implantation. Bone segments containing the implants were processed using a noncalcified method. It assessed new bone formation and osseointegration around the dental implants using the undecalcified method and histomorphological analysis. An experienced blinded investigator measured percentages of mineralized bone-implant contact (BIC), bone area (BAr), and bone perimeter (BPm) to evaluate the bone-implant interface. Statistical analyses were performed using SPSS 21 for Windows, with a significance level set at p<0.05. Results: The histomorphometric parameters revealed a significant increase in BIC, BAr, and BPm values in the CS group compared to the control group on both the 15th and 30th days (p<0.05). There was no statistically significant difference in BIC ratio between the second and fourth stimulation groups. Conclusion: The findings of this experimental study suggest that CS may have a positive impact on the early osseointegration period of dental implants.

A comparison of deep learning segmentation models for synchrotron radiation based tomograms of biodegradable bone implants

Introduction: Synchrotron radiation micro-computed tomography (SRμCT) has been used as a non-invasive technique to examine the microstructure and tissue integration of biodegradable bone implants. To be able to characterize parameters regarding the disintegration and osseointegration of such materials quantitatively, the three-dimensional (3D) image data provided by SRμCT needs to be processed by means of semantic segmentation. However, accurate image segmentation is challenging using traditional automated techniques. This study investigates the effectiveness of deep learning approaches for semantic segmentation of SRμCT volumes of Mg-based implants in sheep bone ex vivo.Methodology: For this purpose different convolutional neural networks (CNNs), including U-Net, HR-Net, U²-Net, from the TomoSeg framework, the Scaled U-Net framework, and 2D/3D U-Net from the nnU-Net framework were trained and validated. The image data used in this work was part of a previous study where biodegradable screws were surgically implanted in sheep tibiae and imaged using SRμCT after different healing periods. The comparative analysis of CNN models considers their performance in semantic segmentation and subsequent calculation of degradation and osseointegration parameters. The models’ performance is evaluated using the intersection over union (IoU) metric, and their generalization ability is tested on unseen datasets.Results and discussion: This work shows that the 2D nnU-Net achieves better generalization performance, with the degradation layer being the most challenging label to segment for all models.

Machine learning-based design for additive manufacturing in biomedical engineering

While ceramic additive manufacturing (AM) technologies have shown great promise to create functional scaffolds with tailored biomechanical properties, the true potential of these advanced techniques has not been fully exploited yet due to lack of practical design optimisation approaches. To address this challenge, a machine learning (ML)-based design approach is proposed herein where ceramic 3D printing techniques are combined to fabricate functionally graded tissue scaffolds composed of Triply Periodic Minimal Surfaces (TPMS), aiming to fulfil the anticipated biomechanical requirements for the target bone regeneration outcomes. The proposed ML based design strategy couples a Bayesian optimisation (BO) algorithm to enable time-dependent mechano-biological optimisation of the 3D printed ceramic scaffolds at a reasonably low computational cost. For a representative example relating to bone scaffolding in a segmental defect of sheep tibia, the simulated results demonstrate that the optimised functionally graded scaffolds significantly enhance bone ingrowth outcomes. Furthermore, a Lithography-based Ceramic Manufacturing (LCM) technique is employed to fabricate the optimised scaffolds based on the proposed ML-based design framework, followed by micro-CT analyses of the additively manufactured ceramic scaffolds to assess their geometric qualities. This study is expected to gain new insights into mechanical sciences on design for varying material conditions and provide an effective design tool for ceramic additive manufacturing.

Mechanical bone strength decreases considerably after microwave ablation-Ex-vivo and in-vivo analysis in sheep long bones.

Bone metastases are on the rise due to longer survival of cancer patients. Local tumor control is required for pain relief. Microwave ablation (MWA) is a technique for minimally invasive local tumor treatment. Tumor tissue is destroyed by application of local hyperthermia to induce necrosis. Given the most common setting of palliative care, it is generally considered beneficial for patients to start mobilizing directly following treatment. No data on mechanical strength in long bones after MWA have been published so far. In- and ex-vivo experiments on sheep tibias were performed with MWA in various combinations of settings for time and power. During the in-vivo part sheep were sacrificed one or six weeks after ablation. Mechanical strength was examined with a three-point bending test for ablations in the diaphysis and with an indentation test for ablations in the metaphysis. MWA does not decrease mechanical strength in the diaphysis. In the metaphysis strength decreased up to 50% six weeks after ablation, which was not seen directly after ablation. MWA appears to decrease mechanical strength in long bone metaphysis up to 50% after six weeks, however strength remains sufficient for direct mobilization. The time before normal strength is regained after the remodeling phase is not known.

Biomechanical comparison of three different surgical methods in the surgical treatment of distal tibial metaphyseal fractures. An animal model study.

The aim of this study is to investigate mechanical properties of minimally invasive plate osteosynthesis (MIPO), supracutaneousplating (SP), and unilateral external fixators (UEF) which can be performed for open tibial fractures. An unstable diaphysial tibia fracture was created in 60 fresh sheep tibia specimens by performing an osteotomy at the middle of bones. Specimens were divided into 3 groups. Specimens underwent fracture fixation with a standard MIPO technique, im-planting the plate 15 mm from the bone for SP group. Unilateral uniplanar external fixators were achieved for UEF group. First, thirty specimens (10 specimen for each group) were loaded vertically along the tibial axis to 1800 N. Second, other 30 preperated bones were used for cyclical loading to avoid metal fatigue. For dynamic tests, a 350 N force was applied for 10,000 cycles. In compression testing (vertical loading up to 1800 N) of the three fixation instruments; construct stiffness was highest in MIPO group when compared with SP and UEF groups. While the stiffness of the MIPO group was similar to SP group, it was statistically higher than UEF group (P=0.08 and P=0.002, respectively). SP group was significantly stiffer than UEF group (P=0.0021). The mean peak load was highest in SP group and lowest in UEF group. The peak load in SP group was similar to the MIPO group, it was statistically higher than the UEF group (P=0.743 and P=0.002, respectively). Based on the biomechanical properties from this in vitro animal model study, SP technique was biomechanically stronger than UEF and has similar biomechanical properties with MIPO in terms of axial loading.

Combined electric and magnetic field therapy for bone repair and regeneration: an investigation in a 3-mm and an augmented 17-mm tibia osteotomy model in sheep

BackgroundTherapies using electromagnetic field technology show evidence of enhanced bone regeneration at the fracture site, potentially preventing delayed or nonunions.MethodsCombined electric and magnetic field (CEMF) treatment was evaluated in two standardized sheep tibia osteotomy models: a 3-mm non-critical size gap model and a 17-mm critical size defect model augmented with autologous bone grafts, both stabilized with locking compression plates. CEMF treatment was delivered across the fracture gap twice daily for 90 min, starting 4 days postoperatively (post-OP) until sacrifice (9 or 12 weeks post-OP, respectively). Control groups received no CEMF treatment. Bone healing was evaluated radiographically, morphometrically (micro-CT), biomechanically and histologically.ResultsIn the 3-mm gap model, the CEMF group (n = 6) exhibited higher callus mineral density compared to the Control group (n = 6), two-fold higher biomechanical torsional rigidity and a histologically more advanced callus maturity (no statistically significant differences). In the 17-mm graft model, differences between the Control (n = 6) and CEMF group (n = 6) were more pronounced. The CEMF group showed a radiologically more advanced callus, a higher callus volume (p = 0.003) and a 2.6 × higher biomechanical torsional rigidity (p = 0.024), combined with a histologically more advanced callus maturity and healing.ConclusionsThis study showed that CEMF therapy notably enhanced bone healing resulting in better new bone structure, callus morphology and superior biomechanical properties. This technology could transform a standard inert orthopedic implant into an active device stimulating bone tissue for accelerated healing and regeneration.

Discovering an unknown territory using atom probe tomography: Elemental exchange at the bioceramic scaffold/bone tissue interface.

Here we report the first atom probe study to reveal the atomic-scale composition of in vivo bone formed in a bioceramic scaffold (strontium-hardystonite-gahnite) after 12-month implantation in a large bone defect in sheep tibia. The composition of the newly formed bone tissue differs to that of mature cortical bone tissue, and elements from the degrading bioceramic implant, particularly aluminium (Al), are present in both the newly formed bone and in the original mature cortical bone tissue at the perimeter of the bioceramic implant. Atom probe tomography confirmed that the trace elements are released from the bioceramic and are actively transported into the newly formed bone. NanoSIMS mapping, as a complementary technique, confirmed the distribution of the released ions from the bioceramic into the newly formed bone tissue within the scaffold. This study demonstrated the combined benefits of atom probe and nanoSIMS in assessing nanoscopic chemical composition changes at precise locations within the tissue/biomaterial interface. Such information can assist in understanding the interaction of scaffolds with surrounding tissue, hence permitting further iterative improvements to the design and performance of biomedical implants, and ultimately reducing the risk of complications or failure while increasing the rate of tissue formation. STATEMENT OF SIGNIFICANCE: The repair of critical-sized load-bearing bone defects is a challenge, and precisely engineered bioceramic scaffold implants is an emerging potential treatment strategy. However, we still do not understand the effect of the bioceramic scaffold implants on the composition of newly formed bone in vivo and surrounding existing mature bone. This article reports an innovative route to solve this problem, the combined power of atom probe tomography and nanoSIMS is used to spatially define elemental distributions across bioceramic implant sites. We determine the nanoscopic chemical composition changes at the Sr-HT Gahnite bioceramic/bone tissue interface, and importantly, provide the first report of in vivo bone tissue chemical composition formed in a bioceramic scaffold.

Biologic Bone Behavior During the Osseointegration Process: Histologic, Histomorphometric, and SEM-EDX Evaluations.

This study evaluated bone behavior during dynamic osseointegration. A total of 12 implants were placed in sheep tibia and analyzed at 15, 30, 60, and 90 days. Quantitative and qualitative bone behaviors were evaluated with histologic, histomorphometric, Alizarin Red S, and SEM-EDX (scanning electron microscopy with energy-dispersive x-ray spectroscopy) analysis. Twenty microanalyses were performed in chambers 1, 3, and 5 (a chamber is the distinctive space/bone volume between two coils of the implant screw) in distinctive zones: the titanium-bone interface (zone A), the middle chamber-bone front (zone B), the bone-surgical threading interface (zone C), and native bone (zone D; used as a control). The dynamic osseointegration index (DOI) and bone quality index (BQI) with calcium/phosphorus (Ca/P) content were detected to evaluate the osseointegration quality, bone-to-implant contact (BIC), and bone density around implants. At 15 days, initial bone formation with osteoid matrix deposition and different color intensities were observed (means: BIC = 23.3% ± 3.9%; DOI = 1.55). SEM-EDX analysis showed low mineralized bone/bone marrow with a very low Ca/P mean value. At 30 days, high new bone deposition with higher color intensity in the crestal portion was recorded (BIC = 77.3% ± 0.4%; DOI = 2.58). At 90 days, tight BIC to the middle and apical implant portions were detected, as well as several osteon structures in the crestal portion (BIC = 86.4% ± 0.6%; DOI = 0.96). During all observed time periods, the BQI showed 25% more Ca/P in zone A. Greater maturation degree and lower BQI were seen at zone A compared to the other zones. After 15 and 30 days, zones B and C (except for P in zone B) showed BQIs slightly over 50% and around 75%, respectively, confirming a progressively higher degree of bone maturation that proceeds with the osseointegration process. After 90 days, the BQI values of zones B and C (greater than 70% in zone B and around 90% in zone C) confirmed the bone mineralization and maturation process and an acceleration of implant osseointegration, while a lower BQI value (25%) was recorded in zone A. This study shows osseointegration as a variable dynamic process with a higher bone deposition in contact with the implant surface during the early phase, while in the active and later osseointegration times, the bone quality maturation showed higher values only "at distance" (growth of native bone to the implant surface, observed later in the osseointegration process). After 3 months (before loading), the BQI evaluation was lower (25%) in zone A, confirming that the healing and maturation process of the bone cannot be considered complete.

Biomechanical Analysis of Bone Graft Treated With Pasteurization or Cryotherapy Using Liquid Nitrogen: A Study Using Sheep Bone Model.

Osteosarcoma is a common primary malignancy of the bone. Osteosarcoma prognosis improves tremendously when chemotherapy is given in adjunct to surgical intervention. Limb reconstruction with sterilized autologous bone graft stabilized by orthopaedics implants has become a choice of treatment, but the biomechanical property of the bone treated with such sterilization method is a point of concern as a graft with inferior biomechanical property might lead to graft failure. This study compares the biomechanical properties of the bones treated with cryotherapy using liquid nitrogen and pasteurization in the form of four-point bending compression tests. Six sheep tibia bones were used for each group of treatment with one control group where no treatment was given. In the four-point bending test, osteotomy was performed at the tibia; the proximal tibia was treated with liquid nitrogen and pasteurization respectively. The treated bone is then reconstructed with the corresponding distal bone with locking plate and screws (Jiangsu Trauhiu Medical Instrument Co. Ltd., Changzhou, China). The four-point bending test was performed with anElectropulse® E3000 universal testing machine (Instron®, High Wycombe, United Kingdom) and results in the form of maximum compressive load, stress, and strain were collected.Photographic analysis of the fracture location and pattern were documented and analysed. We found that both methods of sterilization did not alter the biomechanical properties of the treated bone to the extent of statistical significance in comparison with the control group. However, other factors such as histological changes post treatment, equipment availability, and long-term outcome must be considered.

Boron- and Boric Acid-Treated Titanium Implant Surfaces in Sheep Tibia: A Histologic, Histomorphometric and Mechanical Study.

The aim of this study was to compare the topographical, chemical and osseointegration characteristics of sandblasting and acid-etching (SLA) surfaces and dental implants treated by boron compounds. Titanium (Ti) disks (n = 20) were modified using boron (B) and boric acid (H3BO3) and then compared with the conventional SLA surface via surface topographic characterizations. Dental implants (3.5 mm in diameter and 8 mm in length) with the experimental surfaces (n = 96) were inserted into the tibias of six sheep, which were left to heal for 3 and 7 weeks. Histologic, histomorphometric (bone-implant contact (BIC%)) and mechanical tests (removal torque value (RTV)) were performed. The boron-coated surface (BC group) was smoother (Rz: 4.51 μm ± 0.13) than the SLA (5.86 μm ± 0.80) and the SLA-B (5.75 μm ± 0.64) groups (p = 0.033). After 3 weeks, the highest mean RTV was found in the SLA group (37 N/cm ± 2.87), and the difference compared with the BC group (30 N/cm ± 2.60) was statistically significant (p = 0.004). After 7 weeks, the mean RTV was >80 N/cm in all groups; the highest was measured in the H3BO3-treated (BS) group (89 N/cm ± 1.53) (p < 0.0001). No statistically significant differences were found in the BIC%s during both healing periods between the groups. H3BO3 seems to be a promising medium for dental implant osseointegration.

Degradation behavior and osseointegration of Mg-Zn-Ca screws in different bone regions of growing sheep: a pilot study.

Magnesium (Mg)-based implants are highly attractive for the orthopedic field and may replace titanium (Ti) as support for fracture healing. To determine the implant-bone interaction in different bony regions, we implanted Mg-based alloy ZX00 (Mg < 0.5 Zn < 0.5 Ca, in wt%) and Ti-screws into the distal epiphysis and distal metaphysis of sheep tibiae. The implant degradation and osseointegration were assessed in vivo and ex vivo after 4, 6 and 12 weeks, using a combination of clinical computed tomography, medium-resolution micro computed tomography (µCT) and high-resolution synchrotron radiation µCT (SRµCT). Implant volume loss, gas formation and bone growth were evaluated for both implantation sites and each bone region independently. Additionally, histological analysis of bone growth was performed on embedded hard-tissue samples. We demonstrate that in all cases, the degradation rate of ZX00-implants ranges between 0.23 and 0.75 mm/year. The highest degradation rates were found in the epiphysis. Bone-to-implant contact varied between the time points and bone types for both materials. Mostly, bone-volume-to-total-volume was higher around Ti-implants. However, we found an increased cortical thickness around the ZX00-screws when compared with the Ti-screws. Our results showed the suitability of ZX00-screws for implantation into the distal meta- and epiphysis.

Laser rapid drilling of bone tissue in minimizing thermal injury and debris towards orthopedic surgery

Traditional mechanical bone drilling is prone to heat generation and debris accumulation which will cause tissue damage in orthopedic surgeries. Therefore, research on contactless laser bone drilling has become a mainstream trend in the development of bone surgery. This study presents a laser rapid drilling strategy for bone surgery with minimizing thermal osteonecrosis and debris based on the design of dynamic focusing and spreading droplet cooling. The laser drilled hole suffered from low temperature (Tmax = 46.2 ○C) under clinically accepted threshold of 47 ○C, presenting osteocyte-filled lacunas, visible Haversian canals and increased pullout strength when compared with that following mechanically drilling. An intact bone column without debris was extracted from a 4-mm-deep hole in vitro on a sheep tibia which provides a clean surgical method with increased drilling rate of 0.94 mm3/s. The criteria dimensionless We constant related to spreading droplets leading to effective heat transfer is determined as2.8 × 103 × Re-1/2 ≤ We ≤ 1.9 × 10-2 × Re7, yielding a high convective coefficient of 0.11 W/mm2·K for cooling. The comprehensive results of laser bone drilling proved the effectiveness of the presented technology and setup, which is significant in realizing rapid, debris-free orthopedic surgery.

Screw Analysis, Modeling and Experiment on the Mechanics of Tibia Orthopedic with the Ilizarov External Fixator.

The Ilizarov external fixator plays an important role in the correction of complex malformed limbs. Our purpose in this work was to reveal the transmission of adjustable forces between the external fixator and the broken bone, and express the stress distribution at the end of the broken bone during the orthopedic treatment. Firstly, the screw model of the fixator was established and the theoretical relationship between the adjustable force and the stress was obtained. A sheep tibia was taken as a representative research object and its ediTable 3D entity was obtained by CT scanning. Then the mechanical model of the fixator and tibia was built using the ABAQUS software. Correction experiments were performed on the sheep tibia to measure the adjustable/support forces and tensions of the tibia. The measured results were imported to the screw and mechanical model, and the theoretical and simulation values were calculated. The theoretical tensions calculated by the screw model had a similar shape and doubled the value compared with that of the measured results. The transfer efficiency between the two results was improved and kept at about 50% after the initial 2~3 periods. The maximum stress occurring at the surface of the broken bone end was near the Kirschner wire pinhole. The simulation results for the tensions from the mechanical model showed a similar change trend, and the value was slightly higher. A biomechanical model of the Ilizarov external fixator was derived and verified through calculations, simulations and experiments. The change law of the adjustable forces and the tensions existing in the broken sheep tibias is presented herein, and offers a helpful contribution to orthopedic treatment.

The effect of additional staple in the tibial fixation of anterior cruciate ligament reconstruction: a biomechanical study in sheep tibia

Objectives: The aim of this study was to evaluate the necessity of staple use and the importance of screw diameter in the anterior cruciate ligament (ACL) reconstruction. Methods: Twenty-eight sheep hind legs were divided into four groups in terms of tibial side fixation type as 7 mm bioabsorbable screw (Group 1), 7 mm bioabsorbable screw and staple (Group 2), 8 mm screw (Group 3), and 8 mm screw and staple (Group 4). The maximum force causing insufficiency in the graft, and the fixation strength between the groups were recorded. The results were compared among the groups. Results: As a result of the statistical analysis regarding the necessity of using staple, group 2, with 7 mm screws and staple, was found to be significantly more resistant than group 1 (p = 0.018). In consequence of the biostatistics study, staple use was found not to create a statistically significant difference between group 3 in which an 8 mm bioabsorbable screw was used and group 4 (p = 0.805). In the statistical study to understand the significance of screw diameter, the samples of group 1 and group 3, in which no staple was used, were compared. It was found that group 3 samples with 8 mm screws had higher strength than those with 7 mm screws (p = 0.011). Between group 2 and group 4 in which a staple was used, despite the increase in screw diameter, the value of maximum strength had no remarkable difference statistically (p = 1.00). Conclusions: Fixation strength is higher when fixation was done with a screw 1 mm larger than tibial tunnel diameter. However, using either a screw with 1 mm wider than tibial tunnel diameter and the screw in the same diameter with the tibial tunnel and additional staple have similar fixation strength on the tibial side. Therefore, we conclude that screw width is more important in maintaining stability of the graft fixation.

Biomechanical and fracture characteristics of different filling and fixation methods applied to various proximal tibial metaphyseal defect sizes in an ovine model

BackgroundIdeal treatment method based on the size of the defect in local aggressive bone tumors is yet to be described. We evaluated the mechanical behavior of different fixation methods for various defect sizes located in the proximal tibia. MethodsNinety-one sheep tibiae were distributed in five groups. Each study group was further divided into three subgroups, forming 25%, 50%, and 75% metaphyseal defects. The five groups were divided as follows: 1) control group where tibiae remained intact (n = 7); 2) isolated defect created, without filling (n = 21); 3) filling with cement (n = 21); 4) application of two subchondral cortical screws in addition to cement (n = 21); and 5) application of plate-screw fixation in addition to cement (n = 21). A loading test simulating the axial load applied by the distal femur to the tibia plateau was performed. The maximum failure load was compared between groups according to the defect size and fixation method. FindingsIn 25% defects, group 5 had significantly higher failure load than other groups. However, in 50% and 75% defects, additional fixation did not increase the failure load. Also, additional screw fixation did not increase failure load in all defect sizes. There was a significant positive correlation between fracture morphology and defect size, fixation method, and failure load. InterpretationAdditional plate-screw fixation would increase the stability in defects ≤25%. In defects ≥50%, additional fixation does not increase stability. Screw fixation in addition to cementing does not increase stability in all defect sizes.

Mineralization in a Critical Size Bone-Gap in Sheep Tibia Improved by a Chitosan-Calcium Phosphate-Based Composite as Compared to Predicate Device.

Deacetylated chitin derivatives have been widely studied for tissue engineering purposes. This study aimed to compare the efficacy of an injectable product containing a 50% deacetylated chitin derivative (BoneReg-Inject™) and an existing product (chronOS Inject®) serving as a predicate device. A sheep model with a critical size drill hole in the tibial plateau was used. Holes of 8 mm diameter and 30 mm length were drilled bilaterally into the proximal area of the tibia and BoneReg-Inject™ or chronOS Inject® were injected into the right leg holes. Comparison of resorption and bone formation in vivo was made by X-ray micro-CT and histological evaluation after a live phase of 12 weeks. Long-term effects of BoneReg-Inject™ were studied using a 13-month live period. Significant differences were observed in (1) amount of new bone within implant (p < 0.001), higher in BoneReg-InjectTM, (2) signs of cartilage tissue (p = 0.003), more pronounced in BoneReg-InjectTM, and (3) signs of fibrous tissue (p < 0.001), less pronounced in BoneReg-InjectTM. Mineral content at 13 months postoperative was significantly higher than at 12 weeks (p < 0.001 and p < 0.05, for implant core and rim, respectively). The data demonstrate the potential of deacetylated chitin derivatives to stimulate bone formation.

Iron Cones in the Burials of Ulus Jochi: Aspects of Ethnocultural Identification

Cone-shaped objects, rolled from iron and bronze sheets, are found in the Golden Horde burials of the late 13th – early 15th centuries. The authors collected information on more than 100 burials with iron and bronze cones located in the territory of Ulus Jochi. This article is examines material from 78 iron cone burials. Specific features of the topographic location of these complexes, use of stones in rituals, construction of log cabins around graves is similar to archaeological and ethnographic monuments of Central Asia associated with ethnic Mongols. As a rule, human remains buried in graves are oriented north or northeast with their heads, which is also a feature of the Mongol funeral rite. Accompaniment of the burial with whole or stuffed horses remains in the complexes with cones is not common, but these features are also known in Mongolian cemeteries in Central Asia. The placement of a sheep tibia at the head of the buried occasionally in vertical position is considered a main ethnic feature of the Mongol culture. In general, the sample of the Ulus Jochi burials, united by the iron cones presence in the burial inventory, is characterized by an increased concentration of rather specific ritual signs typical of the Mongols of Central Asia. This allows us to conclude that the considered monuments belong to the same ethnocultural group of population. Moreover, the available anthropological data testify to the Central Asian (Mongolian) origin of the representatives of this group of nomads of Ulus Jochi Burials with iron cones. The authors observe manifestations of pagan shamanic and Buddhist rituals judging by the dominant features of funeral rituals left by the bearers of Mongolian ethnic and cultural traditions.

A machine learning-based multiscale model to predict bone formation in scaffolds.

Computational modeling methods combined with non-invasive imaging technologies have exhibited great potential and unique opportunities to model new bone formation in scaffold tissue engineering, offering an effective alternate and viable complement to laborious and time-consuming in vivo studies. However, existing numerical approaches are still highly demanding computationally in such multiscale problems. To tackle this challenge, we propose a machine learning (ML)-based approach to predict bone ingrowth outcomes in bulk tissue scaffolds. The proposed in silico procedure is developed by correlating with a dedicated longitudinal (12-month) animal study on scaffold treatment of a major segmental defect in sheep tibia. Comparison of the ML-based time-dependent prediction of bone ingrowth with the conventional multilevel finite element (FE2) model demonstrates satisfactory accuracy and efficiency. The ML-based modeling approach provides an effective means for predicting in vivo bone tissue regeneration in a subject-specific scaffolding system.