Split Fracture Research Articles

Experimental study on mechanical properties of raw bamboo fibre-reinforced concrete

Bamboo is an eco-friendly renewable material with a high mechanical performance and short maturation period. The high tensile strength of the raw bamboo fibre is an essential factor for outstanding bamboo properties. In this study, to directly utilize the high tensile strength, the raw bamboo fibre was added to concrete as a reinforcing material. The influence of fibre dosage, length, and maximum aggregate size was systematically studied on the compressive strength, splitting tensile strength, flexural strength, and fracture energy from a macro perspective. In addition, through scanning electron microscopy (SEM), the interfacial bonding between the bamboo fibre and the concrete was further analyzed from a microscopic aspect. The results indicated that the raw bamboo fibre could effectively change the brittle failure mode of the plain concrete. A moderate fibre content, 20 mm fibre length, and 10 mm maximum aggregate size most notably improved the splitting tensile strength and fracture energy, with an increase of 19.8 % and 89.5 %, respectively. From the microscopic aspect, the rough surface structure was conducive to the adsorption of cement hydration products, and hence, improved the mechanical properties and deformation capacity of the raw bamboo fibre-reinforced concrete.

Buckling and failure mechanisms of asymmetric composite sandwich panels subjected to shear loadings

Asymmetric sandwich technology serves as an effective option for introducing loads into sandwich structures in lieu of conventional inserts and joints in lightweight design of thin-walled aeronautical applications. In this study, buckling and failure behaviors are investigated on asymmetric sandwich panels with tapered regions subjected to shearing, where the panels are composed of CFRP laminates as skins and PMI foam as the core. Experimental data and observations are analyzed regarding critical loads, strain distributions, macro- and micro-scaled failure mechanisms. Detailed damage evolution is captured with the developed material and structural models. The influence of the core thickness on stability, load-bearing capacity and failure mechanisms is further investigated. Results show that the shear failure is mainly induced by buckling with an extensive matrix splitting fracture along the diagonal direction for sandwich panels with thin cores. Nonlinearity is observed in strain and deflection responses. Fiber pull-out is formed due to losing support of neighboring matrix. The fracture morphology of fiber breakage roughly appears oblique, indicating that the failure is mainly caused by the combination of tension and shearing. For sandwich panels with a thicker core, i.e. 10 mm and 12 mm, the failure mode switches to pure shear failure. Due to the intensification of tapered edges, local bugling occurs simultaneously with ultimate failure. The ultimate load presents a mounting-up and declining trend with the increase of core thickness, other than a monotonic trend. Conclusively, optimal design parameters exist, such as 10 mm core thickness in the studied case, regarding the load-bearing capacity.

Vertebra-pediculoplasty to Prevent Cement Dislodgment in Coronary Split or Severe Osteoporotic Vertebral Fracture after Cement Augmentation

Vertebra-pediculoplasty to Prevent Cement Dislodgment in Coronary Split or Severe Osteoporotic Vertebral Fracture after Cement Augmentation

Sifat Mekanik Komposit Serat Pelepah Kelapa Sawit sebagai Penguat Komposit Terhadap Kekuatan Tarik dan Impak

Palm fronds are solid waste from oil palm plantations that contain a lot of natural fibers. One of the utilization efforts that can be done is to optimize palm frond fiber waste into composite materials. The use of natural fiber mixtures in composites has produced stronger materials, which can serve as alternative materials for car bumpers. This research was conducted with the aim of knowing the value of impact toughness, tensile strength, and the type of failure that occurs in the fracture cross section. In this study, composites were made using palm frond fibers and polyester resin. The volume fraction variation applied is 30% fiber and 70% matrix with fiber lengths of 20 mm, 40 mm, and 60 mm. Impact toughness testing refers to ASTM E23 standard and tensile strength testing refers to ASTM D638 standard. The impact toughness value obtained in the 20 mm variation was 0.0065 J/mm², 40 mm was 0.0108 J/mm², and the 60 mm variation had the highest value of 0.0164 J/mm². The tensile strength value obtained in the 20 mm variation is 6.18 MPa, the 40 mm variation is 8.26 MPa, and the 60 mm variation has the highest value of 16.45 MPa. Analysis of the fracture cross section is categorized as a splitting fracture in multiple areas and the fracture cross section also shows the occurrence of fiber pull out after the fracture.

Evaluation of colour change, marginal adaptation, fracture strength, and failure type in maxillary and mandibular premolar zirconia endo-crowns

ObjectivesThe objective of this in vitro study was to evaluate the effects of different preparation designs on the mean colour change (ΔE*), marginal adaptation, fracture resistance, and fracture types of maxillary and mandibular premolar endocrowns (ECs).MethodologyA total of 40 extracted maxillary and mandibular premolars were treated endodontically, and each type was subdivided according to the remaining axial height (remaining walls on all surfaces; 2–4 mm) and 2 mm inside the pulp chamber. Specimens were immersed in coffee for 14 days, ΔE* was determined, marginal adaptation was observed, fracture forces test was conducted, and the samples were examined visually at 10× magnification to evaluate failure type and identify fracture origin. The data were entered and analyzed using Statistical Package for Social Sciences, and significance between and within groups was evaluated through ANOVA. The p-value ≤ 0.05 was considered statistically significant.ResultsThe ΔE* values of the maxillary premolar with 2 mm axial height were the highest (6.8 ± 0.89 units), whereas the lowest value was observed in the mandibular premolar with 4 mm axial height (2.9 ± 0.53 units). Significant differences (p < 0.05) in teeth and design were observed. The marginal adaptation of the mandibular premolar with 4 mm axial height was the highest (30.20 ± 1.53 μm), whereas the lowest marginal adaptation was observed in the maxillary premolar with 2 mm axial height (14.38 ± 0.99 μm), and the difference was statistically significant (p < 0.05). The maximum fracture force was observed in maxillary premolars with 2 mm axial height (2248.15 ± 134.74 N), and no statistically significant difference (p = 0.07) was observed between maxillary and mandibular premolars at 4 mm axial height.ConclusionThe recorded ΔE* values of the ECs were within clinically acceptable values or slightly higher, and the marginal adaption values were within acceptable and recommended clinical values in µm. EC preparation with 2 mm axial height in both arches recorded the highest fracture forces. Type III (split fracture) failure was recorded as the highest in the maxillary and mandibular premolar ECs with different axial wall heights.

Fracture Lines and Patterns in Intra-articular Distal Femur Fractures.

Distal femur fractures are complex injuries that often present with multiple fragments, posing notable challenges to fixation. This study aimed to (1) use preoperative CT scans to graphically display fracture lines in intra-articular distal femur fractures and (2) identify common fracture patterns in these injuries. All skeletally mature patients that underwent surgical fixation of Orthopaedic Trauma Association type 33C distal femur fractures between 2012 and 2022 were identified across two level 1 trauma centers (n = 63). Preoperative axial, sagittal, and coronal computed tomography scans were obtained. Fracture lines in each plane were traced out and superimposed on standardized distal femur cross-sections, generating a fracture map for each plane. Injury and fracture characteristics were summarized and compared between fracture patterns. On axial scans, 59 of 63 fractures contained a central intercondylar split from the intercondylar notch to the trochlea. On coronal scans, fracture lines originated at the notch and exited laterally and medially in the supracondylar region, creating a Y-shape. One-third of all fractures contained coronal fracture lines, with most involving the lateral condyle. Based on fracture line orientation and location, fractures were divided into four main fracture pattern types. Type 4 fractures (central split and medial coronal fracture line) were associated with lower average medial fracture height and a lower rate of medial metaphyseal comminution. We found that C-type distal femur fractures can present with four main fracture patterns. Most fractures contain a central sagittal intercondylar split, and a high proportion of fractures contain either medial or lateral coronal fracture lines. Fracture pattern was associated with mechanism of injury, presence of medial comminution, and medial fracture line height. Future studies should focus on clinical outcomes and surgical management of these distinct fracture patterns. IV.

Comparison of color changes, fracture strengths, and failure modes of conventional endocrowns and endocrowns with different design modifications.

Endocrowns (ECs) are alternatives for rebuilding severely damaged teeth and show superior efficacy in molars over premolars. The objective of this in vitro study is to evaluate the effects of different preparation designs with short pulp chambers on the mean color change (Δ⁢E), fracture resistance, and failure types of mandibular molar ECs. A total of 40 extracted mandibular molars were treated endodontically and divided into four groups. Samples in groups 1, 2, 3, and 4 had occlusal preparation depths of 5 mm, 3 mm, 3 mm with ferrule, and 3 mm with boxes, respectively. The samples were immersed in coffee and their Δ⁢E values were measured by using the Commission Internationale de l'Eclairage color system. They were also subjected to a fracture test. Next, all specimens were examined visually under a stereomicroscope to evaluate their failure modes and identify their fracture origins. Data were entered and analyzed by using Statistical Package for Social Sciences. Among all groups, group 4 (3 mm + boxes) presented the highest Δ⁢E (4.15) after immersion in coffee. Moreover, ANOVA revealed that the Δ⁢E of group 4 (occlusal preparation depth of 3 mm with boxes) was significantly different (p< 0.05) from that of group 2 (3 mm + ferrule, 3.07). The EC with a 3 mm chamfer and ferrule showed the highest maximum load of 2847.68 ± 693.27 N, whereas that with a 5 mm chamfer finish line had a marginally reduced load at fracture of 2831.52 ± 881.83 N. The EC with a 3 mm chamber and boxes had a slightly increased maximum load of 2700.75 ± 436.40 N, whereas that with the 3 mm chamber had the lowest maximum load at fracture of 2385.97 ± 465.61 N. One-way ANOVA showed that different EC preparation designs had no effect on maximum fracture load (F [3,16] = 0.550, p= 0.6). The recorded Δ⁢E values of ECs in all groups were equal or marginally higher than the acceptable values. The EC with a 3 mm chamfer and ferrule displayed the highest mean maximum load. The EC with a 5 mm chamfer finish line had a marginally lower maximum load at fracture than other ECs. Failures, such as ceramic fracture, split fracture, and ceramic and tooth splitting above the cemento-enamel junction (CEJ) or vertically were predominant in samples with occlusal preparation depths of 3 mm with ferrule and 5 mm.

The Application of Lag Screws and Digital Positioning Guide in Treating Sagittal Split Fracture of the Mandible.

Sagittal mandibular fractures are challenging to manage using traditional open reduction and internal fixation techniques due to the difficulty in manually reducing mandibular fragments and performing osteosynthesis on the lingual side. In addition, there is a risk of damaging dental roots with screws during fixation. In this case, the authors employed the lag screw technique combined with digitally guided surgery to effectively perform osteosynthesis on the fragments and avoid iatrogenic tooth and nerve injury.

Characterizing Splitting Failure of Concrete Influenced by Material Heterogeneity Based on Digital Image Processing Techniques

Concrete, as a composite material, is subject to heterogeneity in its mechanical properties and damage characteristics responding to load. In this paper, a numerical approach for analyzing the heterogeneous characteristics and the mechanical behavior of concrete specimens in tensile splitting tests using DIP techniques is introduced. The experiment involves the preparation of three types of concrete specimens with different strengths and performances of the tensile splitting test. The contour and position information of the different components in the split surface of a concrete specimen are reflected in the numerical model using the DIP techniques and the fracture of the split surface is realized by three types of cohesive elements in the finite element software ABAQUS. The results of the proposed numerical model are highly consistent with the experimental results with a maximum error of 4.77%, whereby the evolution of the splitting process is discussed. The simulation shows that the concrete fracture develops from the periphery towards the center of the concrete and the ITZ region splits first at similar strain levels, followed by the mortar region and finally the aggregate region. In addition, a simplified modeling scheme with faster computational efficiency and higher accuracy is proposed, which indicates that the shape of the heterogeneous components in concrete has a low effect on mechanical strength. The proposed model can accurately reflect the splitting fracture process of concrete which is instantaneous in the actual process, contributing to the understanding of the mechanism of the splitting fracture process and proposing a new methodology for simulating the fracture process of heterogeneous materials (e.g., concrete, rock). This work contributes to the understanding of the effect of material heterogeneity on concrete’s mechanical behavior and fracturing process and provides valuable hints for the research on the non-destructive prediction of concrete strength.

Greater tuberosity fractures of the humerus: complications and long-term outcomes after surgical treatment

BackgroundIsolated greater tuberosity (GT) fractures typically occur in younger patients following high-energy trauma compared to humeral neck fractures. Surgical treatment is indicated when superior displacement is > 5 mm. This study aimed to assess the complications and long-term outcomes of surgically-treated GT fractures.MethodsA retrospective review of 39 patients who underwent surgery from 2010 to 2014 was conducted. The cohort comprised 54.6% females, with an average age of 56.74 years and a median follow-up of 6.71 years. Only 25 patients returned for reevaluation, with functional outcomes assessed using Constant-Murley score.ResultsWomen were older than men (63.00 ± 12.15 vs. 48.65 ± 16.93, p = 0.006). 18/39 patients (46.1%) sustained avulsion-type, 1 patient out of 39 (2.6%) depression-type, and 20/39 patients (51.3%) split-type fractures. The mean Constant-Murley score was 84.08 ± 18.36, with higher scores observed in men (p = 0.021). Avulsion-type fractures were related to higher postoperative scores compared to split fractures (p = 0.069). Post-surgical complications occurred in 20.5% of patients, with no differences noted between sexes, fracture types, or procedures.ConclusionThis study enhances understanding of the long-term outcomes of surgically-treated GT fractures, aiding in treatment selection. Interfragmentary screws may be preferable in younger male patients, but are associated with the higher risk of reintervention, particularly in fragile bone. Prospective multicentric studies are warranted to further elucidate long-term results and treatment strategies.

Go-karting Accident Causing an Innocuous Dorsal Spine Injury: Lessons Learned from a Rare Case

A young female in her late 20s presented to us with the inability to move both her lower limbs after being involved in a go-karting accident. On examination, the patient has no power in bilateral lower limbs, the sensation was decreased below D7, and the bowel bladder was involved. The perianal sensations were present and the patient had ASIA B neurology. On investigation, the computed tomography scans revealed a coronal split fracture of the D5 vertebrae without any involvement of the posterior vertebral wall or any canal compromise. There was a subtle facetal subluxation at D5–D6. A magnetic resonance imaging was performed which showed contusion of the cord at D6 vertebral level with edema and possible disruption of the posterior ligamentous complex at D5–D6 level. The patient was operated by posterior decompression with pedicle screw fixation. At the final follow-up, the patients showed neurological recovery with improvement to ASIA D neurology.

Off-Label Use of an External Hand Fixator for Craniomaxillofacial Fractures-An Anatomical Feasibility Study.

The lack of resources limits the treatment of craniomaxillofacial fractures (CMF) in low-income countries (LIC). Therefore, Barton bandages and/or interdental wiring are considered in these regions. Fracture reduction is maintained by permanent occlusion for 6 weeks, which often leads to limited compliance and dissatisfying results. The aim of this cadaver-based study is to evaluate the feasibility of the use of an external face fixator (EFF) for the treatment of CMF, its biomechanical values and to define the optimal pin insertion points and angles. An AO hand fixator was used. CMF of types Le Fort 1-3 with split fractures of the hard palate were treated with EFF on 13 anatomical specimens. Fractures were created using a chisel, and pins were placed in specific anatomical regions. The maximal pull-out force [N] of pins was analysed by a tensile force gauge, and Fmax of the mandibular pins was evaluated. Computer tomography scans were performed on the healthy, fractured and EFF-treated skulls. The pull-out forces for the single pins were mandibular pins (n = 15, median 488.0 N), supraorbital pins (n = 15, median 455.0 N), zygomatic pins (n = 14, median 269.1 N), medial hard palate pins (n = 12, median 208.4 N) and lateral hard palate pins (n = 8, median 49.6 N). The results indicate that the operation technique is feasible, and the stability of the EFF is sufficient for maintaining the reduction. The required pins can safely be inserted into the described areas with good reduction results. Using EFF offers a feasible alternative to the non-surgical treatment of CMF in LIC.

Physically consistent nonlocal macro–meso-scale damage model for quasi-brittle materials: A unified multiscale perspective

Despite great efforts in capturing the damage evolution law in multiscale approaches in damage mechanics, much less attention has been paid to the conversion from geometric damage to energy dissipation. In the present paper, the newly proposed nonlocal macro–meso-scale damage (NMMD) model is physically consolidated and a multiscale point of view is consistently adopted in both the damage evolution and energy dissipation. In this model, for each macroscopic material point a mesoscopic structure is attached such that all the point pairs composed of this point and the points in its influence domain are connected to it when the material is intact. The deformation field under loading will result in deformation of point pairs, and thus mesoscopic damage related to a point pair will occur if the deformation index of this point pair exceeds the prescribed threshold. Such mesoscopic change among point pairs connected to a material point within its influence domain has two-fold consequences: geometrically the accumulation of mesoscopic damage will result in macroscopic discontinuity, and simultaneously the free energy will be dissipated, leading to degradation of mechanical behavior of quasi-brittle materials. In other words, the damage as a metric of the geometric discontinuity will lead to the damage in the sense of energy dissipation and degradation of mechanical behavior for quasi-brittle materials, which can be physically captured by the ratio of summation of all the dissipated mesoscopic free energy in point pairs to the free energy of intact material within the influence domain. This energy-based macroscopic damage could then be inserted into the framework of continuum damage mechanics. Therefore, the conversion from geometric damage to energetic damage is implemented on the mesoscale instead of the macroscale, and thus a macroscopic energetic degradation function is not needed. In addition, the structured strain which is suitable for quasi-brittle materials can be adopted to determine the deformation index of point pairs. Correspondingly, the macroscopic free energy can be split into dissipative and non-dissipative parts. In this way, several inconsistencies in the previous NMMD models are remedied. The influence of mesoscopic model parameters is investigated in depth, and several numerical examples including mode-I, mixed-mode and compressive splitting fracture problems of quasi-brittle materials are carried out. Numerical results indicate that the proposed model can not only well capture the cracking process with or without initial cracks but also quantitatively predict the load–deformation curves without mesh size sensitivity. Moreover, due to the inherent physical consistency, in mixed-mode cracking problems the proposed model performs better than the previous NMMD model. Problems to be further studied are also discussed.

Multiaxial failure behavior and fatigue life prediction of unidirectional composite laminates

Complex coupling mechanisms exist between longitudinal and shear stress on the multiaxial fatigue behavior of composites. A thorough reanalysis of matrix shear failure mechanism under multiaxial fatigue loading is presented. Longitudinal single splitting fracture were analyzed and validated as an independent failure mode under multiaxial loading by analogy to the failure mechanism of natural composites. A new multiaxial fatigue life prediction model was established by double projection on the critical and subcritical fracture planes. Experiments on unidirectional tubular specimens were carried out under combined tension-torsion loadings to separate and identify the multiaxial fatigue failure behavior of composites. The proposed model has been verified using unidirectional laminates subjected to cyclic tension-torsion and off-axis loading, and the results showed that the predicted life is in good agreement with the experimental ones. Applications of three-dimensional digital image correlation (3D-DIC) and microscopy regarding verification in multiaxial damage mechanism are also addressed.

Novel calcaneal plate versus traditional philos plate for treating split fractures of humeral greater tuberosity.

To compare the effect of two internal fixation methods of calcaneal plate fixation and Philos plate fixation in treating split fractures of humeral greater tuberosity. A total of 37 patients with split fractures of humeral greater tuberosity were retrospectively analyzed from September 2016 to April 2021. Enrolled patients were divided into Group A (calcaneal anatomical locking plates), and Group B [Proximal Humeral Internal Locking System (PHILOS)]. The demographics, injury-related variables, surgery-related variables, Constant-Murley score, and postoperative complication between the two groups were compared. There were 16 in Group A and 21 in Group B. Fracture union was achieved in all patients, with an average of 11.9 months. The mean length of incision was significantly different between groups (Group A, 6.16 cm ± 1.07 cm; Group B, 9.09 cm ± 1.30 cm, p < 0.05). Significant difference was observed by comparing bleeding loss between Group A and Group B (Group A, 45.41 ± 11.19 ml; Group B, 106.06 ± 11.12 ml, p < 0.05). After 6 months of treatment, the average Constant-Murley score of Group A was significantly higher than that of Group B (p < 0.05). In terms of operation, no significant difference was observed between groups. In addition, two patients had shoulder impingement syndrome in Group B, and none in Group A. Calcaneal anatomical locking plate fixation is superior to Philos plate fixation in surgical trauma and bleeding loss. Our study provides an alternative technique for treating split fractures of humeral greater tuberosity.

Petrographic, Petrophysical, and Mechanical Characterisation of the Ultra- Tight Casa Cruz Sandstone, Moruga Formation, Southern Basin, Trinidad

Durability, compactness, and natural strength of sandstones are pivotal properties for its subsequent application as a building material. If a sandstone is tight and contains petroleum, then hydraulic fracturing is necessary to achieve commercial production. The Casa Cruz Sandstone Member, southern Trinidad, is currently being explored as a potential petroleum target and building material. This study investigates the petrographic, petrophysical, and mechanical characteristics of the Casa Cruz sandstone to understand the factors that control the quality of the sandstone and to determine the sandstone’s suitability as a natural resource. A thin-section analysis was performed to investigate the mineralogy, texture, and diagenesis of the sandstone. Permeability, porosity, density, P- and S-wave velocities, unconfined compressive strength (UCS) and confined compressive strength were measured. The elastic properties (Young’s modulus, shear modulus, bulk modulus, and Poisson’s ratio) were estimated from inversion of the P- and S-wave velocities. The results show that the Casa Cruz sandstone is one of the tightest sandstone types reported in the literature with porosity of 0.7% and permeability of 4.7 x 10-22 m2 (0.47 nD). Authigenic cementation and mechanical compaction are the main diagenetic processes that jointly controlled the quality of the sandstone. The sandstone was classified as a very strong (UCS of 128 MPa) quartz-arenite and is barren of petroleum and bioclasts. Brittle failure behaviour was exhibited, accompanied by axial splitting fractures and shear fractures under unconfined and confined conditions, respectively. The Casa Cruz sandstone is suggested to be an excellent building material as its petrophysical and mechanical properties are comparable to those of commercial industry grade of Westerly granite and Naparima Hill argillite.

Potential problem and solution of lateral plate postposition for the posterolateral tibial plateau fracture

BackgroundThere has been controversial for the treatment of the posterolateral tibial plateau fractures (PTPF). This study aimed to evaluate clinic outcomes of the lateral locking compression plate (LCP) postposition, analyze the feasibility of LCP postposition through anatomical measurement, and address the potential problems of LCP postposition through the biomechanical assessment.Methods39 patients with PTPF undergoing LCP fixation between June 2019 and June 2022 were retrospectively evaluated. All cases were divided into two group: Group A (15 cases) employed plate transverse arm postpositioning with posterolateral (PL) fracture fixation using two raft screws, while Group B (24 cases) utilized non-postpositioning with fixation by a single raft screw. Surgical duration, intraoperative blood loss, the change of lateral tibial plateau angle (LTPA), lateral tibial plateau posterior slope angle (LPSA) and fracture collapse between immediate postoperative and last follow up, range of motion (ROM), HSS knee score, and Lysholm knee score were recorded. CT measurements of the fibular head superior space and LCP transverse arm were taken in 50 healthy adult knees to assess postposition feasibility. Finally, three fracture models were established using finite element analysis: Model A with plate postposition and PL split fracture fixed by two raft screws of transverse arm, Model B with plate non-postposition and PL split fracture fixed by one raft screw, and Model C with plate non-postposition and PL split fracture fixed by one raft screw and anterior–posterior tension screws. Loadings of 250N, 500N, and 750N were applied for the analysis of the displacement degree, von Mises stress distribution.ResultsResults indicate comparable operative duration and intraoperative hemorrhage between groups. Complications were minimal in both groups. Group A demonstrated superior outcomes in terms of radiographic parameters, functional scores, and fracture collapse prevention. CT measurements revealed compatibility in 72% of healthy knees with the postpositioning technique. Finite element analysis indicated favorable biomechanical stability.ConclusionNot all patients with PTPF were applicable to the management of the plate postposition and two raft screws fixation, even though this technique exerted good biomechanical stability and achieved satisfactory clinic outcomes. When the PL fracture was fixed by only raft screw through LCP owing to various reasons, two anterior–posterior tension screws might be necessitated to maintain the fracture stability.

All Arthroscopic Salvage Technique for Intraoperative Vertical Split Coracoid Graft Fracture in Latarjet Procedure—Technical Note

Intraoperative vertical coracoid graft fractures during the Latarjet procedure are well-described complications, which typically have a poor prognosis or may necessitate further iliac crest bone grafting for stabilization. The vertical split coracoid fractures are reasoned to be caused by excessive tightening of the screws, poor bone quality, especially in females and the smaller dimension of the coracoid graft. In this technical note, we propose an arthroscopic salvage technique for salvaging the fractured coracoid graft and to avoid the need for additional bone graft, thereby reducing morbidity to the patient. We use two double-loaded, all-suture anchors (Stryker, India) on either side of the split coracoid graft, and double-pulley configuration of suture tightening is done, providing compression and stability to the fractured graft.

A robust tension-compression asymmetric phase-field fracture model for describing PBX cracking under complex stress states

ABSTRACT The crack behaviors under complex stress states are very important for the safety of polymer-bonded explosives (PBXs) under accidental stimulations, but their accurate description is a challenge. Due to the advances of tracking discontinuities and multi-fields coupling, the phase-field model for complex fracture phenomena is attracting significant interest recently. Conventional phase-field fracture models are tension-compression symmetric or based on volumetric-deviatoric strain energy split, and these conventional phase-field models may lead to unrealistic fracture patterns, which hinders its further application in PBX fracture simulations. In this work, we present an extended, tension-compression asymmetric phase-field fracture model for PBXs, which distinguishes the contributions of tensile and compressive stresses to damage driving energy, and couples the mechanism of mechanical degradation and energy-driving cracking diffusion. We implemented our improved phase-field fracture model into finite element calculations and compared the simulation results with the conventional tension-compression symmetric phase-field fracture model and volumetric-deviatoric strain energy split phase-field fracture model by simulating PBX specimens under static loadings. The results show that our model not only accurately depicts the tensile and compressive cracks, but also describes compression-assisted cracking while suppressing unrealistic damage nucleation caused by small amplitudes of local compressive stresses, making it a very efficient way of describing PBX cracking under complex stress states. This new model is both mathematically and physically concise, and convenient for numerical implementation. Moreover, the novel model can be naturally extended to simulate shock-induced dynamic and/or coupled fracture of PBXs because of its feasibilities for dynamic extension and multi-field coupling.

Does osteotomizing the lower border of the mandible affect the lingual split pattern in a sagittal split ramus osteotomy?

AimThe purpose of this study was to evaluate the effect of adding a fourth osteotomy at the lower border of the mandible on the lingual cortical fracture pattern in bilateral sagittal split ramus osteotomies.Patients and methodsThe sample of the study consisted of 20 patients (12 male and 8 female, with a mean age of 26.79 ± 7.12 years) with mandibular deformities who needed bilateral sagittal split ramus osteotomy. One side underwent a traditional sagittal split ramus osteotomy, and the procedure was modified on the other side by adding a 1 cm horizontal osteotomy at the lower border of the mandible, just distal to the caudal end of the vertical buccal osteotomy cut. A 3D CBCT was used to identify the split pattern.ResultsIn the total sample, 40% of the lingual splits ran vertically toward the lower border of the mandible (LSS1), 20% of the splits passed horizontally to the posterior border of the mandible (LSS2), 32.5% of the splits took place along the inferior alveolar canal (LSS3), and 7.5% of the splits were unfavourable fractures (LSS4). On the inferior border osteotomy sides, the distribution of LSS1, LSS2, LSS3, and LSS4 was 10 (25%), 6 (15%), 4 (10%), and 0 (00), respectively. Their distribution on the sides without inferior border osteotomy was 6 (15%), 8 (20%), 13 (32.5%), and 3 (7.5%), respectively. Statistical analysis revealed a significant difference between the two groups (p < 0.05).ConclusionInferior border osteotomy tends to direct the lingual split fracture line toward the lower and posterior borders of the mandible and minimizes bad splits; however, further studies are needed to confirm our findings.