Good Biomechanical Properties Research Articles

Allograft sterilization and processing: impact on biomechanical strength

The allograft used for anterior cruciate ligament reconstruction (ACLR) must posses good biomechanical properties and it should have similar properties to the original tendon. During reconstruction the allograft must undergo proper sterilization and several sterilization methods have been used in the clinical practice. There are varations in the sterilization process and it has significant impact on the allograft tissue performance during ACL reconstruction. It is advisable to refrain from utilising grafts that have been exposed to radiation doses exceeding 15 kGy, as well as grafts that have undergone more than eight freeze-thaw cycles. Gamma radiation has disadvantages when compared to electron beam radiation in term of loss of mechanical strength.

Mechanical analysis of the femoral neck dynamic intersection system with different nail angles and clinical applications.

The femoral neck dynamic intersection system (FNS) is mechanically more stable than other internal fixation techniques. Current studies have confirmed that the structural design of FNS has good biomechanical properties in European and American populations. However, whether the suitability of the FNS's 130° main nail angle design for Asian populations has been thoroughly investigated remains unclear. To compare the biomechanical stability differences among different main nail angles of the FNS in the treatment of femoral neck fractures in Asian populations. Computed tomography data of the femur of healthy adult male volunteers were imported into Mimics software to create a three-dimensional model of the femur. The model was adapted to the curve using Geomagic software and imported into Solidworks software to construct the Pauwels I femoral neck fracture model and design the FNS internal fixation model using different main nail angles. Afterward, the models were assembled with the FNS fracture model and meshed using the preprocessing Hypermesh software. Subsequently, they were imported into Abaqus software to analyze and evaluate the biomechanical effects of different angles of the FNS main nail on the treatment of femoral neck fractures. The peak displacement of the proximal femur under different angles of FNS fixation under stress was 7.446 millimeters in the 120° group and 7.416 millimeters in the 125° group; in the 130°, 135°, and 140° FNS fixation groups, the peak displacement was 7.324 millimeters, 8.138 millimeters, and 8.246 millimeters, respectively. In the 120° and 125° FNS fixation groups, the maximum stresses were concentrated at the main nail and the anti-rotation screw, which intersected the fracture line of the femur neck, resulting in peak stresses of 200.7 MPa and 138.8 MPa, respectively. Peak stresses of 208.8 MPa, 219.8 MPa, and 239.3 MPa were observed on the angular locking plate distal to the locking screw in the 130°, 135°, and 140° fixation groups. FNS has significant stress distribution properties, a minimal proximal femoral displacement, and an optimal stability for treating femoral neck fractures in Asian populations when performed with a 130° main nail angle.

Chicken utricle stromal cell-derived decellularized extracellular matrix coated nanofibrous scaffolds promote auditory cell production

Stem cell therapy has a broad future in treating sensorineural hearing loss in mammals. But how to produce sufficient functional auditory cells including hair cells, supporting cells as well as spiral ganglion neurons from potential stem cells is the bottleneck. In this study, we aimed to simulate inner ear development microenvironment to induce inner ear stem cells to differentiate into auditory cells. The different mass ratios of poly-l-lactic acid/gelatin (PLLA/Gel) scaffolds were fabricated by electrospinning technology to mimic the structure of the native cochlear sensory epithelium. The chicken utricle stromal cells were isolated and cultured, and then seeded on the PLLA/Gel scaffolds. The chicken utricle stromal cell-derived decellularized extracellular matrix (U-dECM)-coated PLLA/Gel bioactive nanofiber scaffolds (U-dECM/PLLA/Gel) were prepared by decellularization. The U-dECM/PLLA/Gel scaffolds were used for culture of inner ear stem cells, and the effects of the modified scaffolds on the differentiation of inner ear stem cells were analyzed by RT-PCR and immunofluorescent staining. The results showed that U-dECM/PLLA/Gel scaffolds possessed good biomechanical properties can significantly promote the differentiation of inner ear stem cells and make them differentiate into auditory cells. Collectively, these findings indicated that U-dECM-coated biomimetic nanomaterials may be a promising strategy for auditory cell production.

Biomimetic in situ tracheal microvascularization for segmental tracheal reconstruction in one-step.

Formation of functional and perfusable vascular network is critical to ensure the long-term survival and functionality of the engineered tissue tracheae after transplantation. However, the greatest challenge in tracheal-replacement therapy is the promotion of tissue regeneration by rapid graft vascularization. Traditional prevascularization methods for tracheal grafts typically utilize omentum or muscle flap wrapping, which requires a second operation; vascularized segment tracheal orthotopic transplantation in one step remains difficult. This study proposes a method to construct a tissue-engineered tracheal graft, which directly forms the microvascular network after orthotopic transplantation in vivo. The focus of this study was the preparation of a hybrid tracheal graft that is non-immunogenic, has good biomechanical properties, supports cell proliferation, and quickly vascularizes. The results showed that vacuum-assisted decellularized trachea-polycaprolactone hybrid scaffold could match most of the above requirements as closely as possible. Furthermore, endothelial progenitor cells (EPCs) were extracted and used as vascularized seed cells and seeded on the surfaces of hybrid grafts before and during the tracheal orthotopic transplantation. The results showed that the microvascularized tracheal grafts formed maintained the survival of the recipient, showing a satisfactory therapeutic outcome. This is the first study to utilize EPCs for microvascular construction of long-segment trachea in one-step; the approach represents a promising method for microvascular tracheal reconstruction.

PEEK for Oral Applications: Recent Advances in Mechanical and Adhesive Properties.

Polyetheretherketone (PEEK) is a thermoplastic material widely used in engineering applications due to its good biomechanical properties and high temperature stability. Compared to traditional metal and ceramic dental materials, PEEK dental implants exhibit less stress shielding, thus better matching the mechanical properties of bone. As a promising medical material, PEEK can be used as implant abutments, removable and fixed prostheses, and maxillofacial prostheses. It can be blended with materials such as fibers and ceramics to improve its mechanical strength for better clinical dental applications. Compared to conventional pressed and CAD/CAM milling fabrication, 3D-printed PEEK exhibits excellent flexural and tensile strength and parameters such as printing temperature and speed can affect its mechanical properties. However, the bioinert nature of PEEK can make adhesive bonding difficult. The bond strength can be improved by roughening or introducing functional groups on the PEEK surface by sandblasting, acid etching, plasma treatment, laser treatment, and adhesive systems. This paper provides a comprehensive overview of the research progress on the mechanical properties of PEEK for dental applications in the context of specific applications, composites, and their preparation processes. In addition, the research on the adhesive properties of PEEK over the past few years is highlighted. Thus, this review aims to build a conceptual and practical toolkit for the study of the mechanical and adhesive properties of PEEK materials. More importantly, it provides a rationale and a general new basis for the application of PEEK in the dental field.

Finite element analysis of dynamic changes in spinal mechanics of osteoporotic lumbar fracture

AimThis study aims to explore the effects of finite element biomechanical properties of different methods in the treatment of osteoporotic thoracolumbar fractures.MethodsBased on the ultra-thin computed tomography scan data of a volunteer’s thoracolumbar spine, the finite element method was used to simulate the treatment of osteoporotic thoracolumbar fracture. Spiral computed tomography scanning was used to obtain images of the thoracolumbar region, which was then imported into Mimics software to obtain the three-dimensional geometric model. The finite element model of normal T11 – L2 segment was established by finite element software Abaqus and the validity of the model loading was verified. The finite element model of T11 vertebral compression fracture was established based on normal raw data. The clinical overextension reduction manipulation was simulated by different treatment methods and the changes in stress and displacement in different parts of injured vertebrae were analyzed.ResultsAn effective finite element model of T11–L2 segment was established. The maximum stress, axial compression strength, axial compression stiffness, and transverse shear stiffness were significantly better in the percutaneous kyphoplasty and percutaneous vertebroplasty treatment group than in the conservative treatment group and open treatment group (P < 0.05). Additionally, there was no significant difference between the open treatment group and conservative treatment group, or between the PKP and PVP treatment group.ConclusionPercutaneous vertebroplasty and percutaneous kyphoplasty not only met the requirements of normal functional kinematics of thoracolumbar spine, but also restored the stability of thoracolumbar spine. They had good biomechanical properties and remarkable application effects. The application of finite element analysis can help select a scientific, reasonable, and effective treatment scheme for the clinical diagnosis and treatment of osteoporotic thoracolumbar fractures.

Characterization and Biomechanical Study of a Novel Magnesium Potassium Phosphate Cement.

Magnesium potassium phosphate cement (MKPC) has attracted considerable attention as a bone regeneration material. However, there are only a few reports on its biomechanical properties. To evaluate the biomechanical properties of MKPC, we compared the mechanical parameters of pedicle screws enhanced with either MKPC or polymethyl methacrylate (PMMA) bone cement. The results show that the maximum pull-out force of the pedicle screws was 417.86 ± 55.57 and 444.43 ± 19.89 N after MKPC cement setting for 30 min and 12 h, respectively, which was better than that of the PMMA cement. In fatigue tests, the maximum pull-out force of the MKPC cement group was 435.20 ± 7.96 N, whereas that of the PMMA cement in the control group was 346.80 ± 7.66 N. Furthermore, the structural characterization analysis of the MKPC cement revealed that its microstructure after solidification was an irregular tightly packed crystal, which improved the mechanical strength of the cement. The maximum exothermic temperature of the MKPC reaction was 45.55 ± 1.35 °C, the coagulation time was 7.89 ± 0.37 min, and the compressive strength was 48.29 ± 4.76 MPa, all of which meet the requirements of clinical application. In addition, the MKPC cement did not significantly inhibit cell proliferation or increase apoptosis, thus indicating good biocompatibility. In summary, MKPC exhibited good biomechanical properties, high initial strength, good biocompatibility, and low exothermic reaction temperature, demonstrating an excellent application potential in the field of orthopedics.

Application and research of nano-biomaterials in ankle sports injury rehabilitation

The ankle joint is an important weight-bearing joint of the lower limbs. It converts the vertical gravity of the human body into an arched structure. When the ankle joint is exposed to external reaction forces and cannot be effectively cushioned, injuries can easily occur. If improper and untimely treatment can cause joint instability, easy to repeatedly sprain in the future, secondary joint adhesions or traumatic arthritis can cause dysfunction. Therefore, strengthening the treatment of ankle joint injury repair is of great significance to improve prognosis and improve clinical effect. Clinically, the treatment of ankle joint injury is mainly based on protection, rest, cold compress, and drug intervention. It is difficult to achieve the expected therapeutic effect. From a large amount of research data, with the development of tissue engineering and bioengineering, currently the use of artificial biological materials to intervene in the healing and rehabilitation of bone injuries has become increasingly mature, but it is relatively rare in rehabilitation measures for ankle sports injuries. Therefore, in this study, 3D printing technology was used to mix PHBV, calcium silicate, and bioactive glass to successfully prepare a bioglass scaffold BG-Si-PHBV. The micromorphology, porosity, water absorption, weight loss analysis and biomechanical characteristics of the biomaterial scaffold were studied. At the same time, this study established an ankle joint sports injury model with Beagle dogs, implanted BG-Si-PHBV biological bone tissue scaffold material into the ankle joint defect area of the affected limb of Beagle dogs, and detected BG-Si-PHBV tissue engineering materials to repair the ankle joint Feasibility of sports injuries. The BG-Si-PHBV biological bone tissue scaffold material prepared in this research has good porosity, hydrophilicity and biomechanical properties, which can meet the conditions of artificial biological materials after ankle injury. Animal experiments show that BG-Si-PHBV biological bone tissue scaffold is ideal for the rehabilitation of ankle joint sports injuries. This helps to improve the biomechanical properties and has broad application prospects.

Preparation of PU/Fibrin Vascular Scaffold with Good Biomechanical Properties and Evaluation of Its Performance in vitro and in vivo.

PurposeThe development of tissue-engineered blood vessels provides a new source of donors for coronary artery bypass grafting and peripheral blood vessel transplantation. Fibrin fiber has good biocompatibility and is an ideal tissue engineering vascular scaffold, but its mechanical property needs improvement.MethodsWe mixed polyurethane (PU) and fibrin to prepare the PU/fibrin vascular scaffolds by using electrospinning technology in order to enhance the mechanical properties of fibrin scaffold. We investigated the morphological, mechanical strength, hydrophilicity, degradation, blood and cell compatibility of PU/fibrin (0:100), PU/fibrin (5:95), PU/fibrin (15:85) and PU/fibrin (25:75) vascular scaffolds. Based on the results in vitro, PU/fibrin (15:85) was selected for transplantation in vivo to repair vascular defects, and the extracellular matrix formation, vascular remodeling, and immune response were evaluated.ResultsThe results indicated that the fiber diameter of the PU/fibrin (15:85) scaffold was about 712nm. With the increase of PU content, the mechanical strength of the composite scaffolds increased, however, the degradation rate decreased gradually. The PU/fibrin scaffold showed good hydrophilicity and hemocompatibility. PU/fibrin (15:85) vascular scaffold could promote the adhesion and proliferation of mesenchymal stromal cells (MSCs). Quantitative RT-PCR experimental results showed that the expression of collagen, survivin and vimentin genes in PU/fibrin (15:85) was higher than that in PU/fibrin (25:75). The results in vivo indicated the mechanical properties and compliance of PU/fibrin grafts could meet clinical requirements and the proportion of thrombosis or occlusion was significantly lower. The graft showed strong vasomotor response, and the smooth muscle cells, endothelial cells, and ECM deposition of the neoartery were comparable to that of native artery after 3 months. At 3 months, the amount of macrophages in PU/fibrin grafts was significantly lower, and the secretion of pro-inflammatory and anti-inflammatory cytokines decreased.ConclusionPU/fibrin (15:85) vascular scaffolds had great potential to be used as small-diameter tissue engineering blood vessels.

Evaluation of remodeling and regeneration of electrospun PCL/fibrin vascular grafts in vivo.

The success of artificial vascular graft in the host to obtain functional tissue regeneration and remodeling is a great challenge in the field of small diameter tissue engineering blood vessels. In our previous work, poly(ε-caprolactone) (PCL)/fibrin vascular grafts were fabricated by electrospinning. It was proved that the PCL/fibrin vascular graft was a suitable small diameter tissue engineering vascular scaffold with good biomechanical properties and cell compatibility. Here we mainly examined the performance of PCL/fibrin vascular graft in vivo. The graft showed randomly arranged nanofiber structure, excellent mechanical strength, higher compliance and degradation properties. At 9 months after implantation in the rat abdominal aorta, the graft induced the regeneration of neoarteries, and promoted ECM deposition and rapid endothelialization. More importantly, the PCL/fibrin vascular graft showed more microvessels density and fewer calcification areas at 3 months, which was beneficial to improve cell infiltration and proliferation. Moreover, the ratio of M2/M1macrophage in PCL/fibrin graft had a higher expression level and the secretion amount of pro-inflammatory cytokines started to increase, and then decreased to similar to the native artery. Thus, the electrospun PCL/fibrin tubular vascular graft had great potential to become a new type of artificial blood vessel scaffold that can be implanted in vivo for long term.

Preparation of a photocured GelMA hydrogel co-cultured with HOKs and HGFs for an artificial oral mucosal tissue model

Reversible or irreversible damage causes oral mucosal defects, the treatment of which requires biomaterials with good biomechanical properties. In this study, we prepared an artificial oral mucosa tissue model using a photocured methacrylate gelatin (GelMA) hydrogel co-cultured with human gingival fibroblasts (HGFs) and human oral keratinocytes (HOKs). GelMA was fabricated via a chemical reaction between gelatin and methacrylic anhydride (MA), and its structure was confirmed via1H NMR analysis. The culture of HOKs and HGFs was observed on the surface and in the bulk of the GelMA hydrogel, indicating that the hydrogel was biocompatible for cell adhesion and proliferation. In addition, immunofluorescent staining results indicated that HOKs form a three-dimensional cell structure while maintaining their intrinsic keratinocyte properties. Histological evaluations demonstrated that the HGF and HOK bi-layered GelMA hydrogel can be used to develop artificial oral mucosa tissue.

Osteosynthesis of Phalangeal Fractures: Biomechanical Comparison of Kirschner Wires, Plates, and Compression Screws

The aim of this study was to compare several osteosynthesis techniques (intramedullary headless compression screws, T-plates, and Kirschner wires) for distal epiphyseal fractures of proximal phalanges in a human cadaveric model. A total of 90 proximal phalanges from 30 specimens (index, ring, and middle fingers) were used for this study. After stripping off all soft tissue, a transverse distal epiphyseal fracture was simulated at the proximal phalanx. The 30 specimens were randomly assigned to 1 fixation technique (30 per technique), either a 3.0-mm intramedullary headless compression screw, locking plate fixation with a 2.0-mm T-plate, or 2 oblique 1.0-mm Kirschner wires. Displacement analysis (bending, distraction, and torsion) was performed using optical tracking of an applied random speckle pattern after osteosynthesis. Biomechanical testing was performed with increasing cyclic loading and with cyclic load to failure using a biaxial torsion-tension testing machine. Cannulated intramedullary compression screws showed significantly less displacement at the fracture site in torsional testing. Furthermore, screws were significantly more stable in bending testing. Kirschner wires were significantly less stable than plating or screw fixation in any cyclic load to failure test setup. Intramedullary compression screws are a highly stable alternative in the treatment of transverse distal epiphyseal phalangeal fractures. Kirschner wires seem to be inferior regarding displacement properties and primary stability. Fracture fixation of phalangeal fractures using plate osteosynthesis may have the advantage of a very rigid reduction, but disadvantages such as stiffness owing to the more invasive surgical approach and soft tissue irritation should be taken into account. Headless compression screws represent a minimally invasive choice for fixation with good biomechanical properties.

Addition of Platelet-Rich Plasma to Silk Fibroin Hydrogel Bioprinting for Cartilage Regeneration.

The recent advent of 3D bioprinting of biopolymers provides a novel method for fabrication of tissue-engineered scaffolds and also offers a potentially promising avenue in cartilage regeneration. Silk fibroin (SF) is one of the most popular biopolymers used for 3D bioprinting, but further application of SF is hindered by its limited biological activities. Incorporation of growth factors (GFs) has been identified as a solution to improve biological function. Platelet-rich plasma (PRP) is an autologous resource of GFs, which has been widely used in clinic. In this study, we have developed SF-based bioinks incorporated with different concentrations of PRP (12.5%, 25%, and 50%; vol/vol). Release kinetic studies show that SF-PRP bioinks could achieve controlled release of GFs. Subsequently, SF-PRP bioinks were successfully fabricated into scaffolds by bioprinting. Our results revealed that SF-PRP scaffolds possessed proper internal pore structure, good biomechanical properties, and a suitable degradation rate for cartilage regeneration. Live/dead staining showed that 3D, printed SF-PRP scaffolds were biocompatible. Moreover, in vitro studies revealed that tissue-engineered cartilage from the SF-PRP group exhibited improved qualities compared with the pure SF controls, according to histological and immunohistochemical findings. Biochemical evaluations confirmed that SF-PRP (50% PRP, v/v) scaffolds allowed the largest increases in collagen and glycosaminoglycan concentrations, when compared with the pure SF group. These findings suggest that 3D, printed SF-PRP scaffolds could be potential candidates for cartilage tissue engineering. Impact statement Three-dimensional bioprinting of silk fibroin (SF) hydrogel as bioinks is a promising strategy for cartilage tissue engineering, but it lacks biological activities, which favors proliferation of seeded cells and secretion of the extracellular matrix. In this study, we have successfully added platelet-rich plasma (PRP) into SF-based bioinks as an autologous source of growth factors. The 3D, printed SF-PRP scaffold showed an enhanced biological property, thus aiding in potential future development of novel cartilage tissue engineering applications.

Resomer C212© in vertebroplasty or kyphoplasty: A feasibility study on artificial bones with biomechanical and thermal evaluation.

Vertebroplasty and kyphoplasty are now well-established methods for treating compression fractures of vertebral bodies (AO type A) as well as vertebral body metastases[1, 2, 3]. However, polymethylmethacrylate (PMMA) augmented vertebrae show fractures of subsequent vertebral bodies due to the increased stability of the augmented vertebral body[4]. Resorbable cements are currently only used experimentally. Many commercially available resorbable calcium phosphate cements do not exhibit sufficient biomechanical stability to treat vertebral body fractures[5]. Resomer C212© (Evonik Industries AG, Essen, Germany) is a slow resorbable poly-ε-caprolactone that has low melting temperatures and good biomechanical properties. This is a feasibility study on how the poly-ε-caprolactone Resomer C212© can be used for kypho- or vertebroplasty, what temperatures are used in the argumentation and how differences in load capacity are measurable compared to conventional PMMA cement. 23 Sawbones© blocks (7.5 Open Cell Foam, SKU: 1522-09, laminated on both sides, 4 × 4 × 2.9cm, Sawbones, Vashon Island, USA) were divided into three groups: 7 without augmentation, 8 augmented with PMMA cement Traumacem V+© (DePuy Synthes, West Chester, USA) and 8 augmented with Resomer C212©. Temperature measurements were made in a 37∘C water bath centrally in the block and on the top and bottom plates. This was followed by a maximum load of up to 2000N using a universal testing machine (Instron E 10000, Instron Industrial Products, Grove City, USA). In the Resomer C212© test group, the maximum average increase in temperature was 4.15 ± 4.72∘C central, 0.3± 0.31∘C at the top and 0.78 ± 1.27∘C at the base. In the cement test group, the average increase in temperature was 9.80 ± 10.65∘C centrally in the test block, 1.50 ± 0.73∘C at the top plate and 1.42 ± 0.66∘C and the base plate. In the axial compression test, the 7 non-kyphoplasted test blocks showed a first loading peak on average at 275.23 ± 80.98 N, a rigidity of 238.47 ± 71.01N/mm2. In the Traumacem V+© group, the mean peak load was 313.72 ± 46.26 N and rigidity was 353.45 ± 77.23N/mm2. The Resomer C212© group achieved a peak load of 311.74 ± 52.05 N and a stiffness of 311.30 ± 126.63 N/mm2. A compression to 50% could not be seen in any test block under the load of 2000 N. At 2000 N, Traumacem V+©'s average height reduction was 9.26 ± 2.16 mm and Resomer C212© was 10.93 ± 0.81 mm. It has been shown that the application of Resomer C212© in kyphoplasty or vertebroplasty is well feasible. Thermal analysis showed significantly lower temperatures and shorter temperature application in the Resomer C212© group. In the biomechanical load up to 2000 N no significant differences could be observed between the individual groups.

Research progress in internal fixation for treatment of pelvic anterior ring injury

To review the research progress of the application of internal fixation (INFIX) in the treatment of pelvic anterior ring injuries. The recent literature about INFIX in the treatment of pelvic anterior ring injury concerning the surgery technique, biomechanical characteristics, indications, contraindications, advantages, complications, and effectiveness was extensively consulted, reviewed, and summarized. INFIX is a relatively novel technique for the treatment of pelvic anterior ring injuries at present. The advantages include good biomechanical properties, extensive indications, minimally invasion, convenient nursing, less complications, and excellent effectiveness. It is a clinical method with obvious advantages and development potential for treatment of pelvic anterior ring injuries using INFIX, and further study is needed to improve its effectiveness.

Preparation and Optimization of a Biomimetic Triple-Layered Vascular Scaffold Based on Coaxial Electrospinning.

Electrospinning is a promising method for preparing bionic vascular scaffolds. In particular, coaxial electrospinning can encapsulate polymer materials in biological materials and provide vascular scaffolds with good biomechanical properties. However, it is difficult to produce a stable Taylor cone during the coaxial electrospinning process. Moreover, glutaraldehyde cross-linked natural biomaterials are cytotoxic. To address these issues, a novel electrospinning process is proposed in this report. A non-ionic surfactant (Tween 80) was added to poly(lactic-co-glycolic acid) electrospinning solution and gelatin-collagen electrospinning solution, which prevented the interfacial effect of coaxial electrospinning due to different core/shell solutions. The as-prepared materials were then cross-linked with the non-toxic coupling agents N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide/N-hydroxysuccinimide (EDC/NHS). By comparing the biomechanical properties of EDC/NHS cross-linked vascular scaffold with glutaraldehyde vapor-cross-linked vascular scaffold, it was found that the fracture strain and biological performance of EDC/NHS cross-linked vascular scaffold were better than those of the glutaraldehyde cross-linked scaffold. Finally, a three-layer bionic vascular scaffold was prepared by the proposed electrospinning process. Biomechanical performance tests were carried out and the prepared scaffold was found to meet the requirements of tissue-engineered blood vessels. The research in this paper provides a useful reference for the preparation and optimization of vascular scaffolds.

Biomechanical and Performance Evaluation of Magnetic Elliptical-Ring Compressive Anastomoses

BackgroundAfter magnetic compressive anastomosis, anastomat passage through the narrow channels of the digestive tract is difficult owing to the device's large volume. Such passage can lead to mechanical damage to the digestive tract or anastomat's unstable excretion time. This article presents a new magnetic compressive anastomotic approach. MethodsA magnetic elliptical-ring compressive anastomat was designed and evaluated for placement and passage in vitro. Nine young adult dogs underwent laparotomy with intestinal tissue side-to-side anastomosis. Four different groups of magnetic compressive anastomats of two different magnetic force levels (20 N or 30 N) and shapes (round or elliptical) were implanted into each dog simultaneously. Three dogs were euthanized on each of postoperative day 1, day 4, and day 7. Anastomoses were then compared with respect to histology and tensile fracture force. ResultsThe magnetic elliptical-ring compressive anastomat was functional but produced less obstruction compared to its round counterpart during passage through the esophagus and intestine. Nine dogs underwent successful surgery and harvesting of 30 total anastomoses. Histology of anastomotic tissue showed that, along the newly formed tunnel connecting the two sides of anastomotic tissues, compressed tissues became thinner and fell off, and initial anastomoses formed on the seventh postoperative day. There were large differences in tensile fracture force among the anastomoses formed by magnets with different magnetic forces of the same structure. However, the magnetic compressive anastomat structure did not affect anastomotic repair during magnetic compression anastomosis. ConclusionsThe magnetic elliptical-ring compressive anastomat is an efficient anastomotic device that can be used easily and with good passage. The device has good biomechanical properties and can be used with endoscopy to reduce operative time.

Electrospun polycaprolactone/silk fibroin nanofibrous bioactive scaffolds for tissue engineering applications

Degumming of Bombyx mori silk cocoons by a novel and mild process using aqueous ammonia and fabrication of electrospun polycaprolactone/silk fibroin (PCL/SF) nanofibrous scaffolds is reported. Cocoons were degummed in 0.3% w/w solutions of boiling ammonia (28–30%) for 45 min. Degummed SF fibers were dissolved in phosphoric and formic acid (7/3 v/v) mixture, coagulated in methanol, filtered and dried. PCL solutions containing different amounts of SF were electrospun in formic acid, a green solvent. Scaffolds were characterized to confirm the successful incorporation of SF and to demonstrate formation of nanofibrous webs with good biomechanical properties. Cell viability assay was performed by seeding Human BJ fibroblast cells on scaffolds. In vitro analysis showed that the scaffolds produced were non-toxic and incorporation of SF resulted in enhanced cell proliferation. Nanofibrous PCL/SF scaffolds with good biomechanical properties developed through dialysis free processing of silk fibroin can be promising substrates for tissue engineering applications.

Use of intramedullary nailing in poor sanitary conditions: French Military Medical Service experience

IntroductionIntramedullary (IM) nailing is the gold standard for treating long bone fractures in developed countries because of its minimally-invasive application and good biomechanical properties. In precarious conditions, external fixation or open plate fixation are often performed because surgeons do not have the means to carry out IM nailing. However, these procedures can lead to infection-related complications and mechanical failures. The aim of our study was to describe the outcomes and postoperative complications of IM nailing of closed, long bone fractures in patients operated in a French front-line combat surgical unit (role 2+). Our hypothesis was that IM nailing is a reliable technique with low morbidity for the initial treatment of long bone fractures, even in precarious situations. Material and methodsThis was a prospective, single-center, descriptive study of patients operated on between April 2016 and November 2017. All the patients with a closed femur or tibia fracture who were treated by IM nailing were eligible, no matter their time to surgery. The minimum follow-up was 6 months. The primary endpoint was the absence of infection-related complications and the secondary endpoint was fracture union. ResultsFifty-eight patients were reviewed after an average follow-up of 4.7 months (range, 3–15 months). The mean patient age was 35.2 years (15–85 years) and the majority of patients were men (52 of 58). The fracture was in the femur in 74.1% (n=43) of cases and in the tibia in 25.9% (n=15) of cases. The time to surgery averaged 122.3 days (7–720 days) with a median of 60 days. In 74% of cases (n=43), fracture realignment required an open surgical approach. The postoperative course was considered normal in 96.6% of cases (n=51). No infections were reported as of the last follow-up visit. Union occurred in an average of 4 months in 70.7% of cases (n=41). There were three cases of nonunion after 6 months. DiscussionEven in precarious situations, IM nailing is an effective, reliable method with a low complication risk and high union rate for the treatment of neglected long bone fractures. This surgical treatment is well suited to the poor sanitary conditions on the African continent. Level of evidenceII, low-powered prospective study.

Biomechanical study on nickel-titanium three-dimensional memory alloy mesh combined with autologous bone for living model of canine tibial plateau collapse fracture

To evaluate the effect of nickel-titanium three-dimensional memory alloy mesh combined with autologous bone for living model of canine tibial plateau collapse fracture by biomechanical testing. Sixteen healthy 12-month-old Beagle dogs were randomly divided into 4 group, 4 dogs in each group. The dogs were used to establish the tibial plateau collapse fracture model in groups A, B, and C. Then, the nickel-titanium three-dimensional memory alloy mesh combined with autologous bone (the fibula cortical bone particles), the artificial bone (nano-hydroxyapatite), and autologous fibula cortical bone particles were implanted to repair the bone defects within 4 hours after modeling in groups A, B, and C, respectively; and the plate and screws were fixed outside the bone defects. The dogs were not treated in group D, as normal control. At 5 months after operation, all animals were sacrificed and the tibial specimens were harvested and observed visually. The destructive axial compression experiments were carried out by the biomechanical testing machine. The displacement and the maximum failure load were recorded and the axial stiffness was calculated. All animals stayed alive after operation, and all incisions healed. After 1-3 days of operation, the animals could stand and move, and no obvious limb deformity was found. The articular surfaces of the tibial plateau specimens were completely smooth at 5 months after operation. No obvious articular surface collapse was observed. The displacement and maximum failure load of specimens in groups A and D were significantly higher than those in groups B and C ( P<0.05). But no significant difference was found between groups A and D and between groups B and C ( P>0.05). The nickel-titanium three-dimensional memory alloy mesh combined with autologous bone for subarticular bone defect of tibial plateau in dogs has good biomechanical properties at 5 months after operation, and has better axial stiffness when compared with the artificial bone and autologous bone graft.