Fixation Of Bone Fractures Research Articles

Enhanced Degradability of Thiol-Ene Composites through the Inclusion of Isosorbide-Based Polycarbonates.

Open reduction internal fixation metal plates and screws remain the established standard-of-care for complex fracture fixation. They, however, have drawbacks such as limited customization, soft-tissue adhesions, and a lack of degradation. Bone cements and composites are being developed as alternative fixation techniques in order to overcome these issues. One such composite is a strong, stiff, and shapeable hydroxyapatite-containing material consisting of 1,3,5-triazine-2,4,6-trione (TATO) monomers, which cures through high energy visible light-induced thiol-ene coupling (TEC) chemistry. Previous human cadaver and in vivo studies have shown that patches of this composite provide sufficient fixation for healing bone fractures; however, the composite lacks degradability. To promote degradation through hydrolysis, new allyl-functionalized isosorbide-based polycarbonates have been added into the composite formulation, and their impact has been evaluated. Three polycarbonates with allyl functionalities, located at the termini (aPC1 and aPC2) or in the backbone (aPC3), were synthesized. Composites containing 1, 3, and 5 wt % of aPCs 1-3 were formulated and evaluated with regard to mechanical properties, water absorption, hydrolytic degradation, and cytotoxicity. Allyl-functionalized polycaprolactone (aPCL) was synthesized and used as a comparison. When integrated into the composite, aPC3 significantly impacted the material's properties, with the 5 wt % aPC3 formulation showing a significant increase in degradation of 469%, relative to the formulation not containing any aPCs after 8 weeks' immersion in PBS, along with a modest decrease in modulus of 28% to 4.01 (0.3) GPa. Osteosyntheses combining the aPC3 3 and 5 wt % formulations with screws on synthetic bones with ostectomies matched or outperformed the ones made with the previously studied neat composite with regard to bending stiffness and strength in four-point monotonic bending before and after immersion in PBS. The favorable mechanical properties, increased degradation, and nontoxic characteristics of the materials present aPC3 as a promising additive for the TATO composite formulations. This combination resulted in stiff composites with long-term degradation that are suitable for bone fracture repair.

PRECICE nail bending in femur lengthening

IntroIntramedullary nails (ILNs) are commonly used in orthopedic surgery for the fixation of long bone fractures and limb lengthening. Understanding the structural mechanics (i.e. nail bend) of an ILN device is crucial in determining its performance under various loading conditions. Furthermore, nail diameter was found to play a key role in an ILN's susceptibility to plastic deformity. This study aims to investigate the degree of nail bending and incidence of plastic deformity in patients receiving antegrade femoral ILNs (PRECICE, NuVasive, Inc.). MethodsRetrospectively evaluated 130 ILNs (PRECICE, NuVasive, Inc.) in 100 adult patients who underwent limb lengthening done in a single center. Patients who had concomitant osteotomies, tibial lengthening, malunion, non-union, mechanical failure, or revision surgery for any reason were excluded. All nails were inserted through the greater trochanter or piriformis. Patients’ age, weight, height, and body mass index (BMI)were extracted. Radiologic assessments involved analyzing long lower limb standing X-rays before, during, and at consolidation for total distraction and nail bend. Naildiameter and patient characteristics were directly sourced from medical records. ResultsNail bend at consolidation averaged 2.4° (SD 2.4), ranging from 0 to 9. Additionally, total femoral lengthening was assessed, with a mean value of 5.3 cm (SD 2.1). A significant positive association was observed in the nail bend and weight (weight in kg/nail diameter in mm) coefficient (P < 00.01). Bilateral limb lengthening was also correlated to increase nail bend (P < 00.05). ConclusionPatient's weight to nail diameter ratio and bilateral limb lengthening were found to be significant factors affecting nail bend. These findings advance our understanding of the interrelation between the nail biomechanical profile and the patient's physical attributes, offering important implications for limb lengthening. Level of evidenceIII.

Fat Embolism Syndrome: A Rare Case Report

Background: Fat embolism syndrome (FES) is a life-threatening complication in patients with orthopedic trauma, especially long bone fractures. The diagnosis of fat embolism is made by clinical features alone with no specific laboratory findings. FES has no specific treatment and requires supportive care, although it can be prevented by early fixation of bone fractures. Here, we report a case of FES in a patient with a right closed femoral fractrure severe comminutive, which was diagnosed initially by Gurd’s criteria and subsequently confirmed by typical appearances on Magnetic Resonance Imaging (MRI) of the brain. The most important for fat embolism syndrome management is divided two-fold: preventative and supportive. Patient: A 43-year-old male fell from a high-rise building approximately 3 days before admission. A deformity was observed on the right thigh and the patient felt intense pain. After a few hours, the patient became weak and experienced a loss of consciousness. He was diagnosed with Fat Embolism Syndrome (FES) by using Gurd’s criteria. The diagnosis was confirmed after excluding other diagnoses with similar clinical presentation.

Costs of fracture-related infection: the impact on direct hospital costs and healthcare utilisation

PurposeFracture-Related Infection (FRI) is associated with high medical costs and prolonged healthcare utilization. However, limited data is available on the financial impact. The purpose of this study was to investigate the impact of FRI on direct hospital costs and healthcare utilization.MethodsThis was a retrospective cohort study in a level-1 trauma centre in the Netherlands. Patients ≥ 18 years, after open reduction and internal fixation of a long bone fracture between January 1st 2016 and November 1st 2021, were included. Exclusion criteria were Injury Severity Score (ISS) ≥ 16, indefinable data on costs or incomplete follow-up. Hospital costs related to fracture treatment were individually calculated based on procedure codes raised with a fixed percentage of overhead expenses, in line with hospital billing policies.ResultsIn total, 246 patients were included with a median follow-up of 1 year (IQR 0.6–1.8). A total of 45 patients developed FRI, of whom 15 patients had an FRI recurrence. Compared to non-FRI patients, median hospital costs from an FRI patient without and with recurrence, were respectively three (3.1) and seven (7.6) times higher. Compared to non-FRI patients, increased costs in patients with FRI or recurrent FRI are due to respectively a fivefold or even tenfold prolonged length-of-stay, two or seven additional infection-related surgeries, and 21 or 55 days of intravenous antibiotic treatment.ConclusionDirect healthcare costs of patients with single occurrence of FRI after long bone fracture treatment are three times higher compared to non-FRI patients. In case of FRI-recurrence, the differences in costs might even increase to sevenfold. To put this in perspective, cost of severely injured trauma patients were recently established at approximately 25.000 euros. Compared to non-FRI patients, increased costs in patients with FRI or recurrent FRI are due to respectively a fivefold or even tenfold prolonged length-of-stay, two or seven additional infection-related surgeries and 21 or 55 days of intravenous antibiotic treatment. Not only from patient perspective but also from a financial aspect, it is important to focus on prevention of (recurrent) FRI.

Essential surgery delivery in the Northern Kivu Province of the Democratic Republic of the Congo

IntroductionSurgical services are an essential part of a functional healthcare system, but the Lancet Commission of Global Surgery (LCoGS) indicators of surgical capacity such as perioperative workforce and surgical volume are unknown in many low- and middle-income countries (LMICs) including the Democratic Republic of Congo (DRC). We aimed to determine the surgical capacity and its associated factors within the DRC.MethodsHospitals were assessed in the North Kivu province of the DRC. Hospital characteristics and surgical rates were determined using the WHO-PGSSC hospital assessment tool and operating room (OR) registries. The primary outcome of interest was the number of Bellwether operations (i.e. Caesarean sections, laparotomies, and external fixation for bone fractures) per 100,000 people. Univariate and multiple linear regressions were performed. Primary predictors were the number of trained surgeons, anaesthesiologists, and obstetricians (SAOs) and the number of perioperative providers (including clinical officers and nurse anaesthetists) per 100,000 people.ResultsTwenty-eight hospitals in North Kivu were assessed over one year in 2021; 24 (86%) were first-level referral health centres while 4 (14%) were second-level referral hospitals. In total, 11,176 Bellwether procedures were performed in the region in one year. Rates per 100,000 people were 1,461 Bellwether surgical interventions, 1.05 SAOs, and 13.1 perioperative providers. In univariate linear regression analysis, each additional SAO added 239 additional cases annually (p = 0.023), while each additional perioperative provider added 110 cases annually (p < 0.001). In our multiple regression analysis adjusting for other hospital services, the association between workforce and Bellwether surgeries was no longer significant.ConclusionsThe surgical workforce in DRC did not meet the LCoGS benchmark of 20 SAOs per 100,000 people but was not an independent predictor of surgical capacity. Major investment is needed to simultaneously bolster healthcare facilities and increase surgical workforce training.

Mechanics of dynamic compression plate application in fracture fixation

BackgroundDynamic compression plating is a fundamental type of bone fracture fixation used to generate interfragmentary compression. The goal of this study was to investigate the mechanics of the surgical application of these plates, specifically how plate prebend, screw location, fracture gap, and applied torque influence the resulting compressive pressures. MethodsSynthetic bones with transverse fractures were fixed with locking compression plates. One side of the fracture was fixed with locking screws. On the other side of the fracture, a nonlocking screw was inserted eccentrically to induce interfragmentary compression. A pressure mapping sensor within the fracture gap was used to record the resulting pressure distribution. Plate prebends of 0 mm, 1.5 mm, and 3 mm were tested. Three locations of the eccentric screw, four levels of screw torque, and two initial fracture gap conditions also were tested. FindingsWith increasing plate prebend, fracture compression pressures shifted significantly toward the far cortex; however, compression force decreased (P < 0.05). The 1.5 mm prebend plate resulted in the greatest contact area. Increasing screw torque generally resulted in greater fracture compression force. The introduction of a 1 mm fracture gap at the far cortex prior to dynamic compression resulted in little or no fracture compression. InterpretationThe model showed that increasing plate prebend results in an increasing shift of fracture compression pressures toward the far cortex; however, this is accompanied by decreases in compressive force. Initial fracture gaps at the far cortex can result in little or no compression.

Cochrane in CORR ®: Pharmacological Interventions for the Prevention of Bleeding in People Undergoing Definitive Fixation or Joint Replacement for Hip, Pelvic and Long Bone Fractures.

Cochrane in CORR ®: Pharmacological Interventions for the Prevention of Bleeding in People Undergoing Definitive Fixation or Joint Replacement for Hip, Pelvic and Long Bone Fractures.

Pull-out strength of screws in long bones at different insertion angles: finite element analysis and experimental investigations

Abstract Different types of plates are available to allow insertion of screws for internal fixation of long bone fractures. The aim of the study was to determine the effect of the insertion of screws at different angles on a long bone to the pull-out strength. Using 3D printed bone models, we tested the pull-out strength of screws in long bones at insertion angles between 0 and 40° with both finite element analysis and on printed models experimentally and compared the results. Test samples and cortical screws used were modeled with SolidWorks software and analyzed with Ansys software. As the screw insertion angle increases, the pull-out forces on the test specimens increase from 61.14 ± 3.5 N at 0° to 273 ± 6.8 N at 40° with an exception of a small drop between 15 and 20° from 235.4 ± 6.2 to 233 ± 6.9 N. Both methods showed an increase in the pull-out strength of screws as the insertion angle increases. This might be applicable in the clinical practice of bone fixation. Further studies on plate and screw fixation are needed to complement the findings.

Biodegradable Zn-5Dy Alloy with Enhanced Osteo/Angio-Genic Activity and Osteointegration Effect via Regulation of SIRT4-Dependent Mitochondrial Function.

Zinc (Zn)-dysprosium (Dy) binary alloys are promising biodegradable bone fracture fixation implants owing to their attractive biodegradability and mechanical properties. However, their clinical application is a challenge for bone fracture healing, due to the lack of Zn-Dy alloys with tailored proper bio-mechanical and osteointegration properties for bone regeneration. A Zn-5Dy alloy with high strength and ductility and a degradation rate aligned with the bone remodeling cycle is developed. Here, mechanical stability is further confirmed, proving that Zn-5Dy alloy can resist aging in the degradation process, thus meeting the mechanical requirements of fracture fixation. In vitro cellular experiments reveal that the Zn-5Dy alloy enhances osteogenesis and angiogenesis by elevating SIRT4-mediated mitochondrial function. In vivo Micro-CT, SEM-EDS, and immunohistochemistry analyses further indicate good biosafety, suitable biodegradation rate, and great osteointegration of Zn-5Dy alloy during bone healing, which also depends on the upregulation of SIRT4-mediated mitochondrial events. Overall, the study is the first to report a Zn-5Dy alloy that exerts remarkable osteointegration properties and has a strong potential to promote bone healing. Furthermore, the results highlight the importance of mitochondrial modulation and shall guide the future development of mitochondria-targeting materials in enhancing bone fracture healing.

Fatigue Strength of Drilled Glass Fiber/Epoxy Laminates for Bone Fracture Fixation

The metallic bone fracture fixation plates are progressively being replaced by epoxy-reinforced glass fiber laminates (ERGFL) due to a higher strength-to-weight ratio. Bone fracture fixation laminates are required to sustain the cyclic load due to the physical movement of the body. Therefore, the characterizations of glass fiber/epoxy laminates with drilled holes are mandatory to be studied in full. It was already established by the investigator that the drilling process in laminates created damage around the drilled hole and the drilled damage influences the tensile strength of laminates. The present investigation aims to study the fatigue strength of ERGFL with drilled holes.

Antibacterial Immunonegative Coating with Biocompatible Materials on a Nanostructured Titanium Plate for Orthopedic Bone Fracture Surgery.

Periprosthetic infections resulting from bacterial biofilm formation following surgical bone fracture fixation present important clinical challenges. Conventional orthopedic implant materials, such as titanium, are prone to biofilm formation. This study introduces a novel surface for orthopedic titanium plates, optimized for clinical application in human bone fractures. Leveraging nanostructure-based surface coating technology, the plate achieves an antibacterial/immunonegative surface using biocompatible materials, including poloxamer 407, epigallocatechin gallate, and octanoic acid. These materials demonstrate high biocompatibility and thermal stability after autoclaving. The developed plate, named antibacterial immunonegative surface, releases antibacterial agents and prevents adhesion between human tissue and metal surfaces. Antibacterial immunonegative surface plates exhibit low cell toxicity, robust antibacterial effects against pathogens such as Staphylococcus aureus and Pseudomonas aeruginosa, high resistance to biofilm formation on the implant surface and surrounding tissues, and minimal immune reaction in a rabbit femoral fracture model. This innovation holds promise for addressing periprosthetic infections and improving the performance of orthopedic implants.

Augmenting locking plate with autologous bone graft for the treatment of nonunion of long bone fracture in the lower extremity with retaining of the original intramedullary nail

To explore clinical effect of attaching locking plate with bone grafting based on retaining the original intramedullary nail in treating non-union after intramedullary nail fixation of long shaft fractures of lower limbs. A retrospective study was conducted on 20 patients treated with non-union fractures after intramedullary nailing of long shaft fractures of lower limbs from June 2015 to June 2020. All patients were treated with the original intramedullary nailing and bone grafting from the iliac bone, and were underwent open reduction plate internal fixation and bone grafting for old fractures. Among them, 14 were males and 6 were females, aged from 35 to 56 years old with an average of (42.2±9.6) years old. Nine patients were femoral shaft fracture and 11 patients were tibial shaft fracture. According to characteristics of fracture end nonunion, 6 patients were stable/atrophic, 9 patients were unstable/large, and 5 patients were unstable/atrophic. The nonunion time ranged from 8 to 12 months with an average of(9.8±2.0) months after the initial surgery. Visual analogue scale (VAS), knee range of motion, bone healing time, complications and fracture-end healing were recorded before and at the latest follow-up. All patients were followed up for 18 to 48 months with an average of (36.3±10.5) months. The incision of all patients were healed at stageⅠwithout complications such as infection or internal fixation ruptur. Healing time of femur and tibia was (8.5±2.6) months and (9.5±2.2) months. Knee joint motion increased from preoperative (101.05±8.98) ° to postoperative (139.35±8.78) ° at the latest follow-up (t=-12.845, P<0.001). VAS decreased from preoperative (5.15±1.72) to postoperative (0.75±0.96) at the latest follow-up (t=11.186, P<0.001). On the basis of retaining the original intramedullary nail, the addition of locking plate internal fixation and autogenous iliac bone grafting have advantages of simple operation, less trauma, fewer complications and high fracture healing rate. It is one of the effective surgical schemes for the treatment of nonunion after intramedullary nail fixation of long bone fracture of lower extremity.

SIGNIFICANCE OF CHOOSING FIXATORS FOR OSTEOSYNTHESIS IN THE TREATMENT OF PATIENTS WITH FRACTURES OF PROXIMAL FEMORAL PART

Introduction. Fracture of the proximal part of the femur is one of the most common and most life-threatening injuries in the elderly patients. At the current stage, the surgical method has taken the leading place in the treatment of these patients. The growing number of surgical interventions, along with the increase in the elderly population globally, has led to a corresponding increase in the number of complications related to both the biological and mechanical properties of the fixator used. The optimal location of the fixing elements in relation to the center and edge of the femoral head, the value of the cervical-diaphyseal angle, and the technical characteristics of the implants remains a relevant issue today.&#x0D; The purpose of this study was to analyze the cause of complications after surgical treatment in patients with fractures of the femoral proximal part taking into account the biomechanical properties of the fixators.&#x0D; Material and methods. Staged results of surgical treatment of 60 patients with fractures of the proximal part of the thigh, who were hospitalized due to complications related to imperfect mechanical fixation of bone fractures, were studied. Patients were divided into 2 groups depending on the type of fixator used.&#x0D; Results. Migration of fixators with a low level of stability occurs even with the initial correct placement of the implant. Notably, a relatively higher frequency of migration occurred when the fixator was applied to the left limb (23:37). Analysis of immediate post-implantation frontal and axial radiographs revealed that, in all instances of medial migration (cutout effect) and lateral migration (outout effect), the Tip-Apex Distance exceeded 25 mm. The positioning of the cervical component of the fixator did not align with its optimal placement as per the Cleveland zones in 84.6% of cases. A notable incidence of complications in extramedullary osteosynthesis was diagnosed during the early postoperative period. This observation may be attributed to an imperfect plan of the staged rehabilitation functional regime.&#x0D; Conclusions. The use of fixators with a low level of stability does not provide high-quality prediction of the course of the postoperative period in patients with femoral proximal fractures. Placing implants for osteosynthesis of the femoral proximal part should ensure reliable fixation of fragments for successful postoperative rehabilitation by taking into account the number of fixators and the features of their location in the proximal fragment of the fracture.

On the importance of accurate elasto-plastic material properties in simulating plate osteosynthesis failure.

Background: Plate osteosynthesis is a widely used technique for bone fracture fixation; however, complications such as plate bending remain a significant clinical concern. A better understanding of the failure mechanisms behind plate osteosynthesis is crucial for improving treatment outcomes. This study aimed to develop finite element (FE) models to predict plate bending failure and validate these against in vitro experiments using literature-based and experimentally determined implant material properties. Methods: Plate fixations of seven cadaveric tibia shaft fractures were tested to failure in a biomechanical setup with various implant configurations. FE models of the bone-implant constructs were developed from computed tomography (CT) scans. Elasto-plastic implant material properties were assigned using either literature data or the experimentally derived data. The predictive capability of these two FE modelling approaches was assessed based on the experimental ground truth. Results: The FE simulations provided quantitatively correct prediction of the in vitro cadaveric experiments in terms of construct stiffness [concordance correlation coefficient (CCC) = 0.97, standard error of estimate (SEE) = 23.66, relative standard error (RSE) = 10.3%], yield load (CCC = 0.97, SEE = 41.21N, RSE = 7.7%), and maximum force (CCC = 0.96, SEE = 35.04, RSE = 9.3%), when including the experimentally determined material properties. Literature-based properties led to inferior accuracies for both stiffness (CCC = 0.92, SEE = 27.62, RSE = 19.6%), yield load (CCC = 0.83, SEE = 46.53N, RSE = 21.4%), and maximum force (CCC = 0.86, SEE = 57.71, RSE = 14.4%). Conclusion: The validated FE model allows for accurate prediction of plate osteosynthesis construct behaviour beyond the elastic regime but only when using experimentally determined implant material properties. Literature-based material properties led to inferior predictability. These validated models have the potential to be utilized for assessing the loads leading to plastic deformation in vivo, as well as aiding in preoperative planning and postoperative rehabilitation protocols.

Multi-objective property optimisation of a phosphoserine-modified calcium phosphate cement for orthopaedic and dental applications using design of experiments methodology

Phosphoserine is a ubiquitous molecule found in numerous proteins and, when combined with alpha-tricalcium phosphate (α-TCP) powder, demonstrates the ability to generate an adhesive biomaterial capable of stabilising and repairing bone fractures. Design of Experiments (DoE) approach was able to optimise the composition of phosphoserine-modified calcium phosphate cement (PM-CPC) demonstrating that the liquid:powder ratio (LPR) and quantity of phosphoserine (wt%) significantly influenced the handling, mechanical, and adhesion properties. Subsequently, the DoE optimisation process identified the optimal PM-CPC formulation, exhibiting a compressive strength of 29.2 ± 4.9 MPa and bond/shear strength of 3.6 ± 0.9 MPa after a 24 h setting reaction. Moreover, the optimal PM-CPC composition necessitated a mixing time of 20 s and displayed an initial setting time between 3 and 4 min, thus enabling homogenous mixing and precise delivery within a surgical environment. Notably, the PM-CPC demonstrated a bone-to-bone bond strength of 1.05 ± 0.3 MPa under wet conditions, coupled with a slow degradation rate during the first five days. These findings highlight the ability of PM-CPC to effectively support and stabilise bone fragments during the initial stages of natural bone healing. The developed PM-CPC formulations fulfil the clinical requirements for working and setting times, static mechanical, degradation properties, and injectability, enabling surgeons to stabilise complex bone fractures. This innovative bioinspired adhesive represents a significant advancement in the treatment of challenging bone injuries, offering precise delivery within a surgical environment and the potential to enhance patient outcomes. Statement of significanceThis manuscript presents a noteworthy contribution to the field of bone fracture healing and fixation by introducing a novel phosphoserine-modified calcium phosphate cement (PM-CPC) adhesive by incorporating phosphoserine and alpha-TCP. This study demonstrates the fabrication and extensive characterisation of this adhesive biomaterial that holds great promise for stabilising and repairing complex bone fractures. Design of Experiment (DoE) software was used to investigate the correlations between process, property, and structure of the adhesive, resulting in a cost-effective formulation with desirable physical and handling properties. The PM-CPC adhesive exhibited excellent adhesion and cohesion properties in wet-field conditions. This research offers significant potential for clinical translation and contributes to the ongoing advancements in bone tissue engineering.

Preoperative Risk Factors and Postoperative Complications of COVID-Positive Children Requiring Urgent or Emergent Surgical Care

BackgroundPreoperative COVID-19 testing protocols were widely implemented for children requiring surgery, leading to increased resource consumption and many delayed or canceled operations or procedures. This study using multi-center data investigated the relationship between preoperative risk factors, COVID-positivity, and postoperative outcomes among children undergoing common urgent and emergent procedures. MethodsChildren (<18 years) who underwent common urgent and emergent procedures were identified in the 2021 National Surgical Quality Improvement Program Pediatric database. The outcomes of COVID-positive and non-COVID-positive (negative or untested) children were compared using simple and multivariable regression models. ResultsAmong 40,628 children undergoing gastrointestinal surgery (appendectomy, cholecystectomy), long bone fracture fixation, cerebrospinal fluid shunt procedures, gonadal procedures (testicular detorsion, ovarian procedures), and pyloromyotomy, 576 (1.4%) were COVID-positive. COVID-positive children had higher American Society of Anesthesiologists scores (p ≤ 0.001) and more frequently had preoperative sepsis (p ≤ 0.016) compared to non-COVID-positive children; however, other preoperative risk factors, including comorbidities, were largely similar. COVID-positive children had a longer length of stay than non-COVID-positive children (median 1.0 [IQR 0.0–2.0] vs. 1.0 [IQR 0.0–1.0], p < 0.001). However, there were no associations between COVID-19 positivity and overall complications, pulmonary complications, infectious complications, or readmissions. ConclusionsDespite increased preoperative risk factors, COVID-positive children did not have an increased risk of postoperative complications after common urgent and emergent procedures. However, length of stay was greater for COVID-positive children, likely due to delays in surgery related to COVID-19 protocols. These findings may be applicable to future preoperative testing and surgical timing guidelines related to respiratory viral illnesses in children. Level of EvidenceIII.

A novel degradable PCL/PLLA strapping band for internal fixation of fracture

Early fracture fixation is the critical factor in fracture healing. Common internal fracture implants are made of metallic materials, which often affects the imaging quality of CT and MRI. Most patients will choose secondary surgery to remove the internal fixation implants, which causes secondary damage to them. The development of new degradable internal fracture implants has attracted more and more attention from orthopedic surgeons and researchers. Based on these problems, we improved the various properties of medical grade polycaprolactone (PCL) by adding poly(L-lactide) (PLLA). We produced PCL/PLLA strapping bands with different mass ratios by injection molding. We compared the mechanical properties, degradation properties, cell biocompatibility, bone marrow mesenchymal stem cells (BMSCs) adhesion, proliferation, osteogenic differentiation and fracture fixation effect of these strapping bands. The results showed that the tensile strength and yield force of the strapping bands increased with the increase of the content of PLLA. The addition of PLLA could significantly improve the mechanical strength in the early stage and accelerate the degradation rate of the strapping band. PCL/PLLA (80/20) strapping band had no significant cytotoxicity toward rBMSCs and could promote osteogenic differentiation of rBMSCs. The strapping band could ensure femoral fracture healing of beagles in 3 months and didn’t cause damage to the surrounding tissues and main organs. This study will provide some new insights into the biodegradable products of PCL/PLLA blends for internal fixation of fracture.Graphical We produced novel degradable PCL/PLLA strapping bands with different mass ratios by injection molding. We tested the biological safety of the prepared internal fixation strapping bands for fracture, such as cell experiment in vitro and animal experiment, and studied the degradation behavior in vitro. The strapping bands could ensure femoral fracture healing of beagles. This study will provide some new insights into the biodegradable products of PCL/PLLA blends for internal fixation of fracture. A Immunofluorescence staining of rBMSCs (live cells: green; dead cells: red). B Young’s modulus change curve during strapping bands degradation. C The implantation process of strapping bands. D Micro-CT images of the beagle’s fracture recovery after the operation.

On Possibility of Application of COMSOL Multiphysics Software for Topological Optimization of Osteosynthesis Plates

Тhe paper describes a technique of topological optimization of osteosynthesis plates used for internal fixation of bone fractures. The proposed technique is based on the application of the density method and the commercially available COMSOL Multiphysics software intended for finite element modeling. A comparative analysis of the characteristics (axial stiffness, volume and maximum von Mises stress) is presented for initial design of the plate and two optimized variants of the design. It has been established that the optimized variants provide a reduction in the plate volume by 49–54 %. In this case, the axial stiffness decreases by 43–53 %, which is a positive effect in terms of minimizing the effect of stress shielding. The optimized variants of the design possess close values of axial stiffness and maximum von Mises stress, however, in one of them, deflection of the axial segments occurs, resulting in an increase in the total strain energy, which is used as an objective function during optimization. In the variant 2 of the design, the deflection of the longitudinal segments of the plate is eliminated due to the presence of a transverse bridge between them, and the total strain energy takes on a lower value. The variant of the design without a bridge should be additionally studied, since shear stresses resulting from the contact interaction of the longitudinal segments of the plate with the bone can have a positive effect on regeneration of the bone tissue.

Are Absorbable Plates More Resistant to Infection Than Titanium Implants? An Experimental Pre-Clinical Trial in Rabbits.

Background: Infection of orthopaedic implants after internal fixation of bone fractures remains a major complication with occasionally devastating consequences. Recent studies have reported that the use of absorbable materials, instead of metallic ones, may lead to a lower incidence of postoperative infection. In this experimental pre-clinical animal study, we compared the infection rate between absorbable implants consisting of copolymers composed from trimethylene carbonate, L-polylactic acid, and D, L-polylactic acid monomers, and titanium implants after the inoculation of a pathogenic microorganism. Material and Methods: We used an experimental implant-related infection model in rabbits. Sixty animals were randomly and equally divided into two groups. In all animals, the right femur was exposed via a lateral approach and a 2.5 mm two-hole titanium plate with screws (Group A), or a two-hole absorbable plate and screws (Group B), were applied in the femoral shaft. Afterwards, the implant surface was inoculated with Pseudomonas Aeruginosa at a concentration of 2 × 108 CFU/mL. The primary outcome was the comparison of the incidence of developed infection between the two groups. The wound condition was monitored on a daily basis and radiographies were obtained at 12 weeks postoperatively. Infection-related laboratory markers (white blood cell count, erythrocyte sedimentation rate, and C-reactive protein values) were assessed at 3, 6, and 16 weeks postoperatively. Histologic analysis and cultures of tissue samples were also performed to evaluate the presence of infection. Results: Clinical and laboratory signs of infection were evident in 11 rabbits in Group A (36.7%), and 4 in Group B (13.3%). The difference between the groups was statistically significant (p = 0.04). Five animals in Group B (16.7%) had clinical and histologic signs of a foreign-body reaction with significantly elevated CRP and ESR values but no simultaneous presence of infection was identified (p = 0.04). Bone remodelling with thickening of the periosteum and surrounding sclerosis was demonstrated radiologically in animals developing infection or foreign-body reactions. Conclusions: Absorbable plates and screws show lower susceptibility to infection compared to titanium ones. However, their application is associated with foreign-body reaction and the potential need for a second surgical intervention.

Topography and indexing of the nutrient foramina of the adult long bones

The primary source of blood supply for long bones comes from the nutrient arteries that pass through the nutrient foramen. Understanding the location and structure of these foramens is important in surgical procedures to ensure that the bone’s blood supply is not disrupted. To study the morphology and topography of nutrient foramina and to determine the foraminal index of the upper and lower limb long bones. The long bones of the upper and lower limbs including 47 humeri, 38 radii, 38 ulnae, 53 femurs, 57 tibiae, and 44 fibulae were studied. The number and position of primary nutrient foramina were noted and the foraminal index was calculated. Results showed that 82.9% of the humeri had a single nutrient foramen, and 17.0% had double foramina. For the radii, 97.4% had single nutrient foramen and 2.6% had double foramina. A single nutrient foramen was observed in all the ulnae. In the lower limb bone, the femurs had 41.5% of single nutrient foramen, 56.6% had double foramina and only 1.9% had triple nutrient foramina. The tibiae showed 93.0% of the single nutrient foramen and only 7.0% had double foramen. In fibulae, only one nutrient foramen was seen. The mean foraminal index was 57.26 for the humerus, 34.82 for the radius, and 39.32 for the ulna. Similarly, the mean foraminal index of the femur was 44.73, the tibia was 32.32 and the ulna was 46.18. Understanding the location of foramina is crucial inmaintaining bone vasculature during surgical procedures, which can improve the success rates of bone grafting, fracture fixation, and replacement surgeries involving the shoulder, elbow, and knee joints.