Orthopedic Screws Research Articles

Direct detection of microorganisms in sonicated orthopedic devices after in vitro biofilm production and different processing conditions.

The gold standard for microbial detection in prosthetic joint infections is the multiple culture of the peri-prosthetic tissue. The fluid cultures after sonication can improve the recovery of the microorganisms. The aim of this study was to evaluate the sonication technique with a plastic bag and the effect of refrigeration on microorganism detection with conventional culturing, MALDI-TOF MS and qPCR assay on an orthopedic screw model. We produced biofilms of Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans on orthopedic screws, which were stored under different conditions and temperatures before sonication. After sonication, the mass spectrometry by MALDI-TOF, qPCR and culture protocols was performed using the sonicated fluid, for detecting the microorganisms involved in the biofilm. The bacterial bioburden decreased by approximately one log after the refrigeration period, in the screws containing P. aeruginosa and S. aureus biofilms. All the microorganisms involved in the screw biofilms were detected with MALDI-TOF and qPCR. Significant reductions in CFU counts occurred only in groups stored in the plastic bag, indicating that changes in temperature and humidity may favor cell death. However, this variation is not important for this model as it did not affect the detection owing to the high counts obtained. Microbial identification by MALDI-TOF in sonicated fluid is feasible. With qPCR, there were no differences between the detection in the screws processed immediately or after refrigeration. It is necessary to consider whether or not the refrigeration period would affect microbial recovery in an explanted prosthesis.

Recent advances on the antibacterial coating on titanium implant by micro-Arc oxidation process

Titanium (Ti) and its alloy are widely used for artificial joints, dental implantations, orthopedic and bone screws because of their good biocompatibility, magnificent mechanical properties, and great corrosion resistance. As the Ti is bioinert and lacking antibacterial properties, which impact the use of such materials in the field of biomedical applications. When microorganisms attached to the surface of biomaterials it will start the implant related infection, which is a serious clinical issue. Infection frequently begins with bacterial attachment to the implant surface, after that colonization of bacteria started on the implant surface, once the colonization increases to larger extent it forms the biofilm. Once biofilm form, it becomes remarkably impervious to antibiotics and the host immunity defensive system to eliminate the biofilm from implant surface which prompting further complexities. The counteraction of biofilm development by antimicrobial surfaces is the most ideal approach to avoid both the spread of microorganisms and material decay. Antibacterial coating on implant surface is a convincing method to decrease the event of implant related infections. Among available methods micro arc oxidation (MAO) is profoundly reasonable for the development of bioactive and antibacterial coatings on titanium implant. In this paper antibacterial mechanism some of nanoparticles such as Zn, Ag, Cu, and AgO when incorporated in MAO coating is discussed. It was observed that antibacterial activity of silver nanoparticles is due to combination of contact killing and release of Ag nanoparticles, as well as the arrival of Ag+ ions from the coating surface to the electrolyte solutions. Zn coating can restrain bacterial development by producing responsive oxygen species (ROS). ROS is bacteria harmful species. In Cu nanoparticles incorporated antibacterial coating, bacteria absorbed Cu ions and resulted into the formation of cavities in the cell wall of bacteria through interaction with Cu ions.

822. Structural Damage and Biofilm Accumulation on Patient-Ready Orthopaedic Implant (Least Used Cortical Screws), Acquired through Loaner System

BackgroundThe acquisition of reusable medical devices through loaner system is a worldwide phenomenon. Single-use implants, such as orthopaedic screws, that remain in the surgical tray are subjected to multiple handling and reprocessing until they are implanted. Exposure to physical, chemical and biological agents may compromise their quality/safety and favor biofilm formation. The aim of this study was to assess the surface integrity and microbiological conditions of patient-ready orthopaedic surgical implants (least used cortical screws), provided through loaner system.MethodsAfter full reprocessing, clinical trays used for small fragment surgery (3,5) provided through loaner system to a large Brazilian teaching hospital were randomly selected between August to November 2019. Trays were opened in a biological safety cabinet and the least frequently used cortical screws (numbers 10 and 38), therefore, the ones most exposed to biological, chemical and physical agents, were randomly removed and subjected to bacterial culture (n = 3 screws/tray, 9 trays) and Scanning Electron Microscopy (SEM) (n= 1 screw/tray, 5 trays). The 27 screws were individually cultured in Tryptic Soy Broth (TSB), sonicated and vortexed, and incubated at 35oC for up to 28 days (screws were left in TSB). Positive cultures were plate out for automated bacteria identification.ResultsBacterial growth was identified in 2/27 screws. Three bacterial species were isolated, Staphylococcus hominis resistant to rifampicin and Kocuria rhizophila (screw A), and Micrococcus luteus (Screw B). Structural damage and soil were visualized on all screws subjected to SEM (5/5). Extensive biofilms were detected on three screws (3/5) (Figure 1).Figure 1. Scanning electron micrographs of patient-ready orthopaedic implants (screws), acquired through loaner system showing extensive biofilm, with incorporated bacilli/rods and/or cocci shape bacteria. ConclusionRecovery of bacteria, biofilm accumulation and structural damage were detected on patient-ready least frequently used orthopaedic cortical screws. Screws frequently remain in surgical trays for multiple reprocessing, thus, they are repeatedly exposed to contamination and possible damage. These findings point to the need to discuss and review the way these single-use implants are currently made available for surgery.Disclosures All Authors: No reported disclosures

A simple and inexpensive method for evaluation of in vitro cell adhesion on screws.

Only a limited number of techniques are available for assessing the effect of different coating materials on cell adherence to screws. In this study, we describe a simple and inexpensive method for evaluation of cell adhesion on irregular surfaces such as the surgical or implant screws. For this purpose, we prepared semi-submerged screws in the petri dishes using agar. Using BSA- or HA-coated screws, we tested whether BSA or HA could improve cell adherence when used as coating materials. Agar-coated screws were used as internal control. Then the "ratio of cell adherence" was calculated by subtracting the reference RCA value obtained from the agar coated screws (internal control). When compared to that of the non-coated screws both the HA- and BSA-coating improved cell adherence on the screws by 2.34 and 2.72 fold respectively. Similarly, MTT assay data revealed that the metabolic capacities of cells on HA- or BSA-coated screws were improved by 2.36 and 2.86 fold respectively. These findings suggest that this protocol can be used for comparing the ability of cells to attach on irregular surfaces such as dental or orthopedic screws and assessing their viability.

SIMULATION OF THE MECHANICAL STIMULATION EFFECT ON THE PEN JUNCTION BETWEEN BONE AND PELVIC BASED ON FINITE ELEMENT METHODS

Bone remodeling process influenced by cells osteoblast and osteoclast. The remodeling of cortical and trabecular influenced by mechanical stimuli. In this study, cortical and trabecular bones of 25 years old humans were observed, and the result was the cortical bone has the average Young’s modulo 17.9 MPa with the Poisson’s ratio of 0.4. Trabecular bone has the average Young’s modulo of 13 MPa and the Poisson’s ratio of 0.5. The metal orthopedic bone screw, which has used in this research simulation, was is a Titanium screw. The screw has Young’s modulo of 110 GPa and the Poisson’s ratio of 0.29. The results of the simulation of femoral bone elasticity limit with standing activity at the age of 25 were found in the left femur of 112.9416 MPa and the right femur of 115.5134 MPa. The limit of elasticity of the femur due to walking was found in the left femur of 115.2166 MPa with an accuracy of 94.11% and the right femur of 117.6692 MPa.

A Dual-Motor Drill Reduces Plunge, Simultaneously Gauges Depth, and Saves Time When Placing Orthopedic Screws

The technique for placement of orthopedic hardware remains unchanged despite technological advances. The surgeon controls drill bit speed and advancement, which risks drill bit overpenetration, or plunge. Measurement is performed as an additional step, introducing measurement error and increasing operative time. A dual-motor drill was created to control drill variables and combine drilling and measurement into a single step. The purpose of this study was to determine whether a dual-motor drill could reduce drilling and measurement errors while increasing the speed of placement of orthopedic hardware. Five orthopedic surgeons drilled and measured 10 holes with a standard drill and a dual-motor drill in randomized bicortical bone blocks. The bone blocks were placed on standard ballistic gels, which left a defect from drill bit overpenetration that could be measured with a calibrated gauge. The accuracy of drilling was determined by the depth of the defect in the ballistic gel and was compared between groups. Finally, time for drilling and measurement was collected and compared between groups. Overpenetration for the dual-motor drill (0.5±0.3 mm) was significantly less than for the standard drill (8.4±1.9 mm) (P<.0001). Depth measurement error for the dual-motor drill (0.6±0.3 mm) was significantly less than for the standard drill (2.6±0.5 mm) (P<.0001). Drilling and measurement time for the dual-motor drill (6.0±2.2 seconds) was significantly less than for the standard drill (13.4±3.9 seconds) (P<.0001). Use of a dual-motor drill reduced overpenetration, improved measurement accuracy, and reduced time spent during placement of orthopedic hardware. [Orthopedics. 2020;43(5):e465-e470.].

An investigation of tensile strength of Ti6Al4V titanium screw inside femur bone using finite element and experimental tests

The geometric optimization of orthopedic screws can considerably increase their orthopedic efficiency. Due to the high geometric parameters of orthopedic screws, a finite element simulation is an effective tool for analyzing and forecasting the effect of the parameters on the load-bearing capacity of different types of screws and bones. Thus, in the present study, the tensile strength of a typical cortical titanium screw was investigated by the finite element method, and experimental tests confirmed the obtained results. The behavior of the screw in the tensile test was discussed in terms of stress, force, and displacement. The maximum force results show a 14% difference between simulation and experimental works in tensile type loading. Moreover, it was suggested that the trend of force curves in both the experimental test and numerical simulation shows high similarity, and FEM predicts the process with acceptable accuracy. Furthermore, it was concluded that the stress values are higher while moving toward the top surface of the bone.

Additive manufacturing of biodegradable porous orthopaedic screw

Advent of additive manufacturing in biomedical field has nurtured fabrication of complex, customizable and reproducible orthopaedic implants. Layer-by-layer deposition of biodegradable polymer employed in development of porous orthopaedic screws promises gradual dissolution and complete metabolic resorption thereby overcoming the limitations of conventional metallic screws. In the present study, screws with different pore sizes (916 × 918 μm to 254 × 146 μm) were 3D printed at 200 μm layer height by varying printing parameters such as print speed, fill density and travel speed to augment the bone ingrowth. Micro-CT analysis and scanning electron micrographs of screws with 45% fill density confirmed porous interconnections (40.1%) and optimal pore size (259 × 207 × 200 μm) without compromising the mechanical strength (24.58 ± 1.36 MPa). Due to the open pore structure, the 3D printed screws showed increased weight gain due to the deposition of calcium when incubated in simulated body fluid. Osteoblast-like cells attached on screw and infiltrated into the pores over 14 days of in vitro culture. Further, the screws also supported greater human mesenchymal stem cell adhesion, proliferation and mineralized matrix synthesis over a period of 21 days in vitro culture as compared to non-porous screws. These porous screws showed significantly increased vascularization in a rat subcutaneous implantation as compared to control screws. Porous screws produced by additive manufacturing may promote better osteointegration due to enhanced mineralization and vascularization.

Improvement of image quality and diagnostic confidence using Smart MAR - a projection-based CT protocol in patients with orthopedic metallic implants in hip, spine, and shoulder.

In computed tomography (CT) scans, artifacts caused by metallic orthopedic implants still hamper the visualization of important, periprosthetic tissues. Smart MAR metal artifact reduction tool is a promising three-stage, projection-based, post-processing algorithm. To determine whether the Smart MAR tool improves subjective and objective image quality and diagnostic confidence in patients with orthopedic implants of the hip, spine, and shoulder. Seventy-two patients with orthopedic screws, hip/shoulder replacement, or spine spondylodesis were included. CT scans were performed on a single-source multislice CT scanner, raw data were post-processed using Smart MAR. Image quality was evaluated both quantitatively (ROI-based) and qualitatively (rater-based) and compared to iterative reconstructions (ASIR V). As comparative standard for artificial prosthetic breaks or loosening, follow-up examinations were used. Smart MAR reconstructions of the hip (n = 23), spine (n = 26), and shoulder (n = 23) showed a significantly reduced attenuation and noise of regions adjacent to metallic implants (P<0.002). Subjective image quality (P<0.005, shoulder P = 0.038/P = 0.046) and overall diagnostic confidence were higher in Smart MAR (all regions P<0.002). Signal-to-noise ratio (SNR; P = 0.72/P = 0.96) was not improved. Compared to standard ASIR V new, artificial metal extinctions (up to 50%) or periprosthetic hem lines (48%-73%) were introduced by Smart MAR. Smart MAR improved image quality of the hip, spine, and shoulder CT scans resulting in higher diagnostic confidence in evaluation of periprosthetic soft tissues. As shown for spine implants, it should be used with caution and as a complementary tool for evaluation of periprosthetic loosening or integrity of metal implant, as in many cases it introduced new artifacts.

Assessment of the Mechanical Properties of Orthopedic Screws Coated with Polyurethane Acrylate Containing Hydroxyapatite, Intended to Fix the Fragility Fractures

The fragility fracture fixation confronts with the major problem of implant loosening due to the altered bone structure. Techniques used to fragility fracture stabilization includes metals devices, cements or adhesives. Different types of cements and adhesive can be obtained by chemical manipulation in order to provide a more efficient transition between the metal surface and the real bone. Thus, by selecting the appropriate chemical composition and ration between the components, synthetic cement and adhesive can provide a proper interface that ensure a perfect cohesion between the implant material and the natural bone. Most of the studies point the benefit of these synthetic materials in improving screw fixation strength. That is why, currently, the synthetic materials used in prosthesis are improved by associating with natural components of the bone, such as hydroxyapatite. For osteoporosis, which is characterized by demineralization, the association of the implanted material with hydroxyapatite is expected to be a suited solution for bone matrix regeneration after implantation. The aim of the current study was to assess the mechanical properties of orthopedic screws coated with a new polyurethane acrylate polymer containing hydroxyapatite in order to improve the stability of the screw for the subsequent fixation of the fragility fracture. To test the efficiency of the new hydroxyapatite containing polymer, the mechanical behavior of the coated screws was evaluated. Our data show that the augmented screw can be obtained by incorporating lower hydroxyapatite concentrations.

Kinematic Investigation, of a New Flexible Orthopedic Screw (FlexyScrew) for Repairing the Torn Scapholunate Ligament, with the Use of 3D-CT/Scan-Covariant Method and Demonstration on a 3D-Printed Model

Kinematic Investigation, of a New Flexible Orthopedic Screw (FlexyScrew) for Repairing the Torn Scapholunate Ligament, with the Use of 3D-CT/Scan-Covariant Method and Demonstration on a 3D-Printed Model

Bone Fracture Sensing Using Ultrasound Pitch–Catch Measurements: A Proof-of-Principle Study

The most common imaging method used to diagnose and monitor bone fractures and healing is multiple radiographic images performed by highly trained professionals with expensive equipment that can expose patients to high levels of ionizing radiation. Here we introduce and illustrate proof-of-concept of a potential alternative method for measuring bone fractures: ultrasound pitch–catch measurement technique. Measurements are performed with two piezoelectric transducers, housed in standard orthopedic screws and fixed on either side of simulated fractures, with and without an orthopedic plate, in ex vivo pig limb bones. Using this measurement method, we were able to detect significant differences between uncut and 2-, 5- and 10-mm-deep bone cuts using a two-sided t-test with an α level of 5%.

Clinical complications of biodegradable screws for ligament injuries.

Anterior cruciate ligament (ACL) plays a crucial role stabilizing the knee joint while connecting tibia to femur. Lack of proper treatment of injured ACL can lead to meniscus tear and osteoarthritis. Interference screws secure the graft tissue for superior integration of graft on host tissue during autograft fixation. Metal interference screws come with various disadvantages like mechanical load mismatch, graft laceration, secondary surgical removal and hindrance during MRI and CT post-operative scan. Though biodegradable polymeric screws provide various advantages their clinical outcomes reveal unprecedented complications for long term use of such screws. This review highlights polymer and composite screw currently available for surgical fixations and associated adverse reactions with the proposed mechanism for tunnel enlargement, effusion, osteolysis in ligament repairs. The need for suitable material engineering for development of orthopedic screws for successful rigid fixation has been highlighted in this review.

Preliminary Investigation on Mechanical Properties of Polymer Coating Screws for the Future Fragility Fracture Fixation

Bone fracture fixation uses both consecrated materials, such as metals/metal alloys, as well as synthetic materials. Synthetic materials are extremely versatile in terms of simulating biological structures, biocompatibility and, in some cases, avoid the subsequent interventions for removing the prosthetic material. Fixing an osteoporotic fracture presents major risks of failure due mainly to the bone fragility. To reduce the risk of failure, prosthetic materials have been improved with various cements. The purpose of the current study was to assess the mechanical properties of different orthopedic screws covered with a new polyurethane acrylate polymer (PUA) in order to improve the stability of the screw for the subsequent fixation of the fragility fracture. To test the efficiency of the new polymer, the breaking/fracture strength of the orthopedic screws coated with PUA was evaluated, in comparison with the screws without coating material. Our data shows that tested PUA improves the bond between the screw and bone. We estimate that the effect obtained is caused by the partial damping of the loading force due to the elastic component of the polymer.

Evaluation of an alkali-treated and hydroxyapatite-coated orthopedic implant loaded with tobramycin.

An approximately 1-µm thick hydroxyapatite coating was biomimetically deposited on an alkali-treated, commercially available orthopedic screw surface (type II anodized titanium). Tobramycin loaded ...

Development of bone screw using novel biodegradable composite orthopedic biomaterial: from material design to in vitro biomechanical and in vivo biocompatibility evaluation

A novel composite biomaterial for bone-soft tissue fixation applications was developed. MgO-Silk-PCL, Silk-PCL and MgO-PCL composites were prepared with variable filler concentrations (0, 10, 20 and 30% w/w of MgO nanoparticles and 0%, 5%, 10%, 20% and 30% of degummed silk fiber) in PCL polymer. The highest mechanical properties were obtained with 10% MgO and 20% Silk composite (MSP) wih 1.7× better tensile strength and 7.5× tensile modulus over PCL. It exhibited good cell viability, adhesion and hemocompatibility, increased cell proliferation and differentiation. MgO filler contributed more in increasing tensile strength, whereas silk fiber towards modulus, imparting a synergistic effect on mechanical performance. Prototype bone screws were molded using the MSP composite in a custom-designed mold. It showed significantly increased degradation (2.7 fold after 60 days) in PBS attributable to binary filler phase as compared to PCL. In vivo biosafety studies of MgO-silk-PCL composite screw in SD rats by subcutaneous implantation showed moderate inflammation at 2 weeks which subsided after 4th week. No toxic effect was seen in histopathology of vital organs and in blood parameters. Composite screw showed 2× pull-out strength of PCL in synthetic bone, therefore a potential candidate for bone-soft fixation applications like resorbable orthopedic screws for ACL reconstruction.

Enhanced release of calcium phosphate additives from bioresorbable orthopaedic devices using irradiation technology is non-beneficial in a rabbit model: An animal study.

ObjectivesBioresorbable orthopaedic devices with calcium phosphate (CaP) fillers are commercially available on the assumption that increased calcium (Ca) locally drives new bone formation, but the clinical benefits are unknown. Electron beam (EB) irradiation of polymer devices has been shown to enhance the release of Ca. The aims of this study were to: 1) establish the biological safety of EB surface-modified bioresorbable devices; 2) test the release kinetics of CaP from a polymer device; and 3) establish any subsequent beneficial effects on bone repair in vivo.MethodsActivaScrew Interference (Bioretec Ltd, Tampere, Finland) and poly(L-lactide-co-glycolide) (PLGA) orthopaedic screws containing 10 wt% β-tricalcium phosphate (β-TCP) underwent EB treatment. In vitro degradation over 36 weeks was investigated by recording mass loss, pH change, and Ca release. Implant performance was investigated in vivo over 36 weeks using a lapine femoral condyle model. Bone growth and osteoclast activity were assessed by histology and enzyme histochemistry.ResultsCalcium release doubled in the EB-treated group before returning to a level seen in untreated samples at 28 weeks. Extensive bone growth was observed around the perimeter of all implant types, along with limited osteoclastic activity. No statistically significant differences between comparative groups was identified.ConclusionThe higher than normal dose of EB used for surface modification did not adversely affect tissue response around implants in vivo. Surprisingly, incorporation of β-TCP and the subsequent accelerated release of Ca had no significant effect on in vivo implant performance, calling into question the clinical evidence base for these commercially available devices.Cite this article: I. Palmer, S. A. Clarke, F. J Buchanan. Enhanced release of calcium phosphate additives from bioresorbable orthopaedic devices using irradiation technology is non-beneficial in a rabbit model: An animal study. Bone Joint Res 2019;8:266–274. DOI: 10.1302/2046-3758.86.BJR-2018-0224.R2.

Influence of Fine Shot Peening on Mechanical Properties of Orthopedic Plate and Screw

As the bone fracture is now considered the second most serious disease in the world, a huge number of orthopedic devices for bone healing is being developed. However, there happened to be a number of incidents in which the orthopedic plates were broken inside the body due to inadequate strength. The present study aims to investigate the effects of Fine Shot Peening (FSP) conditions on performances of orthopedic plates and screws. In this research, there are 3 types of medical alloys to be studied namely SUS316 alloy, Ti6Al4V alloy and Ti6Al7Nb. In FSP process, 40 and 80 μm diameter of silica media was selected and utilized. FSP was carried out under the pressure of 0.5 MPa in Nitrogen atmosphere. The study shown that Ti6Al4V alloy with FSP media diameter of 80 μm resulted in 11% increment of bending strength and 40% increment of surface hardness. Regarding the orthopedic screw, the result shown that after applying FSP, the pull out strength from bone could be increased above 76%.

A comparative study of tapped and untapped pilot holes for bicortical orthopedic screws - 3D finite element analysis with an experimental test.

The aim of this study was to compare the screw-to-bone fixation strength of two insertion techniques: self-tapping screw (STS) and non-self-tapping screw (NSTS). Finite element analysis (FEA) was used for the comparison by featuring three tests (insertion, pull-out and shear) in a human tibia bone model. A non-linear material behavior with ductile damage properties was chosen for the modeling. To validate the numerical models, experimental insertion and pull-out tests were carried out using a synthetic bone. The experimental and numerical results of pull-out tests correlated well. Thread forming was successfully simulated during the insertion process of STS and NSTS. It is demonstrated that the STS generates higher insertion torque, induces a higher amount of stress after the insertion process and relatively more strength under the pull-out and shear tests than the NSTS. However, the NSTS induces more stiffness under the two tests (pull-out and shear) and less damage to the screw-bone interface compared to the STS. It is concluded that the use of STS ensures tighter bony contact and enables higher pull-out strength; however, the use of NSTS improves the stiffness of the fixation and induces less damage to the cortical bone-screw fixation and thus minimum risk is obtained in terms of bone necrosis.

Liquid Nitriding of Stainless Steel 316L to improve fatigue properties for Orthopedic Screws

Liquid nitrate is an important method used to improve mechanical properties. One of these properties is resistance to fatigue. The aim of this study was to improve the fatigue resistance of the stainless steel 316L. The rotational bending method was used with constant and variable stresses at different times of (1, 3, 5) hours and at (530, 630) C0. These tests were performed before and after nitration.&#x0D; The results showed that the depth of the nitride layer was (0.21, 0.33, 0.45) mm, increasing with time nitriding when the temperature was 530 C0. While the depth of this layer at a temperature of 630 C0 (0.26, 0.39,0.5) mm with increasing time. As a result of these processes, a layer of solid chromium nitrides and other phases of iron nitride were formed on the outer surface. These layers helped to inhibit the growth of the cracks and their progress in addition to the generation of pressure stresses on the surface leading to obstructing the progress of the cracks.&#x0D; This study showed that the fatigue resistance was directly proportional to the increase in nitrate time due to the increased depth of the hardened layer, but this resistance decreased when the temperature was 630 C0 due to the formation of brittle phase with low resistance.