scholarly journals The Effect of External Fixator Configurations on the Dynamic Compression Load: An Experimental and Numerical Study

2019 ◽  
Vol 10 (1) ◽  
pp. 3
Author(s):  
Ana Martins Amaro ◽  
Maria Fátima Paulino ◽  
Luis Manuel Roseiro ◽  
Maria Augusta Neto
Keyword(s):  
External Fixator ◽  
Bone Fractures ◽  
Numerical Study ◽  
Dynamic Compression ◽  
Healing Process ◽  
Laminated Composite ◽  
Composite Plates ◽  
External Fixators ◽  
Compression Load ◽  
Bone Callus

(1) Objective: External fixation systems are commonly used by surgeons to ensure stabilization and consolidation of bone fractures, especially in patients who are at high risk for systematic complications. Both rigid and elastic external fixations are important in the fracture healing process. This study aims to evaluate the behavior of the Orthofix Limb Reconstruction System (LRS)® in the dynamic compression mode. (2) Methods: Experimental and numerical setups were developed using a simplified model of a human tibia which consisted of a nylon bar with a diameter of 30 mm. The bone callus was included in both setups by means of a load cell-based system, which consisted of two carbon epoxy laminated composite plates with a final stiffness of 220 N/mm. The system was evaluated experimentally and numerically, considering different numbers of pins and comparing distances between the external fixator frame and the bone, achieving a good correlation between experimental and numerical results. (3) Results: The results identified and quantified the percental load transferred to the fracture and its sensibility to the distance between the external fixator and bone. Additionally, LRS locking stiffness was evaluated which resulted from the clamp-rail clearances. The results show that the blocking effects of the free clamp movement are directly related to the fixator configuration and are responsible for changes in the amount of load that crosses the bone callus. (4) Conclusions: From the biomechanical point of view, the results suggest that the average bending span of Schanz pins and the weights of the patients should be included into clinical studies of external fixators comparisons purpose.

scholarly journals Optimization of a Patient-Specific External Fixation Device for Lower Limb Injuries

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2661
Author(s):  
Mohammed S. Alqahtani ◽  
Abdulsalam Abdulaziz Al-Tamimi ◽  
Mohamed H. Hassan ◽  
Fengyuan Liu ◽  
Paulo Bartolo
Keyword(s):  
Topology Optimization ◽  
External Fixation ◽  
Polylactic Acid ◽  
External Fixator ◽  
Bone Fractures ◽  
Healing Process ◽  
Patient Specific ◽  
External Fixators ◽  
Fixation Devices ◽  
Limb Injuries

The use of external fixation devices is considered a valuable approach for the treatment of bone fractures, providing proper alignment to fractured fragments and maintaining fracture stability during the healing process. The need for external fixation devices has increased due to an aging population and increased trauma incidents. The design and fabrication of external fixations are major challenges since the shape and size of the defect vary, as well as the geometry of the human limb. This requires fully personalized external fixators to improve its fit and functionality. This paper presents a methodology to design personalized lightweight external fixator devices for additive manufacturing. This methodology comprises data acquisition, Computer tomography (CT) imaging analysis and processing, Computer Aided Design (CAD) modelling and two methods (imposed predefined patterns and topology optimization) to reduce the weight of the device. Finite element analysis with full factorial design of experiments were used to determine the optimal combination of designs (topology optimization and predefined patterns), materials (polylactic acid, acrylonitrile butadiene styrene, and polyamide) and thickness (3, 4, 5 and 6 mm) to maximize the strength and stiffness of the fixator, while minimizing its weight. The optimal parameters were found to correspond to an external fixator device optimized by topology optimization, made in polylactic acid with 4 mm thickness.

scholarly journals A Novel Capacitive Measurement Device for Longitudinal Monitoring of Bone Fracture Healing

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6694
Author(s):  
Angela Sorriento ◽  
Marcello Chiurazzi ◽  
Luca Fabbri ◽  
Michelangelo Scaglione ◽  
Paolo Dario ◽  
...  
Keyword(s):  
Bone Fractures ◽  
Healing Process ◽  
Long Bone ◽  
Sensor Technology ◽  
External Fixators ◽  
X Rays ◽  
Implant Stability ◽  
Measurement Device ◽  
3D Space ◽  
Bone Callus

The healing process of surgically-stabilised long bone fractures depends on two main factors: (a) the assessment of implant stability, and (b) the knowledge of bone callus stiffness. Currently, X-rays are the main diagnostic tool used for the assessment of bone fractures. However, they are considered unsafe, and the interpretation of the clinical results is highly subjective, depending on the clinician’s experience. Hence, there is the need for objective, non-invasive and repeatable methods to allow a longitudinal assessment of implant stability and bone callus stiffness. In this work, we propose a compact and scalable system, based on capacitive sensor technology, able to measure, quantitatively, the relative pins displacements in bone fractures treated with external fixators. The measurement device proved to be easily integrable with the external fixator pins. Smart arrangements of the sensor units were exploited to discriminate relative movements of the external pins in the 3D space with a resolution of 0.5 mm and 0.5°. The proposed capacitive technology was able to detect all of the expected movements of the external pins in the 3D space, providing information on implant stability and bone callus stiffness.

scholarly journals Pre-drilling and self-drilling pins screw-bone fixation stress interaction analysis induced by uniaxial compression loading

2019 ◽  
Vol 15 (1) ◽  
pp. 99-108
Author(s):  
Lim Pei Chee ◽  
Ruslizam Daud ◽  
Shah Fenner Khan Mohamad Khan ◽  
Nurul Alia Md Zain ◽  
Yazid Bajuri
Keyword(s):  
Uniaxial Compression ◽  
External Fixator ◽  
Bone Fractures ◽  
Interaction Analysis ◽  
Compressive Loading ◽  
Three Dimensional ◽  
Maximum Magnitude ◽  
Element Analysis ◽  
Compression Load ◽  
Von Mises

A newly designed Uniaxial external fixator which functions as a universal fixator in the application of all types of bone fractures is recently introduced by both Hospital Universiti Kebangsaan Malaysia (HUKM) and Universiti Malaysia Perlis (UniMAP). The Investigation is focused on identifying and measuring the performance in terms of strength or weakness of the fixator that is needed before the application to the human body. Hence, this research was conducted to determine the performance of Uniaxial external fixator which was based on geometry using different screw drilling techniques applied during an angled uniaxial compression load.  A three-dimensional fixator-bone was constructed using different screw inserting techniques which was then converted into ANSYS v14.5 for the purposes of conducting a finite element analysis (FEA).  Axial compressive loading with various degrees from 60 to 6300 N were applied to bone models to stimulate patient’s daily activities while 10 to 100 N were applied to fixator models for the purposes of reviewing environmental loading to fixator-bone models. Findings revealed that maximum magnitude which caused deformation for predrilling and self-drilling models were located at the highest pin-bone interaction. Conversely, the maximum magnitude of the von Mises strain and stress was located at the lowest pin-bone interaction by omitting the existence of fixator for both Case 1 and 2. There was no obvious difference in the comparison of both models in terms of deformation. However, predrilling models have higher strain and stress than self-drilling models. In sum, findings indicated that self-drilling models have better performance compared to the predrilling models.

scholarly journals Buckling Behaviour of Carbon/Epoxy Laminated Composite Plates under Biaxial Loading

2009 ◽  
Vol 18 (3) ◽  
pp. 096369350901800 ◽  
Author(s):  
Mehmet Aktaş
Keyword(s):  
Boundary Conditions ◽  
Biaxial Loading ◽  
Numerical Study ◽  
Plate Boundary ◽  
Laminated Composite ◽  
Young Modulus ◽  
Load Ratio ◽  
Composite Plates ◽  
Buckling Load

In this numerical and analytical study; the length-to-thickness ratio (a/t), aspect ratio (a/b), Young modulus ratio ( E1/ E2), load ratio ( Nx/ Ny) and different boundary conditions effect on buckling behaviour of carbon/epoxy composite laminated plate were investigated. The composite plate was assumed four plies as [θ°]4. The fibre orientation, θ, was chosen as 0°, 15°, 30°, 45°, 60°, 75° and 90°. The Veres-Kollar approach [ 1 ] was used to calculate the buckling load, analytically. Also, ANSYS 10 commercial software was used for determination of buckling load, numerically. The plate has simple supported boundary condition at four edges during analytical and numerical study. Good agreements between analytical and numerical results were obtained. Results showed that the buckling load changes depend on the dimension and material properties of the plate, boundary conditions and loading cases.

scholarly journals Fracture Healing Assessment Based on Impact Testing: In Vitro Simulation and Monitoring of the Healing Process of a Tibial Fracture with External Fixator

2017 ◽  
Vol 09 (07) ◽  
pp. 1750098 ◽  
Author(s):  
Francesca Di Puccio ◽  
Lorenza Mattei ◽  
Antonia Longo ◽  
Stefano Marchetti
Keyword(s):  
Fracture Healing ◽  
Modal Analysis ◽  
External Fixator ◽  
Healing Process ◽  
Experimental Modal Analysis ◽  
Impact Testing ◽  
Resonant Frequencies ◽  
Bone Callus ◽  
Healing Assessment

In clinical practice, bone healing is monitored with X-rays and manipulation. Its assessment is thus subjective, depending on the skills of the operator. Alternative and quantitative approaches have been proposed, generally based on the estimation of bone stiffness, which is known to increase with the healing process. The present study investigates the application of experimental modal analysis to fracture healing assessment focusing on fractures treated with an external fixator. The aim is to ascertain the capability of this approach to detect changes in the bone-callus stiffness as variations in the resonant frequencies despite the presence of the fixator, which might hide the bone response. In vitro tests were performed on a tibia phantom where the healing process was simulated creating three different types of callus surrogates, using glue and resin. The resonant frequencies of the phantom with screwed pins and of the phantom with the complete fixator were estimated. Results confirm an increase in the frequencies as the simulated bone-callus stiffness increases, encouraging the application of experimental modal analysis to fracture healing monitoring. This approach can offer remarkable advantages with respect to the actual standards: being non-invasive and quantitative, it would allow a more frequent healing monitoring.

scholarly journals Influence of different methods of internal bone fixation on characteristics of bone callus in experimental animals

2014 ◽  
Vol 142 (1-2) ◽  
pp. 40-47
Author(s):  
Djordje Gajdobranski ◽  
Milorad Mitkovic ◽  
Nada Vuckovic ◽  
Miroslav Milankov ◽  
Slobodan Jovanovic ◽  
...  
Keyword(s):  
Bone Fractures ◽  
Plate Fixation ◽  
Stress Test ◽  
Statistical Significance ◽  
Healing Process ◽  
Biomechanical Testing ◽  
Long Bone ◽  
Femoral Diaphysis ◽  
Experimental Animals ◽  
Bone Callus

Introduction. Correct choice of osteosynthesis method is a very important factor in providing the optimal conditions for appropriate healing of the fracture. There are still disagreements about the method of stabilization of some long bone fractures. Critically observed, no method of fracture fixation is ideal. Each osteosynthesis method has both advantages and weaknesses. Objective. The objective of this study was to compare the results of the experimental application of three different internal fixation methods: plate fixation, intramedullary nail fixation and self-dynamisable internal fixator (SIF). Methods. A series of 30 animals were used (Lepus cuniculus) as experimental animals, divided into three groups of ten animals each. Femoral diaphysis of each animal was osteotomized and fixed with one of three implants. Ten weeks later all animals were sacrificed and each specimen underwent histological and biomechanical testing. Results. Histology showed that the healing process with SIF was more complete and bone callus was more mature in comparison to other two methods. During biomechanical investigation (computerized bending stress test), it was documented with high statistical significance that using SIF led to stronger healing ten weeks after the operation. Conclusion. According to the results obtained in this study, it can be concluded that SIF is a suitable method for fracture treatment.

scholarly journals Results of application of external fixation with different types of fixators

2012 ◽  
Vol 140 (5-6) ◽  
pp. 332-338 ◽  
Author(s):  
Predrag Grubor ◽  
Milan Grubor
Keyword(s):  
External Fixation ◽  
External Fixator ◽  
Bone Fractures ◽  
Biomechanical Properties ◽  
Long Bone ◽  
External Fixators ◽  
Vertical Force ◽  
Computer Simulator ◽  
Lateral Plane ◽  
Healthy Part

Introduction. Extra-focal or external fixation is the method of fracture fixation through the healthy part of the bone using pins or wires. Objective. The aim was to determine which external splints (Ortofix, Mitkovic, Charnley and Ilizarov) had the best biomechanical properties in primary stabilization of spiral, transverse and commutative bone fractures. Methods. To determine the investigation methodology of biomechanical characteristics of the external fixator we used mathematical and computer simulator (software), juvidur physical model and clinical examination. Results. Values of advancing fragments in millimetres obtained by the study of mathematical and computer simulator (software): Charnley - 0.080 mm, Mitkovic M 20 - 0.785 mm, Ilizarov - 2.245 mm and Ortofix - 1.400 mm. In testing the juvidur model the following values were obtained: the external fixator Mitkovic M20 - 1.380 mm, Ortofix - 1.470 mm, Ilizarov - 2.410 mm, and Charnley - 2.510 mm. Clinical research of biomechanical characteristics of the effect of vertical force yielded the following results: Mitkovic M20 - 0.89 mm, Ortofix - 0.14 mm, Charnley - 0.80 mm and Ilizarov - 1.23 mm. Conclusion. When determining the total number of the stability test splints under the effect of vertical force (compression) and force effect in antero-posterior, later-lateral plane of cross, spiral and comminuted long bone fractures, the best unified biomechanical stability was shown by the following external fixators: firstly, Mitkovic M20 (0.93mm), secondly, Charnley fixator (1.14 mm), thirdly, Ortofix (1.22 mm), and fourthly, Ilizarov (1.60 mm).

scholarly journals Treatment of fractures and other orthopedic problems in cats and dogs using versatile external fixator

2021 ◽  
Vol 58 ◽  
pp. e182908
Author(s):  
Yetkin Öztürk ◽  
Serhat Özsoy
Keyword(s):  
External Fixator ◽  
Bone Fractures ◽  
Callus Formation ◽  
Clinical Results ◽  
External Fixators ◽  
Different Types ◽  
Ulna Fractures ◽  
Scope Of Application ◽  
Limb Fractures ◽  
New Generation

Many complicated bone fractures can be healed by different techniques including linear external fixation. New generation linear external fixators enhanced the scope of application for bone fractures by mechanical progress. Difficulties include implementing enough pins through fixation clamps to the comminuted fragments or clamp addition and fixing it properly to the rod with the correct pin insertion angle. Effective configurations may not always result. This study sought to reveal the clinical efficiency of modified clamps of a versatile external fixator (VEF) to fix different types of fractures and orthopedic problems according to the radiographic and clinical results. We used this fixator on 17 cats and 17 dogs of different ages and sizes, having different types of antebrachium, humerus, tibia, ulna fractures, and bone-muscle deformities. Clamps had different features to connect fixator pins. Many fixator configurations were created according to the fracture type and body weight of the animals. The most used ones were unilateral and bilateral configurations. The callus formation and visual gait analysis were observed after the operations, until the removal of the fixator. After fixator removal, the visual gait status of the limbs was excellent in 67% of the cases, good in 15%, fair in 12%, and poor in 6%. We found that rods and fixator pins were connected easily by semi-locked clamps. Also, the double pin holding clamps saved space on the fixation rod by the application of two pins through one clamp. We think that clamps of versatile external fixators can easily be constructed to limb fractures and save time during surgery. 

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