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 Optimization of a novel external fixator for orthopaedic applications

2020 ◽  
Vol 318 ◽  
pp. 01025
Author(s):  
Mohammed S. Alqahtani
Keyword(s):  
Topology Optimization ◽  
External Fixator ◽  
Mechanical Performance ◽  
Bone Fractures ◽  
Significant Risk ◽  
Polymeric Materials ◽  
Acrylonitrile Butadiene Styrene ◽  
Patient Specific ◽  
Element Analysis ◽  
Fixation Devices

The use of external fixation devices is a very common method for the treatment of bone fractures. However, these fixators present some limitations in terms of mobility, significant risk of infection, and induce pain and discomfort. Moreover, they are also not fully customized to suit individual patients. To avoid these limitations, this paper presents a novel patient-specific external fixator developed using reverse engineering, finite element analysis and additive manufacturing. The fixator was designed based on a set of computer tomography (CT) scan images of a patient and optimized considering different thickness values and materials. New lightweight designs were produced through a manual process (regular distribution of circular and hexagonal voids) and topology optimization. Different polymeric materials (Polylactic acid (PLA); Acrylonitrile butadiene styrene (ABS) and Polyamide (PA)) were also considered for the fabrication of these designs. It was found that although both PLA and ABS allow to meet the design requirements, and that the best mechanical properties were obtained with fixators made of PLA. Results also showed that the best results in terms of mechanical performance and weight reduction was obtained with topology optimization.

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 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).

Analysis of the lower jaw exoskeleton in finite element programs

2021 ◽  
pp. 88-92
Author(s):  
D. Yu. D’yachenko ◽  
A. A. Vorob’ev ◽  
Iu. A. Makedonova ◽  
О. N. Kurkina ◽  
S. V. D’yachenko ◽  
...  
Keyword(s):  
Finite Element ◽  
External Fixation ◽  
3D Model ◽  
Bone Fractures ◽  
Maxillofacial Region ◽  
Lower Jaw ◽  
Fixation Devices ◽  
Bone Fragments ◽  
External Fixation Device ◽  
Medical University

A special place in the methods of surgical treatment of bone fractures is occupied by transosseous osteosynthesis using external fixation devices of various designs.Objective: to analyze the lower jaw exoskeleton in finite element programs.Materials and research methods. During the research, 36 human lower jaws were involved from the museum of the Department of Oper-ative Surgery and Topographic Anatomy of the Volgograd State Medical University. They were scanned in 3D. All obtained images were loaded into a virtual scene reconstruction program. Fractures of the lower jaws in the corner area were modeled, an apparatus for external fixation of the lower jaw exoskeleton was installed, and the chewing load on the lower jaw was simulated. The place of application of the force was an area on a small fragment of a repositioned 3D model of the mandibular bone corresponding to the place of attachment of the masseter muscle. The evaluation of virtual studies was carried out according to the results of the stress-strain states of the bones and apparatus, the schedule of displacements of objects and the results of the analysis of the safety factor.Research results and discussion. In the course of evaluating the virtual placement of the mini-fixator wires of the apparatus for external fixation of the lower jaw exoskeleton, it was revealed that the main load is applied to the mini-fixator wires on a large fragment and the bone in the area of the wires. For the possibility of precise positioning of the osteofixers of the external fixation device, a device for the safe installation of the spokes of the lower jaw exoskeleton was also developed.Conclusion. Thus, on the basis of computer mathematical analysis, it can be argued that the developed design of the apparatus for external fixation of the lower jaw exoskeleton works under conditions of the maxillofacial region, performs reposition and fixation of bone fragments of the lower jaw under conditions of chewing functioning of the restored fracture of the lower jaw.

Methyl methacrylate in external fixation of supracondylar humerus fractures: An experimental study

2018 ◽  
Vol 232 (10) ◽  
pp. 1025-1029
Author(s):  
Ali Güleç ◽  
Mehmet Ali Acar ◽  
Bahattin Kerem Aydin ◽  
Teyfik Demir ◽  
Mustafa Özkaya
Keyword(s):  
Methyl Methacrylate ◽  
External Fixation ◽  
External Fixator ◽  
External Fixators ◽  
Three Point Bending ◽  
Fixation Methods ◽  
Supracondylar Humerus Fractures ◽  
Methacrylate Group ◽  
Humerus Fractures ◽  
K Wires

Supracondylar humerus fractures are common fractures around the elbow. Open fractures, comminuted metaphyseal fractures and also fractures with bone loss may need to be treated with external fixators. The aim of this study is to compare two different external fixators, tubular external fixators and polymethyl methacrylate with K wires external fixators, with regard to stiffness and stability for metaphyseal-diaphyseal osteotomies of distal humerus close to the joint. Six matched pairs (24 specimens) of second-generation sawbone humerus were prepared in a standard fashion to create a metaphyseal fracture, 5 cm proximal to the distal joint line of humerus and were randomly divided into two groups of 12 specimens each. Each sawbone humerus was osteotomized transversely at the mid-olecranon fossa with a 2-mm oscillating saw to simulate a Gartland type III fracture. The osteotomy was then reduced and stabilized using two different external fixation methods: carbon tubular external fixator with Schanz screws and methyl methacrylate with multiple K wires. Three-point bending and torsion tests were performed on the specimens. Bending and torsional stiffness of specimens were obtained for the fixation methods. According to the results of the study, the methyl methacrylate group has provided higher stiffness than classical tubular fixator with Schanz screws in three-point bending test (7.79 ± 2.33 N/mm vs 3.78 ± 1.18 N/mm, p = 0.006). The methyl methacrylate group also showed better stiffness in torsion test (0.12 ± 0.042 N m/° vs 0.067 ± 0.013 N m/°, p = 0.02). We determined for the first time in literature that external fixation with methyl methacrylate was significantly superior to the classical tubular external fixator with Schanz screws with regard to stiffness and stability under three-point bending and torsional loads. Moreover, methyl methacrylate is inexpensive and easily applied.

scholarly journals Low cost 3D printed clamps for external fixator for developing countries: a biomechanical study

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Felix J. Landaeta ◽  
Jose Nauaki Shiozawa ◽  
Arthur Erdman ◽  
Cara Piazza
Keyword(s):  
Developing Countries ◽  
External Fixation ◽  
Axial Compression ◽  
External Fixator ◽  
Low Cost ◽  
Biomechanical Properties ◽  
External Fixators ◽  
The Novel ◽  
Astm Standard ◽  
3D Printed

Abstract Background External fixation is a mainstream limb reconstruction technique, most often used after a traumatic injury. Due to the high rates of trauma in developing countries, external fixation devices are often utilized for immediate fracture stabilization and soft tissue repair. Proper external fixation treatment too often still fails to be adopted in these regions due to the high cost and trauma complexity. A novel, inexpensive, unilateral fixator was constructed using 3D printed clamps and other readily available supporting components. ASTM standard F1541 tests were used to assess the biomechanical properties of this novel external fixator. Methods Applicable sections of ASTM standard F1541 were used to determine the biomechanical properties of the novel external fixator. 3D printed clamps modeled using SolidWorks and printed with chopped carbon fibers using a fuse deposition modeling (FDM) based 3D printer by Markforged (Boston, MA) were used. This study included 3 different testing configurations: axial compression, anterior-posterior (AP) bending, and medial-lateral (ML) bending. Using the novel unilateral fixator with 3D printed clamps previously sterilized by autoclave, an input load was applied at a rate of 20 N/s, starting at 0 N via a hydraulic MTS tester Model 359. Force and deformation data were collected at a sampling rate of 30 Hz. There was a load limit of 750 N, or until there was a maximum vertical deformation of 6 mm. Also, 4 key dimensions of the 3D printed clamps were measured pre and post autoclave: diameter, width, height and length. Results The novel external fixator had axial compression, AP and ML bending rigidities of 246.12 N/mm (σ = 8.87 N/mm), 35.98 N/mm (σ = 2.11 N/mm) and 39.60 N/mm (σ =2.60 N/mm), respectively. The 3D printed clamps shrunk unproportionally due to the autoclaving process, with the diameter, width, height and length dimensions shrinking by 2.6%, 0.2%, 1.7% and 0.3%, respectively. Conclusion Overall, the biomechanical properties of the novel fixator with 3D printed clamps assessed in this study were comparable to external fixators that are currently being used in clinical settings. While the biomechanics were comparable, the low cost and readily available components of this design meets the need for low cost external fixators in developing countries that current clinical options could not satisfy. However, further verification and validation routines to determine efficacy and safety must be conducted before this novel fixator can be clinically deployed. Also, the material composition allowed for the clamps to maintain the appropriate shape with minimal dimensional shrinkage that can be accounted for in clamp design.

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 Surgical treatment of tibial nonunion after wounding by high velocity missile and external fixators: A case report

2012 ◽  
Vol 140 (7-8) ◽  
pp. 515-520
Author(s):  
Ivan Golubovic ◽  
Zoran Vukasinovic ◽  
Predrag Stojiljkovic ◽  
Zoran Golubovic ◽  
Danilo Stojiljkovic ◽  
...  
Keyword(s):  
External Fixation ◽  
External Fixator ◽  
High Velocity ◽  
Primary Treatment ◽  
External Fixators ◽  
Risk Of Infection ◽  
Tissue Destruction ◽  
Reconstructive Operations ◽  
Delayed Healing ◽  
Tibial Nonunion

Introduction. The missiles of modern firearms can cause severe fractures of the extremity. High velocity missile fractures of the tibia are characterized by massive tissue destruction and primary contamination with polymorphic bacteria. Treatment of these fractures is often complicated by delayed healing, poor position healing, nonhealing and bone tissue infection. Case Outline. We present the management of tibial nonunion after wounding by high velocity missile and primary treatment by external fixation in a 25-year-old patient. The patient was primarily treated with external fixation and reconstructive operations of the soft tissue without union of the fracture. Seven months after injury we placed a compression-distraction external fixator type Mitkovic and started with compression and distraction in the fracture focus after osteotomy of the fibula and autospongioplasty. We recorded satisfactory fracture healing and good functional outcome. Conclusion. Contamination and devitalization of the softtissue envelope increase the risk of infection and nonunion in fractures after wounding by high velocity missile. The use of the compression-distraction external fixator type Mitkovic may be an effective method in nonunions of the tibia after this kind of injury.

scholarly journals 3D Printed Models Improve Surgical Planning for Correction of Severe Postburn Ankle Contracture With External Fixator

2020 ◽  
Author(s):  
Youbai Chen ◽  
Zehao Niu ◽  
Weiqian Jiang ◽  
Yonghong Lei ◽  
Lingli Guo ◽  
...  
Keyword(s):  
External Fixator ◽  
Surgical Planning ◽  
Outcome Variable ◽  
Patient Specific ◽  
Control Group ◽  
External Fixators ◽  
3D Printed ◽  
Operation Duration ◽  
Tract Infections

Abstract Background: Gradual distraction with external fixators such as Ilizarov frame has been widely used for the treatment of severe postburn ankle contracture (PAC). However, the application of external fixator is complex and conventional surgical planning based on 2D imaging is compromised due to a lack of spatial geometry and tactile feedback. The purpose of this study was to evaluate the surgical planning with patient-specific 3D-printed models (3DPM) for the treatment of PAC with external fixators. Methods: A two-centered retrospective cohort study, composed of consecutive patients who underwent external fixation for the treatment of severe PAC, was implemented. Patients were divided into two cohorts (3DPM group vs. Control group) according to whether 3DPM was used for preoperative surgical planning. The primary outcome variable was operation duration. Other outcome variables included improvement in metatarsal-tibial angle (MTA), range of motion (ROM), American Orthopedic Foot and Ankle Society (AOFAS) scores, and complications. Results: Between January 2008 and June 2018, ten patients with an average age of 23.8±14.1 yeas were treated for PAC at two centers. 3DPM were used for surgical planning in 5 patients. 3DPM group had significantly shorter operation duration than the control group (2±0.3 hours vs. 3.2±0.3 hours, p=0.0001). The comparison of preoperative, after removal of external fixator, and follow-up MTA, ROM, and AOFAS between the 3DPM and control group showed no significant differences. A plantigrade foot was achieved and gait was substantially improved in all patients at the final follow-up. Pin-tract infections occurred in 2 patients (one in each group) during distraction and were treated with wound care and oral antibiotics. Conclusion: The results of this study show that surgical planning using patient-specific 3DPM significantly reduced the operation duration while providing similar improvements in MTA, ROM, and AOFAS scores compared to traditional surgical planning for the correction of severe PAC with external fixators.

scholarly journals Use of external fixation devices for optimization of reparative regeneration in pelvic bone fractures

1996 ◽  
Vol 3 (1) ◽  
pp. 52-56
Author(s):  
D. I. Cherkes-Zade ◽  
A. F. Lazarev
Keyword(s):  
External Fixation ◽  
Bone Fractures ◽  
Bed Rest ◽  
Reparative Regeneration ◽  
Pelvic Bone ◽  
Pelvic Bones ◽  
Fixation Devices

The authors present their experience in the application of external fixation devices for the treatment of 96 patients with multiple and combined pelvic bones injuries. It is shown that treatment with use of both pivot and pin devices exerts powerful antishock effect, allows to shorten the duration of bed rest and early activate the patient. Favourable results were achieved in all cases.

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