Investigation of Correction Trajectory Considering Bone End-Plane Orientation and the Shortest Growth Path

2020 ◽  
Author(s):  
Jianfeng Li ◽  
Guotong Li ◽  
Xiaojie Hu ◽  
Mingjie Dong ◽  
Chunjing Tao ◽  
...  
Keyword(s):  
External Fixator ◽  
Deformity Correction ◽  
Joint Space ◽  
External Fixators ◽  
Growth Path ◽  
Plane Orientation ◽  
Adjustment Strategy ◽  
New Strategy ◽  
Adjustment Strategies ◽  
Forward Kinematic

Abstract External fixators are widely used in orthopedics for the purposes of fracture reduction and bone deformity correction. Since there is nonlinear mapping between the joint and operation spaces of the external fixator, bone correction trajectories achieved by equally adjusting the length of the struts in the joint space are usually not the trajectories that clinicians expect. Based on two different adjustment strategies, a new strategy considering bone end-plane orientation and the shortest growth path is proposed to plan the position and orientation of the distal bone end, which is named joint adjustment for equal bone distraction. By proposing the inverse and forward kinematic solutions of an Ortho-SUV external fixator, correction trajectories with three different adjustment strategies are generated and compared, and the bone shapes for each strategy are modeled. The results obtained by comparative analysis indicate that a smooth and uniformly spaced linear trajectory can be acquired using the new adjustment strategy, which can avoid bone end interference and maintain an optimal distraction rate of 1.03 mm/day, with only a 3% error compared with 1 mm/day. The new strategy can perform multiplane corrections simultaneously and is beneficial for stimulating the growth of new bone tissue.

scholarly journals Development and Preliminary Trajectory Verification of the Electromotor-Driven Parallel External Fixator for Deformity Correction

2020 ◽  
Vol 10 (24) ◽  
pp. 9074
Author(s):  
Guotong Li ◽  
Jianfeng Li ◽  
Mingjie Dong ◽  
Shiping Zuo
Keyword(s):  
External Fixator ◽  
Inverse Kinematics ◽  
Medical Training ◽  
Three Dimensional ◽  
Deformity Correction ◽  
External Fixators ◽  
Artificial Bone ◽  
Adjustment Error ◽  
Adjustment Strategies ◽  
Searching Method

External fixators are widely used in deformity correction based on distraction osteogenesis. Traditionally, the rods are manually operated by patients several times a day, which will ensure the patient’s compliance, accumulative adjustment error, and trajectory deviation. To reduce the patients’ compliance and the complexity of adjustment, an electromotor-driven parallel external fixator is developed to gradually correct the deformity, which allows the fixator to be automatically adjusted and can correct any three-dimensional deformity with continuous stability. Two adjustment strategies are proposed through different trajectory control methods based on the inverse kinematics solution, and the trajectory and bone shape are generated to investigate the characteristics of the new bone more intuitively. The range of motion is performed utilizing the numerical searching method to assess the fixator’s correction capability. Finally, the trajectory verification experiment is carried out using the artificial bone model to perform the two adjustment strategies. The results show that the developed external fixator has high correction accuracy with 0.0172 mm, and can accurately and safely realize the preset correction trajectory. The developed fixator system can also be used as a teaching tool for medical training for clinicians to learn deformity correction technology.

scholarly journals Is deep venous thrombosis a common complication in patients treated with Ilizarov external fixator?

2017 ◽  
Vol 3 (6) ◽  
pp. 1180
Author(s):  
Sandeep Reddy ◽  
Harshad M. Shah ◽  
Naveen Kumar L. ◽  
Rahul P. ◽  
Vimal Kumar K. H.
Keyword(s):  
Lower Extremity ◽  
Venous Thrombosis ◽  
Deep Venous Thrombosis ◽  
External Fixator ◽  
Deformity Correction ◽  
External Fixators ◽  
Ilizarov External Fixator ◽  
Cross Sectional ◽  
Non Union ◽  
Post Surgery

<p class="abstract"><strong>Background:</strong> Determining the incidence of deep venous thrombosis (DVT), a prospective study, in patients treated with Ilizarov external fixators for lower extremity fractures, fracture non unions or deformity correction.</p><p class="abstract"><strong>Methods:</strong> A Prospective, observational and cross sectional study. 49 Patients with complex lower extremity injuries, deformities and non-union of fractures were treated with Ilizarov external fixator application, were assessed clinically and radiological (Venous Doppler) at regular intervals- 6 days post-surgery then at 6 weeks, 12 weeks and between 4 to 6 months post-operative. None were given chemoprophylaxis for the prevention of DVT and everyone were assessed pre operatively with a questionnaire and wells criteria was taken for assessment of high risk for developing venous thrombosis. There were 41 men and 8 women, 85.75% of the study group is of age 30 to 60 years.<strong></strong></p><p class="abstract"><strong>Results:</strong> Only 1 of 49 patients developed radiological evident DVT within 6 days of surgery. Patients who underwent application of Ilizarov external fixator electively for deformity correction, osteomyelitis and non-union showed no clinical or radiological evident signs of DVT.</p><p><strong>Conclusions:</strong> The incidence of DVT and PTE is minimal when patients without chemoprophylaxis underwent lower limb Ilizarov external fixator application for acute trauma and electively for deformity correction, treatment of non-union and osteomyelitis. However further comparative and randomized studies need to be done to confirm our results.</p>

scholarly journals A COMPARATIVE STUDY OF IN VIVO EFFECT OF PERCUTANEOUS BONE MARROW INJECTION VS WITHOUT INJECTION ON UNION OF OPEN TIBIAL SHAFT FRACTURES WITH EXTERNAL FIXATOR

2020 ◽  
pp. 1-2
Author(s):  
Hrishikesh Desai ◽  
Kirtiraj G ◽  
Abhay P
Keyword(s):  
Bone Marrow ◽  
External Fixator ◽  
Autologous Bone Marrow ◽  
Tibial Fractures ◽  
External Fixators ◽  
Open Tibial Fractures ◽  
Autologous Bone ◽  
Group 2 ◽  
Radiological Union

Background : Open tibial fractures are notorious fractures because the open wound leaves us with limited options and means multiple operations with long intervals for the patient. The usual method of treatment of contaminated, late presenting and complicated fractures is a temporary external fixator followed by conversion into a costly definitive procedure once the wound has healed. The secondary definitive procedure also means extra cost in an already economically stressed patient.In our set up we have to often let patients leave with a plaster cast after removing the external fixator for economic constrains. Per cetaceous autologous bone marrow injection while the patient is on external fixator is one alternative that we have tried to deal with this problem hoping for a primary union without any costly intervention. Materials and methods : We had 42 cases of open tibial fractures which were treated with external fixator and per cutaneous bone marrow injection while 38 other cases which were used as control with only the external fixator and no injections. We included open fractures of only Gustilo Anderson type II,IIIA and B for our study. Study was conducted between period of June 2012 and December 2013 at SBKS medical college . Results : In group one, 34 of the 42 patients had a radiological union before 12 weeks while another 2 in 16 weeks. For group 2 , only 16 of the 38patients had radiological union at 12 weeks and no more at 16 weeks. The average time of union for group 1 was 10 weeks while of group 2 was 12 weeks .Function of the union cases of both the groups was similar in all aspects including distance of walking and ability to carry out daily activities. Conclusion : Per cutaneous autologous bone marrow injections are cheap , easily available and successful alternative to a secondary procedure for open tibial fractures on external fixators.

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.

Compact Two Degrees-of-Freedom External Fixator System for Correction of Persistent Clubfoot Deformity

2019 ◽  
Vol 13 (2) ◽  
Author(s):  
Ying Ying Wu ◽  
Anton Plakseychuk ◽  
Kenji Shimada
Keyword(s):  
External Fixator ◽  
Degrees Of Freedom ◽  
Soft Tissues ◽  
Three Dimensional ◽  
Deformity Correction ◽  
Current Method ◽  
Tissue Growth ◽  
Learning Curves ◽  
Patient Specific ◽  
Two Degrees Of Freedom

Bone deformities are often complex three-dimensional (3D) deformities, and correcting them is difficult. To correct persistent clubfoot deformity in adolescents or adults, an external fixator is sometimes used to encourage tissue growth and preserve healthy tissues. However, it is difficult to set up, resulting in long surgeries and steep learning curves for surgeons. It is also bulky and obstructs patient mobility. In this paper, we introduce a new approach of defining clubfoot deformity correction as a six degrees-of-freedom (6DOF) correction, and then reducing it to just two degrees-of-freedom (2DOF) using the axis-angle representation. Therefore, only two physical trajectory joints are needed, which in turn enables a more compact fixator design. A computer planner was developed to minimize the bulk of the external fixator, and to optimize the distraction schedule to avoid overstretching the soft tissues. This reduces the learning curve for surgeons and shortens surgery time. To validate the system, a patient-specific clubfoot simulator was developed, and four experiments were performed on the clubfoot simulator. The accuracy of midfoot correction was 11 mm and 3.5 deg without loading, and 41 mm and 11.7 deg with loading. While the external fixator has to be more rigid to overcome resistance against correction, the surgical system itself was able to achieve accurate correction in less than 2 h. This is an improvement from the current method, which takes 2.5–4.5 h.

Evaluation of Stiffness and Stress of External Fixators with Curved Acrylic Connecting Bars

2000 ◽  
Vol 13 (02) ◽  
pp. 65-72 ◽  
Author(s):  
R. Shahar
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stainless Steel ◽  
Axial Compression ◽  
External Fixator ◽  
External Fixators ◽  
Analysis Method ◽  
Lateral Bending ◽  
Element Analysis ◽  
The Finite Element Analysis

SummaryThe use of acrylic connecting bars in external fixators has become widespread in veterinary orthopaedics. One of the main advantages of an acrylic connecting bar is the ability to contour it into a curved shape. This allows the surgeon to place the transcortical pins according to safety and convenience considerations, without being bound by the requirement of the standard stainless steel connecting bar, that all transcortical pins be in the same plane.The purpose of this study was to evaluate the stiffness of unilateral and bilateral medium-sized external fixator frames with different curvatures of acrylic connecting bars. Finite element analysis was used to model the various frames and obtain their stiffness under four types of load: Axial compression, four-point medio-lateral bending, fourpoint antero-posterior bending and torsion. The analysis also provided the maximal pin stresses occurring in each frame for each loading condition.Based on the results of this study, curvatures of acrylic connecting bars of up to a maximal angular difference between pins of 25° will result in very similar stiffness and maximal pin stresses to those of the equivalent, uniplanar stainless steel system. In both unilateral and bilateral systems the stiffness decreases slightly as angulation increases for axial compression and medio-lateral bending, increases slightly for torsion and increases substantially for antero-posterior bending.External fixator systems with curved acrylic connecting bars are commonly used in veterinary orthopaedics. This paper evaluates the biomechanical performance of such systems by applying the finite element analysis method. It shows that external fixators with curved acrylic connecting bars exhibit stiffness and maximal pin stresses which are similar to those of the standard stainless steel system.

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.

Antebrachial Angular Deformities Using Computer-Assisted Hexapod External Fixator Systems in Dogs

2020 ◽  
Vol 33 (04) ◽  
pp. 227-234
Author(s):  
Özlem Şengöz Şirin ◽  
Bruno Peirone ◽  
Lisa Adele Piras ◽  
Hasan Bilgili
Keyword(s):  
Prospective Study ◽  
External Fixator ◽  
Postoperative Period ◽  
Computer Assisted ◽  
External Fixators ◽  
Advantages And Disadvantages ◽  
A Prospective Study ◽  
Navigation Software ◽  
Fixation System ◽  
Angular Deformities

Abstract Objective The aim of this study was to investigate the applicability of computer-assisted hexapod fixators in dogs and to consider the advantages and disadvantages during implementation. Materials and Methods This was a prospective study. The study material consisted of 11 deformed extremities of 6 dogs. The correction plans were defined according to multiple extremity radiographs of the dog and the clinical evaluation of deformities. All measurements were uploaded to Click2Correct software program. Latent, correction and consolidation periods of each dog were recorded. The hexapod external fixators were removed after completion of the correction. Results Data were adapted to the radiographic navigation software to be used during operation and postoperative period. The latent period ranged from 3 to 20 days, the correction period ranged from 7 to 20 days and the consolidation period ranged from 39 to 81 days. It was concluded that special fixators can be used in dogs with complex antebrachial deformities. Clinical significance The ability to perform six axes correction at the same time has a considerable advantage, especially in dogs with complex antebrachial deformities. It is practical to use this fixation system in dogs with antebrachial deformities.

Sign in / Sign up

Export Citation Format

Share Document