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.

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.

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.

Fracture stabilization with type II external fixator vs. type I external fixator with IM pin

2004 ◽  
Vol 17 (02) ◽  
pp. 91-96 ◽  
Author(s):  
Y. Shani ◽  
R. Shahar
Keyword(s):  
External Fixator ◽  
Three Dimensional ◽  
External Fixators ◽  
Type I ◽  
Equivalent Stiffness ◽  
Stiffness Modulus ◽  
Fracture Stabilization ◽  
Solid Models ◽  
Local Shear ◽  
Biomechanical Features

SummaryBilateral external fixator frames are frequently preferred over unilateral frames due to their superior rigidity. The objective of this study was to compare the biomechanical features of bilateral external fixators with those of unilateral external fixators that are combined with an intra-medullary pin. Three-dimensional, solid models were created of several unilateral and bilateral external fixator frames. The callus in the fracture gap was also modeled. Biomechanical analyses of all constructs were performed by the finite element method. This modeling approach allows the determination of stresses, displacements, and strains in the components of the various constructs, and thus the calculation of their relative stiffness. In addition, local shear strain values in the fracture gap, currently thought to be one of the deciding factors in the process of bone healing, can also be determined. The concept of equivalent stiffness modulus, which represents a weighed average stiffness of a construct to various loads, was defined. Using this concept, it was shown that when the intramedullary pin is well seated in the epiphyseal bone, the various unilateral frames have an equivalent stiffness modulus that is similar or even greater than that of bilateral frames with a similar arrangement of transcortical pins.

Three-Dimensional Modeling and Finite Element Analysis of an Ankle External Fixator

2020 ◽  
Vol 899 ◽  
pp. 94-102
Author(s):  
Nur Faiqa Ismail ◽  
Muhammmad Aiman Firdaus Bin Adnan ◽  
Solehuddin Shuib ◽  
Nik Ahmad Hambali Nik Abd Rashid
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
External Fixator ◽  
Three Dimensional ◽  
Von Mises Stress ◽  
External Fixators ◽  
Element Analysis ◽  
Stress And Deformation ◽  
The Stability ◽  
Von Mises

External fixator has played an important role in repairing fractured ankle bone. This surgery is done due to the several factors which are the bone is not normal position or has broken into several pieces. The external fixator will help the broken bone to grow and remodel back to the original appearance. However, there are some issues regarding to the stability of this fixation. Improper design and material are the major factor that decreased the stability since it is related to the deformation of the external fixator to hold the bone fracture area. This study aims to design a stable structure for constructing delta frame ankle external fixator to increase the stability of the fixation. There are two designs of external fixator with two types of material used in this present study. Both external fixators with different materials are analyzed in terms of von Mises stress and deformation by using a conventional Finite Element Analysis software; ANSYS Workbench V15. The result obtained shows the Model 1 with stainless steel has less stress and deformation distributions compared to the Model 2. Hence, by using Model 1 as the external fixator, the stability of the fixation can be increased.

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 Long bone fracture reduction and deformity correction using the hexapod external fixator with a new method: a feasible study and preliminary results

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Yanshi Liu ◽  
Hong Li ◽  
Jialin Liu ◽  
Xingpeng Zhang ◽  
Maimaiaili Yushan ◽  
...  
Keyword(s):  
Soft Tissue ◽  
External Fixator ◽  
Bone Fracture ◽  
Three Dimensional ◽  
Deformity Correction ◽  
Fracture Reduction ◽  
Long Bone ◽  
Computer Assisted ◽  
Electronic Prescription ◽  
Long Bone Fracture

Abstract Background The hexapod external fixator (HEF), such as the Taylor spatial frame (TSF), offering the ability of multidirectional deformities correction without changing the structure, whereas there are so many parameters for surgeons to measure and subjective errors will occur inevitably. The purpose of this study was to evaluate the effectiveness of a new method based on computer-assisted three-dimensional (3D) reconstruction and hexapod external fixator for long bone fracture reduction and deformity correction without calculating the parameters needed by the traditional usage. Methods This retrospective study consists of 25 patients with high-energy tibial diaphyseal fractures treated by the HEF at our institution from January 2016 to June 2018, including 22 males and 3 females with a mean age of 42 years (range 14–63 years). Hexapod external fixator treatments were conducted to manage the multiplanar posttraumatic deformities with/without poor soft-tissue that were not suitable for internal fixation. Computer-assisted 3D reconstruction and trajectory planning of the reduction by Mimics were applied to perform virtual fracture reduction and deformity correction. The electronic prescription derived from the length changes of the six struts were calculated by SolidWorks. Fracture reduction was conducted by adjusting the lengths of the six struts according to the electronic prescription. Effectiveness was evaluated by the standard anteroposterior (AP) and lateral X-rays after reduction. Results All patients acquired excellent functional reduction and achieved bone union in our study. After correction, the mean translation (1.0 ± 1.1 mm) and angulation (0.8 ± 1.2°) on the coronal plane, mean translation (0.8 ± 1.0 mm) and angulation (0.3 ± 0.8°) on the sagittal plane were all less than those (6.1 ± 4.9 mm, 5.2 ± 3.2°, 4.2 ± 3.5 mm, 4.0 ± 2.5°) before correction (P < 0.05). Conclusions The computer-assisted three-dimensional reconstruction and hexapod external fixator-based method allows surgeons to conduct long bone fracture reduction and deformity correction without calculating the parameters needed by the traditional usage. This method is suggested to apply in those unusually complex cases with extensive soft tissue damage and where internal fixation is impossible or inadvisable.

scholarly journals Long Bone Fracture Reduction and Deformity Correction Using the Hexapod External Fixator With a New Method: a Feasible Study and Preliminary Results

2020 ◽  
Author(s):  
Yanshi Liu ◽  
Hong Li ◽  
Jialin Liu ◽  
Xingpeng Zhang ◽  
Maimaiaili Yushan ◽  
...  
Keyword(s):  
External Fixator ◽  
Bone Fracture ◽  
Sagittal Plane ◽  
Three Dimensional ◽  
Deformity Correction ◽  
Fracture Reduction ◽  
Long Bone ◽  
Computer Assisted ◽  
Electronic Prescription ◽  
Long Bone Fracture

Abstract Background: The hexapod external fixator (HEF), such as the Taylor spatial frame (TSF), offering the ability of simultaneous correction of the multidirectional deformities without frame modification, whereas there are so many parameters for surgeons to measure and subjective errors will occur inevitably. The purpose of this study was to evaluate the effectiveness of a new method based on computer-assisted three-dimensional (3D) reconstruction and hexapod external fixator for long bone fracture reduction and deformity correction without calculating the parameters needed by the computer program.Methods: This retrospective study consists of 25 patients with high-energy tibial diaphyseal fractures treated by the HEF at our institution from January 2016 to June 2018, including 22 males and 3 females with a mean age of 42 years (range 14-63 years). Hexapod external fixator treatments were performed due to primary and definitive management of multiplanar posttraumatic deformity and/or severe soft-tissue damage that were not suitable for internal fixation in the tibia. Computer-assisted 3D reconstruction and trajectory planning of the reduction by Mimics were applied to perform virtual fracture reduction and deformity correction. The electronic prescription derived from the length changes of the six struts were calculated by SolidWorks. Fracture reduction was conducted by adjusting the lengths of the six struts according to the electronic prescription. The standard anteroposterior (AP) and lateral X-rays after reduction were taken to evaluate the effectiveness.Results: All patients acquired excellent functional reduction (most cases achieved anatomical reduction) in our study. The mean coronal plane translation (1.0±1.1 mm), coronal plane angulation (0.8±1.2°), sagittal plane translation (0.8±1.0 mm) and sagittal plane angulation (0.3±0.8°) after correction were all less than those (6.1±4.9 mm, 5.2±3.2°, 4.2±3.5 mm, 4.0±2.5°) before correction (P<0.05).Conclusion: The computer-assisted three-dimensional reconstruction and hexapod external fixator-based method allows surgeons to conduct long bone fracture reduction and deformity correction without calculating the parameters needed by the computer program. Considering the radiologic exposure, this method is suggested to apply in those unusually complex cases with extensive soft tissue damage and internal fixation is impossible or inadvisable.

Clinical Value of Computer-Assisted Taylor Three-dimensional External Fixation in the Treatment of Tibiofibular Fracture (Preprint)

2020 ◽  
Author(s):  
Hongfeng Sheng ◽  
Weixing Xu ◽  
Bin Xu ◽  
Hongpu Song ◽  
Di Lu ◽  
...  
Keyword(s):  
Retrospective Study ◽  
Internal Fixation ◽  
External Fixation ◽  
External Fixator ◽  
Theoretical Basis ◽  
New Technology ◽  
Three Dimensional ◽  
Computer Assisted ◽  
Clinical Value

UNSTRUCTURED The retrospective study of Taylor's three-dimensional external fixator for the treatment of tibiofibular fractures provides a theoretical basis for the application of this technology. The paper collected 28 patients with tibiofibular fractures from the Department of Orthopaedics in our hospital from March 2015 to June 2018. After the treatment, the follow-up evaluation of Taylor's three-dimensional external fixator for the treatment of tibiofibular fractures and concurrency the incidence of the disease, as well as the efficacy and occurrence of the internal fixation of the treatment of tibial fractures in our hospital. The results showed that Taylor's three-dimensional external fixator was superior to orthopaedics in the treatment of tibiofibular fractures in terms of efficacy and complications. To this end, the thesis research can be concluded as follows: Taylor three-dimensional external fixation in the treatment of tibiofibular fractures is more effective, and the incidence of occurrence is low, is a new technology for the treatment of tibiofibular fractures, it is worthy of clinical promotion.

scholarly journals The Effect of Lateral Column Lengthening on Subtalar Motion: Are We Trading Deformity for Stiffness?

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0004
Author(s):  
Brittany Hedrick ◽  
Anthony Riccio ◽  
Danielle M. Thomas ◽  
Claire Shivers ◽  
Matthew Siebert ◽  
...  
Keyword(s):  
Motion Capture ◽  
Three Dimensional ◽  
Deformity Correction ◽  
Porous Titanium ◽  
Testing System ◽  
Materials Testing ◽  
Lateral Column ◽  
Fresh Frozen ◽  
Lateral Column Lengthening ◽  
Paired T Test

Category: Hindfoot; Other Introduction/Purpose: While lengthening of the lateral column through a calcaneal neck osteotomy is an integral component of flatfoot reconstruction in younger patients with flexible planovalgus deformities, concern exists as to the effect of this intra- articular osteotomy on subtalar motion. The purpose of this study is to quantify the alterations in subtalar motion following lateral column lengthening (LCL). Methods: The subtalar motion of 14 fresh frozen cadaveric feet was assessed using a three-dimensional motion capture system and materials testing system (MTS). Following potting of the tibia and calcaneus, optic markers were placed into the tibia, calcaneus and talus. The MTS was used to apply a rotational force across the subtalar joint to a torque of 5Nm. Abduction/adduction, supination/pronation, and plantarflexion/dorsiflexion about the talus was recorded. Specimens then underwent LCL via a calcaneal neck osteotomy which was maintained with a 12mm porous titanium wedge. Repeat subtalar motion analysis was performed and compared to pre-LCL motion using a paired t-test. Results:: No statistically significant differences in subtalar abduction/adduction (10.9O vs. 11.8O degrees, p=.48), supination/pronation (3.5O vs. 2.7O, p=.31), or plantarflexion/dorsiflexion (1.6O vs 1.0O, p=.10) were identified following LCL. Conclusion:: No significant changes in subtalar motion were observed following lateral column lengthening in this biomechanical cadaveric study. While these findings do not obviate concerns of clinical subtalar stiffness following planovalgus deformity correction, they suggest that diminished postoperative subtalar motion may be due to soft tissue scarring rather than alterations of joint anatomy.

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