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.

Development of a Human Symbiotic Assist Arm “PAS-Arm” (Experimental System and Creation of Virtual Guiding Surfaces)

2013 ◽  
Vol 25 (2) ◽  
pp. 285-293 ◽  
Author(s):  
Mineo Higuchi ◽  
◽  
Tsukasa Ogasawara ◽  
Keyword(s):  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Experimental System ◽  
Major Axis ◽  
Experimental Results ◽  
Physical Interaction ◽  
Assist Device ◽  
Two Degrees Of Freedom ◽  
Direct Physical Interaction ◽  
Continuously Variable Transmissions

We describe a new robotic assist device: the passive assist arm (PAS-Arm). PAS-Arms are intended for direct physical interaction with a human operator. PASArms are physically passive. The force to manipulate the arm end must be provided by the operator. Their purpose is not to enhance human strength, but to provide virtual guiding surfaces that constrain and guide the motion of the operator. PAS-Arms have three joints and a three dimensional workspace, but possess only two degrees of freedom due to the reduction of degrees of freedom created by a combination of Continuously Variable Transmissions (CVTs) and differential gears. In this paper, we first discuss the manipulability ellipsoid for the PAS-Arm. The major axis of the ellipsoid is the direction in which the arm end may be easily manipulated, and vice versa. We have developed an experimental system for the PAS-Arm. The CVTs of the experimental system may not adjust the transmission ratio to zero. Second, we describe an algorithm to address that problem. Finally, we present initial experiments that verify the PAS-Arm mechanism. The experimental results successfully produced virtual guiding surfaces.1 1. This paper is the full translation from the transactions of JSME, Series C, Vol.76, No.763, pp. 611-618, 2010.

Helical Axis Data Visualization and Analysis of the Knee Joint Articulation

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Ricardo Manuel Millán Vaquero ◽  
Alexander Vais ◽  
Sean Dean Lynch ◽  
Jan Rzepecki ◽  
Karl-Ingo Friese ◽  
...  
Keyword(s):  
Knee Joint ◽  
Lie Algebra ◽  
Degrees Of Freedom ◽  
Spatial Scales ◽  
Three Dimensional ◽  
Patient Specific ◽  
Helical Axis ◽  
Accurate Analysis ◽  
Related Data ◽  
Flexion Extension

We present processing methods and visualization techniques for accurately characterizing and interpreting kinematical data of flexion–extension motion of the knee joint based on helical axes. We make use of the Lie group of rigid body motions and particularly its Lie algebra for a natural representation of motion sequences. This allows to analyze and compute the finite helical axis (FHA) and instantaneous helical axis (IHA) in a unified way without redundant degrees of freedom or singularities. A polynomial fitting based on Legendre polynomials within the Lie algebra is applied to provide a smooth description of a given discrete knee motion sequence which is essential for obtaining stable instantaneous helical axes for further analysis. Moreover, this allows for an efficient overall similarity comparison across several motion sequences in order to differentiate among several cases. Our approach combines a specifically designed patient-specific three-dimensional visualization basing on the processed helical axes information and incorporating computed tomography (CT) scans for an intuitive interpretation of the axes and their geometrical relation with respect to the knee joint anatomy. In addition, in the context of the study of diseases affecting the musculoskeletal articulation, we propose to integrate the above tools into a multiscale framework for exploring related data sets distributed across multiple spatial scales. We demonstrate the utility of our methods, exemplarily processing a collection of motion sequences acquired from experimental data involving several surgery techniques. Our approach enables an accurate analysis, visualization and comparison of knee joint articulation, contributing to the evaluation and diagnosis in medical applications.

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.

Simulation of the human intracranial arterial tree

2009 ◽  
Vol 367 (1896) ◽  
pp. 2371-2386 ◽  
Author(s):  
Leopold Grinberg ◽  
Tomer Anor ◽  
Elizabeth Cheever ◽  
Joseph R. Madsen ◽  
George Em Karniadakis
Keyword(s):  
Degrees Of Freedom ◽  
Domain Decomposition Method ◽  
Three Dimensional ◽  
Control Flow ◽  
Patient Specific ◽  
Arterial Tree ◽  
Flow Equations ◽  
Outflow Boundary Condition ◽  
New Type ◽  
Outflow Boundary

High-resolution unsteady three-dimensional flow simulations in large intracranial arterial networks of a healthy subject and a patient with hydrocephalus have been performed. The large size of the computational domains requires the use of thousands of computer processors and solution of the flow equations with approximately one billion degrees of freedom. We have developed and implemented a two-level domain decomposition method, and a new type of outflow boundary condition to control flow rates at tens of terminal vessels of the arterial network. In this paper, we demonstrate the flow patterns in the normal and abnormal intracranial arterial networks using patient-specific data.

scholarly journals Accuracy of an automated three-dimensional technique for the computation of femoral angles in dogs

2019 ◽  
Vol 185 (14) ◽  
pp. 443-443 ◽  
Author(s):  
Federico Longo ◽  
Gianpaolo Savio ◽  
Barbara Contiero ◽  
Roberto Meneghello ◽  
Gianmaria Concheri ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Three Dimensional ◽  
Deformity Correction ◽  
Patient Specific ◽  
3D Scanner ◽  
Measurement Variability ◽  
Reliable Technique ◽  
Gold Standard Method ◽  
Femoral Torsion ◽  
Custom Made

Aims: The purpose of the study was to evaluate the accuracy of a three-dimensional (3D) automated technique (computer-aided design (aCAD)) for the measurement of three canine femoral angles: anatomical lateral distal femoral angle (aLDFA), femoral neck angle (FNA) and femoral torsion angle.Methods:Twenty-eight femurs equally divided intotwo groups (normal and abnormal) were obtained from 14 dogs of different conformations (dolicomorphic and chondrodystrophicCT scans and 3D scanner acquisitions were used to create stereolithographic (STL) files , which were run in a CAD platform. Two blinded observers separately performed the measurements using the STL obtained from CT scans (CT aCAD) and 3D scanner (3D aCAD), which was considered the gold standard method. C orrelation coefficients were used to investigate the strength of the relationship between the two measurements.Results: A ccuracy of the aCAD computation was good, being always above the threshold of R2 of greater than 80 per cent for all three angles assessed in both groups. a LDFA and FNA were the most accurate angles (accuracy >90 per cent).Conclusions: The proposed 3D aCAD protocol can be considered a reliable technique to assess femoral angle measurements in canine femur. The developed algorithm automatically calculates the femoral angles in 3D, thus considering the subjective intrinsic femur morphology. The main benefit relies on a fast user-independent computation, which avoids user-related measurement variability. The accuracy of 3D details may be helpful for patellar luxation and femoral bone deformity correction, as well as for the design of patient- specific, custom-made hip prosthesis implants.

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.

Calcaneal Lengthening: Investigation of Deformity Correction in a Cadaver Flatfoot Model

2005 ◽  
Vol 26 (2) ◽  
pp. 166-170 ◽  
Author(s):  
Timothy A. DuMontier ◽  
Alexis Falicov ◽  
Vincent Mosca ◽  
Bruce Sangeorzan
Keyword(s):  
Soft Tissues ◽  
Three Dimensional ◽  
Deformity Correction ◽  
Valgus Deformity ◽  
Cadaver Study ◽  
Lateral Column ◽  
Dimensional Changes ◽  
Computed Tomographic ◽  
Structural Bone Graft ◽  
Calcaneal Lengthening

Background: Evans showed that lengthening the lateral column by inserting structural bone graft into the anterior calcaneus could correct abduction and valgus deformity in flatfoot. To better understand the mechanism of correction and the three-dimensional effect of this procedure a cadaver study was done. Methods: Three cadaver flatfoot models were used. Computed tomographic (CT) scans were made of each specimen before and after lengthening. Data from these scans were used to determine the center of volume of the talus, navicular, cuboid, and calcaneus. The angular and translational motions for each bone were determined. Results: On average, relative to the talus, the navicular moved 18.6 degrees of rotation in adduction, 2.6 degrees of rotation in pronation, and 3.4 degrees in plantarflexion. The average translation was 5.6 mm medial, 0.4 mm posterior, and 1.8 mm plantar. The cuboid moved an average of 24.2 degrees of rotation in adduction and lengthening, 13.9 degrees in pronation, and 1.9 degrees in plantarflexion. The average translation was 9.4 mm medial, 2.6 mm distal, and 1.5 mm plantar. The calcaneus moved an average of 4.4 degrees of rotation in adduction, 0.1 degrees of rotation in eversion, and 1.3 degrees of plantarflexion. The average translation was 3 mm medial and 0.7 mm posterior with no plantar translation. Conclusions: The mechanism of Evans calcaneal lengthening involves adduction and plantarflexion of the midfoot relative to the hindfoot. The cuboid and navicular appear to move as a unit. The shape of the talar head, axis of the subtalar joint, degree of initial deformity, competence of plantar soft tissues, such as the long plantar ligament, and adequate length of the Achilles tendon are important. Knowing what qualitative three-dimensional changes take place allows a better understanding of the mechanics of the procedure and its possible applications.

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.

A Viscous/Inviscid Interactive Approach for the Prediction of Performance of Hydrofoils and Propellers with Nonzero Trailing Edge Thickness

2011 ◽  
Vol 55 (01) ◽  
pp. 45-63
Author(s):  
Yulin Pan ◽  
Yulin Pan
Keyword(s):  
Degrees Of Freedom ◽  
Iterative Scheme ◽  
Three Dimensional ◽  
Current Method ◽  
3D Models ◽  
Cavity Surface ◽  
Two Dimensional ◽  
Cavity Pressure ◽  
Interactive Approach ◽  
Trailing Edge

A viscous/inviscid interactive (VII) approach is applied to predict the performance of hydrofoils and propellers with nonzero trailing edge thickness. The emphasis has been put on developing VII models for flow separation. The investigation starts from a two-dimensional (2D) hydrofoil. The current method uses an iterative scheme to find a nonlifting closing extension behind the trailing edge. Two kinds of schemes are applied for the iteration process:a non-lifting extension with 1 or 2 degrees of freedom, in fully wetted condition andan extension which is treated like a cavity surface, but with a nonconstant cavity pressure distribution. The results from these schemes are compared with those from a commercial RANS Solver (Fluent). Next, the current schemes using flap extensions are extended to three-dimensional (3D) propeller flows. The 3D models are developed so that all the span-wise strips of the propeller satisfy similar conditions to those used in 2D. A propeller with significant nonzero trailing edge thickness is analyzed, using several 3D models, and the results are compared with existing experimental data.

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