Accuracy assessment of surgical planning and three-dimensional-printed patient-specific guides for orthopaedic osteotomies

2017 ◽  
Vol 231 (6) ◽  
pp. 499-508 ◽  
Author(s):  
Gwen Sys ◽  
Hannelore Eykens ◽  
Gerlinde Lenaerts ◽  
Felix Shumelinsky ◽  
Cedric Robbrecht ◽  
...  
Keyword(s):  
Accuracy Assessment ◽  
Average Distance ◽  
Three Dimensional ◽  
Patient Specific ◽  
Second Phase ◽  
Experimental Setup ◽  
Operative Planning ◽  
The Difference ◽  
Two Phases ◽  
Improved Accuracy

This study analyses the accuracy of three-dimensional pre-operative planning and patient-specific guides for orthopaedic osteotomies. To this end, patient-specific guides were compared to the classical freehand method in an experimental setup with saw bones in two phases. In the first phase, the effect of guide design and oscillating versus reciprocating saws was analysed. The difference between target and performed cuts was quantified by the average distance deviation and average angular deviations in the sagittal and coronal planes for the different osteotomies. The results indicated that for one model osteotomy, the use of guides resulted in a more accurate cut when compared to the freehand technique. Reciprocating saws and slot guides improved accuracy in all planes, while oscillating saws and open guides lead to larger deviations from the planned cut. In the second phase, the accuracy of transfer of the planning to the surgical field with slot guides and a reciprocating saw was assessed and compared to the classical planning and freehand cutting method. The pre-operative plan was transferred with high accuracy. Three-dimensional-printed patient-specific guides improve the accuracy of osteotomies and bony resections in an experimental setup compared to conventional freehand methods. The improved accuracy is related to (1) a detailed and qualitative pre-operative plan and (2) an accurate transfer of the planning to the operation room with patient-specific guides by an accurate guidance of the surgical tools to perform the desired cuts.

scholarly journals Biphasic pattern in the effect of severe measles infection; the difference between additive and multiplicative scale

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nhat Thanh Hoang Le ◽  
Nhan Thi Ho ◽  
Bryan Grenfell ◽  
Stephen Baker ◽  
Ronald B. Geskus
Keyword(s):  
Infectious Diseases ◽  
Hospital Admission ◽  
Measles Virus ◽  
Hospital Admissions ◽  
Admission Rate ◽  
Second Phase ◽  
Before And After ◽  
The Difference ◽  
Two Phases ◽  
Additive Scale

Abstract Background Infection with measles virus (MeV) causes immunosuppression and increased susceptibility to other infectious diseases. Only few studies reported a duration of immunosuppression, with varying results. We investigated the effect of immunosuppression on the incidence of hospital admissions for infectious diseases in Vietnamese children. Methods We used retrospective data (2005 to 2015; N = 4419) from the two pediatric hospitals in Ho Chi Minh City, Vietnam. We compared the age-specific incidence of hospital admission for infectious diseases before and after hospitalization for measles. We fitted a Poisson regression model that included gender, current age, and time since measles to obtain a multiplicative effect measure. Estimates were transformed to the additive scale. Results We observed two phases in the incidence of hospital admission after measles. The first phase started with a fourfold increased rate of admissions during the first month after measles, dropping to a level quite comparable to children of the same age before measles. In the second phase, lasting until at least 6 years after measles, the admission rate decreased further, with values up to 20 times lower than in children of the same age before measles. However, on the additive scale the effect size in the second phase was much smaller than in the first phase. Conclusion The first phase highlights the public health benefits of measles vaccination by preventing measles and immune amnesia. The beneficial second phase is interesting, but its strength strongly depends on the scale. It suggests a complicated interaction between MeV infection and the host immunity.

scholarly journals Numerical Parametric Study of Paravalvular Leak Following a Transcatheter Aortic Valve Deployment Into a Patient-Specific Aortic Root

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Wenbin Mao ◽  
Qian Wang ◽  
Susheel Kodali ◽  
Wei Sun
Keyword(s):  
Aortic Valve ◽  
Computational Model ◽  
Aortic Root ◽  
Paravalvular Leak ◽  
Patient Specific ◽  
Fe Method ◽  
Transcatheter Aortic Valve ◽  
Operative Planning ◽  
The Difference ◽  
The Impact

Paravalvular leak (PVL) is a relatively frequent complication after transcatheter aortic valve replacement (TAVR) with increased mortality. Currently, there is no effective method to pre-operatively predict and prevent PVL. In this study, we developed a computational model to predict the severity of PVL after TAVR. Nonlinear finite element (FE) method was used to simulate a self-expandable CoreValve deployment into a patient-specific aortic root, specified with human material properties of aortic tissues. Subsequently, computational fluid dynamics (CFD) simulations were performed using the post-TAVR geometries from the FE simulation, and a parametric investigation of the impact of the transcatheter aortic valve (TAV) skirt shape, TAV orientation, and deployment height on PVL was conducted. The predicted PVL was in good agreement with the echocardiography data. Due to the scallop shape of CoreValve skirt, the difference of PVL due to TAV orientation can be as large as 40%. Although the stent thickness is small compared to the aortic annulus size, we found that inappropriate modeling of it can lead to an underestimation of PVL up to 10 ml/beat. Moreover, the deployment height could significantly alter the extent and the distribution of regurgitant jets, which results in a change of leaking volume up to 70%. Further investigation in a large cohort of patients is warranted to verify the accuracy of our model. This study demonstrated that a rigorously developed patient-specific computational model can provide useful insights into underlying mechanisms causing PVL and potentially assist in pre-operative planning for TAVR to minimize PVL.

scholarly journals Accuracy Assessment of Molded, Patient-Specific Polymethylmethacrylate Craniofacial Implants Compared to Their 3D Printed Originals

2020 ◽  
Vol 9 (3) ◽  
pp. 832 ◽  
Author(s):  
Dave Chamo ◽  
Bilal Msallem ◽  
Neha Sharma ◽  
Soheila Aghlmandi ◽  
Christoph Kunz ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Accuracy Assessment ◽  
Three Dimensional ◽  
Production Costs ◽  
Patient Specific ◽  
Patient Specific Implants ◽  
3D Printed ◽  
Cost Efficient ◽  
Craniofacial Implants ◽  
Aided Design

The use of patient-specific implants (PSIs) in craniofacial surgery is often limited due to a lack of expertise and/or production costs. Therefore, a simple and cost-efficient template-based fabrication workflow has been developed to overcome these disadvantages. The aim of this study is to assess the accuracy of PSIs made from their original templates. For a representative cranial defect (CRD) and a temporo-orbital defect (TOD), ten PSIs were made from polymethylmethacrylate (PMMA) using computer-aided design (CAD) and three-dimensional (3D) printing technology. These customized implants were measured and compared with their original 3D printed templates. The implants for the CRD revealed a root mean square (RMS) value ranging from 1.128 to 0.469 mm with a median RMS (Q1 to Q3) of 0.574 (0.528 to 0.701) mm. Those for the TOD revealed an RMS value ranging from 1.079 to 0.630 mm with a median RMS (Q1 to Q3) of 0.843 (0.635 to 0.943) mm. This study demonstrates that a highly precise duplication of PSIs can be achieved using this template-molding workflow. Thus, virtually planned implants can be accurately transferred into haptic PSIs. This workflow appears to offer a sophisticated solution for craniofacial reconstruction and continues to prove itself in daily clinical practice.

scholarly journals A New Model for Nuclear Envelope Breakdown

2001 ◽  
Vol 12 (2) ◽  
pp. 503-510 ◽  
Author(s):  
Mark Terasaki ◽  
Paul Campagnola ◽  
Melissa M. Rolls ◽  
Pascal A. Stein ◽  
Jan Ellenberg ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Fluorescent Protein ◽  
Three Dimensional ◽  
Nuclear Pore ◽  
Permeability Barrier ◽  
Second Phase ◽  
New Model ◽  
Nuclear Envelope Breakdown ◽  
Two Phases ◽  
Green Fluorescent

Nuclear envelope breakdown was investigated during meiotic maturation of starfish oocytes. Fluorescent 70-kDa dextran entry, as monitored by confocal microscopy, consists of two phases, a slow uniform increase and then a massive wave. From quantitative analysis of the first phase of dextran entry, and from imaging of green fluorescent protein chimeras, we conclude that nuclear pore disassembly begins several minutes before nuclear envelope breakdown. The best fit for the second phase of entry is with a spreading disruption of the membrane permeability barrier determined by three-dimensional computer simulations of diffusion. We propose a new model for the mechanism of nuclear envelope breakdown in which disassembly of the nuclear pores leads to a fenestration of the nuclear envelope double membrane.

scholarly journals Boundary conditions of patient-specific fluid dynamics modelling of cavopulmonary connections: possible adaptation of pulmonary resistances results in a critical issue for a virtual surgical planning

2011 ◽  
Vol 1 (3) ◽  
pp. 297-307 ◽  
Author(s):  
Giancarlo Pennati ◽  
Chiara Corsini ◽  
Daria Cosentino ◽  
Tain-Yen Hsia ◽  
Vincenzo S. Luisi ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Boundary Conditions ◽  
Three Dimensional ◽  
Critical Issue ◽  
Patient Specific ◽  
Imaging Data ◽  
Venae Cavae ◽  
Cavopulmonary Anastomosis ◽  
Operative Planning ◽  
The Right

Cavopulmonary connections are surgical procedures used to treat a variety of complex congenital cardiac defects. Virtual pre-operative planning based on in silico patient-specific modelling might become a powerful tool in the surgical decision-making process. For this purpose, three-dimensional models can be easily developed from medical imaging data to investigate individual haemodynamics. However, the definition of patient-specific boundary conditions is still a crucial issue. The present study describes an approach to evaluate the vascular impedance of the right and left lungs on the basis of pre-operative clinical data and numerical simulations. Computational fluid dynamics techniques are applied to a patient with a bidirectional cavopulmonary anastomosis, who later underwent a total cavopulmonary connection (TCPC). Multi-scale models describing the surgical region and the lungs are adopted, while the flow rates measured in the venae cavae are used at the model inlets. Pre-operative and post-operative conditions are investigated; namely, TCPC haemodynamics, which are predicted using patient-specific pre-operative boundary conditions, indicates that the pre-operative balanced lung resistances are not compatible with the TCPC measured flows, suggesting that the pulmonary vascular impedances changed individually after the surgery. These modifications might be the consequence of adaptation to the altered pulmonary blood flows.

scholarly journals TWO PHASES IN THE DEVELOPMENT OF HEDWIG CONRAD-MARTIUS’ ONTOLOGICAL INVESTIGATION ON HUMAN BEING AND LIVING THINGS

2021 ◽  
Vol 10 (2) ◽  
pp. 398-424
Author(s):  
SIMONA BERTOLINI ◽  
Keyword(s):  
Structure Change ◽  
Second Phase ◽  
Human Being ◽  
Human Knowledge ◽  
Living Things ◽  
Ontological Categories ◽  
Biological Ontology ◽  
The Difference ◽  
Two Phases ◽  
Theoretical Results

Interest in the ontological constitution of living beings (with particular reference to the human being) characterizes the whole development of Hedwig Conrad-Martius’ philosophy. Several works written by the philosopher over the years deal with both the phenomenological description and the ontological foundation of the difference between plants, animals, and humans. Specifically, the ontological structure of the human being is investigated as a layered structure which presupposes those of plants and animals while overcoming them in a more complex and spiritual unity, on which human freedom and human knowledge depend. Although this topic maintains a crucial role in Conrad-Martius’ thought, the way the philosopher addresses it and the theoretical results of her phenomenological-ontological inquiry about it do not remain unchanged. Indeed, the ontological structure at the basis of phenomenal differences as well as the metaphysical foundations of this structure change over the decades. This paper aims at distinguishing between two phases, characterized by different ontological categories, through which Conrad-Martius’ anthropology and biological ontology develop. In the first phase, at the beginning of the twenties (precisely in her work Metaphysical Dialogues), the essential differences between plants, animals, and humans are explained with reference to a vital origin preceding the constitution of reality; to describe it Conrad-Martius employs terms such as “abyss” and “under-earthly realm.” In the second phase, exemplified by some writings published in the forties and the fifties, the reference to such a dimension disappears and the eidetic variety within the living world, including human specificity, is exclusively traced back to the finalistic substantiation of essences in the natural beings.

scholarly journals Comparison of post-operative three-dimensional and two-dimensional evaluation of component position for total knee arthroplasty

2021 ◽  
Vol 33 (1) ◽  
Author(s):  
Osamu Tanifuji ◽  
Tomoharu Mochizuki ◽  
Hiroshi Yamagiwa ◽  
Takashi Sato ◽  
Satoshi Watanabe ◽  
...  
Keyword(s):  
Tibial Component ◽  
Sagittal Alignment ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Component Position ◽  
Operative Planning ◽  
Operative Evaluation ◽  
Total Knee ◽  
The Difference ◽  
3D Evaluation

Abstract Purpose The purpose of this study was to evaluate the post-operative three-dimensional (3D) femoral and tibial component positions in total knee arthroplasty (TKA) by the same co-ordinates’ system as for pre-operative planning and to compare it with a two-dimensional (2D) evaluation. Materials and methods Sixty-five primary TKAs due to osteoarthritis were included. A computed tomography (CT) scan of the femur and tibia was obtained and pre-operative 3D planning was performed. Then, 3D and 2D post-operative evaluations of the component positions were performed. KneeCAS (LEXI, Inc., Tokyo, Japan), a lower-extremity alignment assessment system, was used for the 3D post-operative evaluation. Standard short-knee radiographs were used for the 2D post-operative evaluation. Differences between the pre-operative planning and post-operative coronal and sagittal alignment of components were investigated and compared with the results of the 3D and 2D evaluations. Results According to the 3D evaluation, the difference between the pre-operative planning and actual post-operative sagittal alignment of the femoral component and the coronal and sagittal alignments of the tibial component were 2.6° ± 1.8°, 2.2° ± 1.8° and 3.2° ± 2.4°, respectively. Using the 2D evaluation, they were 1.9° ± 1.5°, 1.3° ± 1.2° and 1.8° ± 1.4°, making the difference in 3D evaluation significantly higher (p = 0.013, = 0.003 and < 0.001). For the sagittal alignment of the femoral component and the coronal and sagittal alignment of the tibial component, the outlier (> ± 3°) ratio for the 3D evaluation was also significantly higher than that of the 2D evaluation (p < 0.001, = 0.009 and < 0.001). Conclusions The difference between the pre-operative planning and post-operative component alignment in the 3D evaluation is significantly higher than that of the 2D, even if the same cases have been evaluated. Two-dimensional evaluation may mask or underestimate the post-operative implant malposition. Three-dimensional evaluation using the same co-ordinates’ system as for pre-operative planning is necessary to accurately evaluate the post-operative component position.

Visual Processing of Contour Patterns under Conditions of Inattentional Blindness

2012 ◽  
Vol 24 (2) ◽  
pp. 287-303 ◽  
Author(s):  
Michael A. Pitts ◽  
Antígona Martínez ◽  
Steven A. Hillyard
Keyword(s):  
Visual Processing ◽  
Visual Awareness ◽  
Inattentional Blindness ◽  
Second Phase ◽  
Third Phase ◽  
Random Arrays ◽  
Visual Contour ◽  
The Difference ◽  
Two Phases ◽  
Task Irrelevant

An inattentional blindness paradigm was adapted to measure ERPs elicited by visual contour patterns that were or were not consciously perceived. In the first phase of the experiment, subjects performed an attentionally demanding task while task-irrelevant line segments formed square-shaped patterns or random configurations. After the square patterns had been presented 240 times, subjects' awareness of these patterns was assessed. More than half of all subjects, when queried, failed to notice the square patterns and were thus considered inattentionally blind during this first phase. In the second phase of the experiment, the task and stimuli were the same, but following this phase, all of the subjects reported having seen the patterns. ERPs recorded over the occipital pole differed in amplitude from 220 to 260 msec for the pattern stimuli compared with the random arrays regardless of whether subjects were aware of the patterns. At subsequent latencies (300–340 msec) however, ERPs over bilateral occipital-parietal areas differed between patterns and random arrays only when subjects were aware of the patterns. Finally, in a third phase of the experiment, subjects viewed the same stimuli, but the task was altered so that the patterns became task relevant. Here, the same two difference components were evident but were followed by a series of additional components that were absent in the first two phases of the experiment. We hypothesize that the ERP difference at 220–260 msec reflects neural activity associated with automatic contour integration whereas the difference at 300–340 msec reflects visual awareness, both of which are dissociable from task-related postperceptual processing.

scholarly journals Three-dimensional printing in orthopaedic surgery: a scoping review

2020 ◽  
Vol 5 (7) ◽  
pp. 430-441
Author(s):  
Jasmine N. Levesque ◽  
Ajay Shah ◽  
Seper Ekhtiari ◽  
James R. Yan ◽  
Patrick Thornley ◽  
...  
Keyword(s):  
Orthopaedic Surgery ◽  
Temporal Trends ◽  
Three Dimensional ◽  
Patient Specific ◽  
Three Dimensional Printing ◽  
Operative Outcomes ◽  
Patient Specific Instrumentation ◽  
Wide Range ◽  
Operative Planning ◽  
Dimensional Printing

Three-dimensional printing (3DP) has become more frequently used in surgical specialties in recent years. These uses include pre-operative planning, patient-specific instrumentation (PSI), and patient-specific implant production. The purpose of this review was to understand the current uses of 3DP in orthopaedic surgery, the geographical and temporal trends of its use, and its impact on peri-operative outcomes One-hundred and eight studies (N = 2328) were included, published between 2012 and 2018, with over half based in China. The most commonly used material was titanium. Three-dimensional printing was most commonly reported in trauma (N = 41) and oncology (N = 22). Pre-operative planning was the most common use of 3DP (N = 63), followed by final implants (N = 32) and PSI (N = 22). Take-home message: Overall, 3DP is becoming more common in orthopaedic surgery, with wide range of uses, particularly in complex cases. 3DP may also confer some important peri-operative benefits. Cite this article: EFORT Open Rev 2020;5:430-441. DOI: 10.1302/2058-5241.5.190024

scholarly journals Solving a Real-Life Distributor’s Pallet Loading Problem

2021 ◽  
Vol 26 (3) ◽  
pp. 53
Author(s):  
Mauro Dell’Amico ◽  
Matteo Magnani
Keyword(s):  
Bin Packing ◽  
Real Life ◽  
Second Phase ◽  
Pallet Loading ◽  
Minimum Number ◽  
Loading Problem ◽  
The Difference ◽  
Two Phases ◽  
The Stability ◽  
Selection Of

We consider the distributor’s pallet loading problem where a set of different boxes are packed on the smallest number of pallets by satisfying a given set of constraints. In particular, we refer to a real-life environment where each pallet is loaded with a set of layers made of boxes, and both a stability constraint and a compression constraint must be respected. The stability requirement imposes the following: (a) to load at level k+1 a layer with total area (i.e., the sum of the bottom faces’ area of the boxes present in the layer) not exceeding α times the area of the layer of level k (where α≥1), and (b) to limit with a given threshold the difference between the highest and the lowest box of a layer. The compression constraint defines the maximum weight that each layer k can sustain; hence, the total weight of the layers loaded over k must not exceed that value. Some stability and compression constraints are considered in other works, but to our knowledge, none are defined as faced in a real-life problem. We present a matheuristic approach which works in two phases. In the first, a number of layers are defined using classical 2D bin packing algorithms, applied to a smart selection of boxes. In the second phase, the layers are packed on the minimum number of pallets by means of a specialized MILP model solved with Gurobi. Computational experiments on real-life instances are used to assess the effectiveness of the algorithm.

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