Maximum Total Point Motion of Five Points Versus All Points in Assessing Tibial Baseplate Stability

2021 ◽  
Author(s):  
Abigail Niesen ◽  
Anna L Garverick ◽  
Maury Hull
Keyword(s):  
Degrees Of Freedom ◽  
Stability Limit ◽  
3D Models ◽  
Six Degrees Of Freedom ◽  
Percent Error ◽  
Model Based ◽  
Point Motion ◽  
The Mean ◽  
The Difference ◽  
Total Point

Abstract Maximum total point motion (MTPM), the point on a baseplate that migrates the most, has been used to assess the risk of tibial baseplate loosening using radiostereometric analysis (RSA). Two methods for determining MTPM for model-based RSA are to use either 5 points distributed around the perimeter of the baseplate or to use all points on the 3D model. The objectives were to quantify the mean difference in MTPM using 5 points vs. all points, compute the percent error relative to the 6-month stability limit for groups of patients, and to determine the dependency of differences in MTPM on baseplate size and shape. A dataset of 10,000 migration values was generated using the mean and standard deviation of migration in six degrees of freedom at 6 months from an RSA study. The dataset was used to simulate migration of 3D models (two baseplate shapes and two baseplate sizes) and calculate the difference in MTPM using 5 virtual points vs. all points and the percent error (i.e. difference in MTPM/stability limit) relative to the 6-month stability limit. The difference in MTPM was about 0.02 mm, or 4% percent relative to the 6-month stability limit, which is not clinically important. Furthermore, results were not affected by baseplate shape or size. Researchers can decide whether to use 5 points or all points when computing MTPM for model-based RSA. The authors recommend using 5 points to maintain consistency with marker-based RSA.

scholarly journals Kinematic Analysis of a Six-Degrees-of-Freedom Model Based on ISB Recommendation: A Repeatability Analysis and Comparison with Conventional Gait Model

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Magdalena Żuk ◽  
Celina Pezowicz
Keyword(s):  
Degrees Of Freedom ◽  
External Rotation ◽  
Transverse Plane ◽  
Analysis Model ◽  
Range Of Movement ◽  
Current Standard ◽  
Six Degrees Of Freedom ◽  
Model Based ◽  
The Mean ◽  
Landmark Position

Objective. The purpose of the present work was to assess the validity of a six-degrees-of-freedom gait analysis model based on the ISB recommendation on definitions of joint coordinate systems (ISB 6DOF) through a quantitative comparison with the Helen Hays model (HH) and repeatability assessment.Methods. Four healthy subjects were analysed with both marker sets: an HH marker set and four marker clusters in ISB 6DOF. A navigated pointer was used to indicate the anatomical landmark position in the cluster reference system according to the ISB recommendation. Three gait cycles were selected from the data collected simultaneously for the two marker sets.Results. Two protocols showed good intertrial repeatability, which apart from pelvic rotation did not exceed 2°. The greatest differences between protocols were observed in the transverse plane as well as for knee angles. Knee internal/external rotation revealed the lowest subject-to-subject and interprotocol repeatability and inconsistent patterns for both protocols. Knee range of movement in transverse plane was overestimated for the HH set (the mean is 34°), which could indicate the cross-talk effect.Conclusions. The ISB 6DOF anatomically based protocol enabled full 3D kinematic description of joints according to the current standard with clinically acceptable intertrial repeatability and minimal equipment requirements.

Previously Unrecognized Source of Error in the Change in Maximum Total Point Motion to Determine Continuous Migration of Unstable Tibial Baseplates

2021 ◽  
Author(s):  
Abigail Niesen ◽  
Maury Hull
Keyword(s):  
Stability Limit ◽  
Implicit Assumption ◽  
Independent Variables ◽  
Time Zero ◽  
Error Magnitude ◽  
Point Motion ◽  
The Difference ◽  
Relative Errors ◽  
Total Point ◽  
Source Of Error

Abstract In radiostereometric analysis (RSA), continuous migration denoted as ΔMTPM is the difference between maximum total point motion (MTPM) at 2 years relative to time zero and MTPM at 1 year relative to time zero. Continuous migration has been used to diagnose tibial baseplates as stable versus unstable when compared to a specified stability limit (i.e. value of ΔMTPM). If the same point experiences MTPM at 2 years and at 1 year (usually the case for marker-based RSA), then an implicit assumption is that the migration path between 2 years and 1 year is the same as the path between 1 year and time zero. This paper uses vector analysis to demonstrate a source of error in ΔMTPM not previously recognized and estimates the error magnitude based on the interplay of independent variables which affect the error. The two independent variables which affect the error are the angle between the two migration vectors (i.e., MTPM between time zero and 2 years and MTPM between time zero and 1 year) and the difference in magnitude of the two vectors. The relative error increased in an absolute sense as the angle between the vectors increased and decreased for larger differences in the magnitudes of the two vectors. For magnitude ratios ranging from 1.25 to 2, relative errors ranged from -21% to -3% at 10° and from -78% to -42% at 60°, respectively. Knowledge of these errors highlights a limitation in the use of ΔMTPM not previously recognized.

Research on Network Communication Model of Intelligent Ship Handling Simulator

2011 ◽  
Vol 97-98 ◽  
pp. 787-793 ◽  
Author(s):  
Shen Hua Yang ◽  
Guo Quan Chen ◽  
Xing Hua Wang ◽  
Yue Bin Yang
Keyword(s):  
Mathematical Model ◽  
Degrees Of Freedom ◽  
Communication Process ◽  
Network Communication ◽  
Communication Model ◽  
Test Results ◽  
Six Degrees Of Freedom ◽  
Model Based ◽  
Hydraulic Servo ◽  
Ship Handling

Due to the target ship in the traditional ship handling simulator have not the ability to give way to other ships automatically to avoid collision, this paper put forward a new idea that bringing the hydraulic servo platform, six degrees of freedom ship mathematical model, the actual traffic flow, researching achievement of automatic anti-collision in research of the new pattern ship handling simulator, and successfully develop the Intelligent Ship Handling Simulator(ISHS for short). The paper focuse on the research on the network communication model of ISHS. We took the entire simulator system as three relatively independent networks, proposed a framework of communication network that combined IOCP model based on TCP with blocking model based on UDP, and gave the communication process and protocols of system. Test results indicate that this is an effective way to improve the ownship capacity of ship handling simulator and meet the need of multi-ownship configuration of desktop system of ship handling simulator.

scholarly journals Implementasi Implementasi Metode Bahtsul Masail Berbasis Pendidikan Pesantren untuk Meningkatkan Kemampuan Berpikir Kritis dan Kemampuan Menganalisis Peserta Didik pada Pembelajaran Fisika di SMA

2020 ◽  
Vol 13 (2) ◽  
pp. 50-54
Author(s):  
Sri Jumini ◽  
Jauharotul Insiyyah ◽  
Ahmad Khoiri
Keyword(s):  
Degrees Of Freedom ◽  
Student Thinking ◽  
Control Group ◽  
Control Group Design ◽  
Gain Score ◽  
Significance Level ◽  
Group Design ◽  
Thinking Ability ◽  
The Mean ◽  
The Difference

The aims of this study to (1) determine the student ability of critical think and analyze, using the bahtsul masail method, (2) to find out the difference between the bahtsul masail method and the conventional method in physics learning. The method in this study using a true experimental quantitative method with a pretest-posttest control group design. The population used was all class XI students of SMA NU Al-Ma'ruf Kudus  and samples were students of class XI MIPA 2 and MIPA 4 taken by random sampling techniques. The data collection used the pretest and posttest to determine the effect of the bahtsul masail method. The results shows (1) The student thinking ability using the Bahtsul Masail method get higher results. (2) Based on the results of data analysis using paired t-test, it is obtained tcount of -7.4828 and ttable of 1.67 with a significance level of 5% and degrees of freedom of 58 so that if t <ttable, then Ho is rejected and Ha is accepted; This means that there is a difference between the mean pretest and posttest scores, there is also a positive and significant relationship between the bahtsul masail model with students' critical thinking and analyzing abilities. The N-gain value is obtained by an average N-gain score of 0.5902 in the medium category. And for the N-gain score obtained an average of 59,023 which is categorized as quite effective. Thus the application of the bahtsul masail method is effective enough to be applied in a lesson.

scholarly journals THE DOLLAR/EURO EXCHANGE RATE AND A COMPARISON OF MAJOR MODELS

2009 ◽  
Vol 10 (3) ◽  
pp. 199-205 ◽  
Author(s):  
Yu Hsing ◽  
Bruno S. Sergi
Keyword(s):  
Exchange Rate ◽  
Monetary Model ◽  
Percent Error ◽  
Mean Absolute Percent Error ◽  
Model Based ◽  
The Mean ◽  
Absolute Percent Error

This article analyzes the behaviour of the USD/EUR exchange rate based on four major models. Using the mean absolute percent error (MAPE) as a criterion, the extended Mundell‐Fleming model performs best, followed by the PPP model using the relative PPI, the monetary model, the PPP model using the relative CPI, and the UIP model. The widely used log‐log form in the PPP model based on the relative PPI or CPI can be rejected at the 5% level. The insignificant coefficients or unexpected signs of some variables in the monetary and other models may pose some challenges in applications.

The influence of dead spaces and the designs of injectors on the amount of drug dose in intra-vitreal injection

2020 ◽  
pp. 112067212097782
Author(s):  
Erol Havuz ◽  
Seda Güdül Havuz ◽  
Onur Gokmen
Keyword(s):  
Drug Dose ◽  
Distilled Water ◽  
Becton Dickinson ◽  
Maximum Increase ◽  
Percent Error ◽  
Before And After ◽  
Drug Doses ◽  
The Mean ◽  
The Dead ◽  
The Difference

Aim: To evaluate the dead spaces resulting from different designs of the insulin injectors used for intravitreal injections and the amounts of drug doses. Methods: In the study, five different brands of sterile insulin injectors of 1 mL were used for the test. The weight of the injectors was determined before and after filling the injectors with 0.05 and 0.1 mL distilled water. The weight of the injectors was measured with and without the needle after the water within the injectors had been taken out and weight differences were measured. The difference between the intended amount of fluid to be thrown out and the weight of the fluid remaining in the injector was calculated as percent error. Results: After throwing out 0.05 mL distilled water from the injector, weights of the Beybi®, Traf®, Becton Dickinson®, Ayset®, and Setojet® brands of injectors with 30 G needle were detected to increase the mean 0.0220 ± 0.006 g, 0.0208 ± 0.008 g, 0.0355 ± 0.016 g, 0.0219 ± 0.017 g, and 0.0150 ± 0.007 g, respectively compared to the weights of the dry injectors. The 0.1 mL injector group was found to be mean 0.0350 ± 0.014 g, 0.0264 ± 0.008 g, 0.0405 ± 0.015 g, 0.0272 ± 0.013 g, and 0.0245 ± 0.014 g, respectively. The maximum increase due to the dead spaces in the injectors was found in the Becton Dickinson® injector, both in the 0.05 mL and the 0.1 mL groups ( p < 0.000). Conclusion: The injector designs may affect the dose of IVI required to be given. More correct amounts of drugs may be administered via the intra-vitreal route through designs that reduce the dead spaces at the end part of the injector and between the inner wall and the plunger.

scholarly journals Clinical experience of craniospinal intensity-modulated spot-scanning proton therapy using large fields for central nervous system medulloblastomas and germ cell tumors in children, adolescents, and young adults

2019 ◽  
Vol 60 (4) ◽  
pp. 527-537
Author(s):  
Takayuki Hashimoto ◽  
Shinichi Shimizu ◽  
Seishin Takao ◽  
Shunsuke Terasaka ◽  
Akihiro Iguchi ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Germ Cell Tumors ◽  
Adolescent And Young Adult ◽  
Hematological Toxicity ◽  
Six Degrees Of Freedom ◽  
Intensity Modulated ◽  
Patient Table ◽  
Biological Effectiveness ◽  
The Mean ◽  
Beam Delivery

Abstract The outcomes of intensity-modulated proton craniospinal irradiation (ipCSI) are unclear. We evaluated the clinical benefit of our newly developed ipCSI system that incorporates two gantry-mounted orthogonal online X-ray imagers with a robotic six-degrees-of-freedom patient table. Nine patients (7–19 years old) were treated with ipCSI. The prescribed dose for CSI ranged from 23.4 to 36.0 Gy (relative biological effectiveness) in 13–20 fractions. Four adolescent and young adult (AYA) patients (15 years or older) were treated with vertebral-body-sparing ipCSI (VBSipCSI). Myelosuppression following VBSipCSI was compared with that of eight AYA patients treated with photon CSI at the same institution previously. The mean homogeneity index (HI) in the nine patients was 0.056 (95% confidence interval: 0.044–0.068). The mean time from the start to the end of all beam delivery was 37 min 39 s ± 2 min 24 s (minimum to maximum: 22 min 49 s – 42 min 51 s). The nadir white blood cell, hemoglobin, and platelet levels during the 4 weeks following the end of the CSI were significantly higher in the VBSipCSI group than in the photon CSI group (P = 0.0071, 0.0453, 0.0024, respectively). The levels at 4 weeks after the end of CSI were significantly higher in the VBSipCSI group than in the photon CSI group (P = 0.0023, 0.0414, 0.0061). Image-guided ipCSI was deliverable in a reasonable time with sufficient HI. Using VBSipCSI, AYA patients experienced a lower incidence of serious acute hematological toxicity than AYA patients treated with photon CSI.

PATHS OF FREELY FALLING DISKS

2009 ◽  
Vol 23 (03) ◽  
pp. 373-376 ◽  
Author(s):  
HONGJIE ZHONG ◽  
CUNBIAO LEE
Keyword(s):  
Degrees Of Freedom ◽  
Center Of Mass ◽  
Vertical Plane ◽  
Stereoscopic Vision ◽  
Six Degrees Of Freedom ◽  
Mass Distributions ◽  
First Case ◽  
The Mean ◽  
Thin Disks ◽  
Free Falling

The free falling motion of round thin disks in quiescent water was investigated experimentally. The mean density of the disks were about 1.05 g/cm3, slightly larger than water, and thickness to diameter ratio is 0.1. In this letter, We reported two cases with different mass distributions, in one case the disk's center of mass coincided with the geometry center and in another case it was deviated. Two CCD cameras were used to photograph the falling disk simultaneously, the disk's six degrees of freedom were obtained via a stereoscopic vision method. In the first case fluttering motion was observed, the disk's oscillatory motion confined in a vertical plane, and the pitching motion occurred about an axis normal to the plane. In the second case, steady helical falling was observed, the disk moved in a helical path at constant speed, the attacking angle is constant.

scholarly journals 3D CT Analysis of Distal Tibiofibular Syndesmosis Symmetry

2017 ◽  
Vol 2 (3) ◽  
pp. 2473011417S0000
Author(s):  
Daniel Hoopes ◽  
Bruce Sangeorzan ◽  
William Ledoux ◽  
Connor Pihl ◽  
Kylie Edinger ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
3D Models ◽  
Mean Difference ◽  
Absolute Difference ◽  
3D Ct ◽  
Current Standard ◽  
3D Measurements ◽  
The Mean ◽  
Natural Symmetry ◽  
The Right

Category: Ankle, Trauma Introduction/Purpose: As medical imaging of the syndesmosis prior to ankle injury is usually not available, researchers have diagnosed and surgically reduced syndesmotic disruptions based on presumed symmetry with the healthy contralateral limb. The purposes of this study are to quantify the degree of symmetry present in the DTFS using 3D CT modeling, and to compare the accuracy of common clinical two-dimensional (2D) measurements to 3D CT measurements for assessing syndesmotic symmetry and measuring diastasis. Methods: Bilateral lower limb CT (n=65) were assessed, were segmented, and reconstructed into 3D surface models, and an anatomically-defined coordinate system was applied to orient the 3D models uniformly. Symmetry was assessed three- dimensionally to overlap the left and right. The relative differences between the two fibulae were quantified in six degrees of freedom. For comparative purposes, four 2D measures were also measured. These measures included anteroposterior (AP), mediolateral (ML), and rotational displacement of the fibula relative to the tibia, measured using axial CT, and longitudinal displacement, measured using coronal radiographs. The four measures were automatically calculated using custom software to reduce the influence of inter- and intra-rater variability. The absolute difference was calculated for each 3D and 2D measure. The differences measured represent the amount of translation or rotation needed to match the position of the left fibula to the position of the right fibula after reflection and optimal tibial alignment. Results: The mean difference in AP displacement was approximately double the mean difference in ML displacement for the 2D measurements (1.65 mm vs 0.71 mm), while AP and ML displacement differences for the 3D measurements were comparable (0.57 mm and 0.44 mm). As a general trend, the 2D measurements exhibited larger values of absolute differences than the 3D measurements. The average difference in fibular rotation detected was larger for the 2D measurements (6.1°) than the 3D measurements (0.59°). . The 2D AP displacement differences varied between 1.41 -1.95 mm (95% CI), which is beyond the suggested 1 mm tolerance level. The 3D analog of this measurement varied between 0.47-0.70 mm (95% CI), which is within the suggested threshold. Conclusion: Some clinical reports suggest that 1 mm misalignment can cause pain and require surgical revision, but detecting asymmetry below 1 mm is limited by the quality of clinical 2D imaging. Our findings suggest that the current standard practice of using 2D measures to assess the DTFS may exaggerate the amount of asymmetry present, which may lead to misdiagnoses and subsequent surgical revisions. Natural symmetry exists in uninjured syndesmoses. More accurate comparisons of syndesmotic alignment may be needed to determine the accuracy of DTFS diastasis.

A Model-Free Feature-Based Bi-Planar RSA Method for Kinematic Analysis of Total Knee Arthroplasty

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Shahram Amiri ◽  
Carolyn Anglin ◽  
Kenard Agbanlog ◽  
Bassam A. Masri ◽  
David R. Wilson
Keyword(s):  
Total Knee Arthroplasty ◽  
Knee Arthroplasty ◽  
Kinematic Analysis ◽  
3D Models ◽  
Cement Interface ◽  
Model Based ◽  
Feature Based ◽  
Total Knee ◽  
The Mean

Fluoroscopic imaging is commonly used for assessing relative motions of orthopaedic implants. One limiting factor to in vivo model-based roentgen stereophotogrammetric analysis of total knee arthroplasty is the need for 3D models of the implants.The 3D models of the implant components must be reverse-engineered, if not provided by the company, which makes this method impractical for a clinical study involving many types or sizes of implants. This study introduces a novel feature-based methodology that registers the features at the implant-bone or implant-cement interface of the components that have elementary shapes. These features include pegs with hemispherical heads, and straight, circular or curved edges located on flat faces of the box of the femoral component or the stem geometry of the tibial component. Software was developed to allow easy registration of these features through a graphical user interface. The accuracy and precision of registration for multiple flexion angles from 0 to 120 deg was determined with reference to registered poses of the implants through experiments on bone replica models and also on a cadaver specimen implanted with total knee prostheses. When compared to an equivalent bi-planar model-based registration, the results were comparable: The mean accuracy of this feature-based method was 1.45 deg and 1.03 mm (in comparison to 0.95 deg and 1.32 mm for the model-based approach), and the mean precision was 0.57 deg and 0.26 mm (in comparison to 0.42 deg and 0.44 mm for the model-based approach).The methodology and the developed software can easily accommodate different design of implants with various fixation features. This method can facilitate in vivo kinematic analysis of total knee arthroplasty by eliminating the need for 3D models of the implant components.

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