Patellar Maltracking: No Longer Just a 2D Problem

2003 ◽  
Author(s):  
Andrea J. Rebmann ◽  
Barry P. Boden ◽  
Frances T. Sheehan
Keyword(s):  
Degrees Of Freedom ◽  
Measurement Techniques ◽  
Two Dimensions ◽  
Future Research ◽  
Joint Mechanics ◽  
Patellar Tilt ◽  
Six Degrees Of Freedom ◽  
Patellar Maltracking ◽  
Clinical Diagnoses

In order to correctly diagnose and treat pathological knee joint mechanics we must be able to non-invasively quantify the 3D in vivo kinematics of this joint. Unfortunately, the majority of clinical diagnoses, for this joint, are based upon static 2D imaging. This is due to the fact that currently there is a scarcity of noninvasive measurement techniques that acquire 3D in vivo data dynamically. Thus, in vivo patellofemoral (PF) kinematic measurements typically compress a 3D time-dependent joint attitude to a static 2D representation. The purpose of this study was to investigate if patellar maltracking is limited to two dimensions, as assumed clinically, or if it is a complete six-degree of freedom problem. To do this, we quantified the 3D patellofemoral and tibiofemoral (TF) kinematics in both healthy individuals and those with suspected patellofemoral maltracking using fast-phase contrast magnetic resonance imaging, a technique developed in our previous work. Our data suggest that variations in kinematics were not confined to the standard axial plane measures (e.g. patellar tilt, patellar subluxation), but variations are exhibited in all six degrees of freedom. Therefore, future clinical diagnoses and interventions along with future research will be most effective if the measures used are broadened to include all six-degrees of freedom.

A Six-Degree-of-Freedom Test System for the Study of Joint Mechanics and Ligament Forces

1995 ◽  
Vol 117 (4) ◽  
pp. 383-389 ◽  
Author(s):  
J. M. Hollis
Keyword(s):  
Degrees Of Freedom ◽  
Test System ◽  
Testing System ◽  
Joint Mechanics ◽  
Six Degrees Of Freedom ◽  
Position Feedback ◽  
Six Degree Of Freedom ◽  
Good Agreement

A joint testing system was designed to transmit a specified motion or force to a joint in all six degrees of freedom (d.o.f.) using a spatial linkage system for position feedback. The precise reproducibility of position provided by this method of position feedback allows determination of in situ ligament forces for external joint loadings. Load on the structure of interest is calculated from six d.o.f. load cell output after the loaded position is reproduced with all other structures removed. In a test of this system, measured loads showed good agreement with applied loads.

Study on the Control Law for Water Trajectory of Unpowered Carrier under Wave Force

2013 ◽  
Vol 401-403 ◽  
pp. 525-530
Author(s):  
Guang Pan ◽  
Yao Shi ◽  
Peng Wang ◽  
Xiao Xu Du
Keyword(s):  
Degrees Of Freedom ◽  
Reference Value ◽  
Wave Theory ◽  
Wave Force ◽  
Calculation Model ◽  
Two Dimensions ◽  
Control Law ◽  
Engineering Research ◽  
Six Degrees Of Freedom ◽  
Movement Stability

During the process of exiting from water, the unpowered carrier launched by submarine will be disturbed by the wave force. It will have impact on the trajectory of carrier. Based on carrier vehicle exiting water requirement the six degrees of freedom mathematical model of carrier was established. The calculation model for wave force was built based on the two dimensions wave theory. The steering sequence of carrier was designed and the process of the carrier out of water was simulated under the influence of wave force. The results show that the vehicle movement stability, the control law is reasonable and the simulation methods and results of engineering research had a certain reference value.

Joint Models, Degrees of Freedom, and Anatomical Motion Measurement

1983 ◽  
Vol 105 (1) ◽  
pp. 55-62 ◽  
Author(s):  
G. L. Kinzel ◽  
L. J. Gutkowski
Keyword(s):  
Measurement Technique ◽  
Degrees Of Freedom ◽  
Measurement Techniques ◽  
Kinematic Model ◽  
Joint Motion ◽  
Review Of The Literature ◽  
Joint Models ◽  
Motion Measurement ◽  
Six Degrees Of Freedom ◽  
Six Degree Of Freedom

When the motion associated with an anatomical joint is to be measured, a kinematic model for the joint must first be established. The joint model will have from one to six degrees of freedom, and both the measurement technique and the means used to describe the motion will be influenced by the model and its degrees of freedom. This paper discusses the modeling and measurement of anatomical joint motion from a kinematics viewpoint. A review of the literature pertaining to measurement techniques, kinematic assumptions, and motion descriptions for anatomical joint motion is presented. One, two, three and six degree-of-freedom models for various anatomical joints have appeared in the literature, and the applicability of these models is compared and discussed.

scholarly journals THE “DUAL” VARIABLES OF YANG-MILLS THEORY AND LOCAL GAUGE-INVARIANT VARIABLES

1996 ◽  
Vol 11 (32) ◽  
pp. 5701-5728 ◽  
Author(s):  
ORI GANOR ◽  
J. SONNENSCHEIN
Keyword(s):  
Degrees Of Freedom ◽  
Two Dimensions ◽  
Three Dimensions ◽  
Two Dimensional ◽  
Gauge Invariant ◽  
Yang Mills ◽  
Six Degrees Of Freedom ◽  
Local Gauge ◽  
Dual Variables ◽  
Topological Part

After adding auxiliary fields and integrating out the original variables, the Yang-Mills action can be expressed in terms of local gauge-invariant variables. This method reproduces the known solution of the two-dimensional SU (N) theory. In more than two dimensions the action splits into a topological part and a part proportional to αs. We demonstrate the procedure for SU (2) in three dimensions where we reproduce a gravitylike theory. We discuss the four-dimensional case as well. We use a cubic expression in the fields as a space-time metric to obtain a covariant Lagrangian. We also show how the four-dimensional SU (2) theory can be expressed in terms of a local action with six degrees of freedom only.

An Experiment for the Study of Free-Flying Supercavitating Projectiles

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Peter J. K. Cameron ◽  
Peter H. Rogers ◽  
John W. Doane ◽  
David H. Gifford
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Measurement Techniques ◽  
Theoretical Models ◽  
Dynamics Simulation ◽  
Small Scale ◽  
Successful Operation ◽  
Six Degrees Of Freedom ◽  
Impact Location ◽  
Simulation Based

Applications and research utilizing supercavitation for high-speed underwater flight has motivated study of the phenomenon. In this work, a small scale laboratory experiment for studying supercavitating projectiles has been designed, built, and tested. Similar existing experimental work has been documented in literature but using large, elaborate facilities, or has been presented with ambiguous conclusions from test results. The projectiles were 63.5 mm in length and traveled at speeds on the order of 145 m/s. Measurement techniques are discussed and used to record projectile speed, supercavity dimensions, and target impact location. Experimental observations are compared with a six degrees-of-freedom dynamics simulation based on theoretical models presented in literature for predicting supercavity shape and hydrodynamic forces on the supercavitating projectile during flight. Experimental observations are discussed qualitatively, along with quantitative statistics of the measurements made. Successful operation of the experiment has been demonstrated and verified by agreement with theoretical models.

Do SiNx coatings bear the potential to reduce the risk of micromotion in modular taper junctions?

2020 ◽  
Vol 234 (9) ◽  
pp. 897-908
Author(s):  
Henning Haschke ◽  
Adrian Falkenberg ◽  
Michael M Morlock ◽  
Gerd Huber
Keyword(s):  
Degrees Of Freedom ◽  
Hip Prosthesis ◽  
Joint Arthroplasty ◽  
Daily Activities ◽  
Clinical Failure ◽  
Metal Contacts ◽  
Six Degrees Of Freedom ◽  
Metal On Metal ◽  
Corrosion Risk

Fretting corrosion is one contributor to the clinical failure of modular joint arthroplasty. It is initiated by micromotion in metal junctions exposed to fluids. Omitting metal-on-metal contacts could help to reduce the corrosion risk. The coating of one metal taper partner with a ceramic-based silicon nitride (SiNx) coating might provide this separation. The aim of the study was to identify whether a SiNx coating of the male taper component influences the micromotion within a taper junction. Hip prosthesis heads made of CoCr29Mo6 (Aesculap) and Ti6Al4V (Peter Brehm) were assembled (2000 N) to SiNx-coated and uncoated stem tapers made of Ti6Al4V and CoCr29Mo6 (2×2×2 combinations, each n = 4). Consecutive sinusoidal loading representing three daily activities was applied. Contactless relative motion in six degrees of freedom was measured using six eddy-current sensors. Micromotion in the junction was determined by compensating for the elastic deformation derived from additional monoblock measurements. After pull-off, the taper surfaces were microscopically inspected. Micromotion magnitude reached up to 8.4 ± 0.8 µm during loading that represented stumbling. Ti6Al4V stems showed significantly higher micromotion than those made of CoCr29Mo6, while taper coating had no influence. Statistical differences in pull-off forces were found for none of the taper junctions. Microscopy revealed CoCr29Mo6 abrasion from the head taper surface if combined with coated stem tapers. Higher micromotion of Ti6Al4V tapers was probably caused by the lower Young’s modulus. Even in the contact areas, the coating was not damaged during loading. The mechanics of coated tapers was similar to uncoated prostheses. Thus, the separation of the two metal surfaces with the objective to reduce in vivo corrosion appears to be achievable if the coating is able to withstand in vivo conditions. However, the hard ceramic-based stem coating lead to undesirable debris from the CoCr29Mo6 heads during loading.

In vivo and noninvasive six degrees of freedom patellar tracking during voluntary knee movement

2003 ◽  
Vol 18 (5) ◽  
pp. 401-409 ◽  
Author(s):  
Fang Lin ◽  
Mohsen Makhsous ◽  
Alison H. Chang ◽  
Ronald W. Hendrix ◽  
Li-Qun Zhang
Keyword(s):  
Degrees Of Freedom ◽  
Patellar Tracking ◽  
Six Degrees Of Freedom ◽  
Knee Movement

J0210301 Evaluation for the Length Patterns in the Posterior Cruciate Ligament of Knee Based on the Motion Analysis of Six Degrees of Freedom In Vivo

2014 ◽  
Vol 2014 (0) ◽  
pp. _J0210301--_J0210301-
Author(s):  
Yoshitaka SHIRAISHI ◽  
Kazunori HINO ◽  
Yoshio ONISHI ◽  
Tatsuhiko KUTSUNA ◽  
Kazuho NISHIMATSU ◽  
...  
Keyword(s):  
Posterior Cruciate Ligament ◽  
Motion Analysis ◽  
Degrees Of Freedom ◽  
Cruciate Ligament ◽  
Six Degrees Of Freedom

scholarly journals Simultaneous Constant Velocity Measurement of the Motion Errors of Linear Axes

2020 ◽  
Vol 14 (3) ◽  
pp. 417-428
Author(s):  
Jonathan Miller ◽  
Simon Fletcher ◽  
Andrew Longstaff ◽  
Simon Parkinson ◽  
◽  
...  
Keyword(s):  
Constant Velocity ◽  
Degrees Of Freedom ◽  
Measurement Techniques ◽  
Correlation Coefficients ◽  
Ball Screw ◽  
Current Standard ◽  
Six Degrees Of Freedom ◽  
Static Measurement ◽  
Pitch Error ◽  
Full Effect

The current standard for machine tool calibration supports the use of quasi-static measurement techniques. When measuring the six degrees of freedom motion errors, the measurements are typically taken consecutively. This introduces uncertainty when comparing the results due to machine deformation during individual measurements. Furthermore, quasi-static measurement techniques are known to be time consuming, a problem that is exacerbated as each degree of freedom must be measured separately. Additionally, the spatial resolution between the selected target positions can have an impact on calibration quality. In the following paper, the benefits of measuring the six motion errors simultaneously while the axis under test is traversing at a nominally constant velocity are presented. Firstly, the motivation for simultaneous continuous capture is presented. Secondly, continuous motion measurements are compared with quasi-static measurements for the six degrees of freedom motion errors showing sub-micrometer and sub-arcsecond correlation. The full effect of a ball screw pitch error is shown which can be missed using traditional quasi-static measurement techniques. Finally, wavelet analysis is performed for further spatial diagnostics along with correlation coefficients calculated to quantify the linear dependency between the six error motions.

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