In Vitro Measurement of the Tracking Pattern of the Human Patella

1999 ◽  
Vol 121 (2) ◽  
pp. 222-228 ◽  
Author(s):  
A. M. Ahmed ◽  
N. A. Duncan ◽  
M. Tanzer
Keyword(s):  
Coefficient Of Variation ◽  
Normal Population ◽  
General Pattern ◽  
Three Dimensional ◽  
Knee Extension ◽  
Flexion Extension ◽  
Average Coefficient ◽  
Fresh Frozen ◽  
Six Degree Of Freedom

This study sought to determine whether a general pattern describing the three-dimensional tracking characteristics of the human patella could be established, and if not, then to determine the extent and nature of interspecimen variations in the characteristics in a normal population. Using 32 fresh-frozen knees subjected to extensor moment magnitudes similar to those in “static-lifting” and “leg-raising against resistance” maneuvers, patellar displacements were measured in the knee extension range 120 to 0 deg. For static-lifting, a constant foot-floor reaction of 334 N was applied. For leg-raising, a constant net quadriceps tension of 668 N was used throughout the extension range. Measurements were taken with a calibrated six-degree-of-freedom electromechanical goniometer and a displacement coordinate system referenced to the geometry of individual specinens. The three patellar displacements in the plane of knee extension/flexion (extension rotation, and anterior and proximal translations) consistently demonstrated the same pattern in the entire knee extension range with an average coefficient of variation of 13 percent. For knee angles greater than 45 deg, the three other displacements (medial lateral translation, and rotations about the anterior–posterior and proximal–distal axes) followed a general pattern. However, for knee angles less than 45 deg, these displacements differed considerably between specimens for each loading condition, both in terms of magnitude (average coefficient of variation: 70 percent), and direction.

Correlation of Patellar Tracking Pattern With Trochlear and Retropatellar Surface Topographies

2000 ◽  
Vol 122 (6) ◽  
pp. 652-660 ◽  
Author(s):  
A. M. Ahmed ◽  
N. A. Duncan
Keyword(s):  
Three Dimensional ◽  
Knee Extension ◽  
The Other ◽  
Lateral Direction ◽  
Dial Gage ◽  
Passive Restraint ◽  
Out Of Plane ◽  
Fresh Frozen ◽  
Six Degree Of Freedom ◽  
Anterior Posterior

The study was aimed to test the hypothesis that in the knee extension range 100 to 30 deg, the patellar “out-of-plane” tracking pattern is controlled by the passive restraint provided by the topographic interaction of the patellofemoral contacting surfaces. The out-of-plane tracking pattern, i.e., the pattern of patellar displacements not in the plane of knee extension/flexion, consists of translation in the medial–lateral direction, and rotations about the anterior–posterior axis (spin) and the proximal–distal axis (tilt). Using 15 fresh-frozen knees subjected to extensor moment magnitudes comparable to those in the “static-lifting” activity (foot-ground reaction=334 N), the patellar displacements were measured using a calibrated six-degree-of-freedom electromechanical goniometer. The topographies of the trochlear and retropatellar surfaces were then measured using a calibrated traveling dial-gage arrangement and the same coordinate system used for the displacement measurements. Three indices were defined to quantify particular natural features of the three-dimensional topographies that are expected to control the patellar displacements. Correlation of the indices with their corresponding displacements showed that topographic interaction was significant in the control of all three displacements. However, for patellar spin, unlike for the other two displacements, the direction of the active quadriceps tension vector was also a significant controlling factor. Patellar medial–lateral translation was found to be controlled dominantly by the trochlear topography, while retropatellar topography also had a significant role in the control of the other two displacements. [S0148-0731(00)01406-0]

Right–Left Differences in Knee Extension Stiffness for the Normal Rat Knee: In Vitro Measurements Using a New Testing Apparatus

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Keith L. Markolf ◽  
Denis Evseenko ◽  
Frank Petrigliano
Keyword(s):  
Joint Stiffness ◽  
Knee Extension ◽  
Angular Rotation ◽  
Joint Injury ◽  
Surgical Interventions ◽  
Testing Apparatus ◽  
Knee Stiffness ◽  
Flexion Extension ◽  
Normal Rat

Knee stiffness following joint injury or immobilization is a common clinical problem, and the rat has been used as a model for studies related to joint stiffness and limitation of motion. Knee stiffness measurements have been reported for the anesthetized rat, but it is difficult to separate the contributions of muscular and ligamentous restraints to the recorded values. in vitro testing of isolated rat knees devoid of musculature allows measurement of joint structural properties alone. In order to measure the effects of therapeutic or surgical interventions designed to alter joint stiffness, the opposite extremity is often used as a control. However, right–left stiffness differences for the normal rat knee have not been reported in the literature. If stiffness changes observed for a treatment group are within the normal right–left variation, validity of the results could be questioned. The objectives of this study were to utilize a new testing apparatus to measure right–left stiffness differences during knee extension in a population of normal rat knees and to document repeatability of the stiffness measurements on successive testing days. Moment versus rotation curves were recorded for 15 right–left pairs of normal rat knees on three consecutive days, with overnight specimen storage in a refrigerator. Each knee was subjected to ten loading–unloading cycles, with the last loading curve used for analysis. Angular rotation (AR), defined here as the change in flexion–extension angle from a specified applied joint moment, is commonly used as a measure of overall joint stiffness. For these tests, ARs were measured from the recorded test curves with a maximum applied extension moment of 100 g cm. Mean rotations for testing days 2 and 3 were 0.81–1.25 deg lower (p < 0.001) than for day 1, but were not significantly different from each other. For each testing day, mean rotations for right knees were 1.12–1.30 deg greater (p < 0.001) than left knees. These right–left stiffness differences should be considered when interpreting the results of knee treatment studies designed to alter knee stiffness when using the opposite extremity as a control.

Reaction Forces and Flexion-Extension Moments Imposed On Functional Spinal Units with Constrained and Unconstrained in Vitro Testing Systems

2021 ◽  
Author(s):  
Jackie D. Zehr ◽  
Jack P. Callaghan
Keyword(s):  
Dynamic Compression ◽  
Peak Load ◽  
In Vitro Testing ◽  
Floating Base ◽  
Flexion Extension ◽  
Fixed Base ◽  
Joint Reaction Forces ◽  
Reaction Forces ◽  
Six Degree Of Freedom

Abstract A mechanical goal of in vitro testing systems is to minimize differences between applied and actual forces and moments experienced by spinal units. This study quantified the joint reaction forces and reaction flexion-extension moments during dynamic compression loading imposed throughout the physiological flexion-extension range-of-motion. Constrained (fixed base) and unconstrained (floating base) testing systems were compared. Sixteen porcine spinal units were assigned to both testing groups. Following conditioning tests, specimens were dynamically loaded for 1 cycle with a 1 Hz compression waveform to a peak load of 1 kN and 2 kN while positioned in five different postures (neutral, 100% and 300% of the flexion and extension neutral zone), totalling ten trials per FSU. A six degree-of-freedom force and torque sensor was used to measure peak reaction forces and moments for each trial. Shear reaction forces were significantly greater (25.5 N - 85.7 N) when the testing system was constrained compared to unconstrained (p &lt; 0.029). The reaction moment was influenced by posture (p = 0.037), particularly in C5C6 spinal units. In 300% extension (C5C6), the reaction moment was, on average, 9.9 Nm greater than the applied moment in both testing systems and differed from all other postures (p &lt; 0.001). The reaction moment error was, on average, 0.45 Nm at all other postures. In conclusion, these findings demonstrate that comparable reaction moments can be achieved with unconstrained systems, but without inducing appreciable shear reaction forces.

Design and Development of an Unconstrained Dynamic Knee Simulator

1993 ◽  
Vol 115 (2) ◽  
pp. 144-148 ◽  
Author(s):  
C. A. McLean ◽  
A. M. Ahmed
Keyword(s):  
Mechanical Response ◽  
Dynamic Activity ◽  
Walking Gait ◽  
Knee Simulator ◽  
In Vitro Investigation ◽  
Flexion Extension ◽  
Time Histories ◽  
Fresh Frozen ◽  
Force Components

A dynamic knee simulator has been developed to allow in-vitro investigation of the mechanical response of the joint corresponding to dynamic functional activities, e.g., walking. In the simulator, the controlled inputs are the time-histories of three parameters of a given dynamic activity: the flexion angle, and the flexion/extension moment and tibial axial force components of the foot-to-floor reaction. A combination of stepping motors and electro-hydraulic actuators is used to apply to a knee specimen, simultaneously and independently, the specified load and/or displacement inputs while allowing unconstrained relative motion between the joint members. Satisfactory performance of the simulator has been established for walking gait conditions based on measurements on three fresh-frozen specimens.

Three-dimensional patellar motion at the natural knee during passive flexion/extension. An in vitro study

2009 ◽  
Vol 27 (11) ◽  
pp. 1426-1431 ◽  
Author(s):  
Claudio Belvedere ◽  
Alberto Leardini ◽  
Andrea Ensini ◽  
Luca Bianchi ◽  
Fabio Catani ◽  
...  
Keyword(s):  
Three Dimensional ◽  
In Vitro Study ◽  
Vitro Study ◽  
Flexion Extension ◽  
Passive Flexion

In Vitro Determination of Midfoot Motion

Foot & Ankle ◽  
1989 ◽  
Vol 10 (3) ◽  
pp. 140-146 ◽  
Author(s):  
Tye J. Ouzounian ◽  
Michael J. Shereff
Keyword(s):  
Dimensional Space ◽  
Plantar Flexion ◽  
Three Dimensional ◽  
First Metatarsal ◽  
Below The Knee ◽  
Medial Cuneiform ◽  
Second Metatarsal ◽  
Fresh Frozen ◽  
Vitro Model

Midfoot motion was determined using an in vitro model. Ten fresh-frozen below-the-knee amputation specimens were instrumented by inserting reference pins into each of the bones of the hindfoot, midfoot and metatarsals. Dorsiflexion-plantar flexion and supination-pronation were simulated and the reference pin location in three dimensional space was determined. Comparing the location of the reference pins at each simulated position, motion was determined. Motion occurring through each articulation (dorsiflexion-plantar flexion/supination-pronation) in degrees was: talonavicular (7.0/17.7), calcaneocuboid (2.3/ 7.3), naviculo-medial cuneiform (5.0/7.3), naviculo-middle cuneiform (5.2/3.5), naviculo-lateral cuneiform (2.6/2.1), medial cuneiform-first metatarsal (3.5/1.5), middle cuneiform-second metatarsal (0.6/1.2), lateral cuneiform-third metatarsal (1.6/2.6), cuboid-fourth metatarsal (9.6/11.1), and cuboid-fifth metatarsal (10.2/9.0).

scholarly journals Numerical Modelling of the Behaviour of the Cervical Spine under the Effect of a Flexion / Extension

2019 ◽  
Vol 01 (02) ◽  
pp. 144-153 ◽  
Author(s):  
Nadir Damba ◽  
Abdellatif OUDRANE ◽  
Benaoumeur AOUR ◽  
Mohammed Salah BENNOUNA ◽  
Nabil BELKAHELLA ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Classical Mechanics ◽  
Three Dimensional ◽  
Individual Variability ◽  
In Vitro Tests ◽  
Three Dimensional Model ◽  
Major Interest ◽  
Flexion Extension

Numerical simulation is today widely used in several fields of engineering, and research undertaken for more than 20 years concerning the geometric and mechanical modeling of the spine gradually leads to clinical applications of major interest. Indeed, the in vivo and in vitro evaluation tools pose a certain number of limitations: non-standardized procedures and inter-specimen variability for in vitro tests, medical, ethical constraints, and inter-individual variability for in vivo. These limitations are actually obstacles to comparison. It is notably within the framework of implant comparisons that the methods of structural calculation, and more particularly finite element modeling, widely used in classical mechanics, find their usefulness. in this context, this present work consists in developing a three-dimensional model of the cervical spine, in order to subsequently optimize the fitting of disc prostheses

scholarly journals Three-Dimensional Measurement of Intervertebral Kinematics in Vitro Using Optical Motion Analysis

2005 ◽  
Vol 219 (6) ◽  
pp. 393-399 ◽  
Author(s):  
C A Holt ◽  
S L Evans ◽  
D Dillon ◽  
S Ahuja
Keyword(s):  
Coordinate System ◽  
Range Of Motion ◽  
Motion Analysis ◽  
Vertebral Body ◽  
Three Dimensional ◽  
Vertebral Body Replacement ◽  
Spinal Implant ◽  
Flexion Extension ◽  
Anatomical Axis

Measurement of the stiffness of spinal motion segments is widely used for evaluating the stability of spinal implant constructs. A three-dimensional motion analysis technique has been developed that allows accurate measurement of the relative movement of the vertebral bodies about a well-defined anatomical axis system. The position of marker clusters on each vertebra is tracked using digital infrared cameras (Qualisys AB, Gothenburg). Landmarks are identified using a marked pointer, and an anatomical coordinate system is defined for each vertebra. The transformation relating the upper and lower vertebrae is calculated, using the joint coordinate system approach of Grood and Suntay to find the rotations and translations in each anatomical plane. The stiffness of vertebrectomy constructs was investigated using a Synex vertebral body replacement and an anterior rod with one or two screws in each vertebral body, with or without damage to the posterior longitudinal ligament (PLL). A moment of 2 N m was applied about each anatomical axis, and the range of motion about each axis was calculated. The range of motion in flexion-extension and lateral bending was significantly greater with only one screw. When the PLL was cut, there was no significant increase in the range of motion.

Ultrastructural Investigations of the Contractile Filaments of Amoebae

1974 ◽  
Vol 32 ◽  
pp. 188-189
Author(s):  
P.L. Moore
Keyword(s):  
Cytoplasmic Streaming ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Amoeboid Movement ◽  
Different Types ◽  
Chemical Conditions ◽  
Complete Interpretation

Previous freeze fracture results on the intact giant, amoeba Chaos carolinensis indicated the presence of a fibrillar arrangement of filaments within the cytoplasm. A complete interpretation of the three dimensional ultrastructure of these structures, and their possible role in amoeboid movement was not possible, since comparable results could not be obtained with conventional fixation of intact amoebae. Progress in interpreting the freeze fracture images of amoebae required a more thorough understanding of the different types of filaments present in amoebae, and of the ways in which they could be organized while remaining functional.The recent development of a calcium sensitive, demembranated, amoeboid model of Chaos carolinensis has made it possible to achieve a better understanding of such functional arrangements of amoeboid filaments. In these models the motility of demembranated cytoplasm can be controlled in vitro, and the chemical conditions necessary for contractility, and cytoplasmic streaming can be investigated. It is clear from these studies that “fibrils” exist in amoeboid models, and that they are capable of contracting along their length under conditions similar to those which cause contraction in vertebrate muscles.

Correlated Studies of Cellular Interactions Using TEM, Freeze Etching, and SEM

1974 ◽  
Vol 32 ◽  
pp. 320-321
Author(s):  
J. P. Revel
Keyword(s):  
Developmental Stages ◽  
Three Dimensional ◽  
Cell Movement ◽  
Cellular Interactions ◽  
Serial Sections ◽  
Cell Sheets ◽  
Freeze Etching ◽  
Early Developmental

Movement of individual cells or of cell sheets and complex patterns of folding play a prominent role in the early developmental stages of the embryo. Our understanding of these processes is based on three- dimensional reconstructions laboriously prepared from serial sections, and from autoradiographic and other studies. Many concepts have also evolved from extrapolation of investigations of cell movement carried out in vitro. The scanning electron microscope now allows us to examine some of these events in situ. It is possible to prepare dissections of embryos and even of tissues of adult animals which reveal existing relationships between various structures more readily than used to be possible vithout an SEM.

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