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.

A Simple Unconstrained Dynamic Knee Simulator

1987 ◽  
Vol 109 (3) ◽  
pp. 247-251 ◽  
Author(s):  
O. Szklar ◽  
A. M. Ahmed
Keyword(s):  
Compressive Force ◽  
Simultaneous Action ◽  
Knee Simulator ◽  
Active Flexion ◽  
Flexion Extension ◽  
Joint Dynamics ◽  
Time Histories ◽  
Electrohydraulic Servo System ◽  
Flexible Cables

The design of a simple dynamic knee simulator is described. In the simulator the joint dynamics are reproduced in-vitro in a knee specimen by controlling the time-histories of the tensions in two flexible cables acting as lumped muscle group equivalents, without constraining the natural conjunct and passive motions of the specimen. The two cable tensions acting individually are used to control the active flexion/extension motion, while their simultaneous action is used to control joint compressive force. The characteristics of the electrohydraulic servo system acting under real-time microprocessor control are described. The system performance during simulation of an idealized level-walking function is evaluated.

Sensitization to Mechanical Stimulation by Inflammatory Mediators and by Mild Burn in Canine Visceral Nociceptors In Vitro

2002 ◽  
Vol 87 (4) ◽  
pp. 2043-2051 ◽  
Author(s):  
Hisashi Koda ◽  
Kazue Mizumura
Keyword(s):  
Mechanical Stimulation ◽  
Inflammatory Mediators ◽  
Mechanical Response ◽  
Second Messengers ◽  
Intracellular Camp ◽  
Solution Ph ◽  
In Vitro Investigation ◽  
Anesthetized Dogs ◽  
C 30

Hyperalgesia to mechanical stimulation and heat is commonly observed in inflamed conditions. Although sensitization to heat is well documented and its mechanism has also been well studied, it remains unclear whether and how nociceptors are sensitized to mechanical stimulation. Therefore we conducted in vitro investigation of which inflammatory mediators (bradykinin, histamine, prostaglandin E2, and protons) sensitize nociceptors to suprathreshold mechanical stimulation and at what concentrations. In addition, we studied the effects of possible second messengers for these mediators downstream of the receptors and also the effects of mild burn. Single polymodal receptor activities were recorded in canine testis-spermatic nerve preparations excised from deeply anesthetized dogs. Mechanical stimulation was applied to the identified receptive field for 10 s with a servo-controlled mechanical stimulator. Bradykinin at 0.001 μM induced neither excitation nor facilitation of the mechanical response; however, it facilitated the mechanical response at 0.01 μM and higher, levels at which significant excitation was also induced by bradykinin alone. Histamine excited the nociceptor and sensitized it to mechanical stimulation at 10 μM and higher. PG E2 also sensitized the mechanical response, but starting at 1 μM, without inducing excitation by itself. The effects of two possible intracellular messengers for these mediators were studied using forskolin (10 μM), which increases intracellular cAMP, and a protein-kinase-C-stimulating phorbol ester, phorbol 12,13-dibutyrate (0.1 μM). Both substances reversibly facilitated the mechanical response of testicular polymodal receptors. In contrast, low-pH solution (pH: 6.6–4.5) seldom induced excitation and failed to facilitate the mechanical response. After 55°C, 30-s heat stimulation, testicular polymodal receptors were sensitized to mechanical stimulation. These results demonstrated that inflammatory mediators and burn sensitized nociceptor responses to mechanical stimulation and provide support for the idea that peripheral nociceptor sensitization is a mechanism involved in hyperalgesia to mechanical stimulation in inflamed tissues.

Foot Movement and Tendon Excursion: An In Vitro Study

1994 ◽  
Vol 15 (7) ◽  
pp. 386-395 ◽  
Author(s):  
Beat Hintermann ◽  
Benno M. Nigg ◽  
Christian Sommer
Keyword(s):  
Degrees Of Freedom ◽  
Function Analysis ◽  
In Vitro Study ◽  
Tibialis Posterior ◽  
Flexor Hallucis Longus ◽  
Moment Arms ◽  
In Vitro Investigation ◽  
Flexion Extension ◽  
Tendon Excursion

The purpose of this study was to determine tendon excursions resulting from selected foot movement and to derive moment arms with respect to the eversion-inversion and flexion-extension axes of the foot. A lower legholding device with 6 degrees of freedom was used for the in vitro investigation of 15 fresh foot-leg specimens. Although high variation among the subjects existed, there was a pronounced uniformity of tendon excursion throughout a given foot eversion-inversion or flexion-extension range of motion. With reference to the tibialis posterior (1.00), average inverter moment arms with respect to the foot eversion-inversion axis were found to be as follows: flexor digitorum longus, 0.75; flexor hallucis longus, 0.62; tibialis anterior, 0.59; soleus, 0.24; extensor hallucis longus, 0.22; extensor digitorum longus, −0.26; peroneus longus, −0.82; and peroneus brevis, −0.85. A trend toward decreasing evertor/invertor moment arms was observed during the ranges of foot eversion, as well as when the foot was in flexion. Flexor and extensor moment arms were found to be substantially dependent on foot flexion-extension angle. Increasing flexor moment arms were observed when rotating the foot throughout the range from extension to flexion. The obtained results may have significant implications in foot surgery, muscle function analysis, and general considerations of foot function.

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.

Development of a six station knee wear simulator and preliminary wear results

1997 ◽  
Vol 211 (1) ◽  
pp. 37-47 ◽  
Author(s):  
I C Burgess ◽  
M Kolar ◽  
J L Cunningham ◽  
A Unsworth
Keyword(s):  
Ex Vivo ◽  
Wear Test ◽  
Total Knee Replacements ◽  
Delamination Wear ◽  
Knee Simulator ◽  
Flexion Extension ◽  
Posterior Translation ◽  
Anterior Posterior

In order to assess the wear performance of different designs of total knee replacements (TKR), a six station multi-axis knee simulator has been designed, built and commissioned. The most important features of a knee simulator are representative angles of flexion-extension synchronized with a dynamically applied load, and a combination of rolling and sliding motion. The simulator typically applies flexion-extension of 0-65°, anterior-posterior translation of up to 15 mm, a dynamic load of up to 5.0 kN, and operates at 1.0 Hz. The loads and motions are applied using computer controlled servohydraulic actuators and hence their profiles are easily modified. A preliminary wear test has been conducted using a Kinemax (Howmedica, United Kingdom) TKR. The test was conducted in 30 per cent bovine serum which was changed every 150 000 cycles, at which time the bearing surfaces were examined and the UHMWPE tibial component was weighed. Over eight million cycles, a tibial wear rate of 2.62 mg/106 cycles was measured. The mild wear observed was characterized by burnishing and slight scratching in the anterior-posterior direction. These observations are broadly in line with both in vitro and ex vivo studies reported in the literature for this type of prosthesis. Delamination wear sometimes observed in vivo was not seen.

In vitro investigation of Varizella zoster virus as an oncolytic virus in glioblastoma therapy

2008 ◽  
Vol 35 (S 01) ◽  
Author(s):  
H Leske ◽  
A Baiker ◽  
C Schichor ◽  
J.C Tonn ◽  
R Goldbrunner ◽  
...  
Keyword(s):  
Oncolytic Virus ◽  
In Vitro Investigation ◽  
Varizella Zoster Virus

An In Vitro Investigation of Synergy or Antagonism between Antimicrobial Combinations against Isolates from Bacterial Keratitis

2010 ◽  
Vol 51 (8) ◽  
pp. 4151 ◽  
Author(s):  
Henri Sueke ◽  
Stephen B. Kaye ◽  
Timothy Neal ◽  
Amanda Hall ◽  
Stephen Tuft ◽  
...  
Keyword(s):  
Bacterial Keratitis ◽  
In Vitro Investigation ◽  
Antimicrobial Combinations

Design and In vitro Investigation of Grafted Chitosan as Chitosan Nanoparticles Containing Deflazacort Drug Coated by Calcium Starch Glycolate

2020 ◽  
Vol 21 (12) ◽  
pp. 2718-2728
Author(s):  
Elsayed M. Abdel Bary ◽  
Ammar N. Harmal ◽  
Mona E. Ibrahim ◽  
Moustafa A. Gouda
Keyword(s):  
Chitosan Nanoparticles ◽  
In Vitro Investigation
Sign in / Sign up

Export Citation Format

Share Document