EXPERIMENTAL DETERMINATION OF IN VIVO PRESSURE DISTRIBUTION IN BIOLOGIC JOINTS

2000 ◽  
Vol 04 (01) ◽  
pp. 1-7 ◽  
Author(s):  
W. Herzog ◽  
E. M. Hasler ◽  
T. R. Leonard
Keyword(s):  
Muscle Force ◽  
Experimental Approach ◽  
Pressure Distributions ◽  
Joint Contact ◽  
Hindlimb Movement ◽  
Joint Contact Pressure ◽  
Contact Pressures

The purpose of this communication is to present an idea, and its technical implementation, on how to estimate experimentally in vivo joint contact pressure distributions. The idea is illustrated for the cat patellofemoral joint. For this particular joint, the approach requires muscle force and hindlimb movement measurements during unrestrained locomotion, and the quantification of the joint contact pressures in situ for conditions approximating the in vivo conditions as closely as possible. Although the approach is time-consuming and has its limitations, it is, as far as we know, the first purely experimental approach to determine the in vivo joint contact pressures during normal movement. "Purely experimental" refers to the idea that the required movements, muscle forces and contact pressures are all measured rather than estimated theoretically.

scholarly journals Biomechanics of a novel extra-articular implant for younger patients with knee osteoarthritis

2018 ◽  
Vol 4 (1) ◽  
pp. 203-205
Author(s):  
Mehdi Saeidi ◽  
Maziar Ramezani ◽  
Piaras Kelly ◽  
Mohd Sabri Hussin ◽  
Thomas Neitzert
Keyword(s):  
Knee Joint ◽  
Cartilage Regeneration ◽  
Stress Distributions ◽  
Element Analysis ◽  
Medial Side ◽  
Pressure Distributions ◽  
Joint Contact ◽  
As Stress ◽  
Joint Contact Pressure ◽  
Contact Pressures

AbstractThis research aimed to study the efficacy of a novel implant for osteoarthritic knees. This implant is designed to eliminate excessive loads through the knee and to provide suitable conditions for possible tibiofemoral cartilage regeneration. The implant was designed for the medial side of the knee joint. Finite Element Analysis (FEA) was performed for an extended knee position of the knee joint. Contact pressure distributions on the medial and lateral compartments were investigated as well as stress distributions throughout the implant’s plates. Results with and without the implant were compared, and it was seen that the contact pressures on the surface of the distal femur were reduced by more than 90% after the introduction of the implant.

In-vivo determination of patellofemoral joint contact pressures

1993 ◽  
Vol 26 (3) ◽  
pp. 352 ◽  
Author(s):  
Janet L. Ronsky ◽  
Walter Herzog ◽  
Thomas D. Brown ◽  
Tim Leonard
Keyword(s):  
Patellofemoral Joint ◽  
Joint Contact ◽  
Contact Pressures

Effects of Surgical Repair or Reconstruction on Radiocarpal Mechanics From Wrists With Scapholunate Injury

2011 ◽  
Author(s):  
Joshua E. Johnson ◽  
Sang-Pil Lee ◽  
Terence E. McIff ◽  
E. Bruce Toby ◽  
Kenneth J. Fischer
Keyword(s):  
Contact Forces ◽  
Joint Mechanics ◽  
Imaging Data ◽  
Contact Patterns ◽  
Radiocarpal Joint ◽  
Joint Contact ◽  
Ligament Disruption ◽  
Joint Contact Pressure ◽  
Contact Pressures

Scapholunate dissociation (SL ligament disruption) due to trauma can cause changes in joint kinematics and contact patterns, which can lead to scapholunate advanced collapse (SLAC wrist) with secondary radiocarpal osteoarthritis (OA) [1]. The relationship between consequent abnormal mechanics and the onset of OA is not clearly understood, however elevated joint contact pressure is believed to be an associated factor. Knowing how injuries affect joint physiology and mechanics and how well surgical repairs restore the mechanics may improve surgical efficacy and help predict OA risk. Recently a method was proposed to measure joint contact mechanics from in vivo imaging data during functional loading [2]. The objective of this study was to compare radiocarpal joint mechanics (contact forces, contact areas, peak and average contact pressures) of injured and post-operative wrists to contralateral controls using MRI-based contact modeling. We hypothesized that average contact pressures and peak contact pressures would be higher in the injured wrists, and that these measures would decrease post-operatively.

Sensitive and accurate determination of neurotransmitters from in vivo rat brain microdialysate of Parkinson's disease using in situ ultrasound-assisted derivatization dispersive liquid–liquid microextraction by UHPLC-MS/MS

RSC Advances ◽  
2016 ◽  
Vol 6 (110) ◽  
pp. 108635-108644 ◽  
Author(s):  
Xian-En Zhao ◽  
Yongrui He ◽  
Ping Yan ◽  
Na Wei ◽  
Renjun Wang ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Rat Brain ◽  
Accurate Determination ◽  
Ultrasound Assisted ◽  
Dispersive Liquid Liquid Microextraction ◽  
Liquid Microextraction

In situ UA-DDLLME coupled with UHPLC-MS/MS has been developed for simultaneous determination of neurotransmitters and baicalein from Parkinson's disease rats.

Colonization of the rat liver by syngeneic tumor cells An experimental approach by in vivo and in situ studies

1988 ◽  
Vol 55 (1) ◽  
pp. 111-116
Author(s):  
E. Solberg ◽  
T. Gjøen ◽  
R. Seljelid ◽  
S. O. Kolset
Keyword(s):  
Tumor Cells ◽  
Rat Liver ◽  
Experimental Approach ◽  
In Situ Studies ◽  
Syngeneic Tumor

Determination of mosquito bloodmeal pH in situ by ion-selective microelectrode measurement: implications for the regulation of malarial gametogenesis

Parasitology ◽  
2000 ◽  
Vol 120 (6) ◽  
pp. 547-551 ◽  
Author(s):  
O. BILLKER ◽  
A. J. MILLER ◽  
R. E. SINDEN
Keyword(s):  
Xanthurenic Acid ◽  
Mosquito Vector ◽  
Dependent Manner ◽  
Ph Increase ◽  
Ph Range ◽  
Dose Dependent

Malarial gametocytes circulate in the peripheral blood of the vertebrate host as developmentally arrested intra-erythrocytic cells, which only resume development into gametes when ingested into the bloodmeal of the female mosquito vector. The ensuing development encompasses sexual reproduction and mediates parasite transmission to the insect. In vitro the induction of gametogenesis requires a drop in temperature and either a pH increase from physiological blood pH (ca pH 7·4) to about pH 8·0, or the presence of a gametocyte-activating factor recently identified as xanthurenic acid (XA). However, it is unclear whether either the pH increase or XA act as natural triggers in the mosquito bloodmeal. We here use pH-sensitive microelectrodes to determine bloodmeal pH in intact mosquitoes. Measurements taken in the first 30 min after ingestion, when malarial gametogenesis is induced in vivo, revealed small pH increases from 7·40 (mouse blood) to 7·52 in Aedes aegypti and to 7·58 in Anophěles stephensi. However, bloodmeal pH was clearly suboptimal if compared to values required to induce gametogenesis in vitro. Xanthurenic acid is shown to extend the pH-range of exflagellation in vitro in a dose-dependent manner to values that we have observed in the bloodmeal, suggesting that in vivo malarial gametogenesis could be further regulated by both these factors.

Comparison of postnatal lung growth and development between C3H/HeJ and C57BL/6J mice

2006 ◽  
Vol 100 (5) ◽  
pp. 1577-1583 ◽  
Author(s):  
Shawn E. Soutiere ◽  
Wayne Mitzner
Keyword(s):  
Lung Volume ◽  
Lung Development ◽  
Inbred Mice ◽  
Left Lung ◽  
Transpulmonary Pressure ◽  
Mean Linear Intercept ◽  
Old Mice

Previous work by our group has demonstrated substantial differences in lung volume and morphometric parameters between inbred mice. Specifically, adult C3H/HeJ (C3) have a 50% larger lung volume and 30% greater mean linear intercept than C57BL/6J (B6) mice. Although much of lung development occurs postnatally in rodents, it is uncertain at what age the differences between these strains become manifest. In this study, we performed quasi-static pressure-volume curves and morphometric analysis on neonatal mice. Lungs from anesthetized mice were degassed in vivo using absorption of 100% O2. Pressure-volume curves were then recorded in situ. The lungs were then fixed by instillation of Zenker’s solution at a constant transpulmonary pressure. The left lung from each animal was used for morphometric determination of mean air space chord length ( Lma). We found that the lung volume of C3 mice was substantially greater than that of B6 mice at all ages. In contrast, there was no difference in Lma (62.7 μm in C3 and 58.5 μm in B6) of 3-day-old mice. With increasing age (8 days), there was a progressive decrease in the Lma of both strains, with the magnitude of the decrease in B6 Lma mice exceeding that of C3. C3 lung volume remained 50% larger. The combination of parenchymal architectural similarity with lung air volume differences and different rates of alveolar septation support the hypothesis that lung volume and alveolar dimensions are independently regulated.

scholarly journals Chromatin is frequently unknotted at the megabase scale

2019 ◽  
Author(s):  
Dimos Goundaroulis ◽  
Erez Lieberman Aiden ◽  
Andrzej Stasiak
Keyword(s):  
Gene Regulation ◽  
Human Genome ◽  
Single Locus ◽  
Chromosome 21 ◽  
Cellular Processes ◽  
Potential Source ◽  
Localization Errors

Knots in the human genome would greatly impact diverse cellular processes ranging from transcription to gene regulation. To date, it has not been possible to directly examine the genome in vivo for the presence of knots. Recently, methods for serial fluorescent in situ hybridization have made it possible to measure the 3d position of dozens of consecutive genomic loci, in vivo. However, the determination of whether genomic trajectories are knotted remains challenging, because small errors in the localization of a single locus can transform an unknotted trajectory into a highly-knotted trajectory, and vice versa. Here, we use stochastic closure analysis to determine whether a genomic trajectory is knotted in the setting of experimental noise. We analyse 4727 deposited genomic trajectories of a 2Mb long chromatin interval from chromosome 21. For 243 of these trajectories, their knottedness could be reliably determined despite the possibility of localization errors. Strikingly, in each of these 243 cases, the trajectory was unknotted. We note a potential source of bias, insofar as knotted contours may be more difficult to reliably resolve. Nevertheless, our data is consistent with a model where, at the scales probed, the human genome is often free of knots.

A Novel Quantitative Approach for Evaluating Contact Mechanics of Meniscal Replacements

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
E. Linder-Ganz ◽  
J. J. Elsner ◽  
A. Danino ◽  
F. Guilak ◽  
A. Shterling
Keyword(s):  
Contact Area ◽  
Peak Pressure ◽  
Contact Forces ◽  
Articular Surfaces ◽  
Joint Contact ◽  
Bench Testing ◽  
Contact Pressures ◽  
Implant Dislocation ◽  
Total Contact Area

One of the functions of the meniscus is to distribute contact forces over the articular surfaces by increasing the joint contact areas. It is widely accepted that total/partial loss of the meniscus increases the risk of joint degeneration. A short-term method for evaluating whether degenerative arthritis can be prevented or not would be to determine if the peak pressure and contact area coverage of the tibial plateau (TP) in the knee are restored at the time of implantation. Although several published studies already utilized TP contact pressure measurements as an indicator for biomechanical performance of allograft menisci, there is a paucity of a quantitative method for evaluation of these parameters in situ with a single effective parameter. In the present study, we developed such a method and used it to assess the load distribution ability of various meniscal implant configurations in human cadaveric knees (n=3). Contact pressures under the intact meniscus were measured under compression (1200 N, 0 deg flexion). Next, total meniscectomy was performed and the protocol was repeated with meniscal implants. Resultant pressure maps were evaluated for the peak pressure value, total contact area, and its distribution pattern, all with respect to the natural meniscus output. Two other measures—implant-dislocation and implant-impingement on the ligaments—were also considered. If any of these occurred, the score was zeroed. The total implant score was based on an adjusted calculation of the aforementioned measures, where the natural meniscus score was always 100. Laboratory experiments demonstrated a good correlation between qualitative and quantitative evaluations of the same pressure map outputs, especially in cases where there were contradicting indications between different parameters. Overall, the proposed approach provides a novel, validated method for quantitative assessment of the biomechanical performance of meniscal implants, which can be used in various applications ranging from bench testing of design (geometry and material of an implant) to correct implant sizing.

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