scholarly journals In Vivo Kinematic Analysis of Bicruciate-Retaining Total Knee Arthroplasty Focused on Function of the ACL

2021 ◽  
Author(s):  
Kosei Ishigaki ◽  
Hideyuki Aoki ◽  
Ryo Takamatsu ◽  
Yuji Nishiwaki ◽  
Hiroshi Takahashi ◽  
...  
Keyword(s):  
Femoral Component ◽  
Kinematic Analysis ◽  
Repeated Measures ◽  
Tibial Component ◽  
Rotational Angle ◽  
Contact Points ◽  
Lateral Translation ◽  
Lateral Rotation ◽  
Bcr Tka

Abstract uncertain. In this study, we performed an in vivo kinematic analysis of squat motion on level ground and on a downward slope in patients treated with BCR-TKA to examine the value of anterior cruciate ligament (ACL) preservation.Methods: The subjects were ten valgus knees that underwent TKA (BCR: 5 knees, CR: 5 knees) at our hospital. We evaluated in vivo kinematics of the knee using fluoroscopy and investigated the femoral component translation relative to the tibial component from extension to maximum flexion, and the rotation angle between the components under the two conditions. Statistical analysis was conducted by Mann-Whitney U test to compare the rotational angle, the location of lateral and medial contact points per flexion angle. Differences in these parameters between the BCR and CR groups across the flexion angles were compared by repeated measures ANOVA. Results: Rotation of the femoral component to the tibial component occurred gradually as flexion continued. On level ground, lateral rotation at 0° to 120° flexion was 14.5±1.95° in the BCR group and 7.9±0.47° in the CR group. Medial translation was 4.1±1.73mm in the BCR group and 2.5±1.64mm in the CR group, and lateral translation was 13.2±1.6mm in the BCR group and 7.1±1.74mm in the CR group. On a forward slope, lateral rotation was 12.7±1.45° in the BCR group and 7.57±0.47° in the CR group. Medial translation was 5.87±1.78mm in the BCR and 2.9±0.81mm in the CR, and lateral translation was 13.6±1.84mm in the BCR and 7.4±0.96mm in the CR.Conclusion: An in vivo kinetics analysis of deep flexion motion was conducted on level ground and on a forward slope to stress the ACL. Under both conditions, kinetics close to screw home movement were found in the BCR group and rotation was significantly larger than that in the CR group. The medial contact point between components was located significantly more anterior in the BCR group. In conclusion, BCR-TKA was found to have in vivo kinetics close to those of a normal knee, in comparison with CR-TKA.

scholarly journals In Vivo Kinematic Analysis of Bicruciate-retaining Total Knee Arthroplasty Focused on Function of the ACL

2021 ◽  
Author(s):  
Kosei Ishigaki ◽  
Hideyuki Aoki ◽  
Ryo Takamatsu ◽  
Yuji Nishiwaki ◽  
Hiroshi Takahashi ◽  
...  
Keyword(s):  
Total Knee Arthroplasty ◽  
Femoral Component ◽  
Knee Arthroplasty ◽  
Kinematic Analysis ◽  
Tibial Component ◽  
Lateral Translation ◽  
In Vivo Kinetics ◽  
Total Knee ◽  
Bcr Tka

Abstract Background: The utility of a bi-cruciate retaining total knee arthroplasty (BCR-TKA) is uncertain. In this study, we performed an in vivo kinematic analysis of squat motion on level ground and on a downward slope in patients treated with BCR-TKA to examine the value of anterior cruciate ligament (ACL) preservation.Methods: The subjects were ten valgus knees that underwent TKA (BCR: 5 knees, CR: 5 knees) at our hospital. We evaluated in vivo kinematics of the knee using fluoroscopy and investigated the femoral component translation relative to the tibial component from extension to maximum flexion, and the rotation angle between the components under the two conditions. Statistical analysis was conducted by Mann-Whitney U test to compare the rotational angle, the location of lateral and medial contact points per flexion angle. Differences in these parameters between the BCR and CR groups across the flexion angles were compared by repeated measures ANOVA.Results: Rotation of the femoral component to the tibial component occurred gradually as flexion continued. On level ground, lateral rotation at 0° to 120° flexion was 14.5±1.95° in the BCR group and 7.9±0.47° in the CR group. Medial translation was 4.1±1.73mm in the BCR group and 2.5±1.64mm in the CR group, and lateral translation was 13.2±1.6mm in the BCR group and 7.1±1.74mm in the CR group. On a forward slope, lateral rotation was 12.7±1.45° in the BCR group and 7.57±0.47° in the CR group. Medial translation was 5.87±1.78mm in the BCR and 2.9±0.81mm in the CR, and lateral translation was 13.6±1.84mm in the BCR and 7.4±0.96mm in the CR.Conclusion: An in vivo kinetics analysis of deep flexion motion was conducted on level ground and on a forward slope to stress the ACL. Under both conditions, kinetics close to screw home movement were found in the BCR group and rotation was significantly larger than that in the CR group. The medial contact point between components was located significantly more anterior in the BCR group. In conclusion, BCR-TKA was found to have in vivo kinetics close to those of a normal knee, in comparison with CR-TKA.

An Optimized Image Matching Method for Determining In-Vivo TKA Kinematics with a Dual-Orthogonal Fluoroscopic Imaging System

2006 ◽  
Vol 128 (4) ◽  
pp. 588-595 ◽  
Author(s):  
Jeffrey Bingham ◽  
Guoan Li
Keyword(s):  
Femoral Component ◽  
Tibial Component ◽  
Degrees Of Freedom ◽  
Imaging System ◽  
Matching Algorithm ◽  
Translational Accuracy ◽  
Fluoroscopic Imaging ◽  
Total Knee ◽  
Accuracy And Repeatability

This study presents an optimized matching algorithm for a dual-orthogonal fluoroscopic image system used to determine six degrees-of-freedom total knee arthroplasty (TKA) kinematics in-vivo. The algorithm was evaluated using controlled conditions and standard geometries. Results of the validation demonstrate the algorithm’s robustness and capability of realizing a pose from a variety of initial poses. Under idealized conditions, poses of a TKA system were recreated to within 0.02±0.01 mm and 0.02±0.03 deg for the femoral component and 0.07±0.09 mm and 0.16±0.18 deg for the tibial component. By employing a standardized geometry with spheres, the translational accuracy and repeatability under actual conditions was found to be 0.01±0.06 mm. Application of the optimized matching algorithm to a TKA patient showed that the pose of in-vivo TKA components can be repeatedly located, with standard deviations less than ±0.12 mm and ±0.12 deg for the femoral component and ±0.29 mm and ±0.25 deg for the tibial component. This methodology presents a useful tool that can be readily applied to the investigation of in-vivo motion of TKA kinematics.

scholarly journals Force Generation on the Hallux Is More Affected by the Ankle Joint Angle than the Lesser Toes: An In Vivo Human Study

Biology ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 48
Author(s):  
Junya Saeki ◽  
Soichiro Iwanuma ◽  
Suguru Torii
Keyword(s):  
Repeated Measures ◽  
Joint Angle ◽  
Plantar Flexion ◽  
Human Study ◽  
Force Generation ◽  
Functional Difference ◽  
Multiple Comparison Test ◽  
The Difference ◽  
Metatarsophalangeal Joints

The structure of the first toe is independent of that of the other toes, while the functional difference remains unclear. The purpose of this study was to investigate the difference in the force generation characteristics between the plantar-flexion of the first and second–fifth metatarsophalangeal joints (MTPJs) by comparing the maximal voluntary plantar-flexion torques (MVC torque) at different MTPJs and ankle positions. The MVC torques of the first and second–fifth MTPJs were measured at 0°, 15°, 30°, and 45° dorsiflexed positions of the MTPJs, and at 20° plantar-flexed, neutral, and 20° dorsiflexed positions of the ankle. Two-way repeated measures analyses of variance with Holm’s multiple comparison test (MTPJ position × ankle position) were performed. When the MTPJ was dorsiflexed at 0°, 15°, and 30°, the MVC torque of the first MTPJ when the ankle was dorsiflexed at 20° was higher than that when the ankle was plantar-flexed at 20°. However, the ankle position had no significant effect on the MVC torque of the second–fifth MTPJ. Thus, the MVC torque of the first MTPJ was more affected by the ankle position than the second–fifth MTPJs.

scholarly journals Quantitative analysis on the wear of monolithic zirconia crowns on antagonist teeth

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Zhenyu Tang ◽  
Xinyi Zhao ◽  
Hui Wang
Keyword(s):  
Epoxy Resin ◽  
Tetragonal Zirconia ◽  
Fatigue Wear ◽  
Posterior Teeth ◽  
Contact Points ◽  
Significant Difference ◽  
Zirconia Crowns ◽  
Natural Teeth ◽  
Monolithic Zirconia

Abstract Background The present study aimed to quantitate the wear of the highly transparent Yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) ceramic monolithic zirconia crown on the enamel in vivo and discuss the prone position of the wear and the underlying mechanism. Methods A total of 43 patients with 43 posterior teeth were selected for full zirconia crown restoration and examined immediately, at 6 months, and at 1 year after restoration. During the follow-up visit, the fine impression of the patients’ monolithic zirconia crowns, the antagonist teeth, the corresponding contralateral natural teeth, the super plaster cast, and epoxy resin model was ontained. The model of epoxy resin was observed under a stereo microscope, and the microstructure parts were observed under a scanning electron microscope. Results After 1 year, the mean depth and volume of wearing of the monolithic zirconia crown were the smallest (all P < 0.01), while those of the antagonist teeth were significantly larger than those of the natural teeth (P < 0.0001), and no significant difference was found among the natural teeth (P = 0.3473, P = 0.6996). The amount of wear after one year was remarkably higher than that at 6 months (P < 0.0001). The microscopic observation revealed the tendency of wearing of the monolithic zirconia crown on the antagonist teeth at the protruding early contact points. Electron micrographs of tooth scars showed that the wearing mechanism of the monolithic zirconia crown on natural teeth was mainly abrasive and fatigue wear. Conclusions Although the self-wearing is insignificant, the monolithic zirconia crown can cause wear of the antagonist teeth via occlusal or early contact significantly; the amount of wearing is higher than that of natural teeth and increases over time. The wearing mechanism is mainly abrasive and fatigue wear.

scholarly journals Anatomical correlation between left atrium pulmonary vein ablation targets of atrial fibrillation and adjacent bronchi and pulmonary arteries by MSCT

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yan-Jing Wang ◽  
Huan Sun ◽  
Xiao-Fei Fan ◽  
Meng-Chao Zhang ◽  
Ping Yang ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Left Atrium ◽  
Pulmonary Vein ◽  
Pulmonary Arteries ◽  
Contact Points ◽  
Pulmonary Vein Ablation ◽  
Adjacent Structures ◽  
Anatomical Correlation ◽  
The Right

Abstract Background The ablation targets of atrial fibrillation (AF) are adjacent to bronchi and pulmonary arteries (PAs). We used computed tomography (CT) to evaluate the anatomical correlation between left atrium (LA)-pulmonary vein (PV) and adjacent structures. Methods Data were collected from 126 consecutive patients using coronary artery CT angiography. The LA roof was divided into three layers and nine points. The minimal spatial distances from the nine points and four PV orifices to the adjacent bronchi and PAs were measured. The distances from the PV orifices to the nearest contact points of the PVs, bronchi, and PAs were measured. Results The anterior points of the LA roof were farther to the bronchi than the middle or posterior points. The distances from the nine points to the PAs were shorter than those to the bronchi (5.19 ± 3.33 mm vs 8.62 ± 3.07 mm; P < .001). The bilateral superior PV orifices, especially the right superior PV orifices were closer to the PAs than the inferior PV orifices (left superior PV: 7.59 ± 4.14 mm; right superior PV: 4.43 ± 2.51 mm; left inferior PV: 24.74 ± 5.26 mm; right inferior PV: 22.33 ± 4.75 mm) (P < .001). Conclusions The right superior PV orifices were closer to the bronchi and PAs than other PV orifices. The ablation at the mid-posterior LA roof had a higher possibility to damage bronchi. CT is a feasible method to assess the anatomical adjacency in vivo, which might provide guidance for AF ablation.

Dilutional Acidosis following Hetastarch or Albumin in Healthy Volunteers

2000 ◽  
Vol 93 (5) ◽  
pp. 1184-1187 ◽  
Author(s):  
Jonathan H. Waters ◽  
Clifford A. Bernstein
Keyword(s):  
Healthy Volunteers ◽  
Repeated Measures ◽  
Base Excess ◽  
Rank Test ◽  
Albumin Concentration ◽  
Acid Base Balance ◽  
Arterial Blood Gas ◽  
Arterial Blood ◽  
The Impact

Background The intent of this study was to evaluate the impact of the commonly used colloids-hetastarch and albumin-on in vivo acid-base balance. From this evaluation, a better understanding of the mechanism of dilutional acidosis was expected. Methods In a prospective, randomized fashion, 11 healthy volunteers were administered 15 ml/kg hetastarch solution, 6%, or 15 ml/kg albumin, 5%, intravenously over 30 min. Four weeks later, the study subjects were administered the other colloid. Arterial blood gas and electrolyte parameters were measured at baseline and at 30, 60, 90, 120, 210, and 300 min after colloid administration. Pre- and postlaboratory values were compared within groups using a paired t test and a Wilcoxon signed rank test and between groups using repeated-measures analysis of variance and a Wilcoxon rank sum test. Results Thirty min after infusion, subjects who were administered hetastarch showed statistically significant changes (P &lt; 0.05) in base excess (from 2.5 +/- 0.9 mEq/l to 0.7 +/- 1.1 mEq/l), HCO3- concentration (from 27 +/- 1.0 mEq/l to 25 +/- 1.3 mEq/l), Cl- concentration (from 108 +/- 2 mEq/l to 112 +/- 2 mEq/l), albumin concentration (from 4.4 +/- 0.2 g/dl to 3.5 +/- 0.5 g/dl), and arterial carbon dioxide tension (Paco2; from 40.8 +/- 2.3 mmHg to 39. 2 +/- 3.2 mmHg), whereas only the albumin concentration (from 4.4 +/- 0.2 g/dl to 4.8 +/- 0.6 g/dl) changed significantly in the albumin-treated group. Conclusions Decreases in base excess were observed for 210 min after hetastarch administration but not after albumin. The mechanism for this difference is discussed.

Abstract MP03: ROCK2 Specific Inhibition Attenuates Angiotensin II-induced Hypertension In Mice

Hypertension ◽  
2021 ◽  
Vol 78 (Suppl_1) ◽  
Author(s):  
Daniel J Fehrenbach ◽  
Meena S Madhur
Keyword(s):  
Blood Pressure ◽  
T Cell ◽  
Angiotensin Ii ◽  
Repeated Measures ◽  
Flow Cytometric Analysis ◽  
Coiled Coil ◽  
Ang Ii ◽  
Induced Hypertension

Hypertension, or an elevated blood pressure, is the primary modifiable risk factor for cardiovascular disease, the number one cause of mortality worldwide. We previously demonstrated that Th17 activation and interleukin 17A (IL-17A)/IL-21 production is integral for the full development of a hypertensive phenotype as well as the renal and vascular damage associated with hypertension. Rho-associated coiled-coil containing protein Kinase 2 (ROCK2) serves as a molecular switch upregulating Th17 and inhibiting regulatory T cell (Treg) differentiation. We hypothesize that hypertension is characterized by excessive T cell ROCK2 activation leading to increased Th17/Treg ratios and ultimately end-organ damage. We first showed in vitro that KD025, an experimental orally bioavailable ROCK2 inhibitor inhibits Th17 cell proliferation and IL-17A/IL-21 production. To determine if hypertensive stimuli such as endothelial stretch increases T cell ROCK2 expression, we cultured human aortic endothelial cells exposed to 5% (normotensive) or 10% (hypertensive) stretch with circulating human T cells and HLA-DR+ antigen presenting cells. Hypertensive stretch increased T cell ROCK2 expression 2-fold. We then tested the effect of ROCK2 inhibition with KD025 (50mg/kg i.p. daily) in vivo on angiotensin II (Ang II)-induced hypertension. Treatment with KD025 significantly attenuated the hypertensive response within 1 week of Ang II treatment (systolic blood pressure: 139± 8 vs 108±7mmHg) and this persisted for the duration of the 4 week study reaching blood pressures 20 mmHg lower (135±13mmHg) than vehicle treated mice (158±4mmHg p<0.05 effect of treatment 2-way Repeated Measures ANOVA). Flow cytometric analysis of tissue infiltrating leukocytes revealed that KD025 treatment increased Treg/Th17 ratios in the kidney (0.61±0.03 vs 0.79±0.08, p<0.05 student’s t-test). Thus, T cell ROCK2 may be a novel therapeutic target for the treatment of hypertension.

scholarly journals Influence of Contact Points on the Performance of Caries Detection Methods in Approximal Surfaces of Primary Molars: An in vivo Study

2015 ◽  
Vol 49 (2) ◽  
pp. 99-108 ◽  
Author(s):  
Apoena A. Ribeiro ◽  
Flávia Purger ◽  
Jonas A. Rodrigues ◽  
Patrícia R.A. Oliveira ◽  
Adrian Lussi ◽  
...  
Keyword(s):  
Lesion Detection ◽  
In Vivo Study ◽  
Caries Detection ◽  
Primary Molars ◽  
Contact Points ◽  
Diagnodent Pen ◽  
Sensitivity Specificity ◽  
Approximal Caries ◽  
Approximal Surfaces

This in vivo study aimed to evaluate the influence of contact points on the approximal caries detection in primary molars, by comparing the performance of the DIAGNOdent pen and visual-tactile examination after tooth separation to bitewing radiography (BW). A total of 112 children were examined and 33 children were selected. In three periods (a, b, and c), 209 approximal surfaces were examined: (a) examiner 1 performed visual-tactile examination using the Nyvad criteria (EX1); examiner 2 used DIAGNOdent pen (LF1) and took BW; (b) 1 week later, after tooth separation, examiner 1 performed the second visual-tactile examination (EX2) and examiner 2 used DIAGNOdent again (LF2); (c) after tooth exfoliation, surfaces were directly examined using DIAGNOdent (LF3). Teeth were examined by computed microtomography as a reference standard. Analyses were based on diagnostic thresholds: D1: D₀ = health, D1-D4 = disease; D2: D₀, D1 = health, D2-D4 = disease; D3: D₀-D2 = health, D3, D4 = disease. At D1, the highest sensitivity/specificity were observed for EX1 (1.00)/LF3 (0.68), respectively. At D2, the highest sensitivity/specificity were observed for LF3 (0.69)/BW (1.00), respectively. At D3, the highest sensitivity/specificity were observed for LF3 (0.78)/EX1, EX2 and BW (1.00). EX1 showed higher accuracy values than LF1, and EX2 showed similar values to LF2. We concluded that the visual-tactile examination showed better results in detecting sound surfaces and approximal caries lesions without tooth separation. However, the effectiveness of approximal caries lesion detection of both methods was increased by the absence of contact points. Therefore, regardless of the method of detection, orthodontic separating elastics should be used as a complementary tool for the diagnosis of approximal noncavitated lesions in primary molars.

scholarly journals Prediction and control of symmetry breaking in embryoid bodies by environment and signal integration

2018 ◽  
Author(s):  
Naor Sagy ◽  
Shaked Slovin ◽  
Maya Allalouf ◽  
Maayan Pour ◽  
Gaya Savyon ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Cell Fate ◽  
Developmental Process ◽  
Primitive Streak ◽  
Early Embryo ◽  
Embryoid Bodies ◽  
Neighboring Cell ◽  
Contact Points

AbstractDuring early embryogenesis, mechanical signals, localized biochemical signals and neighboring cell layers interaction coordinate around anteroposterior axis determination and symmetry breaking. Deciphering their relative roles, which are hard to tease apart in vivo, will enhance our understanding of how these processes are driven. In recent years, in vitro 3D models of early mammalian development, such as embryoid bodies (EBs) and gastruloids, were successful in mimicking various aspects of the early embryo, providing high throughput accessible systems for studying the basic rules shaping cell fate and morphology during embryogenesis. Using Brachyury (Bry), a primitive streak and mesendoderm marker in EBs, we study how contact, biochemical and neighboring cell cues affect the positioning of a primitive streak-like locus, determining the AP axis. We show that a Bry-competent layer must be formed in the EB before Bry expression initiates, and that Bry onset locus selection depends on contact points of the EB with its surrounding. We can maneuver Bry onset to occur at a specific locus, a few loci, or in an isotropic peripheral pattern. By spatially separating contact and biochemical signal sources, we show these two modalities can be integrated by the EB to generate a single Bry locus. Finally, we show Foxa2+ cells are predictive of the future location of Bry onset, demonstrating an earlier symmetry-breaking event. By delineating the temporal signaling pathway dependencies of Bry and Foxa2, we were able to selectively abolish either, or spatially decouple the two cell types during EB differentiation. These findings demonstrate multiple inputs integration during an early developmental process, and may prove valuable in directing in vitro differentiation.

A different fixation of the femoral component in total knee arthroplasty may lead to preservation of femoral bone stock

2003 ◽  
Vol 217 (5) ◽  
pp. 325-332 ◽  
Author(s):  
M Barink ◽  
N Verdonschot ◽  
M de Waal Malefijt
Keyword(s):  
Femoral Component ◽  
Knee Arthroplasty ◽  
Bone Remodelling ◽  
Significant Loss ◽  
Bone Stock ◽  
Femoral Bone ◽  
Secondary Effects ◽  
Total Knee ◽  
The Stability

Good femoral bone stock is important for the stability of the femoral component in revision knee arthroplasty. However, the primary total knee replacement (TKR) may cause significant loss of bone stock in the distal anterior femur. Earlier stress-induced bone remodelling simulations have suggested that a completely debonded component may save bone stock in the distal anterior region. However, these simulations did not consider the fixation of a debonded implant and possible secondary effects of micromotions and osteolysis at the interface. The current study tries to combine the preservation of bone stock with adequate component fixation. Different bone remodelling simulations were performed around femoral knee components with different sizes of bonding area and different friction characteristics of the debonded area. The fixation of the femoral component with different bonding characteristics is quantified with calculated implant-bone interface stresses. The results show that a bonded femoral component with a debonded inner side of the anterior flange may significantly reduce bone resorption in the endangered distal anterior femur, without jeopardizing the fixation of the femoral implant. This effect may be obtained in vivo by using a femoral component with a highly polished inner side of the anterior flange.

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