Quantitative measurement of patellofemoral joint stability: Force–displacement behavior of the human patella in vitro

2003 ◽  
Vol 21 (5) ◽  
pp. 780-786 ◽  
Author(s):  
W. Senavongse ◽  
F. Farahmand ◽  
J. Jones ◽  
H. Andersen ◽  
A. M. J. Bull ◽  
...  
Keyword(s):  
Patellofemoral Joint ◽  
Quantitative Measurement ◽  
Joint Stability ◽  
Displacement Behavior ◽  
Force Displacement

scholarly journals Biomechanical validation of an artificial tooth–periodontal ligament–bone complex for in vitro orthodontic load measurement

2012 ◽  
Vol 83 (3) ◽  
pp. 410-417 ◽  
Author(s):  
Zeyang Xia ◽  
Jie Chen
Keyword(s):  
Stress Relaxation ◽  
Thin Layer ◽  
Periodontal Ligament ◽  
Published Data ◽  
Mechanical Behaviors ◽  
Biological Studies ◽  
Displacement Behavior ◽  
Force Displacement ◽  
Artificial Tooth

ABSTRACT Objectives: To develop an artificial tooth–periodontal ligament (PDL)–bone complex (ATPBC) that simulates clinical crown displacement. Material and Methods: An ATPBC was created. It had a socket hosting a tooth with a thin layer of silicon mixture in between for simulating the PDL. The complex was attached to a device that allows applying a controlled force to the crown and measuring the resulting crown displacement. Crown displacements were compared to previously published data for validation. Results: The ATPBC that had a PDL made of two types of silicones, 50% gasket sealant No. 2 and 50% RTV 587 silicone, with a thickness of 0.3 mm, simulated the PDL well. The mechanical behaviors (1) force-displacement relationship, (2) stress relaxation, (3) creep, and (4) hysteresis were validated by the published results. Conclusion: The ATPBC simulated the crown displacement behavior reported from biological studies well.

Medial Patellofemoral Ligament Influence on Patellofemoral Joint Kinematics: An In-Vitro Analysis

2013 ◽  
Vol 29 (10) ◽  
pp. e116-e117 ◽  
Author(s):  
Stefano Zaffagnini ◽  
Francesca Colle ◽  
Bharat Sharma ◽  
Simone Bignozzi ◽  
Nicola Francesco Lopomo ◽  
...  
Keyword(s):  
Patellofemoral Joint ◽  
Medial Patellofemoral Ligament ◽  
Joint Kinematics ◽  
Vitro Analysis ◽  
In Vitro Analysis

In vitro friction and lubrication of large bearing hip prostheses

2009 ◽  
Vol 224 (7) ◽  
pp. 853-864 ◽  
Author(s):  
S Flanagan ◽  
E Jones ◽  
C Birkinshaw
Keyword(s):  
Large Diameter ◽  
Calf Serum ◽  
Mixed Lubrication ◽  
Joint Stability ◽  
Bovine Calf Serum ◽  
Reinforced Polymer ◽  
Metal On Metal ◽  
Different Diameters ◽  
Friction And Lubrication

New material combinations and designs of artificial hip implants are being introduced in an effort to improve proprioception and functional longevity. Larger joints in particular are being developed to improve joint stability, and it is thought that these larger implants will be more satisfactory for younger and more physically active patients. The study detailed here used a hip friction simulator to assess the friction and lubrication properties of large-diameter hip bearings of metal-on-metal and ceramic-on-reinforced-polymer couplings. Joints of different diameters were evaluated to determine what effect, if any, bearing diameter had on lubrication. In addition, the effects of lubricant type are considered, using carboxymethyl cellulose and bovine calf serum, and the physiological lubricant is shown to be considerably more effective at reducing friction. The frictional studies showed that the metal-on-metal joints worked under a mixed lubrication regime, producing similar friction factor values to each other. The addition of bovine calf serum (BCS) reduced the friction. The ceramic-on-reinforced-polymer samples were shown to operate with high friction factors and mixed lubrication. When tested with BCS, the larger-diameter bearings showed a decrease in friction compared with the smaller-size bearings, and the addition of BCS resulted in an increase in friction, unlike the metal-on-metal system. The study demonstrated that the component's diameter had little or no influence on the lubrication and friction of the large bearing combinations tested.

Needle Insertion Force Modeling using Genetic Programming Polynomial Higher Order Neural Network

2013 ◽  
pp. 58-76
Author(s):  
Mehdi Fallahnezhad ◽  
Hashem Yousefi
Keyword(s):  
Neural Network ◽  
Biological Tissue ◽  
Constant Velocity ◽  
Phase 1 ◽  
Needle Insertion ◽  
Prostate Brachytherapy ◽  
Force Modeling ◽  
Needle Insertion Force ◽  
Force Displacement

Precise insertion of a medical needle as an end-effecter of a robotic or computer-aided system into biological tissue is an important issue and should be considered in different operations, such as brain biopsy, prostate brachytherapy, and percutaneous therapies. Proper understanding of the whole procedure leads to a better performance by an operator or system. In this chapter, the authors use a 0.98 mm diameter needle with a real-time recording of force, displacement, and velocity of needle through biological tissue during in-vitro insertions. Using constant velocity experiments from 5 mm/min up to 300 mm/min, the data set for the force-displacement graph of insertion was gathered. Tissue deformation with a small puncture and a constant velocity penetration are the two first phases in the needle insertion process. Direct effects of different parameters and their correlations during the process is being modeled using a polynomial neural network. The authors develop different networks in 2nd and 3rd order to model the two first phases of insertion separately. Modeling accuracies were 98% and 86% in phase 1 and 2, respectively.

Dynamic analysis of elastically and plastically graded spherical and cylindrical contact

2019 ◽  
Vol 233 (11) ◽  
pp. 1712-1728 ◽  
Author(s):  
Tamonash Jana ◽  
Anirban Mitra ◽  
Prasanta Sahoo
Keyword(s):  
Dynamic Analysis ◽  
Material Properties ◽  
Static Force ◽  
Contact Interface ◽  
Response Curves ◽  
Initial Displacement ◽  
Finite Element Software ◽  
Displacement Behavior ◽  
Force Displacement ◽  
Plastically Graded

A dynamic analysis of a hemispherical and cylindrical contact, material properties of which are graded elastically and plastically along the radius, is presented. The static force–displacement behavior of a hemisphere and a semi-cylinder in contact with a rigid flat is obtained using finite element software. The force–displacement is used in a further dynamic analysis for undamped-free as well as for forced-damped vibration of the contact interface. For the undamped free vibration, variation of natural frequency w.r.t. initial displacement is furnished for different values of elastic and plastic gradation parameter. In addition, variation of maximum initial displacement for contact loss is also demonstrated. The forced-damped vibration characteristics of the spherical and cylindrical contact interfaces are presented in the form of frequency response curves with jump up and jump down frequencies. Spherical and cylindrical contact interfaces are found to exhibit softening and hardening type nonlinearity, respectively.

ACCELERATED IN VITRO HAEMOSTASIS AND DECREASED SPONATEOUS THROMBOLYSIS IN DIABETICS

1987 ◽  
Author(s):  
M Rademaker ◽  
D J Thomas ◽  
J D Kirby ◽  
I B Kovaos
Keyword(s):  
Quantitative Measurement ◽  
Diabetic Control ◽  
Diabetic Patients ◽  
Blood Flows ◽  
Increased Risk ◽  
New Instrument ◽  
Polyethylene Tubing ◽  
Vascular Occlusions ◽  
Plug Formation

Diabetics have an increased risk of developing coronary, cerebral, and peripheral vascular occlusions. The mechanism of the accelerated haemostatic/thrombotic system is not known and studies on 'hyperactive platelets' and the fibrinolytic system in diabetes are inconclusive. We have used the Haemostatometer to assess haemostasis and thrombolysis in diabetic patients. The Haemostatometer, a new instrument, allows quantitative measurement of haemostasis by monitoring the pattern of haemostatic plug formation (HPF) in holes punched through polyethylene tubing through which non-anticoagulated blood flows under standard conditions (1,2). The pattern and speed of blood coagulation subsequent to HPF was also measured as was the spontaneous thrombolysis time (STT) (taken as the time until expulsion of the haemostatic plug from heparinised blood). Blood was sampled from 20 diabetic patients (10 insulin (IDD) and 10 non-insulin dependant (NIDD)) as well as 20 age mathched controls. All values are for mean ± SEM. Both IDD and NIDD had shorter bleeding times (HPF) than did controls: 2.16 ± 0.44 min vs 3.08 ± 1.14 min (p=0.03) (the initial phase of HPF was even more significantly shorter: 0.53 ± 0.06 min vs 1.03 ± 0.14 min (p<0.0l). The STT in NIDD was significantly longer than in controls: 56.8 ± 3.1 min vs 36.9 ± 4.0 min (p=0.002) while in IDD, the STT was shorter at 22.0 ± 0.5 min (p=0.018 when compared vs controls 36.9 ± 4.0 min).The shortened bleeding time (HPF) in diabetics is most probably a manifestation of hyperactive platelets and could contribute to the increased risk of thrombosis seen. In NIDD the prolonged thrombolysis (STT) may be a contributing factor to the development of diabetic angiopathy, which is thought to be prevented by good diabetic control (ie insulin). This suggests that the diabetic vascular endothelium retains some capacity to generate plasminogen activator in response to insulin.(1). Gorog P and Kovacs IB. Haemostasis 16: 337-345, 1986.(2). Gorog P. Angiology 37: 99-105, 1986.

scholarly journals Function of ankle ligaments for subtalar and talocrural joint stability during an inversion movement – an in vitro study

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Lu Li ◽  
Albert Gollhofer ◽  
Heinz Lohrer ◽  
Nadja Dorn-Lange ◽  
Guiseppe Bonsignore ◽  
...  
Keyword(s):  
In Vitro Study ◽  
Vitro Study ◽  
Joint Stability ◽  
Ankle Ligaments ◽  
Talocrural Joint
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