Laboratory of BiotribologyProf. Svatava Konvičková
Laboratory of Experimental Biotribologie (LEB) is a part of the Laboratory of Biomechanics man at the Technical University in Prague. The laboratory is fully equipped with devices enabling studies biotribologic and biocorrosion properties of joint replacement components. The experimental tribological tests are evaluated from the perspective of the wear rate and qualitative characteristic of damage at contact surface. They are performed simplified and realistic testing of new and modified materials. Was designed and built the new test equipment KKK ELO 2011, which allows to conduct experiments for kinematic and dynamic conditions approaching the situation in the joint after implantation.
Experimental equipment of the laboratory:
Four independent simulators of knee loading. Each of them allow us to mimic real movement regimes as normal gait, walking up/down stairs, running, walk with a load, sitting on a chair / standing,...). The simulator is equipped by accurate one- or six- axis force sensors. Working place of tested prosthesis (inside silicone capsule) is heated on 37°C using thermostats.
System for monitoring of corrosive potential of replacement against a reference electrode - Magic XBC E (Gryf HB) measuring electrodes. It measures also pH and temperature. See the project
USM microscope (zoom up to 800x) - for quick inspection of contact surfaces on tested prosthesis
WTW pH 315i/SET - the set for pH measurement of lubricant
Spider 8 HBM - specialized data acquisition system (measuring and recording of forces, pressure, location, etc.)
Procedures used for wear evaluation:
1) visual inspection - photos from the microscope or the camera
A photo of a small-joint-cup from microscop (ZOOM 800x)
2) measurement of material (volume) loss - accurate scanning of geometry on a device (RedLux)
Reconstruction of 8-mm joint head. More than 150,000 points were scanned. Colours in this case denote deviation between reconstructed surface and mean sphere. It is possible to evaluate also the diference between the surface before wear loading test and the surface after the test. For more information about the scanner, see, the link.
4) analysis of wear particles - amount, shape, cytotoxicity (carried out in collaboration with the Institute of Physiology AS CR)
Left: An analysis of wear particles, Right: measuring system xCELLigence (in the Institute of Physiology AS CR) to measure electric impedance. The cell index may be evaluated wrom electric impedance. It correlates indirectly with a toxicity of wear particles in the samples.
The following figure describes the structure of the simulator. For more detail information see the presentation about the simulator
Degrees of freedom of the simulator with standard knee prosthesis
Testing of Hinge-type knee prosthesis. This experimental setup allow us to scan corrosive potential.
Testing of a small joint (thumb joint endoprosthesis)
Projects in realisation
- Research of technical and biological composite materials
- Relationship between blood vessel wall architecture and constitutive behavior
- Influence of inhomogeneities on the mechanical behavior of blood vessels - bifurcations
- Constitutive modeling of blood vessels
- The corrosive potential as a marker of endoprosthesis failure
- Biotribology of joint replacements
- Wear of thumb joint replacement