Moderní léčebnou metodou lokálního ohraničeného poškození zdravé kloubní chrupavky je transplantace štěpů kultivovaných autologních chondrocytů na poškozené místo. Po transplantaci, která je provedena artroskopicky, se transplantát hojí přibližně rok. Pro sledování pooperační fáze hojení transplantátu bylo vyvinuto dotykové měřidlo pro měření tuhosti kloubní chrupavky. Dotykové měřidlo je artroskopický diagnostický nástroj, kterým je porovnána tuhost fyziologické a transplantované chrupavky pacienta. Funkce je založena na snímání deformace měřící části, která je při artroskopickém zákroku vsunuta do kloubu a přitlačena k povrchu chrupavky. Cílem práce bylo navrhnout konstrukční řešení měřidla, navrhnout elektrické vybavení, kalibrace měřidla, ověření měřících metod a plná automatizace měřícího procesu. Konstrukce a funkce měřidla je v souladu s náročnými požadavky na artroskopický diagnostický nástroj.

Modern surgical healing method of large local defects placed on the physiological articular cartilage was transplantation of cultivated autologous chondrocyt graft on the defect. First, there was sample healthy chondrocyt tissue of patient. This tissue was cultivated and after that was transplanted back on the defect. Surgical investigation was done arthroscopicly. Transplanted tissue had different mechanical properties in comparison with physiologic tissue. Graft healed approximately one year and then the mechanical properties were the same. For the purpose of monitoring of surgical phase healing graft with clinical practise indentation instrument for the measurement of cartilage stiffness was developed. Indentation instrument was arthroscopic diagnostic instrument which compared stiffness of physiological and transplanted cartilage of the patient. The result of patient investigation was percentage value of stiffness of transplanted cartilage. By means of the result was given diagnosis. Cartilage stiffness was measured by the front indentation part which was inserted into the joint and pressed to the surface of the physiological and transplanted cartilage during investigation. Function of indentation instrument was based on measurement of the bending deformation of indentation part. Indentation part consisted of two beams, external tube and internal rod. Deformation was measured by three strain gauges which were placed on perimeter of external indentation part and two strain gauges on internal indentation part. Each of the three external strain gauges were connected to own Wheatstone bridge and there were three output signals from them. Other two internal strain gauges were connected to one Wheatstone bridge and there was only one output signal. Output signals obtained from the strain gauges were processed and analyzed automatically. It was necessary to ensure always the same conditions of measurements for correct result and repeatability of measurements. The conditions of measurements were value of indentation force and value of angle deviation of force application. The three output signals from strain gauges of external indentation part were used for calculation of measurements conditions. The one output signal from two strain gauges of internal part was used for cartilage stiffness measurement. Value of this output signal was saved for investigation of transplanted and physiological cartilage for the same conditions of measurements. Value of signal for investigation of physiological cartilage determined the maximum stiffness. Values of signals were compared and the result was percentage value of stiffness of transplanted cartilage. Design of indentation instrument corresponded to exacting requirement on arthroscopic diagnostic instrument. The indentation instrument was reliable and safe in wet environment, made from biocompatible materials, waterproof, chemical resistant and had small weight.

Laboratoř biomechaniky člověka Ústav mechaniky biomechaniky a mechatroniky Fakulta strojní ČVUT Praha

Arthroscopic instrument for transplanted cartilage grafts diagnosis

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