KneesUp lends a virtual hand to improve artificial finger joints implants

Brussels 26 November 1997 Patients suffering from rheumatoid arthritis or some kind of physical trauma often are faced with artificial finger joint implant's surgery. Most common used nowadays are one-piece silastic implants which unfortunately tend to fail within about five years. The HPCN-TTN organisation has engaged itself in the KneesUp-project to develop techniques simulating the movements of prostheses. In collaboration with the Sheffield University, the so-called SIGMA glove has been designed to output real-time kinematic data of the finger movements. Interfaced to a digitised skeleton of the hand on a PC, the 'virtual hand' on screen precisely indicates by means of finite element analysis techniques the critical stress-spots in silastic prostheses.

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Patients suffering from rheumatoid arthritis or some kind of physical trauma often are faced with artificial finger joint implant's surgery. Most common used nowadays are one-piece silastic implants which unfortunately tend to fail within about five years. The HPCN-TTN organisation has engaged itself in the KneesUp-project to develop techniques simulating the movements of prostheses. In collaboration with the Sheffield University, the so-called SIGMA glove has been designed to output real-time kinematic data of the finger movements. Interfaced to a digitised skeleton of the hand on a PC, the 'virtual hand' on screen precisely indicates by means of finite element analysis techniques the critical stress-spots in silastic prostheses.

Since there exists little quantitative data on the forces in and distortions of the artificial finger joint implants, researchers are trying to understand the operational envelope of the implant. The SIGMA (Sheffield Instrumented Glove for Manual Assessment) glove especially has been designed for proper clinical usage and features integral bend sensors over each finger joint. The patient has to perform a series of well defined standard tasks which reflect normal daily hand executed activities. In this way, the stress distribution in each system can be evaluated. Both surgeon and implant designer get an immediate feel for the particular needs of an individual patient thanks to the fast and highly interactive animation.

A major problem however constitutes the fact that the implants are not cemented to the bones. To reduce the computation time to acceptable proportions when calculating the simulated stress-provoking movements, fast multi-processor computers are required. The High-Performance Computing and Networking-Technology Transfer Nodes organisation has entered the KneesUp project to cope with these challenges. Simulation of a single flexion-extension envelope of a single prosthesis runs in approximately five hours instead of the usual hundred if performed on multi-processor platforms. At this level, implementations in design improvement and assessment in clinical environments become practicable.

The final and ideal outcome of course remains 'real time' simulation with direct and individual clinical interpretation. The multi-disciplinarian approach in any case seems to have some promising results in store taking in account that the software package for the Sigma glove originally has been developed to evaluate the mechanics of collisions for the automobile industry by Pam System International. Soon, researchers have discovered that its explicit solution and surface contact algorithms were particularly appropriate for simulation studies of biological implants. As a result, a triumvirat of private industry, academic research and high-computing performance and networking is shaking 'virtual' hands in the KneesUp-project supported by the European Union's initiative Esprit.

More details about improvement of human artificial joints designing is to be found at the Technology Transfer Nodes web site.


Leslie Versweyveld

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