Sensor Technology Ltd. - PRODUCT NEWS
 


        

          


          Piezo technology helps access artificial joints.

          


          
A medical
          researcher is using an industrial torque sensor to analyse

          the performance of implanted eplacement knee joints, hoping to
          increase

          the understanding of their long term post-surgery performance.



          The programme is being run by Judith Lane, between now and the
          end of 2007 at Queen Margaret University College in Edinburgh.
          As well as this research, which should lead to the awarding of
          a PhD, she holds a Masters degree in bioengineering, is a qualified
          physiotherapist and lectures at both undergraduate and postgraduate
          level in the School of Health Sciences.



          Before beginning this latest research Lane had to design, build
          and validate a rig that could assess the performance of patients'
          artificial joints. Explaining the reasons for the project, she
          said: "Most replacement knee joint surgery is extremely
          successful, but a few patients do not achieve the function we
          would expect. By exploring the relationship between function
          and stiffness, this research hopes to reveal if stiffness in
          the joint is the reason why."



          The rig developed for the project centred on a 100Nm Torqsense
          transducer from Sensor Technology, with an extended through shaft
          supporting crank arms on both ends.



          "We very carefully align the axis of the transducer with
          the patient's knee and attach the ankle to the end of one crank.
          We can then use the other crank to move the knee without the
          patient having to put in any muscular effort. This means that
          we have isolated the joint and can run through a series of tests
          with the transducer constantly monitoring torque so that we can
          build up a profile of the knee's performance."



          Non-contact sensing head

          The sensing head of the Torqsense transducer does not contact
          the shaft under test, so exerts no back torque that has to be
          accounted for in calculations. Instead, two piezo-ceramic combs,
          designed to deform microscopically as torque in the shaft changes,
          are glued to the shaft and monitored over a radio wave connection.
          Because the combs are based on piezo technology they can be supplied
          with sufficient operating power via the radio signals. Their
          electro resistive characteristics vary with the deformation,
          changing the output radio signal proportionally to the torque
          in the shaft.



          "By using the Torqsense transducer, we can calculate the
          resistance to movement created by soft tissues around the knee,
          at any point in range," said Lane.



          For each patient several readings are taken to develop a picture
          of the dynamics of the knee joint. This data will then be correlated
          with the findings from a battery of tests to establish the ability
          of the knee to undertake common activities such as climbing stairs,
          sitting down and getting into the bath. "By cross referencing
          the two sets of data we should be able to build up an exact profile
          of the joint's performance, and assist decision-making between
          the patient, physiotherapist and orthopaedic surgeon relating

          to future treatment."

          _________________________________________________

          
For further
          information, please contact:-

          
Sensor Technology
          Ltd.

          Tel:
          +44(0)1295 730746

          Fax: +44(0)1295 738966

          Email: info@sensors.co.uk

          Website: www.sensors.co.uk

          ______________________________________________



          March 2006

          



                
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