The University of Exeter is using materials testing solutions from Lloyd Instruments to investigate the behavioural mechanics of one of the world's largest selling replacement hip joints
The University of Exeter is currently using the latest materials testing solutions from Lloyd Instruments to investigate the behavioural mechanics of one of the world's largest selling replacement hip joints.
Research engineers are using the Lloyd Instruments' 20kN EZ20 universal testing machine to analyse load transmission characteristics of the Exeter Total Replacement Hip Joint, and other designs, to gain a better understanding of how these clinically successful devices actually work inside patients.
With comparatively little published data on the stress/strain performance of artificial hip joints, the wide range of hip joint designs available today makes pre-surgical choices difficult.
This current study aims to remove the uncertainty.
Using the the EZ20, fitted with a thermal cabinet, biomedical engineers are able to test joint components at body temperature to investigate the effects of differing surface finish (matt or polished) and different physical shape of the femoral stems available.
The EZ20 universal testing machine is used in many industries and applications.
'This machine came highly recommended for its flexibility, accuracy and ease of use', says Dr Clive Lee, at the University of Exeter.
'We designed the special testing rig ourselves, but it is the company's NEXYGEN? MT data analysis control software that allows us to switch effortlessly between load and strain modes required to model the complex load patterns a typical artificial hip would face.' The first Exeter Total hip replacement (then known as the Ling Lee hip) was used on November 27, 1970.
More than thirty years on, hip replacement surgery has become common practise.
Implant materials have also changed.
The femoral stem is now made from a high fatigue strength stainless steel, the acetabular cup (in the pelvis) is made from high density ultra high molecular weight polyethylene, and the bone cement is a self curing polyethylmethycrylate.
