Testing of Artificial Testing of Artificial Joints Joints Dr Tom Joyce Dr Tom Joyce 26 26 th th October 2009 October 2009 MEC8017 MEC8017 - Bioengineering Bioengineering Overview of this lecture Overview of this lecture Why do we test artificial joints? Why do we test artificial joints? How do we test artificial joints? How do we test artificial joints? Testing artificial hip joints Testing artificial hip joints Testing other artificial joints Testing other artificial joints Why do we test artificial joints? Why do we test artificial joints? Because it is ethical to do so Because it is ethical to do so To verify or validate: To verify or validate: New designs New designs Geometrical, material or manufacturing Geometrical, material or manufacturing changes to existing products changes to existing products To benefit: To benefit: Ultimately the patient Ultimately the patient Also the manufacturer, clinicians, fellow Also the manufacturer, clinicians, fellow scientists and regulatory bodies scientists and regulatory bodies Test methods Test methods European, British, International and European, British, International and American standards American standards Other published test methods Other published test methods In In- - house test methods house test methods Wear is the main cause of failure of most Wear is the main cause of failure of most artificial joints artificial joints Difficulty of modelling the wear process, Difficulty of modelling the wear process, therefore testing is undertaken therefore testing is undertaken Implant testing Implant testing Implants shall: Implants shall: ‘be evaluated to demonstrate that the be evaluated to demonstrate that the intended performance is achieved intended performance is achieved’ ’ ‘undergo undergo pre pre- - clinical clinical evaluation by evaluation by … analysis of data obtained from testing analysis of data obtained from testing … (which) shall simulate conditions of use (which) shall simulate conditions of use’ BS EN ISO 14630: 1998 BS EN ISO 14630: 1998 ‘ ‘ General General requirements for non requirements for non- -active surgical active surgical implants implants’ ’ How do we know if a test is How do we know if a test is successful? successful? Validate by comparing with explants Validate by comparing with explants Explants may be of two types: those Explants may be of two types: those retrieved at revision operation (failures) retrieved at revision operation (failures) and those retrieved while functioning and those retrieved while functioning correctly (i.e. at post mortem) correctly (i.e. at post mortem) Test methods must produce same type of Test methods must produce same type of ‘ failures failures’ as those seen in the body, or the as those seen in the body, or the same same ‘ ‘ features features’ ’ of explanted joints of explanted joints
