Total knee arthroplasty (TKA) is an effective orthopaedic intervention that is annually performed around 1.0 million times in the European Union, providing pain relief and restoration of function. However, TKA currently does not provide a lifelong solution, particularly in younger patients which have a longer life expectancy and are more active and demanding. Failure of TKA depends on the primary fixation that is achieved during surgery. This fixation is mainly defined by the mechanical behaviour of the peri-prosthetic bone and is affected by the viscoelastic response of the bone, leading to a loss of fixation strength due to bone stress relaxation.

In my project, the fundamental mechanics of bone relaxation will be established in experiments with human cadaveric bone specimens, to define a material law relating stress relaxation to bone density and stress level. Subsequently, the impact of viscoelasticity on TKA will be investigated in stress-relaxation experiments and computational models of implant placement. Finally, its effect on primary fixation will be evaluated in micromotions analyses.

The material models and computational analyses developed in the current project provide researchers with better tools to understand the mechanical response of bone and implant fixation, and will provide insights into the consequences of implant design on primary fixation. The ultimate goal is to develop implant systems that last a lifetime, thereby annually preventing 3,000 unnecessary revision surgeries, saving millions of euros in healthcare costs each year.