Enhanced pre-clinical experimental simulation of the natural knee

Wear of joint replacements remains a major factor determining their reliability and lifetime. In the knee, the wear of polyethylene is a key factor determining longevity, with increased failure, osteolysis and loosening in younger more active patients who live longer (Swedish Joint Registry). The pre-clinical determination and prediction of wear is currently undertaken experimentally by joint simulators under a limited set of conditions, which do not take into account the wide variation of clinical conditions in the patient.
Our Stratified Approach For Enhanced Reliability (SAFER) approach takes into account variations in surgical delivery, variations in kinematics, variations in the patient population and degradation of the biomaterials technology, and indeed combinations of all these different conditions. With regards to surgical delivery there has recently been a shift towards kinematic alignment as opposed to more conventional mechanical axes alignment. Although kinematic alignment has been associated with better flexion and clinical outcome [A] there is no understanding of the implications of this on wear of the knee replacement.
Testing under such a wide portfolio of stratified conditions cannot be achieved using experimental simulation alone, as too many experimental simulations are needed. Hence a new computational modelling approach has recently been developed, which can be combined with the experimental approach [B].
In this PhD project this unique combined computational and experimental approach will be used to specifically investigate the influence of variations in surgical delivery (such as mechanical versus kinematic alignment) on the wear performance of total knee replacements.
This PhD project addresses the healthcare challenge '50 active years after 50' through research and development of computational and experimental pre-clinical test methods of the wear of knee replacements under this wider set of surgical and patient dependent conditions.
Aim:
To investigate the influence of surgical alignment on wear of a DePuy Synthes Total Knee Replacement (TKR) through a combined experimental and computational approach.

Objectives:
- To develop an experimental simulation model of surgical alignment and apply it to a DePuy Synthes TKR to determine wear
- To develop a computational model of the DePuy Synthes TKR, which will be validated against experimental simulation.
- To determine the effects on wear of kinematic versus mechanical surgical alignment through the combined experimental & computational simulation approach

Facilities:
Experimental simulation will be carried out in the iMBE Mechanical Engineering laboratories.
This project will advance our computational and experimental pre-clinical biomechanical and biotribological methods for the assessment of knee replacements. It will inform us as to what are the influence of variations in surgical delivery, variations in kinematics, variations in the patient population and degradation of the biomaterials technology, and indeed combinations of all these different conditions on the wear of knee replacements. These advanced methods will be applied to clinical products with our industry collaborator, DePuy Synthes, and translated into international standards.