The aim of this project is to develop a new mixed numerical/experimental methodology in order to predict the second stability (long-term) of the cementless hip implant prior to the clinical tests. The combination of computational models together with in vitro measurements will enable
-to evaluate the device attributes (such as its endurance),
-to evaluate the performance of the device in vivo when subject to various physiological or pathological conditions
-to carry out a complete performance evaluation and risk analysis of any new design solution prior to undertaking lengthy and extensive clinical trials.
This would be particularly useful in reducing poor initial designs, which often in the past have only been noticed after clinical treatment. The development of this pre-clinical tool to assess the design evolution of new implants systems will allow a significant increase of the success rate of cementless hip implants all the patient life. Furthermore, the improved design and simulation will result also into an increased acceptance of the hip replacement and improved articulation of movements.
A wide range of skeletal diseases affects the joints of the middle-aged & older population, osteoarthritis of the hip being the most common. When conservative methods of treatment fail, it is needed to replace the affected joint with an artificial replacement called joint prosthesis. Every year more than 500 000 citizens worldwide undergo hip replacement.
Total hip replacements are therefore the most important implantable orthopaedic device. Cementless hip prosthesis, the most recent type of hip prosthesis, represents today 35% of the European market. The current trend is to significant increase of its market share due to its lower failure rate that cemented hip prosthesis. Although total hip arthroplasty can be considered as a reliable surgical, between 5 & 20% of cementless hip prosthesis fail after 10 years. Today most failures are related to the design of the implant and the lack of methodology and tool to validate in the long term the design before the clinical tests.
Therefore the aim of the project is to develop and validate a new mixed numerical/experimental methodology in order to predict the long-term stability of the cementless hip implant before the clinical tests.
The specific RTD goals are the following:
-Definition of a complete "failure mode Vs. biomechanical cause Vs. associated hazard" (MODE-CAUSE-HAZARD) scenario.
- Development of innovative computational procedures to capture the biomechanical effect of the biological bone response with special reference to the bone/implant interface.
-Application of this pre-clinical validation framework to a given design of prostheses, to assess its effectiveness and its applicability within an industrial context.
In order to achieve these objectives the workprogramme is divided into 5 workpackages:
1 - Technical specifications definition
2 - Identification of failure modes of cementless hip implants and their biomechanical causes
3 - Modelling and tests in vitro for the bone behaviour
4 - Development of a predictive computer model
5 - Industrial validation: Development and in vitro evaluation of enhanced stem designs
The major milestones are:
-Obtention of clear and exploitable information on clinical failures of hip implants
-Completion of the viscoelastic modelling of bone behaviour
-Prescription of step-by-step bone interface movement
-Estimation of the sensitivity of the stability of the implant
-Definition of an optimal implant design on the basis of the failures models
The combination of computational models together with in vitro measurements in the developed pre-clinical tool will enable:
- The evaluation of the device attributes (such as its endurance)
- The performance of the device in vivo when subject to various physiological or pathological conditions.
- To carry out a complete performance evaluation & risk analysis of any new design solutions prior to undertaking lengthy & expensive clinical trials.
This would be particularly useful in reducing poor initial designs, which often in the past have only been noticed after clinical treatment.
Funding SchemeCRS - Cooperative research contracts
CF14 4XY Cardiff