Traditional methods of treatment for conditions such as arthritis of the knee involve physiotherapy and medication. However, when the condition becomes excessively painful for the patient, surgical intervention is undertaken. Movement of the natural knee joint involves the base of the femur bone articulating against the top of the tibia bone. The surfaces of these bones are covered by articular cartilage which allows smooth, pain free movement at the joint. The base of the femur and the top of the tibia have two surfaces or 'condyles'; in severe cases, the cartilage is worn away from both condyles, and they have to be replaced by a total knee arthroplasty (TKA). In some cases only one of the condyles is affected by arthritis, and yet both condyles are replaced in a TKA procedure. Unicondylar Knee Arthroplasty (UKA), which resurfaces only the affected side, is an alternative to TKA which is becoming an increasingly popular because of its improved functional outcome, favourable long term clinical results and the benefits of minimally invasive surgical techniques. In particular, UKA offers a more effective solution than TKA for more active patients with single compartment knee disease, because the mechanics of the knee are better preserved, and more functional anatomy is maintained. UKA also has advantage of rapid rehabilitation, short hospital stay, quicker operation and quicker recovery. Evidence suggests that revision of a UKA to a TKA results in performance similar to a primary TKA and has been reported to be an easier procedure than the typical revision TKA. However, despite this, UKA is still under-exploited as an alternative to TKA. This is partly related to perception issues, and partly to historically higher failure rates due to improper technique. Therefore, it is desirable to improve the understanding of how surgical technique impacts UKA performance and failure risks, to inform clinical decision-making for UKA with best-practice surgical technique. Most attempts to assess the performance of a joint replacement computationally have involved a 'deterministic' approach, that is, a single implant is modelled in a single bone and a single load is applied. This represents only one possible situation, when potentially many thousands could exist. Recently, there has been a move to replace deterministic approaches with statistical approaches, which attempt to take into account all sources of variability in the system. For example, the performance of an implant in a series of bones under varying loads can be analysed. In this project, statistical approaches will be applied to analyse the performance of UKA. The research will utilise a 'statistical knee joint' based on a large library of bone CT scans. This statistical knee joint represents a wide population of patients into which the unicondylar implant will be implanted. Variations in surgical technique will be accounted for by altering the nature of the surgical cuts and positions of the surrounding soft tissue structures. In this way, a knowledge of how the surgical technique can affect implant performance, in how quickly it wears and how likely it is to loosen, can be ascertained. This knowledge will be used to develop a tool that can be used to guide surgeons on what aspects of their surgical technique need careful consideration when planning their surgery in order to achieve improved patient outcomes. Industry can also benefit from the tool as part of the implant design process. The performance of new and existing implants can be robustly evaluated rapidly at the design stage, and the number of physical tests required can be reduced dramatically. In addition, designs that are predicted to perform poorly can be eliminated at an early stage, leading to substantial cost and time benefits for the design process. The commensurate benefit of this tool will be more robust implants with a longer lifespan, benefiting both the patient and the healthcare provider.

To maintain continuity with MATCH Phase 1, it has been requested that MATCH Phase 2 follows the current programme breakdown in terms of Projects A-F from 2008-2013 / a vision that is described below. We note that MATCH changed dramatically in creating the projects A-F and that further changes in the themes are inevitable. An overview of these themes is given below.Projects A, B and C address economic evaluation and its impact in decision-making by companies, governments and procurement agencies. We have identified a major demand for such research, but note that there is some convergence between these themes (for instance, A and C may well coalesce under the Bayesian banner). In particular, a 'methodologies' theme is likely to emerge in this. Under the former theme, a truly integrated Bayesian framework for medical devices would represent a strategically important achievement.On the other hand, the business of delivering these developments to industry, and the organisations or franchises that might ultimately provide the best vehicle for doing so, still requires further exploration and negotiation, and at this point there is considerable uncertainty about how this will best be done. However the critical element has been established, namely that MATCH can provide useful tools for, and attract significant levels of funding from industry. To this extent, the applied side of Project A-F and Project 5 might well evolve into a series of programmes designed to spin out tools, training and best practice into industry. Project 5 remains for the present because we have set it up with a framework within which company IP can be protected, and within which we can expedite projects to company goals and time scales.A similar pattern is likely to emerge from the single User project (D), where there is considerable scope for capability, and methodological development / and the size of this team needs to increase. The aim is to develop a suite of methods, guidelines and examples, describing when a given method is useful and when user needs assessment must be cost-effective. We will gain and share experience on what approach works best where. Our taxonomy will recognise circumstances where the novelty of a proposed device may undermine the validity of user needs assessment conducted before the 'technological push' has had a fair opportunity to impact on the human imagination.Moreover, new research is needed to 'glue' some of these themes together. Some of this is already included (for instance, in Projects C and D below) to link the user-facing social science with the economics, or the pathway-changing experiences (F) with formal economic evaluation, will require new, cross-disciplinary research. This type of research is essential to developing the shared view of value, which MATCH is pursuing. Similarly, integrating supply-chain decision-making and procurement elements of theme (E) with economic evaluation would represent an important element of unification.To achieve this, we will need to bring in some news skills. For instance, we are already freeing up some funding to bring in an economics researcher at Ulster; more statistical mathematical support may be needed to further develop the Bayesian theme; and we need to bolster the sociological element within the team.Finally, this vision cannot be funded entirely within a research framework, and we expect critical elements to be achieved under other funding (for instance, Theme E by the NHS, in due course).