Perspectives of numerical modelling in pressure ulcer research

Abstract

The primary cause of pressure ulcers is some form of prolonged mechanical load, although environmental and intrinsic factors have an influence on the development. Without the mechanical loading no wound will develop. This means that studying the response of soft biological tissues to mechanical loading is a critical issue and this may be achieved by the use of theoretical models. There is a surprising dearth of published studies on pressure ulcers backed by some form of theoretical analysis. Speculative and intuitive statements on the role of mechanical loads and the influences of shear, pressure and traction on tissue behaviour and on the assumed occlusion of blood vessels are abundant, however, on occasion supported by experimental evidence. One can only guess why this is the case. One reason might be the paucity of bioengineers involved in pressure ulcer research, although it is also true that the level of sophistication of theoretical models has long been far from realistic. However, it is believed that the current prospects are very good, and this is an opportune moment to examine the potential of available theoretical, numerical models as a tool in pressure ulcer research. The objective of this chapter is to show where mechanical modelling can be important or even indispensable. This will include a description of how models were used in the past, what can be expected in the near future and which are the bottlenecks in this research. Basically there can be two reasons for the development of theoretical models. The first is to use models as a design tool for patient support surfaces in the most general sense, ranging from beds and wheelchairs or wheelchair cushions to prostheses for patients with an amputation. This approach will obviate the need for extensive prototyping and may lead to computer-aided optimization of patient support surfaces. The first section is devoted to modelling that is used for this purpose. The second reason to use theoretical models is to understand the very complex phenomena in soft tissues such as skin, fat and muscle under prolonged mechanical load. In studies on the aetiology of pressure ulcers these models are indispensable. The second section is devoted to these models.