The biomechanics of sitting-acquired pressure ulcers in patients with spinal cord injury or lesions.

Sitting-acquired pressure ulcers (SAPU) in permanent wheelchair users with traumatic or non traumatic disorders of the central nervous system (CNS) are a great medical challenge. The purpose of this review is to summarise what is currently known concerning the aetiology of SAPU, particularly in its severe form, which may now be classified as a 'deep tissue injury' according to the US National Pressure Ulcer Advisory Panel. Specifically, this review focuses on biomechanical aspects of deep SAPU and describes the relevant bioengineering methodologies and research evidence. It discusses the unique biomechanical conditions in deep tissues, which are caused by chronic sitting associated with CNS disorders, and overall, the present review indicates that avoiding interface pressures above 32 mmHg in such patients is not necessarily a 'pressure relief.'