An animal model for simulating deep tissue injury for pressure ulcer research on spinal cord injury

Abstract

Current animal models examining deep tissue injury (DTI) development as a mechanism for pressure ulcer (PU) formation are limited, as the created animal wounds do not usually reflect clinically observed tissue necrosis. This study aimed to establish a more clinically relevant rat PU model by including a SCI condition in the model and by examining the role of a simulated bony prominence in DTI formation. Tissue injury percentage of compressed tibialis anterior (TA) muscle from eight SCI (T9) rats was compared against eight neurologically intact control rats to examine PU development over the flat surface of the tibia. To examine DTI formation, five other rats were implanted with a hemispheric polypropylene bone mimic beneath the TA muscle and were allowed to heal prior to compression. The rats in the DTI model were then separated into three groups and were administered different levels of compression to determine the best experimental conditions for the model. Both MRI and light microscopy were used to analyze tissue necrosis due to compression, and histological data was processed and quantified using a custom Matlab code. Postoperative ultrasound images of the implant two weeks after surgery showed the implant was correctly oriented on the surface of the bone. Results from this experiment and subsequent histological analysis and MRI observation confirmed these models are successful in simulating a clinically relevant pressure‐induced deep tissue injury.