Relaxation and Recovery of Colon After Application of a Mechanical Stress

Jenifer Barrie, Zahra Ehteshami, Peter Culmer, David G. Jayne, and Anne Neville


Biomaterials, Biomechanics, Viscoelasticity, Colonic tissue


Introduction The colon is a soft biological tissue that exhibits complex viscoelastic behaviour. The aim of this study is to mechanically model relaxation of colonic tissue after indentation, to eventually quantify tissue recovery after stress application. Methods A single stress value of 51kPa was applied to ex vivo porcine colon for 5, 30 and 60 seconds. 20 indentations were applied to either the mucosal or muscular layers. The relaxation portion was analysed by calculating the difference between the highest and lowest force (ΔF). The Maxwell and Wiechert models were fitted to the data and compared. Histological evidence of tissue damage was assessed. Results Mean ΔF was higher with indentations at the muscular surface as compared to mucosal surface at 5 and 30s time-points. This reversed at 60s. The Wiechert model fit improved with longer duration (30 and 60s). Evidence of histological damage was found consistently in the stressed region. Conclusion The Maxwell model is the simplest form that exhibits viscoelastic behaviour, but refining this and linking it to the anatomical tissue structure, using the Wiechert model, provides a better fit. We will now use this model in further studies correlating the model coefficients with histological damage grading.

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