Ex vivo biomechanical evaluation of tissue construct strength in an equine colopexy model.

Abstract

To compare strength of left paramedian colopexies using various techniques in equine ex vivo models. Experimental study. Equine cadavers euthanized for nongastrointestinal pathology (36 specimens derived from 9 horses). Colopexies were performed after euthanasia. Suture pattern (horizontal mattress vs. cruciate) and incorporation of dorsal sheath of the rectus abdominis (partial-thickness) versus incorporation of dorsal and ventral sheath of the rectus abdominis (full-thickness) were evaluated. Single cycle load to failure, work to peak load, stiffness, and mode of failure of colopexy tissue constructs were assessed. Mean load to failure of all constructs ranged from 102.26 to 166.38 N. Partial-thickness bites demonstrated a mean load to failure and standard deviation (SD) of 111.91 (35.88) N and 102.26 (30.06) N (p < .05) which was significantly lower than the mean and SD of full-thickness bites (166.3 [72.42] N and 163.21 [51.40 N]), respectively. All full-thickness bites regardless of suture pattern and over half of partial-thickness bites failed at the colonic wall. There was no significant difference in load to failure compared to mode of failure. A stronger colopexy was achieved with a full-thickness bite regardless of the suture pattern. The most common mode of failure was the colon wall. Incorporating ventral and dorsal fascia of the rectus abdominus provided a stronger colopexy structure, which may necessitate a second incision or subcutaneous palpation of the needle when performing a colopexy. The lateral band of the colon failed in most constructs (77%) regardless of technique, which could weaken the colonic wall and risk colonic rupture.