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

Objective: To compare strength of left paramedian colopexies using various techniques in equine ex vivo models.

Study design: Experimental study.

Sample population: Equine cadavers euthanized for nongastrointestinal pathology (36 specimens derived from 9 horses).

Methods: 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.

Results: 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.

Conclusion: 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.

Clinical significance: 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.