Ex vivo comparison of the bursting strength of surgeon’s knot compared to self-locking knots for closure of ventral midline celiotomy in horses.

Abstract

It is not uncommon for the equine population to experience abdominal pain referred to as ‘colic’. It is estimated that approximately 9% of the general population of horses that experience colic require surgical intervention. The most common approach to gain access to the equine abdomen is through the ventral midline, with the horse under general anesthesia. Frequently, incisional complications occur post operatively with reported rates as high as 44%. As a result, investigators strive to identify risk factors associated with morbidity and improve techniques and conditions for surgical exploration, abdominal closure, and post-operative care. Previous studies have identified the surgical knot as the weakest part of the suture, with failure occurring at the knot 90-100% of the time. Although the most commonly used knot is the surgeon’s knot, in vitro studies examining self-locking knots revealed that they are stronger and more secure. The objective of this study was to compare the bursting strength and failure mode of ventral midline celiotomy closure using a simple continuous suture pattern with one of two knot combinations, a novel self-locking knot combination of forwarder start with an Aberdeen end knot (F-A) compared to a traditional knot combination of a surgeon’s start with a surgeon’s end knot (S-S). An ex vivo cadaver study was performed. A 20-cm ventral midline celiotomy was created in 14 equine cadavers. Horses were assigned to celiotomy closure with a F-A or S-S knot combination. Prior to closure, a 200L inflatable bladder was placed in the abdomen and insufflated until failure of the celiotomy closure. The horses’ signalment, weight, breed, age, knot combination type, mode of failure, closure time (minutes) and bursting strength in millimeters of mercury (mmHg) were recorded. The median bursting strength of closure with F-A knot combination (388 mmHg) was significantly greater than the median bursting strength of closure with the S-S knot combination (290 mmHg) (P=0.035). The majority (6 out of 7) of F-A combinations failed along the fascia, in contrast to the majority (6 out of 7) of S-S combinations that failed at the knot. There were no significant differences in closure times (P=0.48). The self-locking F-A knot combination had a significantly higher bursting strength compared to the traditional S-S knot. Our results indicate that closure of a ventral midline celiotomy with a FA knot combination may offer a more secure closure than that of a traditional S-S knot combination, increasing bursting strength by an average of 25%.