A new direction in anastomotic research: should we redesign the 'angle of sorrow'?

INTRODUCTION: Despite advances in oncological outcomes in colo-rectal surgery, rates of anastomotic leak have not improved. The precise mechanisms of anastomotic leak remain poorly understood. Current research has focused on anastomotic reinforcement to tackle anastomotic leak with little success. The 'Angle of Sorrow', the corner of the anastomosis is prone to anastomotic leak, but remains a persistent feature in the gastrointestinal anastomosis. The tendency for stress forces to concentrate in the vulnerable 'Angle of Sorrow' prompts the need for anastomotic design research.

AIM: The aim of this study is to explore if redesigning the 'Angle of Sorrow' can reduce the stress forces in the ileocolic anastomosis.

METHODS: A simulation-based experimental study compared two anastomotic designs: traditional Slit Enterotomy Anastomosis (SEA) vs a novel Radiused Enterotomy Anastomosis (REA). The finite element analysis simulations were performed using FEBIO to measure peak sheer stress in pressurised bowel.

RESULTS: Tissue stress was found to concentrate at the 'Angles of Sorrow' in traditional anastomosis design while the REA design distributed sheer stress across the anastomosis. The SEA model had greater peak sheer stress factors than REA for the hand-sewn and stapled 'Barcelona' anastomosis (1.58 (k) vs 0.64 (k), 0.91 (k) vs 0.63 (k)). The REA anastomosis resulted in significantly less peak stress across all anastomotic experiments (p = 0.0047). The mucosa of the SEA model tended to unfavourably evert.

CONCLUSION: Redesigning the 'Angle of Sorrow' decreased tissue stress concentration. The direction of future anastomotic research may involve going back to the drawing board, rather than attempting to reinforce a potentially flawed design. Despite advances in colorectal surgery, rates of anastomotic leak have not improved. The 'Angle of Sorrow', the corner of the anastomosis is prone to anastomotic leak, but remains a persistent feature in gastrointestinal anastomosis. The direction of future research may involve going back to redesign this vulnerable area.