Quantifying fascial tension in ventral hernia repair and component separation.

BACKGROUND: Excessive fascial tension is a major cause of ventral hernia recurrence. Although hernias are commonly characterized by area, the tension experienced by fascia is directly proportional to the surrounding tissue stiffness. We demonstrate an accurate and simple technique for intra-operative measurement of fascial closing tension and quantify the decrease in tension following Component Separation (CS).
METHODS: A tensiometer was created using a spring with a known recoil constant (k) and a surgical clamp. Using Hooke's law (Force = kX; X = spring displacement), fascial tension was calculated. This method was first validated on a bench-top model and then applied to the anterior fascia of 4 fresh cadavers (8 hemi-abdomens) over a range of simulated hernia defect sizes. When fascia could no longer reach midline, CS was performed and measures repeated. Tissue stiffness was calculated by plotting defect size versus resulting tension.
RESULTS: Fascial defects ranged from 1- to 18-cm wide with average midline closing tension prior to release 36.1 N (range 17-48) and 8.2 N (range 5-11) after CS, a mean 76% decrease (range 70%-85%). Mean R2 values between defect size and tension for the synthetic and cadaver models were 0.99 (p < 0.01) and 0.91 (p = 0.01; all hemi-abdomen measurements significant). Inter-rater Pearson's correlation consistently found R2 values > 0.95 (p < 0.01) for each hemi-abdomen, showing high precision and reproducibility.
CONCLUSION: We have applied a cheap, simple, and precise method to sterilely assess fascial tension during herniorrhaphy and also quantified the decrease in tension following component separation. This technique may be rapidly translated into the operating room with minimal equipment to provide objective data critical for intraoperative decision-making.