Strength of tissue bonds as a function of surface apposition

Laser assisted vascular anastomoses have potential advantages over sutured anastomoses, but the mechanism of bonding is not understood. Current theories propose that the bonding process is primarily thermal, but recent work has implicated dehydration as an important factor. Bonds created by dehydration have shown similarities to argon laser bonds, but the wide range of scatter in bond strength warranted further investigation. This was addressed through creation of in vitro tissue bonds at 55°C. Following rehydration, bond integrity was evaluated by measurement of breaking strength. A progressive series of modifications was applied to bonding technique to investigate the effect of particular parameters on breaking strength. These included use of a microtome to cut smoother tissue faces, removal of inter-surface air gaps and varying the pressure applied to the bonding surfaces. Mean bond strength remained constant except when bonding under high pressure. Scatter in bond strength about the mean was markedly reduced by improving surface intimacy through removal of inter-surface air gaps.