Introduction: The classic teaching in flexor tendon repair suggests that a 10mm bite is important for the integrity of the repair regardless of the other features of the technique. Although this has been widely accepted since Bunnell’s first descriptions of accurate flexor tendon repair there appear to be little data to support it. An extensive review of the literature showed no biomechanical data relating specifically to size of bite in flexor tendon repair. We hypothesised that decreased bite may cause less damage to the tendon during repair while still offering adequate mechanical strength.

Aim: To investigate the effect of different bite sizes on the mechanical properties of flexor tendon repairs.

Methods: Twenty fresh-frozen cadaveric flexor tendons were divided at their centres. One side of a modified Kessler repair was used on each side taking a 6mm bite on one side and a 10mm bite on the other. The tendons underwent tensile testing on a mechanical testing frame by pulling on the ends of the suture with the tendon secured in pneumatic grips. Data for stiffness and ultimate load to failure were recorded.

Results: An increased bite size made no significant difference to stiffness of the repairs. There was a difference in load to failure noted but this was not significant. The ultimate load to failure was noted after the specimens had been distracted over 2mm, which would result in clinical failure.

Conclusions: These results suggested that a 10mm bite may be excessive in flexor tendon repair and could cause more tissue damage than lesser bites. Further study of in vivo effects of decreased bite size is required.