Triggering after partial tendon laceration.

Triggering and tendon flap formation were studied after a transverse laceration of 50% of the width of the flexor digitorum profundus tendons of the hind limb of 14 adult sheep at various intervals after injury. The tendon laceration was not repaired and there was no post-operative immobilization. Triggering was not caused by bulbous scar formation but by the bunching of the tendon fibres proximal or distal to the laceration site. This bunched part of the tendon appeared to become incorporated into the healing process, with gradual spontaneous resolution of triggering. Failure of incorporation of this bunched part resulted in the formation of a flap in two tendons.