Tendon injury response: Assessment of biomechanical properties, tissue morphology and viability following flexor digitorum profundus tendon transection

Insertion site injuries of the flexor digitorum profundus (FDP) tendon often present for delayed treatment. Apart from gross observations made at the time of surgery, the changes that occur in the flexor tendon stump during the interval from injury to repair are unknown. These changes may include tendon softening and loss of viability, which may contribute to the poor outcomes observed clinically and experimentally. Thirty-eight FDP tendons from 23 adult dogs were transected sharply from their insertions on the distal phalanges and were not repaired. Dogs were allowed full weight bearing and were euthanized 7 or 21 days after injury. Biomechanical testing indicated that the resistance of injured tendons to pullout of a Kessler-type suture was not different from control tendons at 7 days and was increased at 21 days by 25% (p