[Flexor tendon repair: timing of surgery and sheath management]

Effect of timing of repair and management of sheath on functions of injuried tendons was evaluated in a clinical relevant model using 60 white leghorn chickens. The flexor digitorum profundus (FDP) tendons of the long toes were cut and were repaired at 1, 4, 8, 14 and 20 days after injury. The sheath on the left foot was closed and that on the right excised. The tendon excursion, toe motion, morphology of the sheath and tendon healing were studied 6 weeks after tendon repair. Tendon functions were the best in primary repair, and they got worse as the delay became longer. Repair in the late stage produced significantly worse tendon functions. Sheath closure with remarkable tension worsened tendon healing. We conclude that the optimal timing for tendon repair is at the primary stage. Delayed tendon repair can be performed within 3 weeks to one month after injury, but the repair is preferably done in initial several days of delay. Direct sheath closure is not advocated in tendon repair in the delayed period.