Evaluation of freeze-dried flexor tendon grafts in the dog

Twenty-eight freeze-dried profundus tendon homo grafts were studied in 14 adult beagles. Two digits in a paw of each of these animals were operated on. In one digit the host profundus tendon was excised and replaced with a freeze-dried graft, leaving the host superficialis tendon and annular ligaments intact with no trauma to the osseous floor of the digital tunnel. In the other digit the host profundus and superficialis tendons both were excised, preserving the annular ligaments; the osseous floor of the digital tunnel was severely and deliberately disrupted and traumatized before the freeze-dried graft was inserted. After graft insertion and suture, the operated paws were immobilized for 3 1/4 weeks, after which time unrestricted activity was allowed. Of the 28 grafts inserted, there was spreading or partial separation with intervening scar tissue at the proximal (palmar) junction in five digits. All other junctures remained intact until the time the animal was put to death, 2 to 12 weeks after functional use. The freeze-dried grafts all remained intact, with no adhesions to the grafts within the osseofibrous digital tunnel, regardless of whether or not the flexor tunnel had been severely traumatized. In every instance there was full, unrestricted passive flexion of the digit on application of a flexion force to the graft in the palm. A smooth-surfaced sheath had formed around each graft in a manner very similar to the sheath that normally forms about silicone rod implants.