[An experimental study on repair and restoration of gliding function of the injured flexor tendon of the finger. Part 6: A mode of vascularization of the grafted tendon within the pseudosheath (author's transl)].

The so-called two-stage procedure has been used in the reconstructive surgery for the severely injured flexor tendon of the finger. However, only little has been known as to vascularity of the grafted tendon within the pseudosheath. In order to clarify this problem, a series of experimental studies were carried out using young chickens. First, the flexor tendon of the fourth digit of chicken with its sheath was replaced by a silicone rod. The distal end of the rod was sutured to the stump of the flexor digitorum profundus and the proximal end left free. Then, in ten to sixteen weeks, upon removal of the rod, the flexor digitorum profundus of the third digit was grafted through into the newly formed pseudosheath. The paw was immobilized with plaster case in moderate flexion for three weeks, then the chicken was allowed to walk freely. At the different time intervals, starting from the third day to the fifteen weeks after surgery, a mode of vascularization of the grafted tendon and its surrounding tissue was examined microangiographically. The vessels appear at the area of proximal and distal stump of the grafted tendon a week postoperatively, and additional vessels appear at the contact area of the pseudosheath and the grafted tendon two weeks postoperatively. These vessels formed mutual anastomosis in five to six weeks. With time, the vessels connecting between the epitenon and the pseudosheath gradually enlarge and assemble together to form vascular bundles, so that the appearance of the structure becomes similar to that of the mesotenon. Three weeks postoperatively, the vessels appeared in the grafted tendon, and grew gradually so that these vessels ran through the full length of the grafted tendon in five to six weeks. About ten weeks, the vascularity of the grafted tendon is more abundant than that of the normal tendon, but diminished gradually so as to resemble that of the normal tendon at the fifteeth week. Thus, the growth of the vessels of the tendon grafted by two-stage procedure is delayed by two weeks compared with that by the primary tendon grafting.