EFFECTS OF HYDROXYAPATITE AND ALUMINA SHEATHS ON POSTOPERATIVE PERITENDINOUS ADHESIONS IN CHICKENS

Two experimental methods for restoring flexor tendon sheath integrity and preventing adhesions around traumatized flexor tendons utilizing a rtificial tendon sheaths made of either hydroxyapatite (HAp) or alumin a were studied in a flexor tendon-trauma model and compared to a stand ard tendon sheath repair and a control. Eighty toes were divided equal ly into a control group, a sheath repair group, an HAp group, and an a lumina group. Profundus tendons in zone II were divided and repaired a fter sublimis excision in all groups. In the sheath repair group, the flexor sheath was also repaired after suturing the tendon. In artifici al sheath groups, sheaths made of HAp and alumina were placed over the repair sites to protect them from the surrounding tissues. In the con trol group, after repairing the tendon, the flexor sheath was excised and no artificial sheaths were used. Each toe was immobilized in a pla ster cast for 3 weeks. After three weeks, the plaster cast was removed followed by the removal of the sheaths in the artificial sheath group s through a small incision in the skin in zone II. Active mobilization was encouraged in each group. Postoperative adhesions were examined a t 3, 6, 9, and 12 week intervals by using light microscopic techniques . To further explore the effects of artificial sheaths on tendon heali ng, transmission electron microscopy was done for the HAp and alumina groups at 3, 6, and 12 week intervals. Results demonstrated decreased severity of postoperative adhesions in the HAp as well as in the alumi na groups in comparison with the sheath repair and controls. A space r esembling the fibro-osseous canal was formed around the tendon after r emoving the sheaths. This space remained patent until 12 weeks, 9 week s after removing the sheaths, and a newly formed tendon sheath-like st ructure lined by synovial cells and with a peritenon-like structure ov er the tendon surface was observed. In the sheath repair and control g roups, the severity of adhesions was decreased with the passage of tim e, to some extent due to unrestricted mobility. However, a newly forme d tendon sheath or peritenon-like structure was not observed. Electron microscopic studies confirmed good healing at the suture in the HAp a nd alumina groups with no evidence of necrosis. These results are qual itative in nature as no statistical tests were performed. From these r esults we conclude that if the tendon is separated from the surroundin g granulation tissue by a barrier with good biocompatibility, the tend on can heal with fewer adhesions. Artificial sheaths may be used to re duce adhesions in severe injuries of the hand where postoperative immo bilization is necessary due Co fractures, vascular, or nerve injuries. (C) 1995 John Wiley and Sons, Inc.