Effects of collagen gel mixed with hydroxyapatite powder on interface between newly formed bone and grafted Achilles tendon in rabbit femoral bone tunnel

The Achilles tendon was implanted into a bone tunnel made in the femoral co ndyle of 20 rabbits. In the left femur, collagen gel mixed with hydroxyapat ite powder (C-HAp) was injected between the graft and the bone tunnel. On t he other hand, as a control, simple saline was injected in the right femur. Five rabbits were sacrificed at 4, 8, 12, and 16 weeks after surgery. Hist ological findings showed that in the C-HAp group, the grafted tendon came i n direct contact with new bone, and Sharpey-like collagen fibers arising fr om the grafted tendon were observed to penetrate new bone by 4 weeks after surgery. In the control group, however, fibrous tissue was observed between new bone and the grafted tendon, but no penetrating fibers From the grafte d tendon into the new bone were observed until 16 weeks. The area of new bo ne in the C-HAp group was significantly greater than that in the control gr oup 4, 8, and 12 weeks after surgery (p < 0.0001, p < 0.0007, p < 0.0013, r espectively). (C) 2001 Elsevier Science Ltd. All rights reserved.