[Experimental study on repairing rabbit femoral condyles defect by small intestinal submucosa and HA-TCP compositions at different ratios].

Objective: To study an optimal ratio of small intestinal submucosa (SIS) and (hydroxyapatite-tricalcium phosphate, HA-TCP, SIS/HA-TCP) compositions according to the effect of SIS/HA-TCP compositions with different ratios on repairing rabbit femoral condyle defect.

Methods: Thirty-six rabbits were made into bone defect models of 6 mm in diameter and 10 mm in depth in both sides of femoral condyles. Three different ratios of SIS/HA-TCP compositions (w/w: 1, 0. 5, 0. 25) were implanted into rabbit femoral condyle defect. After 2, 4, 8 and 12 weeks of operation, the repair effect was observed grossly. The histological evaluations were performed by histological scoring system and computer imaging analysis system.

Results: The amount of new bone formation in SIS/HA-TCP(0. 5) group was more than that in SIS/HA-TCP(1) and SIS/HA-TCP(0. 25) groups. Histological observation: In SIS/HA-TCP (1) group, few new bone formation was seen and bone defect was repaired in the 12th week. In SIS/HA-TCP (0.5) group, immature woven bone was found in the defect in the 2nd week; more immature woven bone appeared and formed trabeculae in the 4th week; the regenerated bone was vigorously growing into the interspaces of the implanted materials in the 8th week; the implanted materials was basically replaced by bony structure and the lamellar bone appeared in the 12th week. The results of SIS/HA-TCP (0. 25) group were similar to that of SIS/HA-TCP(0. 5) group. The histological scoring was higher in SIS/HA-TCP (0.5) and SIS/HA-TCP (0.25) groups than that in SIS/HA-TCP (1) group (P<0.05) in the 2nd, 4th, 8th, and 12th weeks. The scoring was higher in SIS/HA-TCP (0.5) group than that in SIS/HA-TCP (0.25) group in the 2nd and 12th weeks (P< 0.05). In new bone formation and the degradation of HA-TCP, SIS/HA-TCP (0.5) and SIS/HA-TCPC (0.25) groups were superior to SIS/HA-TCP (1) group (P<0.05), SIS/HA-TCP (0.5) group was superior to SIS/HA-TCP (0.25) group (P<0.05).

Conclusion: SIS/ HA-TCP (0.5) has better effects of repairing bone defect and it can be used as a reference ratio in constructing bone scaffolds.