Abstract: Objective: The biodegradable coralline hydroxyapatite cylinder was implanted into the bone defect of the distal femur of rabbits, and the formation of new bone of coralline hydroxyapatite cylinder was dis-cussed, so as to provide references for the timing of implant placement. Methods: 30 white New Zealand rabbits were randomly divided into 24 rabbits in the test group and 6 in the control group. In the experi-mental group, 48 coralline hydroxyapatite were implanted in the distal femur of the rabbit, and 8 rabbits were sacrificed at 4, 8 and 12 weeks, respectively. Gross specimens were observed and histologically ana-lyzed. In the control group, all the animals were killed at 12 weeks, and the corresponding analysis was performed. Results: The 24 rabbits in the test group healed well. At the 4th week, there was only a few new bone formation at the edge of the implant. At the 8th week, there was obvious new bone ingrowth in the implant center. At the 12th week, both the edge of the implant and the new bone in the center in-creased. The percentage of new bone area in the test group was statistically significant between the 4th week and the 8 week, and there was no significant difference between the 8 week and the 12 week. In the control group, only a small amount of inflammatory cells and fibroblasts grew into the defect center, and no bone tissue was formed. Conclusion: The biodegradable coralline hydroxyapatite cylinder healed well after implantation into the bone defect of rabbit femur, and at 8 weeks, new bone was formed in the center of the bone, which is suitable for implant placement.

Key words: coralline hydroxyapatite cylinder, critical bone defect, percentage of new bone area, os-teoconduction