背景和目的：要決定生醫材料的成效便是利用動物模型製造骨缺損來測試。所以本篇研究的目的就是測試兩種生醫材料，分別是博納骨替代材及老鼠胎盤幹細胞，在2 及4週後兔子脛骨的絕對骨缺損癒合時促進新骨生成的效能。方法：本篇研究使用8 隻紐西蘭白兔。隨機選取4 隻兔子在脛骨上手術製造8 釐米的圓形骨缺損，另外4 隻兔子在脛骨上製造11 釐米的骨缺損。測試兩種生醫材料，分別是博納骨替代材及老鼠胎盤幹細胞。之後分別在2 及4 週後將兔子犧牲，利用放射影像、組織學檢查來觀察骨缺損骨生成的比例。結果：從放射影像學檢查顯示出充填博納骨替代材及老鼠胎盤幹細胞的8 釐米及11 釐米骨缺損都有骨生成。8 釐米骨缺損相較11 釐米有較大量的放射不透性物質生成。此外，4週後比起2 週後新骨生成的量都是比較多。組織學檢查結果呈現出充填博納骨替代材及老鼠胎盤幹細胞兩組在2 及4 週後新骨生成比例都比無充填材料組較高。結論：本研究的結果顯示在早期兔子脛骨的骨缺損癒合時，博納骨替代材及老鼠胎盤幹細胞都具有促進新骨生成的效能。但是，需要更多的研究來證實這些結果。

Background and Purpose: The critical size defect has been used in experimental animal models to determine the effectiveness of newly developed biomaterials. The aim of the present study was to evaluate the early healing process of BonaGraft ( composed of HA and β-TCP ) and placenta-derived multipotent cells (PDMCs) in rabbit tibia at 2 and 4 weeks. Materials and methods: Eight New Zealand white rabbits were used in this study. Eight-millimeter defects were created in the tibiae of 4 randomly selected rabbits, and 11-mm defects were created in another 4 rabbits. Two kinds of biomaterials, BonaGraft and PDMCs of mice, were used. The defects were analyzed by means of radiographic, histologic , and histomorphometric analyses after the animals were killed at 2 and 4 weeks, respectively, after surgery. Results: The radiographic findings showed that the defects gradually closed over time. The 8-mm defects were filled with a larger amount of radiopaque substance than 11-mm defects. In addition, new bone formations were greater at 4 weeks than at 2 weeks, and large amounts of bone regeneration and bone marrow began to appear. The histomorphometric analysis suggested that the defects with both BonaGraft and PDMCs of mice filled had more new bone formation than those without material filling at 2 and 4 weeks. Conclusions: The results of the present study suggest that both BonaGraft and PDMCs of mice show new bone formation in the early phase of healing process. However, more studies are needed to confirm these results.