海绵状、泥灰状脱钙骨基质修复骨缺损

目的探讨海绵状脱钙骨基质(DBM)和泥灰状DBM修复骨缺损的能力。方法将兔四肢长骨骨干脱脂、脱钙后制成长度为500～1000 μm的纤维状及直径为200～400μm的颗粒状DBM,并与2%明胶混合分别制成海绵状DBM和泥灰状DBM。在9只兔双侧桡骨中段做一长10mm的骨膜骨缺损,分别植入海绵状DBM和泥灰状DBM及空白对照,每组各6个缺损,术后观察6周,于4、6周时拍摄X线片,并对实验动物的大体标本、骨密度、生物力学、新生骨矿化率及病理组织学改变进行观察。结果术后4、6周X线片显示两实验组骨缺损均修复,骨髓腔完整;空白对照组无一例修复骨缺损。骨密度测量显示海绵状DBM组新生骨骨密度与正常桡骨间差异无显著性(P >0.05),但泥灰状DBM组的新生骨骨密度与正常桡骨间差异有显著性(P< 0.05)。术后6周生物力学测定显示海绵状DBM组新生骨极限压缩强度值与正常桡骨差异无显著性(P >0.05),泥灰状DBM组低于正常桡骨且差异有显著性(P< 0.05)。两实验组新生骨矿化率差异无显著性(P >0.05)。组织学观察显示两实验组中DBM绝大部分被吸收,形成板状骨骨小梁及完整的骨髓腔,塑形完整, 新生骨内可见骨单位及局部尚未完全骨化的新生骨。结论海绵状DBM和泥灰状DBM均具有诱导成骨活性和骨传导能力,使用方便,新生骨塑形完整,生物力学强度高,矿化

An experimental study of spongy and putty-like demineralized bone matrix (DBM) in the repair of segmental defects

Objective To evaluate the osteogenic effects of of spongy and putty-like demineralized bone matrix (DBM) in repairing segmental defects. Methods The spongy network of DBM (sDBM) was prepared by mixing DBM fibers with 2% gelatin solution and lyophilized; the putty-like DBM (pDBM) was prepared by mixing DBM particles into 2% solution of gelatin. The two forms of DBM were then sealed in syringes and sterilized by ethylene oxide. A 10 mm long bone defect was made bilaterally on the radius of 9 New Zealand White rabbits. The defects were randomly divided into 3 groups: 6 defects were grafted with 50 mg sDBM, 6 grafted with 1ml pDBM (contained 50 mg DBM particles), and the remaining 6 void as control group. The animals were sacrificed at 6 weeks postoperatively. The implantation sites were harvested and evaluated. Results All the radius defects healed completely after the treatment with both sDBM and pDBM and intact cortical bones were present, but there were no union of defects in control animals. The measurement of BMD revealed no differences between new bone which was grafted with sDBM and the normal radius (P> 0.05), whereas the value of new bone grafted with pDBM was significantly lower than that of the normal group (P< 0.05). There were no significant differences between the groups of grafted with sDBM and normal radius in the ultimate compressive strength (CUS) (P>0.05); but the CUS of the pDBM grafted group was significantly lower than that of normal radius (P< 0.05). There was no significantly statistical difference in MAR between the sDBM group and pDBM group (P>0.05). Histological analysis exhibited that most of the DBM was absorbed and substituted by matured new cortical bone in the treated defects of both groups 6 weeks postoperatively, whereas in the untreated group, the defects were only filled with fibrous connective tissue in their mid-portion. Conclusion The sDBM and pDBM are both effective in repairing segmental bone defects. The properties of new bone induced by grafts with sDBM are superior to that of pDBM in biomechanics. These materials can be used in clinical practice as bone graft extenders or enhancers.