应力对聚乳酸作为骨形态发生蛋白和庆大霉素载体修复骨缺损的影响

目的：观察应力对聚乳酸(PLA)作为骨形态发生蛋白(BMP)和庆大霉素载体的骨密度和骨伤愈合的影响。方法：将实验大白鼠40只随机分为A组20只，制造兔双侧胫腓骨中段1cm长的横断骨缺损．使用外固定架调整距离固定；B组20只．仅于单侧胫骨中段制造1cm长的横断骨缺损．用普通直形钢板调整距离固定。2组骨缺损中均植入PLA作为BMP载体的庆大霉素缓释体。于第3个月后A组拆除外固定架。而B组仍保留固定钢板。第4个月处死动物，作不脱钙切片观察，骨密度、X线片、扭转实验等项检查及剪切实验。结果：①2组在第3个月时骨缺损处均达到骨性愈合及骨髓腔再通。且均未出现感染。②2组扭转实验结果差异无显著性。其余各项检查结果显示A组骨伤恢复均优于B组，并且无B组的应力遮挡效应。结论：使用PLA作为BMP和庆大霉素载体修复骨缺损在3个月时拆除固定器．能自然增加应力．促使骨密度增加；并且不会出现炎症、畸形及延迟愈合等情况。

Effect of Stress on the Repair of Bone Defect Using Polylactic Acid as Carriers of Bone morphogenetic Protein and Gentamycin

Ojbective: To observe the effect of stres s on the consistency and bone healing using polylactic acid (PLA) as carriers of b one morphogenetic protein (BMP) and gentamycin. Methods:Forty white rats were r andomly divided into group A ( n =20) and group B ( n =20). In the group A, traverse bone defects of 1 cm at the middle of bilateral tibia and fibula were m ade and external fastness frame was used to fix the bones by adjusting the dista nce. In the group B, traverse bone defects of 1 cm at the middle of only one sid e of tibia were done and general straight shape armor plate was used to fix the bones by adjusting the distance. In the two groups, PLA as the carriers of BMP a nd gentamycin was implanted into the bone defects. On the 3rd month, the externa l fastness frame was withdrawn in the group, while the armor plate was not remov ed in the group B. On the 4th month, all animals were killed and following exami nations and experiments were performed: observation of the sections, bone densit y; X-ray, torsion and cut. Results:In the two groups, the bone defects obtained bony union and the marrow cavity was re-opened, and on infection occurred on th e 3rd month. The torsion experiment revealed there was no significant difference between the two groups, but other experiments and examinations showed that the recovery of the bone defects in the group A was superior to that in the group B. Conclusion:Using PLA as the carriers of BMP and gentamycin to repair the bone defects can naturally increase the stress and promote the increase of bone consi stency after removal of the fixator on the 3rd month. No inflammation, deformity and delayed union occurred.