OBIF棒内固定治疗家兔股骨髁骨折的实验研究

A study on the treatment of rabbit thighbone condyle fracture by internal fixation with OBIF rod

目的：研究OBIF可吸收材料棒对家兔股骨髁部骨折内固定模型的动态力学性能。方法：选取新西兰大白兔作随机自身对照,造成股骨外髁外1/3骨折,复位后治疗侧用1支OBIF棒固定,对照侧用1支SR-PGA棒固定;术后定期行X线及CT检查,术后2、4、8、12周时每次处死7只,取股骨外髁骨折部作剪切力测试,取OBIF棒和SR-PGA棒作抗剪切和抗弯曲强度测试,取骨折部软组织和骨折面骨痂分别作光镜和透视电镜的观察,其中固定棒上有骨痂附着或长入时取作扫描电镜观察。结果：OBIF棒初始剪切和弯曲强度是松质骨的剪切和弯曲强度的10~12倍,随时间的迁移,其剪切强度和弯曲强度均下降,但一直到松质骨骨折愈合仍为松质骨强度的10~6倍,OBIF棒的弹性模量较SR-PGA更接近松质骨的弹性模量,OBIF棒植入8周时有表面吸收,凹凸不平,有大量的骨痂长入,12周时棒与骨痂结合紧密。结论：OBIF材料是一种有效的松质骨骨折内固定的材料,能在体内被逐渐吸收,可免去再次手术取出。

Objective：To investigate the dynamic mechanical properties of OBIF （bioabsorbable material internal fixation） rod on the rabbit model of thighbone condyle fracture. Methods： We Selected adult New Zealand rabbits as self-control randomly and made lateral 1/3 thighbone condyle fracture. After reposition, the treatment side was fixed by an OBIF rod, and the contrast side was fixed by an SR-PGA rod. After operation every rabbit would take X-ray film and CT examination in determinated time, and every 7 rabbits were killed during the next 2,4,8,12 weeks. The thighbone epicondylus lateralis was taken out for shearing force test, and the OBIF rod and the SR-PGA rod for anti-shearing test and anti-bowing test, and the soft tissues around the fracture and the bony callus for the light and electron microscope exam respectively. Any bony callus attaching to or growing into the fixation rob should be taken out for the scanning electron microscope exam. Results：The initial anti-shearing strength and anti-bowing strength of the OBIF rod were 10 to 12 times of those of cancellous bone. Both the anti-shearing and anti-bowing strength would decrease with time passing. Until bone healing, the strength would still be 6 to 10 times of that of the cancellous bone. Compared with the SR-PGA rod, the elasticity of the OBIF rod was much like that of cancellous bone. 8 weeks later, the surface of OBIF was absorbed and became uneven. Lots of bony callus grew into it.12 weeks later, the rod and the bony callusis would bind tightly. Conclusion：The OBIF is an effective material for internal fixation of cancellous bone fracture. It can be absorbed gradually and need not be taken out again.