摘要
目的 探讨应力松弛接骨板体内应力遮挡率变化及其对骨折愈合的影响。方法 作兔两侧胫骨干截骨 ,分别以应力松弛接骨板 (实验组 )和坚硬接骨板 (对照组 )固定 ,术后 2～ 48周采用X线、光镜 (含偏光 )、及力学测试 ,对两组骨折愈合过程进行研究。结果 两组固定后 ,应力遮挡率均在 70 %左右 ,随着固定时间的延长 ,实验组应力遮挡率逐渐下降 ,至术后 8周 ,明显低于对照组 ;术后 36～ 48周稳定在 2 7%左右。 2～ 4周时 ,实验组外骨痂丰富 ,并有软骨骨痂形成 ;8～ 12周 ,骨痂开始向板层骨转化 ,胶原排列渐趋整齐 ,愈合骨力学性能也逐渐增加。对照组早期外骨痂少 ,后期骨痂改建以骨吸收为主 ,48周时最大三点弯曲强度为正常骨的5 7.95 %。结论 应力松弛接骨板体内应力遮挡率的下降与固定时间有良好的相关性 ,促进了骨痂的形成和改建 ,并有利于愈合和骨力学性能的恢复。
Objective To study the changes of stress shielding rate of Stress-relaxation plate in vivo and its influences on healing of fracture. Methods Both Stress-relaxation plate (SRP) and Rigid plate (RP) were applied to osteotomized New Zealand rabbits tibia, The fracture healing process by fixing either with SRP or RP (control) underwent a comparative study by radiography, light (include polarized light) and biomechanical test from 2 to 48 weeks postoperatively. Results The stress shielding rate of fixing either with SRP or RP was about 70% at the begining of fixation, but the stress-shielding rate of SRP decreased gradually with prolongation of fixation time, by 8 weeks after fracture, it was significantly lower than that of RP( P <0.05) and stabilized at 27% during 36-48 weeks after fixation. According to the radiographic and histological examinations, there were abundant external callus around fracture site accompanied by the formation of cartilaginous callus in SRP group during 2～4 weeks postoperatively, and started to transform to lamellar bone with formation of new Haver's system and well organized collagen fibers by 8～12 weeks. The mechanical strength of united bone restored gradually. As a control, in RP group, only a little of external callus formed at fracture site without formation of cartilaginous callus at the early stage of fracture, also the calius remodeling became disordered and showed formation of resorption cavities in the synthetic bone at the later stage of fracture. These changes led to reduced mechanical strength of united bone in RP group, The ultimate bending strength (UBS) was only 57.95 percent of the normal rabbit's tibia by 48 weeks. Conclusion The stress shielding rate of SRP reduces gradually with prolongation of fixation time, and has a good relativity with the fixation time, therefore, provides an ideal mechanical environment which enhances callus formation and remodeling, favoring healing of fracture with high mechanical strength.(Shanghai Med J, 2000,23∶734-737)
出处
《上海医学》
CAS
CSCD
北大核心
2000年第12期734-737,共4页
Shanghai Medical Journal
基金
国家自然科学基金!资助项目 (No .39470 6 98)
关键词
接骨板
骨折愈合
应力松驰
应力遮扫
Bone plate
Fracture healing
Stress relaxation
Stress shield|
