骨应力刺激仪的叩击力与下肢骨折断端压力的变化关系

目的 应用骨应力刺激仪的叩击力作用于不同部位和不同固定方法的下肢骨折断端,研究体外施加的叩击力与下肢骨折断端所产生的压力的变化关系.方法 5具完整新鲜成人尸体下肢标本10例,按照股骨骨折、胫骨骨折、胫腓骨骨折顺序造模,并先后采用外固定架、钢板固定,不同骨折部位的两种同定方法下各组均对10例标本进行了观察.各组标本造模成骨干中段的横形骨折,骨折断端放置触力传感器.用骨应力刺激仪在标本的足跟处施加叩击力,分别记录不同骨折部位两种固定方法下施加的叩击力和骨折断端产生的压力,并分析其间存在的相关性.结果 各组骨应力刺激仪的叩击力(50-350N)与骨折断端所产生的压力均呈直线相关(均r=1.000,P=0.000).在相同叩击力作用下,同一固定方法的骨折断端压力,胫腓骨组＞胫骨组＞股骨组(P＜0.05);同一部位的骨折断端压力,外固定架组＞钢板组(P＜0.05).结论 下肢骨折固定后,体外施加叩击力时骨折断端能够产生相应的压力,临床上可以根据骨折部位或固定方式的不同选取不同大小的叩击力促进固定后骨折的愈合.

The changing relationship between rap force of stimulator of bone stress and compressive stress at the fracture ends of lower limbs

Objective To study the rap force produced by stimulator of bone stress on fracture ends of lower limbs in different positions and fixation methods, and to examine changing relationship of rap force in vitro with the stress at fracture ends. Methods Ten complete fresh lower limb specimens of 5 cadavers were used to establish models of femur fracture, tibia fracture and tibiofibular fracture in sequence. The specimens with various fracture positions were all fixed with external fixators and plates successively. Ten specimens of each group under two fixation methods over various fracture positions were observed. Pressure sensor was located on transverse fracture over midshaft of specimens and fracture ends. Stimulator of bone stress was used to rap the heel of specimen. Rap force produced by stimulator and the compressive stress at the fracture ends under two fixation methods over various fracture positions were recorded, and their correlation was analyzed. Results A liner correlation was observed between rap force (50～350N) and fracture end stress (all r=1.000, P=0.000). Under the same rap force, the fracture end stress under the same fixation method was as follows: tibiofibular group ＞ tibia group ＞ femur group (P＜0.05). As to fracture ends stress on the same position, external fixator group is bigger than plate group (P＜0.05). Conclusions Corresponding stress over fracture end appears when rap force was given after fracture fixation. It is advised to give corresponding rap force on individual fracture position and fixation method so as to promote healing.