静态应力作用下骨盆侧方撞击的生物力学研究

目的构建侧方静态应力作用下骨盆骨的尸体模型,运用生物力学试验技术在垂直应力试验机上对单纯侧方受力导致的旋转不稳定骨盆骨折的生物力学特点及其发病机制进行初步探讨。方法选取正常成人骨盆试验标本12具,其中男性7例,女性5例;年龄45～68岁,平均年龄57.32岁。分为2组,每组6具。构建侧方撞击的生物力学模型,测量单纯静态侧方应力作用于髂嵴或股骨大粗隆时,不同工况下骶髂关节、髋臼、耻骨支等骨盆常见骨折部位的受力状况,用应变仪获得各试验点的主应变、主方向、垂直位移,以及测量静态应力下骨盆骨折阈值,并构建应变-时间曲线。结果①500 N静态侧方应力作用于髂嵴时,骨盆环结构中固定侧髂骨翼,对侧耻骨上支承载压（397±43）、拉应变（113.2±11.4）最大,受力侧坐骨支应变最小（23±7）;髂骨翼位移最大（4.6 mm）,髂嵴在静态侧方应力作用下的极限载荷（3 752±425）N;②股骨大粗隆在500 N静态侧方应力作用下,在骨盆环结构中,对侧耻骨上支承载压（277±31）、拉应变（401±53）最大,受力侧髂骨应变值最小（35±11）;左耻骨支位移最大（2.3 mm）。股骨大粗隆在侧方应力作用下的极限载荷（4 207±617）N;③静态侧方应力作用于股骨大粗隆时产生的骨盆各点位移均小于作用于骨盆髂嵴时产生的位移。结论①耻骨支及耻骨联合等骨盆前环结构对于维持侧方应力下骨盆环旋转稳定性至关重要。②生物力学试验能较好地反映静态侧方应力撞击下骨盆骨的生物力学特性。

Biomechanical study on pelvic lateral impact under static stress

Objective To construct biomechaoical model of the pelvic bone under static lateral stress, and preliminarily study the biomechanical characteristics and pathogenesis of the rotational unstable pelvic fracture by purely lateral force on a vertical stress test machine. Methods Twelve normal adult pelvic samples were selected, male 7, female 5, aged 45 - 68 years old, mean age 57.32 years old, which were divided into 2 groups（n = 6）. The biomechanical model of lateral impaction was constructed, and the force status of the pelvic common fracture sites such as sacroiliac joint, acetabulum, pubic branch was measured under different condition while placing simply lateral stress on iliac crest or greater trochanter. Each experimental point of main strain, main direction, vertical displacement were obtained by strain gauge, the pelvic fracture threshold static stress were measured, and the strain-time curve was constructed. Results ①When placing 500 N static lateral stress on iliac crest, the fixed wing of ilium and pubis were loaded the maximum strain（397 ± 43 and 113.2±1 1.4）, and the forced side of ischial was loaded the least strain （23 ± 7）. The maximum displacement of iliac was 4.6 mm, and the threshold of static lateral stress on the iliac crest was （3 752 ± 425） N;②When loading static lateral stress on femoral greater trochanter, the fixed superior ramus of pubis was loaded the maximum tensile strain（401 ± 53） and the maximum compressive strain was 277 ± 31. The maximum displacement was 2.3 mm, the minimum strain value of ipsilateral ilium was 35 ±11, and the threshold of fracture in static lateral stress was （4 207 ±617） N; ③The displacement of the pelvic caused by static lateral stress in femoral greater trochanter was less than that of pelvic iliac crest. Conclusion It is demonstrated that： ①pubic branch and pubic symphysis of pelvic ring structures are important and essential for maintenance of pelvic ring rotational stability under lateral stress; ②the biomechanical properties of pelvic under static lateral stress could be better reflected by this biomechanical experiment.