骨盆的垂直动态冲击试验研究

为探讨骨盆在垂直冲击载荷下发生骨折的机理,为临床手术治疗提供科学依据.将采集的人体新鲜骨盆骨骼标本10具,分别行垂直动态冲击试验和静态破坏试验,测量动态骨折时的一系列动力学参数,确定骨折的动力学特性.结果显示,骨盆骨折的形态与受到冲击能量大小有关.低能量冲击加载,大都发生骶髂关节骨折.当高能量冲击时,骶骨发生以下三种方式骨折(按Denis骶骨骨折分类):Ⅰ型为侧块骨折和关节旁骨折,Ⅱ型为劈裂骨折、骶骨孔骨折,Ⅲ型为中央椎管骨折,Ⅱ型和Ⅲ型可累及骨盆一侧神经根损伤或两侧神经根损伤.骨盆的动态破坏机制与静态破坏机制两者在力学性质上有很大的不同,不但极限载荷不同,而且前者随应变速率的提高而快速增加,冲击能量达到25焦耳以上会产生劈裂状通过骶骨孔骨折,并累及神经根损伤;当低于20焦耳能量时,以发生骶髂关节骨折和骶骨骨折为多,处于20～25焦耳能量之间易产生Ⅰ型骨折;而静态大多为骶髂关节骨折.说明骨盆的动态纵向冲击是一种高能量损伤,以Ⅱ型劈裂状通过骶骨孔骨折居多,常累及一侧或两侧神经根神经,与骨盆的力学结构、力的传导、冲击动力学特性以及应力、应变分布相关.

AN EXPERIMENTAL STUDY OF VERTICAL DYNAMIC IMPACT ON THE PELVIS

The objective of the paper is to study the mechanism of pelvis fracture under vertical impact load and to offer the scientific basis for the clinical surgical treatment. Vertical dynamical impact tests and static destructive tests were made on 10 fresh human pelvis samples, respectively and the serial kinetic parameters when the dynamic fracture occurs were measured as to find out the kinetic characteristics of the fracture. The results showed that the shape of pelvic fracture is related to the impact energy size on the pelvis: the low energy impact load mostly causes sacroiliac-joint fracture; the high energy impact causes the following three types of sacral fracture according to Denis sacral fracture classification: type I: lateral mass fracture and juxta-articular fracture; type II: split fracture and sacral-foramen fracture; type III: central spinal-canal fracture. Types II and III may involve the monolateral or bilateral nerve root of the pelvis. There is a great difference of the dynamic destructive mechanism from the static one in the mechanical property. Not only the load limits of them are different, but also the former may rapidly increase with the strain speed increase with over 25 joules causing split fracture through the sacral foramen and involving the nerve root; with less than 20 joules mostly causing sacroiliac-joint or sacral fracture; with 20 to 25 joules tending to cause the fracture of type I. However, the static destructive mechanism mostly causes sacroiliac fracture. It was indicated that the injuries from the dynamic longitudinal impact on the pelvis are high-energy; most of them being split fracture through the sacral foramen, often involving monolateral or bilateral nerve root, which may be related to the pelvic mechanical structure, force conduction, impact dynamic characteristics and the distribution of the stress and strain.