颌面部撞击伤的生物力学研究

目的　研究颌面部撞击伤的生物力学机制、损伤特点以及生物力学参数与损伤之间的相互关系。　方法　采用水平气动式撞击机分别以(4.8±0.5)m/s（A组）、(9.2±0.7)m/s（B组）和(14.0±0.7)m/s（C组）的不同速度对兔左侧面中部进行撞击，每组兔数为6只。观察致伤后兔生命体征的变化，并对颌面部软组织、眼、脑等邻近组织进行损伤的大体和光、电镜观察，测定伤后6h血清中脂质过氧化物(LPO)、超氧化物歧化酶(SOD)、一氧化氮(NO)的含量变化，同时记录致伤瞬间脑内压力和头颅冲击加速度。　结果　C组的加速度、颅内压峰值均明显高于A、B两组（P<0.01）。形态学改变A组为单纯局部损伤，B组为较严重的多发性骨折，C组为局部粉碎性骨折、骨缺损合并眼和脑组织损伤。兔伤后6h血清中LPO和SOD值C组均显著高于A、B组（P<0.05），而NO值C组显著低于A、B组（P<0.05）。　结论　撞击速度、头颅冲击加速度响应以及脑内压响应是衡量颌面损伤以及合并邻近器官损伤的重要生物力学参数。

Biomechanical study on maxillofacial impact injury in rabbits

Objective　To study injury characteristics and biomechan ical mechanism of maxillofacial impact injury in rabbits.　Methods　Eighteen rabbits were impacted on the left middle fac e under different impact velocities (4.8±0.5) m/s（Group A）, (9.2±0.7) m/s（G roup B）and (14.0±0.7) m/s（Group C）, each group with 6 rabbits. The head acc elerat ion and the encephalic stress during the impact period were monitored. The pa tho logical characteristics of correlative tissues at the time 6 hours after impact was examined in detail. The contents of LPO, SOD and NO in blood and instant in tracranial pressure and acceleration rate were measured at the same time. 　Results　The contents of LPO and SOD were significantly increa sed but the contents of NO reduced along with the increase of impact velocity（ P<0.05). The animals in Group A, Group B and Group C represented respectivel y single fracture, multiple fractures and severe maxillofacial injury associated with brain and eye injury. The peak value of head acceleration and encephalic s tress of Group C was higher than that of Group A and Group B.　Conclusions　 The impact velocity, response of head accelerati on, encephalic stress and intracranial pressure during the impact are important biomechanical parameters influencing the injury severity of maxillofacial injur y and adjacent apparatus.