Purpose: This study presents cases of fracture-dislocation of the thoracic spine in extension during severe rear impacts. The mechanism of injury was investigated. Methods: Four crashes were investigated where a lap-shoulder belted, front-seat occupant experienced fracture-dislocation of the thoracic spine and paraplegia in a severe rear impact. Police, investigator and medical records were reviewed, the vehicle was inspected and the seat detrimmed. Vehicle dynamics, occupant kinematics and injury mechanisms were determined in this case study. Results: Each case involved a lap-shoulder belted occupant in a high retention seat with >l,700 Nm moment or >5.5 kN strength for rearward loading. The crashes were offset rear impacts with 40-56 km/h delta V involving under-ride or over-ride by the impacting vehicle and yaw of the struck vehicle. In each case, the occupant's pelvis was restrained on the seat by the open perimeter frame of the seatback and lap belt. The rear loading caused the head, neck and upper body to displace off the side or top of the seatback. The seatback frame acted like a fulcrum as the unsupported head and upper body was accelerated forward causing extension of the spine around the seatback frame as the head and shoulders moved rearward of the frame. In each case, there was fracture-dislocation of the thoracic spine in extension with spinal cord injury resulting in paraplegia. Two occupants were overweight and two were obese, which increased inertial loads on the spine. Conclusions: High retention seats have improved safety of occupants in rear crashes, but there are situations where the upper body becomes unsupported in a severe rear crash. This can lead to extension loads on the spine causing fracture- dislocation, spinal cord injury and paraplegia. Injury is a result of the strong seat frame remaining upright, the lap belt holding the pelvis on the seat and the upper body moving off the seatback concentrating load on the thoracic spine. The seatback frame acts like a fulcrum resulting in fracture-dislocation of the spine in extension.
展开▼
机译：目的：本研究介绍了在严重的后部撞击过程中，伸展时胸椎骨折脱位的病例。研究了损伤的机理。方法：对四次撞车事故进行了调查，在这些撞车事故中，肩部安全带，前座乘员在严重的后部撞击中经历了胸椎骨折脱位和截瘫。对警察，调查人员和病历进行了审查，检查了车辆并调整了座椅的位置。在本案例研究中确定了车辆动力学，乘员运动学和伤害机制。结果：每例患者均在高保持力座椅中系上了肩带式安全带乘员，其向后载荷大于1,700 Nm力矩或大于5.5 kN。碰撞以40-56 km / h的增量V抵消了后方的碰撞，涉及碰撞车辆的超驰或超驰以及撞车的偏航。在每种情况下，乘员的骨盆都通过座椅靠背和安全带的开放式周边框架约束在座椅上。向后的负重使头部，颈部和上半身从座椅靠背的侧面或顶部移位。当无支撑的头部和上半身向前加速时，座椅靠背框架就像一个支点，当头部和肩膀向后移动时，脊柱围绕座椅靠背框架延伸。在每种情况下，胸椎均发生骨折脱位并伴有脊髓损伤，导致截瘫。两名乘员超重，两名乘员肥胖，这增加了脊柱的惯性负荷。结论：高保持力座椅在后撞事故中提高了乘员的安全性，但在严重的后撞事故中，有时上半身无法支撑。这会导致脊柱的拉伸负荷，导致骨折脱位，脊髓损伤和截瘫。受伤是由于牢固的座椅框架保持直立，将骨盆保持在座椅上的腰带以及上半身脱离座椅靠背而使胸椎集中负荷而造成的。椅背框架的作用像支点，导致脊椎伸展时骨折脱位。
展开▼
