Ex-vivo evaluation of the three-column concept in canine thoracolumbar fractures

ABSTRACT Traumatic events such as a motor vehicle accident or falling from heights are very common in veterinary medicine and often lead to vertebral fracture-luxation with concomitant spinal cord injuries, mostly in the thoracolumbar spine. The purpose of this cadaveric biomechanical study was to determine the feasibility of the three-column concept in canine thoracolumbar segments with induced fractures. Eighteen Functional Spinal Units (FSU) of the thoracolumbar segments (T12-L2) were collected from 18 medium-sized adult dog cadavers and were subjected to flexion-extension and lateral bending tests so that range of motion (ROM) was recorded with a goniometer. Fractures were induced by compressive loads applied by a universal testing machine (EMIC®). After this, specimens were screened using computed tomography (CT) and the fractures were graded as affecting one, two or three columns, and divided into groups A, B, and C, respectively. Post-fracture range of motion (ROM) was compared with the previous results. Groups B and C (with fractures in two or three columns) had instability in the two axes evaluated (P<0.05). The outcomes of this study support the applicability of the three-column theory to thoracolumbar spines of dogs, as the FSUs that suffered fractures in two or more columns showed axial instability.

摘要：创伤事件如机动车事故或高处坠落在兽医学中极为常见，常引发伴随脊髓损伤的椎体骨折脱位，此类损伤多累及胸腰椎。本尸体生物力学研究旨在验证三柱理论（three-column concept）在人工致伤犬胸腰椎节段中的可行性。研究从18只成年中型犬尸体上采集了胸腰椎节段（T12-L2）的18个功能脊柱单元（Functional Spinal Units，FSU），对其进行屈伸及侧方弯曲试验，用测角仪记录活动度（range of motion，ROM）。通过万能试验机（universal testing machine，EMIC®）施加压缩载荷构建骨折模型，随后采用计算机断层扫描（computed tomography，CT）对标本进行影像学筛查，将骨折按累及脊柱柱的数量分为单柱、双柱及三柱损伤，分别对应A、B、C三组。将骨折后测得的活动度与术前基线结果进行对比分析，结果显示B、C两组（对应双柱或三柱骨折）在两个测试轴向均表现出显著不稳定（P<0.05）。本研究结果证实三柱理论可适用于犬胸腰椎脊柱，因为累及两柱及以上的功能脊柱单元均出现了轴向不稳定。