Baranto Adad, Ekström Lars, Hellström Mikael, Lundin Olof, Holm Sten, Swärd Leif
Department of Orthopaedic, Sahlgrenska University Hospital, The Sahlgrenska Academy at Göteborg University, Göteborg, Sweden.
Spine (Phila Pa 1976). 2005 Jan 1;30(1):75-82. doi: 10.1097/00007632-200501010-00014.
To expose functional spinal units from adolescent porcine to mechanical flexion-compression and extension-compression to failure. The biomechanical, radiologic, magnetic resonance imaging, and histologic characteristics are described.
The aim of the present study was to investigate the fracture pattern of functional spinal units from adolescent porcine lumbar spines in in vitro compression loading and bending.
In several studies, it has been shown that the adolescent spine, especially the vertebral growth zones, is vulnerable to trauma. A high frequency of abnormalities affecting the spine has been found among athletes participating in sports with high demands on the back. The etiology of these abnormalities is still a controversial issue.
Sixteen functional spinal units obtained from eight adolescent male pigs were used. Eight functional spinal units were exposed to flexion-compression and eight functional spinal units to extension-compression loading to failure. They were examined with plain radiography and magnetic resonance imaging before and after the loading. The functional spinal units were finally examined macroscopically and histologically.
Fractures/separations were seen in the growth zone anteriorly and more frequently, posteriorly in functional spinal units exposed to flexion-compression. In the extension-compression group, such injuries occurred only anteriorly. Only large fractures could be seen on plain radiographs and on magnetic resonance imaging. Macroscopically, a fracture/separation could be seen in 15 cases and histologically in all 16 cases. The median angle at failure for the flexion group was 17 degrees (range, 12-19) and for the extension group 17 degrees (range, 13-19 degrees). The median ultimate compression load in the flexion-compression group was 1894 N (range, 1607-3138 N) and in the extension-compression group 1801 N (range, 1158-2368 N).
The weakest part of the growing porcine lumbar spine, when compressed into flexion- or extension-compression, was the growth zone. The injury was more extensive in extension loading than during flexion loading. Growth zone injuries of the adolescent spine may go undetected on plain radiographs and magnetic resonance imaging.
将青春期猪的功能性脊柱单元暴露于机械性屈曲-压缩和伸展-压缩直至破坏。描述其生物力学、放射学、磁共振成像及组织学特征。
本研究旨在调查青春期猪腰椎功能性脊柱单元在体外压缩负荷和弯曲情况下的骨折模式。
多项研究表明，青春期脊柱，尤其是椎体生长区，易受创伤。在参与对背部要求较高运动的运动员中，发现影响脊柱的异常情况频率较高。这些异常的病因仍是一个有争议的问题。
使用从八只青春期雄性猪获取的16个功能性脊柱单元。八个功能性脊柱单元暴露于屈曲-压缩，八个功能性脊柱单元暴露于伸展-压缩负荷直至破坏。在负荷前后对它们进行X线平片和磁共振成像检查。最后对功能性脊柱单元进行宏观和组织学检查。
在暴露于屈曲-压缩的功能性脊柱单元中，骨折/分离在前侧生长区可见，且后侧更常见。在伸展-压缩组中，此类损伤仅发生在前侧。在X线平片和磁共振成像上仅能看到大的骨折。宏观上，15例可见骨折/分离，组织学上16例均可见。屈曲组破坏时的中位角度为17度（范围12 - 19度），伸展组为17度（范围13 - 19度）。屈曲-压缩组的中位极限压缩负荷为1894 N（范围1607 - 3138 N），伸展-压缩组为1801 N（范围1158 - 2368 N）。
生长中的猪腰椎在被压缩成屈曲或伸展-压缩时，最薄弱的部分是生长区。伸展负荷时的损伤比屈曲负荷时更广泛。青春期脊柱生长区损伤在X线平片和磁共振成像上可能未被发现。
