胸椎椎弓根外固定技术的临床应用☆

应用椎弓根外内固定技术2004/2007年在中山大学附属第三医院骨科治疗34例患者，固定前采用CT加密扫描测量进钉点、进钉点至椎体前缘的深度、进钉角度和直径，固定中椎弓根钉入点为横突尖，进钉方向为平均向头侧倾斜10°~ 20°、与中线成角30°~40°，顺椎弓根外侧皮质进入椎体，固定后CT加密扫描观察螺钉周围的皮质骨是否完整、是否靠近节段血管、是否穿透皮质骨，评价置入钉的准确性和安全性。34例患者共置入160枚胸椎椎弓根螺钉,固定后CT加密扫描和X射线片观察到148枚(92.5% )螺钉置入准确，12枚(7.5%)螺钉发生错置。实验结果表明，胸椎椎弓根根外内固定与椎弓根内固定相比，具有更宽的置入宽度，更长的螺钉长度，以及更大的内聚角度，具有安全可靠、简单实用等优点，并具有生物力学优越性，是胸椎后路内固定的一种良好选择。

Clinical application of extrapedicular screw fixation in thoracic spine

From 2004 to 2007, 34 cases were treated with extrapedicular screw fixation in Department of Orthopaedics, Third Affiliated Hospital of Sun Yat-sen University. The screw entry point, angle, depth and diameter were measured and defined on the thoracic vertebrae pedicle by CT thin-slice scan in standard prone for all cases before operation. The screw entry point was located at the tip of transverse process. The average inclination angle should be 10°-20° headward and 30°-40° toward neutral line respectively. The screw was inserted and entered into the vertebral body along the external cortex of pedicle. The integrity of cortical bone around screws, the distance to segmental blood vessels and the penetration of cortex were observed after operation to evaluate the accuracy and safety of screw placement. Among 160 thoracic pedicle screws that were implanted in 34 cases, 148 screws (92.5%) were accurately inserted inside the costotransverse unit, and 12 screws (7.5%) were misplaced according to the image of X-ray and CT thin-slice scan. Compared to the transpedicular fixation, extrapedicular fixation has advantages of wider insertion area, longer screw and bigger cohesion angle. So, it is a safer and simpler alternative for thoracic posterior fixation because of its theoretical biomechanical superiority.