Liebsch Christian, Obid Peter, Vogt Morten, Schlager Benedikt, Wilke Hans-Joachim
Institute of Orthopaedic Research and Biomechanics, Trauma Research Centre Ulm, Ulm University Medical Centre Ulm Germany.
Department of Orthopaedics and Trauma Surgery Freiburg University Medical Centre Freiburg Germany.
JOR Spine. 2024 Dec 18;7(4):e70028. doi: 10.1002/jsp2.70028. eCollection 2024 Dec.
Effects of rigid posterior instrumentation on the three-dimensional post-operative spinal flexibility are widely unknown. Purpose of this in vitro study was to quantify these effects for characteristic adolescent idiopathic scoliosis instrumentations.
Six fresh frozen human thoracic and lumbar spine specimens (C7-S) with entire rib cage from young adult donors (26-45 years) without clinically relevant deformity were loaded quasi-statically with pure moments of 5 Nm in flexion/extension, lateral bending, and axial rotation. Primary and coupled motions of all segments were measured using optical motion tracking. Specimens were tested without instrumentation and with posterior rod instrumentations ranging from T2 to L1 (for Lenke Type 2) and from T8 to L3 (for Lenke Type 5) based on survey results among spinal deformity surgeons. Statistical differences were evaluated using the pairwise Friedman test.
Primary ranges of motion were significantly ( < 0.05) reduced in all six motion directions in the entire thoracic spine (T1-L1) for both instrumentations, but solely in extension and axial rotation in the entire lumbar spine (L1-S) for T8-L3 instrumentation. Without instrumentation, strong ipsilateral axial rotation during primary lateral bending and strong contralateral lateral bending during primary axial rotation were detected in the thoracic spine (T1-L1) and slight inverse coupled motions in the lumbar spine (L1-S). While coupled axial rotation was significantly ( < 0.05) reduced, especially in the upper thoracic spine (T1-T5) for T2-L1 instrumentation and in the lumbar spine (L1-S) for T8-L3 instrumentation, coupled lateral bending was solely significantly ( < 0.05) reduced in the upper thoracic spine (T1-T5) for T2-L1 instrumentation. Coupled motions in primary flexion and extension were non-existent and not affected by any fixation ( > 0.05).
Instrumentation reduces the primary flexibility and diminishes the natural coupling behavior between lateral bending and axial rotation, primarily in the upper thoracic spine, potentially causing correction loss and junctional deformity in the long-term.
刚性后路内固定对术后脊柱三维灵活性的影响尚不明确。本体外研究的目的是量化这些对典型青少年特发性脊柱侧凸内固定的影响。
从无临床相关畸形的年轻成年供体（26 - 45岁）获取6个带有完整胸廓的新鲜冷冻人胸腰椎标本（C7 - S），在屈伸、侧屈和轴向旋转时以5 Nm的纯力矩进行准静态加载。使用光学运动跟踪测量所有节段的主运动和耦合运动。根据脊柱畸形外科医生的调查结果，对标本在未进行内固定以及进行从T2至L1（用于Lenke 2型）和从T8至L3（用于Lenke 5型）的后路棒状内固定情况下进行测试。使用配对弗里德曼检验评估统计学差异。
两种内固定方式下，整个胸椎（T1 - L1）的所有六个运动方向的主运动范围均显著减小（<0.05），但对于T8 - L3内固定，仅整个腰椎（L1 - S）的伸展和轴向旋转方向主运动范围减小。在未进行内固定时，在胸椎（T1 - L1）中检测到主侧屈时强烈的同侧轴向旋转以及主轴向旋转时强烈的对侧侧屈，在腰椎（L1 - S）中检测到轻微的反向耦合运动。虽然耦合轴向旋转显著减小（<0.05），特别是对于T2 - L1内固定在上胸椎（T1 - T5）以及对于T8 - L3内固定在腰椎（L1 - S），但耦合侧屈仅对于T2 - L1内固定在上胸椎（T1 - T5）显著减小（<0.05）。主屈伸中的耦合运动不存在且不受任何固定影响（>0.05）。
内固定降低了主灵活性，并减少了侧屈和轴向旋转之间的自然耦合行为，主要在上胸椎，长期来看可能导致矫正丢失和交界性畸形。
