Liebsch Christian, Graf Nicolas, Wilke Hans-Joachim
Institute of Orthopaedic Research and Biomechanics, Trauma Research Centre (ztf), Ulm University, Helmholtzstraße 14, 89081, Ulm, Germany.
Eur Spine J. 2017 May;26(5):1401-1407. doi: 10.1007/s00586-016-4768-x. Epub 2016 Sep 17.
The influence of the anterior rib cage on the stability of the human thoracic spine is not completely known. One of the most common surgical interventions on the anterior rib cage is the longitudinal median sternotomy and its fixation by wire cerclage. Therefore, the purpose of this in vitro study was to examine, if wire cerclage can restore the stability of the human thoracic spine after longitudinal median sternotomy.
Six fresh frozen human thoracic spine specimens (C7-L1, 56 years in average, range 50-65), including the intact rib cage without intercostal muscles, were tested in a spinal loading simulator and monitored with an optical motion tracking system. While applying 2 Nm pure moment in flexion/extension (FE), lateral bending (LB), and axial rotation (AR), the range of motion (ROM) and neutral zone (NZ) of the functional spinal units of the thoracic spine (T1-T12) were studied (1) in intact condition, (2) after longitudinal median sternotomy, and (3) after sternal closure using wire cerclage.
The longitudinal median sternotomy caused a significant increase of the thoracic spine ROM relative to the intact condition (FE: 12° ± 5°, LB: 18° ± 5°, AR: 25° ± 10°) in FE (+12 %) and AR (+22 %). As a result, the sagittal cut faces of the sternum slipped apart visibly. Wire cerclage fixation resulted in a significant decrease of the ROM in AR (-12 %) relative to condition after sternotomy. ROM increased relative to the intact condition, in AR even significantly (+8 %). The NZ showed a proportional behavior compared to the ROM in all loading planes, but it was distinctly higher in FE (72 %) and in LB (82 %) compared to the ROM than in AR (12 %).
In this in vitro study, the longitudinal median sternotomy resulted in a destabilization of the thoracic spine and relative motion of the sternal cut faces, which could be rectified by fixation with wire cerclage. However, the stability of the intact condition could not be reached. Nevertheless, a fixation of the sternum should be considered clinically to avoid instability of the spine and sternal pseudarthrosis.
胸廓前部对人体胸椎稳定性的影响尚未完全明确。胸廓前部最常见的手术干预之一是纵向正中胸骨切开术及其钢丝环扎固定。因此，本体外研究的目的是检验钢丝环扎能否在纵向正中胸骨切开术后恢复人体胸椎的稳定性。
六个新鲜冷冻的人体胸椎标本（C7-L1，平均56岁，范围50-65岁），包括无肋间肌的完整胸廓，在脊柱加载模拟器中进行测试，并用光学运动跟踪系统进行监测。在施加2 Nm的纯力矩进行屈伸（FE）、侧弯（LB）和轴向旋转（AR）时，研究胸椎（T1-T12）功能脊柱单元的活动范围（ROM）和中性区（NZ）：（1）完整状态下；（2）纵向正中胸骨切开术后；（3）钢丝环扎胸骨闭合术后。
纵向正中胸骨切开术导致胸椎ROM相对于完整状态显著增加（FE：12°±5°，LB：18°±5°，AR：25°±10°），在FE中增加了12%，在AR中增加了22%。结果，胸骨的矢状切面明显分开。钢丝环扎固定导致相对于胸骨切开术后状态，AR中的ROM显著降低（-12%）。相对于完整状态，ROM增加，在AR中甚至显著增加（+8%）。在所有加载平面中，NZ与ROM呈比例关系，但与ROM相比，FE（72%）和LB（82%）中的NZ明显高于AR（12%）中的NZ。
在本体外研究中，纵向正中胸骨切开术导致胸椎不稳定和胸骨切面相对运动，通过钢丝环扎固定可纠正。然而，无法达到完整状态的稳定性。尽管如此，临床上应考虑固定胸骨以避免脊柱不稳定和胸骨假关节。
