McGregor W E, Trumble D R, Magovern J A
Department of General Surgery, Northside Medical Center, Forum Health, Youngstown, Ohio, USA.
J Thorac Cardiovasc Surg. 1999 Jun;117(6):1144-50. doi: 10.1016/s0022-5223(99)70251-5.
Unstable median sternotomy closure can lead to postoperative morbidity. This study tests the hypothesis that separation of the sternotomy site occurs when physiologic forces act on the closure.
Median sternotomy was performed in 4 human cadavers (2 male) and closed with 7 interrupted stainless steel wires. The chest wall was instrumented to apply 4 types of distracting force: (1) lateral, (2) anterior-posterior, (3) rostral-caudal, and (4) a simulated Valsalva force. Forces were applied in each direction and were limited to physiologic levels (< 400 N). Four sets of sonomicrometry crystals were placed equidistantly along the sternum to measure separation at the closure site.
Sternal separation occurred as a result of the wires cutting through the bone. Less force was needed to achieve 2.0-mm distraction in the lateral direction (220 +/- 40 N) than in the anterior-posterior (263 +/- 74 N) and rostral-caudal (325 +/- 30 N) directions. More separation occurred at the lower end of the sternum than the upper. During lateral distraction, xiphoid and manubrial displacement averaged 1.85 +/- 0.14 and 0.35 +/- 0.12 mm, respectively. Anterior-posterior distraction caused 1.99 +/- 0.04-mm xiphoid displacement and 0.26 +/- 0.12-mm manubrial displacement. During a simulated Valsalva force, more separation occurred in the lateral (2.14 +/- 0.11 mm) than in the anterior-posterior (0.46 +/- 0.29 mm) or rostral-caudal (0.25 +/- 0.15 mm) directions.
These data suggest that sternal dehiscence can occur under physiologic loads and that improved sternal stability may be readily achieved via mechanical reinforcement near the xiphoid. Closure techniques designed to minimize wire migration into the sternum should also be developed.
不稳定的正中胸骨切开术闭合可导致术后发病。本研究检验了这样一种假设，即当生理力作用于闭合处时，胸骨切开部位会发生分离。
对4具人类尸体（2具男性）进行正中胸骨切开术，并用7根间断不锈钢丝进行闭合。在胸壁上安装仪器以施加4种类型的牵张力：（1）侧向，（2）前后向，（3）头尾向，以及（4）模拟瓦尔萨尔瓦动作力。在每个方向上施加力，并限制在生理水平（<400 N）。沿着胸骨等距放置四组超声骨密度计晶体，以测量闭合部位的分离情况。
钢丝切割骨头导致胸骨分离。在侧向方向实现2.0毫米的牵张所需的力（220±40 N）比前后向（263±74 N）和头尾向（325±30 N）方向要小。胸骨下端比上端发生更多的分离。在侧向牵张过程中，剑突和胸骨柄的位移平均分别为1.85±0.14毫米和0.35±0.12毫米。前后向牵张导致剑突位移1.99±0.04毫米，胸骨柄位移0.26±0.12毫米。在模拟瓦尔萨尔瓦动作力期间，侧向（2.14±0.11毫米）比前后向（0.46±0.29毫米）或头尾向（0.25±0.15毫米）方向发生更多的分离。
这些数据表明，在生理负荷下可能发生胸骨裂开，并且通过在剑突附近进行机械加强可以很容易地提高胸骨稳定性。还应开发旨在尽量减少钢丝向胸骨内迁移的闭合技术。
