新生儿臂丛上半椎韧带的组织学与生物力学研究

C7 roots vulnerable to avulsion in newborns： histological and biomechanical basis for obstetric palsy of brachial plexus

目的研究新生儿臂丛根部上半椎韧带的组织学和生物力学特性，以了解产瘫损伤机制的特殊性并指导临床实践。方法①在6具新鲜新生儿尸体标本上取双侧C5-7神经根的上半椎韧带，行HE及Mallory胶原三色染色观察，并计算胶原纤维面积比。②在4具新鲜新生儿尸体标本中检测双侧C5-7神经根上半椎韧带的断裂强度。结果①C7神经根上半椎韧带内胶原纤维面积比（41．5％±10．0％）小于C5（51．1％±10．5％）、C6（50．7％±10．8％），差异均有统计学意义（P值分别为0．032和0．039）。在C5、C6上半椎韧带与横突附着处有大量Sharpey纤维而C7上半椎韧带Sharpey纤维稀少。②C7神经根上半椎韧带的断裂强度[（5．03±1．05）N]明显低于C5[（6．47±1．12）N]、C6[（6．23±1．21）N]（P值分别为0．019和0．046），C5、C6之间差异无统计学意义（P=0．678）。结论新生儿C7上半椎韧带薄弱造成的抗张强度较低，是产瘫患儿C7神经根容易发生撕脱性损伤的主要原因。

Objective To investigate anatomical and biomechanical features of the semiconic posterosuperior ligaments at the brachial plexus roots in newborns in order to understand the specific mechanism of obstetric palsy of brachial plexus. Methods In 6 fresh newborn cadavers, the C5-7 nerve roots were histologically analyzed using hematoxylin and Mallory trichrome staining to observe the semiconic posterosuperior ligaments. In 4 newborn cadavers, the complex of nerve roots-ligament-transverse process was bilaterally removed and a biomechanical test was performed to examine the failure load of the complex. Results The area of collagen fiber of the ligament around C7 nerve roots was significantly smaller than that of the ligaments around nerve roots of C5 and C6 （ P 〈 0. 05）. The semiconic posterosuperior ligament around the C5 and C6 nerve roots was reinforced by Sharpey fibers at its insertion to the transverse process. Sharpey fibers were hardly seen at the ligament around the C7 nerve roots. The failure loads of the attachments around the C5, C6 and C7 nerve roots were respectively （6.47 ±1.12）, （6. 23 ±1.21） and （5.03 ±1.05） N. The failure loads of the attachments around the C5 and C6 nerve roots were significantly larger than that around the C7 nerve roots （ P = 0. 019 and 0. 046 respectively）. Conclusion High incidence of C7 avulsion injury in obstetric palsy of brachial plexus may be attributed to the relatively weak semiconic posterosuperior ligament in newborns.