Apaydin Nihal, Bozkurt Murat, Sen Tulin, Loukas Marios, Tubbs R Shane, Ugurlu Mahmut, Tekdemir Ibrahim, Elhan Alaittin
Department of Anatomy, School of Medicine, Ankara University, Ankara, Turkey.
Surg Radiol Anat. 2008 Jun;30(4):355-60. doi: 10.1007/s00276-008-0336-3. Epub 2008 Mar 11.
Nerve injury is a common complication during anterior shoulder surgery. The purpose of the study was to evaluate the musculocutaneous nerve (MN) anatomically and to clarify the relationship of the MN to the glenoid labrum and coracoid process in different arm positions. The study was carried out on 40 shoulders of 20 adult cadavers fixed in 10% formaldehyde. The minimum distance of the MN at the entrance point of the nerve into the coracobrachialis to the anteromedial aspect of the coracoid tip and the distance between the MN and the top, middle, and inferior points of the glenoid labrum were measured. All measurements were performed with a digital caliper while the arm was in a neutral position, 45 degrees and 90 degrees of abduction, 90 degrees of abduction-internal rotation and 90 degrees of abduction-external rotation to evaluate whether arm position effects the results statistically or not. The results demonstrated that the position of the arm significantly changes the distance between the coracoid process (CP) and the MN or its cord. The change in distance between the glenoid labrum and the MN or its cord was also statistically significant. The distance between the CP and MN was greatest when the arm was abducted to 45 degrees (mean 3.4 cm) and least when the arm was positioned to 90 degrees of abduction-internal rotation (mean 2.0 cm). While the distance between the MN and the coracoid process was least at 90 degrees of abduction and internal rotation, the distance between the MN and glenoid labrum was lest with 90 degrees of abduction and external rotation. The distance between the glenoid labrum and MN was greatest with 45 degrees of abduction. The results of this study might be of use in avoiding the MN especially during Bristlow operations and certain rotator cuff procedures. Transferring the coracoid process during Bristow operations or placing arthroscopic portals when the arm is abducted to 45 degrees appears to be the safest position in terms of MN injury. Based on our results, when the arm needs to be abducted to 90 degrees during operation, externally rotating it may decrease the tension on the brachial plexus thus increasing the distance between the MN and the portals or retractors.
神经损伤是肩关节前路手术中常见的并发症。本研究的目的是对肌皮神经（MN）进行解剖学评估，并阐明在不同手臂位置时MN与关节盂唇和喙突的关系。本研究在20具用10%甲醛固定的成年尸体的40个肩部上进行。测量了神经进入肱二头肌短头处的MN到喙突尖前内侧的最小距离，以及MN与关节盂唇上、中、下点之间的距离。所有测量均使用数字卡尺，测量时手臂处于中立位、外展45度和90度、外展90度内旋和外展90度外旋，以评估手臂位置是否对结果有统计学影响。结果表明，手臂位置显著改变了喙突（CP）与MN或其神经束之间的距离。关节盂唇与MN或其神经束之间距离的变化也具有统计学意义。当手臂外展至45度时，CP与MN之间的距离最大（平均3.4厘米），而当手臂处于外展90度内旋位时最小（平均2.0厘米）。虽然MN与喙突之间的距离在90度外展和内旋时最小，但MN与关节盂唇之间的距离在90度外展和外旋时最小。关节盂唇与MN之间的距离在45度外展时最大。本研究结果可能有助于避免MN损伤，尤其是在Bristlow手术和某些肩袖手术过程中。就MN损伤而言，在Bristow手术中转移喙突或在手臂外展至45度时放置关节镜入口似乎是最安全的位置。根据我们的结果，手术中当手臂需要外展至90度时，将其向外旋转可能会降低臂丛神经的张力，从而增加MN与入口或牵开器之间的距离。
