Simple and Complex Fractures of the Humerus by Filippo Castoldi Davide Blonna & Marco Assom

Author:Filippo Castoldi, Davide Blonna & Marco Assom
Language: eng
Format: epub
Publisher: Springer Milan, Milano

14.6 Prevention of Iatrogenic Lesion

Some anatomic considerations are useful to prevent iatrogenic nerve injuries especially concerning the axillary nerve. Landmarks of the location of the axillary nerve are taken from the acromion or from the greater tuberosity. When the acromion is considered as landmark, the mean distance from the superior border of the axillary nerve to the anteroinferior border of the acromion is about 6.3 ± 0.5 cm [34]. When the greater tuberosity is considered as reference, the distance between this landmark and the axillary nerve is relatively constant from 3.5 ± 0.2 to 4.6 cm [35]. The surgeon must take into account that the greater tuberosity may be displaced after a fracture. In this case, the course of the axillary nerve can be estimated from the acromion [36].

Another important consideration is the position of the arm during surgical procedures. When the arm is moved, both nerves and arteries may modify their position. In fact in neutral position (0° rotation, 20° abduction, 0° forward flexion), the axillary nerve is located about 6 cm from the acromion; when the arm is placed in 60° of abduction, the distance from the nerve to the acromion decreases to 5.4 cm. The safe zone for hardware placement in neutral shoulder position is up to 5 cm distal from the mid-acromion. The danger area has been reported with slight differences among authors from 5 to 9 cm according to Cheung, Ruedi, and Yung-Fen [36–38]. Distal to 9 cm, the deltoid may be safely split again with minimal risk of injuring the axillary nerve [38], but in any case, rough handling and strenuous retraction of the deltoid muscle should be avoided to minimize risk of axillary nerve damage [36].

These anatomic considerations are valid not only for open reduction and internal fixation by means of plates but also for synthesis with anterograde nails and for percutaneous fixation when screws and pins are used around the shoulder region. In particular, during humeral nailing, screw positioning should be as close as possible to the acromion in order to reduce the risk of nerve injuries. Moreover, the arm should be left in neutral position avoiding internal rotation that comes near the nerve to the entry site of screw [18].

In Fig. 14.2, we reported a schematic view of the anatomy of suprascapular and axillary nerve in the posterior aspect.

Fig. 14.2Posterior anatomy of suprascapular and axillary nerve. Distance from the posterior acromion to the axillary nerve—safe zone

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