The surgical anatomy of the dorsal scapular nerve: a triple-tendon transfer perspective.

BACKGROUND: Iatrogenic or traumatic injury to the spinal accessory nerve is a rare but debilitating injury. An effective treatment, known as the Eden-Lange modification triple-tendon transfer procedure, involves the transfer of the rhomboid major (RM), rhomboid minor (Rm), and levator scapulae (LS). Careful detachment of their insertions is necessary to avoid injury of the dorsal scapular nerve (DSN). This study evaluated the surgical anatomy and safety of the DSN relative to this procedure.

METHODS: The study used 12 cadavers (22 shoulders). The RM, Rm, and LS were detached from their insertions, and the DSN was dissected. Measurements were taken to evaluate the anatomy of each relative to the triple-tendon transfer procedure. Additional measurements were taken to identify "danger zones" for DSN injury, regarding detachment of RM, Rm, and LS from their respective insertions.

RESULTS: Measurements of the 22 shoulders included in the study showed wide variation in anatomy. The minimum distance between the scapula and the DSN at the vertebral scapular border was 0.7 cm, suggesting that care and precision are needed to perform this technique. The region where the DSN crosses the superior border of the Rm was shown to be the greatest "danger zone" of this technique, with a mean distance to the scapula of 1.61 ± 0.53 cm CONCLUSIONS: This study provides insight into the surgical anatomy of the DSN relative to a rare but successful procedure used to treat trapezius paralysis. The results of this study can inform the surgeon regarding potential anatomic considerations when performing the triple-tendon transfer.