Introduction: The thoracolumbar junction is frequently accessed through an anterolateral approach with an incision and muscle dissection extending from the lower thoracic region to the lateral border of the rectus abdominis muscle. This approach is frequently associated with the subsequent development of an unsightly and uncomfortable relaxation of the ipsilateral abdominal wall, or “flank bulge,” secondary to denervation injury of the intercostal nerves. However, the etiology of this complication is not widely recognized by spine surgeons.
Methods: We performed 32 cadaveric dissections and 6 intraoperative EMG evaluations in order to better define the relevant anatomy and innervation of the anterolateral abdominal wall musculature.
Results: Our cadaveric dissection studies and intraoperative EMG evaluations provide detailed anatomy of the anterolateral abdominal wall and its innervation.
Conclusions: Based on our anatomical and electrophysiological evaluations, we classify the three potential zones of injury that may occur during an anterolateral approach to the thoracolumbar junction. Finally, suggestions regarding modifications of operative technique to avoid this complication are discussed.
Patient Care: Educating spine surgeons about this complication and techniques for its avoidance will hopefully decrease the incidence of this complication.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) recognize the post-op abdominal flank bulge complications, 2) describe the innervation of the abdominal wall, 3) describe the etiology of post-op abdominal flank bulge, 4) describe techniques for avoiding this complication.