Over-the-ALA Fixation for Neuromuscular Scoliosis – Is the L5 Nerve Root at Risk?

· (a – Synthes)

12 patients with neuromuscular scoliosis were operated with over-the-ala instrumentation. Of these 9 had documented longterm follow-up. Four of these patients had persistent sciatic pain postoperatively. The cause was unclear. A review of anatomic studies showed that the L5 nerve root traverses just lateral to the vertebral body and anterolaterally over the sacral ala and distally to join the sciatic nerve. A cadaver dissection was performed after instrumentation in order to visualize the L5 nerve root at the front of the ala. Clearly, the nerve is jeopardized by the rod which passes over and anterior to the ala. It appeared that placing these rods as laterally as possible would decrease the risk of nerve impingement. While rod impingement could not be proven as the cause of sciatic pain in these patients, the anatomical evidence raises the possibility. Caution should be used in placing these rods in patients who are sensate.

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