Transient postoperative femoral neuropathy following prone positioning for posterior spine surgery: illustrative case.

backgroundNeurological deficits are a concern following spine surgeries. Determining the etiology is critical as this dictates management options. The authors present the case of a transient bilateral femoral neuropathy following prone positioning for a revision spinal fusion with osteotomies that improved with conservative management. OBSERVATIONS: A 69-year-old male with a prior L2-S1 posterior fusion presented with back pain, and imaging showed pseudarthrosis and hardware failure. He underwent a first-stage L2-4 lateral interbody fusion, and 1 week later a revision T10-pelvis posterior spinal instrumented fusion and bilateral posterior column osteotomies at L1-2 and L2-3. Postoperatively, he had 0/5 power in his bilateral quadriceps muscles with patchy sensory loss in the medial thigh and knees without pain. Imaging did not reveal any compressive cause. The most likely etiology was a peripheral neuropathy of the femoral nerve at or below the level of the inguinal ligament, which was managed conservatively with subsequent improvement. LESSONS: A careful neurological examination and imaging review can determine a peripheral nerve injury that is expected to resolve with conservative management compared with a postsurgical nerve root injury or hematoma that would benefit from immediate surgical exploration. https://thejns.org/doi/10.3171/CASE25239.