J Neurosurg Spine 45:700–705, 2026
In 20 adults undergoing lumbar pedicle subtraction osteotomy, surgeons achieved a mean correction of 24.0° at the osteotomy against a planned 24.2°. Yet the trunk remained farther forward on the first standing radiograph than the software had predicted. The distinction matters when deciding how to judge correction after closing the wedge, because the local angle captures only one component of standing balance.
Study and key findings
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This single-center retrospective series included thoracolumbar fusions spanning at least six levels. Surgeons performed each osteotomy at the level specified in the UNiD plan, most often L4 or L5. They closed the osteotomy with a separate short rod and used patient-specific pre-bent rods to stabilize the surrounding construct. The investigators compared the plan with immediate postoperative standing lateral radiographs.
Mean sagittal vertical axis measured 110 mm preoperatively, with a planned postoperative value of 10 mm and an observed value of 56 mm. Pelvic tilt fell from 31° to 12°, exceeding the planned reduction to 21°. Individual osteotomy angles also varied around the close group means, with a standard deviation of 8.6° for the paired difference.
Interpretation and limitations
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Pelvic rotation and reciprocal changes in unfused spinal segments may help explain why a planned wedge angle can yield a different standing profile. The study measured alignment early in recovery. Subsequent compensation and its relationship to function remain uncertain. All 20 patients received pre-bent rods, so the contribution of rod design cannot be isolated from the osteotomy and other corrective maneuvers.
Clinical takeaway
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After wedge closure, assess the correction at the osteotomy and the position of the trunk over the pelvis. The authors suggest checking overall alignment with a long-cassette radiograph or stitched fluoroscopic images before leaving the operating room. Their study evaluated postoperative standing films and leaves the clinical benefit of that intraoperative check open.