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Updated: May 21, 2026
Multilevel Oblique Lumbar Interbody Fusion in Degenerative Lumbar Disc Disease with Instability
Published on: July 25, 2025
Accuracy of patient-specific rods in long segment multilevel fusions: a single-institution study
William Snyder1, Barnabas Obeng-Gyasi2, Anoop S Chinthala1
1Indiana University School of Medicine, Indianapolis, IN, USA.
Background:
Accurate restoration and maintenance of sagittal alignment are critical in multilevel thoracolumbar fusion. Patient-specific rods (PSRs), preoperatively designed to match individualized alignment goals, may enhance surgical precision and durability. While often used in adult spinal deformity (ASD) correction, their utility extends to long segment fusions where the objective is preservation of alignment and prevention of loss of lordosis. The objective of this study was to evaluate the accuracy of PSRs in achieving planned sagittal alignment and maintaining lumbar lordosis (LL) in long segment thoracolumbar fusions.
Methods:
We retrospectively reviewed 18 patients undergoing ≥3-level thoracolumbar fusions with PSRs between 2022 and 2023 at a single institution. Radiographic parameters: LL, pelvic incidence-LL (PI-LL), sagittal vertical axis (SVA), T1 pelvic angle (TPA), and pelvic tilt (PT), were measured at three timepoints. Target attainment was assessed using Scoliosis Research Society-Schwab (SRS-Schwab) and TPA thresholds.
Results:
LL increased from 37.6° to 50.4° (P=0.002), PI-LL decreased from 19.9° to 6.8° (P=0.003), SVA improved from 66.3 to 26.6 mm (P=0.007), and TPA decreased from 23.8° to 17.5° (P=0.03). PT improved modestly. Planned and achieved values did not differ significantly, indicating high plan to execution fidelity. Postoperatively, 83% achieved SVA ≤40 mm, 67% achieved PI-LL ≤10°, and 67% achieved TPA ≤20°. Radiographic overcorrection below physiologic thresholds was uncommon, occurring in <17% for any of the measured variables.
Conclusions:
PSRs enabled precise sagittal alignment targets across a spectrum of long segment fusions. Minimizing variance between planned and achieved parameters, PSRs not only support deformity correction but also help maintain favorable alignment in patients without major preoperative imbalance. These findings highlight their versatility in enhancing surgical accuracy and preventing loss of lordosis.
