OTSR - 2026-04-23 - Journal Article
Radiographic assessment of immediate postoperative lumbar lordosis redistribution after pedicle subtraction osteotomy with pre-contoured rods: A retrospective study.
Chevillotte T, Cojean T, Grobost P, Darnis A, Dautel T, Silvestre C
Topics
Key Takeaway
After L4/L5 PSO with pre-contoured rods, postoperative lumbar lordosis consistently undershot rod curvature by a mean of 12–13.5°, with rod angulation being the strongest predictor of this mismatch (r = -0.593).
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Summary
This study quantified the mismatch between pre-contoured rod curvature (40°, 65°, or 90°) and achieved postoperative lordosis in 51 patients undergoing L4 or L5 PSO with lumbosacral fusion. LL Global increased 5.3° (9.8%, p=0.009) and LL L1S1 increased 8.2° (16.2%, p<0.001), with SLR improving 86.1%; however, postoperative lordosis fell short of rod curvature by 12° and 13.5° respectively. Rod angulation was the dominant predictor of mismatch magnitude, and higher preoperative PI, PT, and LL also correlated with larger discrepancy.
Key Limitation
The study captures only immediate postoperative radiographs, so it cannot determine whether the rod-lordosis mismatch persists, worsens with rod stress relaxation, or correlates with pseudarthrosis or sagittal alignment failure at follow-up.
Original Abstract
BACKGROUND
Sagittal alignment is a major determinant of clinical outcomes in adult spinal deformity surgery. This study assessed the effect of pre-contoured rods (40°, 65°, or 90°) with a short-radius bend on postoperative lumbar lordosis after lumbosacral fusion with Pedicle Subtraction Osteotomy (PSO). This radiographic study was designed (1) to assess immediate postoperative redistribution in Global Lumbar Lordosis (LL Global ) and L1S1 Lumbar Lordosis (LL L1S1 ) after L4 or L5 PSO with pre-contoured rods, (2) to quantify the mismatch (ΔL) between postoperative lordosis and rod curvature, (3) to test whether ΔL differed according to sex, revision status, osteotomy level, or fusion length, and (4) to evaluate correlations between ΔL and preoperative spinopelvic parameters.
HYPOTHESIS
Combining factory pre-contoured rods featuring a short-radius sagittal bend with L4 or L5 PSO effectively restores and redistributes lumbar lordosis.
PATIENTS AND METHODS
This retrospective cohort included 51 patients (mean age 52 ± 14 years) who underwent L4 or L5 PSO with sacral fixation using 40°, 65°, or 90° factory pre-contoured rods. Preoperative and immediate postoperative EOS imaging was analysed. ΔL Global - rod and ΔL L1S1 - rod were calculated. The Spinal Lordosis Ratio (SLR), defined as the ratio between the upper and lower arc angles of lumbar lordosis, was also assessed." Paired comparisons, ANOVA, and Pearson correlations were performed.
RESULTS
LL Global increased by 5.3° ± 14.0° (9.8 %, p = 0.009) and LL L1S1 by 8.2° ± 15.3° (16.2%, p < 0.001). Spinal Lordosis Ratio (SLR) improved by 86.1% (p < 0.001). Postoperative lordosis remained lower than rod curvature, with average mismatches of -12° ± 15.7 (ΔL Global - rod ) and -13.5 ± 16.8° (ΔL L1S1 - rod ). No significant differences in ΔL were observed according to sex, revision status, osteotomy level, or fusion length. Rod angulation was the strongest predictor of ΔL (r = -0.593, p < 0.001), with higher angulations associated with greater absolute mismatch. Higher preoperative Pelvic Incidence (PI), Pelvic Tilt (PT), and Lumbar Lordosis (LL) also correlated with larger ΔL values.
CONCLUSIONS
PSOs at L4 or L5 combined with pre-contoured rods restore lumbar lordosis and redistribute sagittal alignment, but a persistent mismatch between rod curvature and postoperative alignment remains, more pronounced for strong angulations.
LEVEL OF EVIDENCE
IV; Retrospective, single-center observational cohort study.