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Study Design: This was an innovative concept and a preliminary prospective series. Objective: The aim of this study was to present the concept and the technical aspects of patient-specific rods (PSR), and compare preoperative and postoperative sagittal parameters (after PSR implantation), with a special focus on the difference pelvic incidence (PI)—lumbar lordosis (LL). Background: Despite established techniques for planning and proven correlations between quality of life and sagittal alignment, some patients do not achieve optimal radiologic outcomes after surgery and are still hypolordotic and imbalanced. We hypothesize that the use of PSR could improve the correspondence between planning and surgical realization. Methods: The planning was based on spinopelvic parameters evaluated on a full-spine x‐ray. The surgical procedure including osteotomies was simulated using a dedicated program to reach the following objectives: PI-LL<10 degrees, a pelvic tilt <20 degrees, and sagittal vertical axis <50 mm. From the virtually corrected spine, the rod curvature and length were defined. Two PSRs were thus precisely manufactured and bent to this specification. Adults with degenerative spinal disorders requiring a construct ≥5 levels were implanted with PSR and prospectively included. We compared ratios through the χ2 test. Results: A total of 60 patients (mean age of 64.4 years old; range, 34–83) were included. Follow-up was carried out over a period of 1 year. Average pedicle screws construct was of 6.4 levels (range, 5–9). Eight patients underwent a pedicle subtraction osteotomy. PI-LL was <10 degrees at baseline in 29/60 patients, and at follow-up in 50/60 (odds ratio=5, P=E-5). Conclusions: The ratio of patients with optimal PI-LL improved significantly from PSR implantation. In comparison with published data for conventional surgery, patients implanted with PSR were 2.6 times more likely to be optimally corrected. The expected benefits of PSR include the optimal execution of the plan, decreased mechanical complications, and reduced operating time, no longer requiring the bending of rods during surgery. A randomized trial on sagittal correction using PSR is ongoing.

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Study Design: Retrospective cross-sectional study. Objective: The aim was to describe existing global sagittal alignment parameters across ages and to analyze differences according to gender and pelvic incidence (PI). Summary of Background Data: Variability with age has been reported. It remains unclear how gender and spinopelvic morphology could additionally influence global alignment parameters. Materials and Methods: Radiographs of 2599 individuals (5–93 y) were analyzed. Translation parameters were: Sagittal Vertical Axis (SVA)-C7, SVA-C2, SVA-Center Acoustic Meatus (CAM), C7/Sacrofemoral Distance (SFD) ratio. Inclination parameters were: C7-Vertical Tilt (VT), T1-VT and T9-VT, Odontoid-Hip Axis (OD-HA), OD-CAM. Pelvic compensation parameters were: T1-Pelvic Angle (TPA), Global Tilt (GT), Spino-Sacral Angle (SSA). Global sagittal alignment (GSA) was considered among formulae. The distribution of parameters was analyzed using a Bayesian inference. Correlations with spinopelvic parameters were investigated. Results: SVA-C7, SVA-C2, SVA-CAM were larger in males and high PI, and increased significantly after 50 years (Pr>0.9999). C7/SFD decreased during growth and was larger in low PI (Pr=0.951). There was no correlation with spinopelvic parameters. Age-related variations of inclination parameters were nonsignificant. T1-VT and T9-VT increased with PI and were significantly larger in high PI (Pr>0.95). C7-VT was significantly larger in low PI (Pr>0.9999). OD-HA and OD-CAM were constant and increased after 80 years. TPA and GT increased with PI (Pr>0.9999) and age after 35 years (Pr>0.9999). SSA decreased nonsignificantly after 50 years. TPA correlated with PI (ρ=0.6130) and pelvic tilt (PT) (ρ=0.8375). GT correlated with PI (ρ=0.5961) and PT (ρ=0.8996). SSA correlated with sacral slope (ρ=0.9026). GSA was larger in high PI (Pr>0.9999) and increased after 35 years (Pr>0.9999). GSA correlated with PT (ρ=0.7732). Conclusion: Translation parameters increase with age, more prominently in males and high PI. Variations of inclination parameters are smaller. Pelvic compensation parameters and GSA increase with age and are closely related to PT and spinopelvic morphology. Level of Evidence: Level III.