The effect of degenerative scolioisis on segmental thoracolumbar sagittal alignment compared to age- and pelvic incidence-matched reference values

Vincent Lamas; Renan Chapon; Solène Prost; Benjamin Blondel; Stéphane Fuentes; Erik André Sauleau; Yann Philippe Charles

doi:10.1007/s00586-024-08618-7

The effect of degenerative scolioisis on segmental thoracolumbar sagittal alignment compared to age- and pelvic incidence-matched reference values

Eur Spine J. 2025 Jan 13. doi: 10.1007/s00586-024-08618-7. Online ahead of print.

Authors

Vincent Lamas¹, Renan Chapon², Solène Prost³, Benjamin Blondel³, Stéphane Fuentes⁴, Erik André Sauleau⁵, Yann Philippe Charles⁶

Affiliations

¹ Service de Chirurgie du Rachis, Hôpitaux Universitaires de Strasbourg, Université de Strasbourg, 1 Avenue Molière, Strasbourg, France. lamas.vincent@gmail.com.
² Service de Neurochirurgie, Centre Hospitalier Universitaire Dijon-Bourgogne, Dijon, France.
³ Unité de Chirurgie Rachidienne, Centre Hospitalier Universitaire de la Timone, Aix-Marseille Université, Marseille, France.
⁴ Service de Neurochirurgie, Centre Hospitalier Universitaire de la Timone, Aix-Marseille Université, Marseille, France.
⁵ Service de Santé Publique, Hôpitaux Universitaires de Strasbourg, Université de Strasbourg, Strasbourg, France.
⁶ Service de Chirurgie du Rachis, Hôpitaux Universitaires de Strasbourg, Université de Strasbourg, 1 Avenue Molière, Strasbourg, France.

PMID: 39800820
DOI: 10.1007/s00586-024-08618-7

Abstract

Introduction: In asymptomatic subjects, variations of sagittal alignment parameters according to age and pelvic incidence (PI) has been reported. The aim of this observational study was to describe thoraco-lumbar sagittal alignment in patients with degenerative scoliosis and to compare them to asymptomatic individuals, seeking for the specific effect of deformity in similar age and PI groups.

Materials and methods: Full spine radiographs of 235 asymptomatic subjects and 243 scoliosis patients were analyzed: cervico-thoracic inflexion point (CTIP), thoraco-lumbar inflexion point (TLIP), lumbar lordosis (LL) L1-S1, LL (TLIP-S1), LL superior arch (TLIP-lumbar apex), LL inferior arch (lumbar apex-S1), PI, thoracic kyphosis (TK) T5-T12, TK T1-T12, number of vertebrae CTIP-TLIPandTLIP-S1. The distribution of parameters was analyzed using a Bayesian inference (significant when Pr > 0.975 or Pr < 0.025). Comparisons between reference (R) and pathologic (P) groups were matched according to age (40-60 years; >60 years) and PI (< 45°; 45-60°; >60°).

Results: LL L1-S1 was significantly lower in the P-group (Pr = 1.0), decreased with age (Pr > 0.99) and increased with PI (Pr < 0.001). In contrast, there was no significant decrease with age for LL (TLIP-S1) or LL (superior arch) (respectively Pr < 0.92 and Pr > 0.19). LL in the inferior arch was significantly lower in the P-group (Pr = 1.0) and decreased with age (Pr = 0.99). The number of vertebrae TLIP-S1 was significantly lower in the P-group compared to the reference group (Pr < 0.001).Thoracic kyphosis T1-T12 was significantly lower in the P-group (Pr < 0.001), without significant influence of age or PI. The number of vertebrae CTIP-TLIP increased significantly in the P-group (Pr < 0.001) and with PI (Pr < 0.004).

Conclusion: This observational study highlights specific thoraco-lumbar sagittal alignment adaptations in degenerative scoliosis, matched on age and PI. Beyond the decrease in LL due to aging, degenerative scoliosis leads to a distal migration of the TLIP, an increase in the number of vertebrae in TK and a decrease in LL. This phenomenon was linked to kyphosis at the thoraco-lumbar junction due to scoliosis and was more important in high PI.

Keywords: Adult spinal deformity; Inflexion points; Lumbar lordosis; Pelvic incidence; Sagittal balance; Thoracic kyphosis.