Roussouly type 2 could evolve into type 1 shape as sagittal spinal alignment deterioration progresses with age

Area of Science:

• Spine biomechanics
• Radiographic analysis
• Degenerative spinal conditions

Background:

• Roussouly classification categorizes sagittal spinal alignment.
• Understanding the progression of spinal types is crucial for managing spinal health.
• Age-related changes significantly impact spinal alignment and biomechanics.

Purpose of the Study:

• To investigate the potential evolution of Roussouly type 2 spinal alignment into type 1.
• To determine the influence of primary degenerative scoliosis on this progression.
• To analyze age-related changes in sagittal spinal parameters.

Main Methods:

• Cross-sectional study of 270 subjects with low pelvic incidence (PI).
• Measurement of sagittal parameters including T1 pelvic angle (TPA), lumbar lordosis (LL), PI, pelvic tilt (PT), and others.
• Comparison of parameters across age groups and between subjects with and without primary (de novo) degenerative scoliosis (PDS).

Main Results:

• A stepwise increase in type 1 proportion and decrease in type 2 with age was observed.
• Sagittal parameters like TPA, PT, PI-LL, TLK, and LDI generally increased with age.
• Type 2 showed increased TPA, PT, PI-LL, and TLK, with decreased LL and L4-S1, while type 1 showed different parameter changes.
• LSA and NVL decreased with age in subjects without PDS and with type 2, but not significantly in type 1.
• PDS subjects had distinct parameter differences compared to non-PDS groups, though Roussouly type distribution was similar.

Conclusions:

• Roussouly type 1 may represent an aged form of type 2, not a distinct type.
• Deterioration of sagittal spinal alignment with age can lead to the type 2 to type 1 transition.
• Primary degenerative scoliosis has minimal impact on the type 2 to type 1 evolution, necessitating consideration in sagittal balance restoration.