Global Alignment and Proportion (GAP) score in asymptomatic individuals: is it universal?

Area of Science:

• Spine surgery
• Radiographic analysis
• Orthopedic research

Background:

• The Global Alignment and Proportion (GAP) score, developed using Western populations, may not accurately reflect sagittal alignment in the Chinese population due to ethnic variations.
• Understanding ethnicity-specific spinal alignment is crucial for accurate clinical assessment and surgical planning.

Purpose of the Study:

• To evaluate the applicability of the GAP score in an asymptomatic Chinese cohort.
• To investigate age- and gender-related differences in spinopelvic parameters and GAP score components within this population.

Main Methods:

• A prospective cross-sectional study included 490 asymptomatic Chinese volunteers (aged 20-79).
• Radiographic parameters (PI, PT, SS, LL, SVA, GT) and GAP score components (RPV, RLL, LDI, RSA) were measured and calculated.
• Subjects were stratified by age (<60 vs. ≥60) and gender for comparative analysis.

Main Results:

• The distribution of GAP categories and Roussouly classification differed significantly from other populations.
• Age and gender significantly impacted spinopelvic measurements and GAP parameters, with more pronounced differences between age groups and genders.
• The linear relationships between pelvic incidence and other parameters deviated from the "ideal" GAP score models.

Conclusions:

• The GAP score's applicability is questionable in the Chinese population due to distinct ethnic sagittal alignment.
• Feasibility of the GAP score is reduced in older and female subjects, suggesting a need for population-specific adjustments or alternative assessment tools.