Summary: True global sagittal balance must take into consideration the position of the head in relation to the spine and pelvis. We have performed a prospective analysis of asymptomatic adults in two age groups, 20‐40 and 60‐80 years old, establishing normal values of cranial sagittal balance with comparison to C2 and C7 sagittal alignment.
Introduction: The C7 plumbline defines thoracolumbar sagittal balance and has been shown to have significant impact on patient outcomes. However, the C7 plumbline fails to take into consideration the position of the head in relation to the pelvis. With this study we aim to determine normal values for cranial sagittal balance in asymptomatic individuals.
Methods: 100 asymptomatic 20‐40 year‐old patients and 100 asymptomatic 60‐80 year‐old patients were enrolled. 14x36 inch standing scoliosis radiographs were obtained. Cranial center of mass (CCOM), C2, and C7 plumblines were drawn and measured from the superior posterior endplate of S1.
Results: 78 asymptomatic 20‐40 year‐old patients and 62 asymptomatic 60‐80 year‐old patients had usable radiographs. The mean plumbline values in the 20‐40 year‐old patients and 60‐80 year‐old patients respectively were as follows; CCOM 9.0 mm ± 31.5 and 41.2 mm ± 35.7; C2 ‐2.7 mm ± 32.7 and 32.1 mm ± 33.6; C7 27.9 mm ± 21.4 and 110.2 mm ± 27.9. One‐way ANOVA and t‐tests verified that these mean plumbline values were significantly different between young and old patients (p<0.001). The change at each level over time correlated to the other levels (R > 0.97, p<.001) as did the degree of change between groups (R > 0.81, p<.001).
Conclusion: Spinal pelvic alignment in conjunction with CCOM has increased our understanding of spinal balance by including the head and may better represent true global spinal balance than the traditional C7 measurement. CCOM is an easily measured parameter by using the nasion‐inion technique.
Significance: With this study we have established a normal range for cranial sagittal balance for asymptomatic individuals in both a young and old population.