"positive balance: the plumb line passes >2 cm in front of the posterosuperior corner of the S1 vertebral body"
"neutral balance: C7 plumb line intersects the posterosuperior corner of S1 (mean SVA in asymptomatic adults is 0.5 cm +/- 2.5 cm) 1"
"negative balance: the plumb line passes more than 2 cm behind the posterosuperior corner of the S1 vertebral body"
"Sagittal vertical axis/alignment (SVA) is one of the simplest and most widely used methods to assess sagittal balance 1-3."
"neutral balance: C7 plumb line intersects the posterosuperior corner of S1 (mean SVA in asymptomatic adults is 0.5 cm +/- 2.5 cm) 1"
"The position of this line can be positive, neutral or negative:"