sagittal vertical axis

Full Definition

The sagittal vertical axis (SVA) is a key radiographic parameter used to evaluate global spinal balance in the sagittal plane. It is measured as the horizontal distance between a vertical line dropped from the center of the C7 vertebral body and the posterior-superior corner of the S1 vertebral body on standing lateral radiographs. Normal values are typically less than 5cm, with positive values indicating forward spinal imbalance. SVA is crucial for surgical planning and outcome assessment in spinal deformity correction procedures.

Usage

Usage note: Always include measurement units (cm) when reporting values.

In Context

• "Preoperative radiographs showed a sagittal vertical axis of 12cm indicating severe positive sagittal imbalance." — Deformity assessment report
• "Postoperative improvement in sagittal vertical axis correlated with enhanced functional outcomes." — Surgical outcome analysis