General Principles of Spinal Alignment and Balance

Spine sagittal alignment is a broad name regrouping different mechanisms of alignment at the spine, from the neck to the pelvis. In a clinical setting, sagittal alignment is often miss-considerate as an academic exercise, with too many confusing parameters, resulting in a complex concept requiring too much time to be assessed. In this chapter, the authors aimed at simplifying sagittal alignment analysis by describing the most relevant radiographic parameters. These include pelvic parameters, regional curvatures and global alignment which are related and should be compared to have a better understanding of an individual patient’s pathology. A simple approach to evaluate the sagittal plane in clinical settings was proposed. The approach was divided into three main sections: (1) Identification of the driver of deformity, (2) analysis of the compensatory mechanism and (3) Assessment of global alignment and horizontal gaze.