1) Boden technique: The first technique was adapted from Boden et al., where a straight line was drawn through the spinous process, and the angle between the facet joints and a
perpendicular tangent originating at posterior aspect of the vertebral body was calculated. Later authors modified this technique by eliminating the need to place a line at the posterior aspect of the vertebral body and simply calculated the angle between the facets and the spinous process.
This was subsequently validated, and was chosen for use in this study by using the same-level spinous process (as opposed to the more rostral spinous process in radiographic studies). Lumbar vertebrae were placed in a sandbox, and leveled using a circular bubble Bullseye level (Hopkins Towing and Hardware Inc., Emporia, KS). After ensuring a perfectly flat surface, axial
photographs were captured and a line was drawn down the center of the spinous process. The corresponding angles between the superior articular facets were measured from the caudad (same-level) vertebral body segment of each zygapophyseal joint (Figure 1). For example, the L1-L2 facet angle was measured using the L2 vertebral body’s superior articular facet joints and spinous process. The L5-S1 facet joint angle was measured by leveling the sacral endplate and calculating the angle between the center of the spinous process and the zygapophyseal joints.
Measurements were taken using ImageJ software package (National Institute of Health, Bethesda, MD).
