Lateral Lumbar Analysis: 

Lumbosacral Disc Angle:  

• Draw line parallel and through the inferior endplate of L5 and the superior endplate of S1.  Measure the angle formed by these lines.  This is the Lumbosacral Disc Angle.  Normal range is 10-15°.  An increase suggests facet impaction; a decrease suggests possible disc herniation.

Ferguson’s Line:  

• Locate the center of L3 by intersecting diagonal lines from opposing body corners.  Drop a vertical line from this intersection down through the sacrum.  This is Ferguson’s line and should fall within the anterior 2/3 of the sacrum.  If the line falls in the anterior to the sacrum, curve is hypolordotic.  If posterior 1/3 of the sacrum, curve is hypolordotic.