The new lumbar elliptical curve template was developed from data used to determine the average and ideal lumbar sagittal curvature from 50 normal subjects which was consistent with studies using larger patient populations of up to 552 subjects.
These CBP® research projects have been published at the Journal of Spinal Disorders and the Journal of Orthopedic Research. The extent of the lumbar elliptical curve is from posterior-inferior T12 to posterior-superior S1. The use of the posterior-inferior of S1 is only to draw the Vertical Axis Line (VAL), not to draw the elliptical normal arc. The template was arranged in its final configuration in May 1997 and has been available since July 1997.
With the lateral lumbo-pelvic radiograph on the view box, draw a vertical line (VAL) from the posterior-inferior body corner of S1 (parallel to vertical edge of film).
Draw a horizontal line through the posterior-inferior body corner of T12.
Locate the red line on the elliptical curve template for the posterior-superior sacral base. Place this point on the plastic tool (using one of the cut out curves) on the patient’s posterior-superior sacral base. Pivot the plastic tool until the top of the chosen cut out curve intersects VAL. Measure the distance from this cut out intersection with VAL to the intersection of the T12 horizontal line with VAL.
Try the above procedure with the next curve cut out. Determine the distance which is minimum. (several curves may be tried). The curve with the minimum distance to the intersection of the T12 horizontal line and VAL is the Best Fit Curve.
Holding this cut out Best Fit Curve in place from sacral base to VAL, draw the “RED” line through the cut out area from S1 to the height of T12.
Using a black x-ray marking pencil draw along George’s line from S1 to T12.
You are now ready for your Report of Findings “The Black line is you, the Red line is normal,…… can you see that you’re not normal?”