Chiropractic X-Ray Method Published in Spine as
3-Part Series
by Deed E. Harrison, DC
For the first time ever, a Chiropractic x-ray line drawing method has
been published in a medical/orthopedic journal. A 3-part series on our
Harrison Posterior Tangent radiographic method has been published in
Spine in 2000 and 2001. This makes CBP®’s 4th publication in Spine since
our Harrison cervical spine model was published in Spine in 1996 and our
recent lateral cervical reliability project (part 1 of our 3-part
series) was published in an August 2000 issue of Spine.
In January and February 2001, I received acceptance letters for two CBP®
research papers from Dr. James Weinstein, Editor-in-Chief at Spine.
These two projects were (1) Centroid, Cobb or Harrison Posterior
Tangents: Which to Choose for Analysis of Thoracic Kyphosis? and (2)
Determination of Lumbar Lordosis: Cobb Method, Centroidal Method, TRALL
or Harrison Posterior Tangents? by Harrison DE, Cailliet R, Harrison DD,
Janik TJ, Holland B. These two papers were just recently published
on-line in the June 1st, 2001 issue of Spine.
It was my idea to compare our posterior tangents to the Cobb and
Centroid methods and the cervical radiographs were pulled from my office
files. The thoracic and lumbar views were full spine radiographs, used
in other studies, and were obtained with the help of the Life CBP® Club
and Dr. Phil Paulk of Stockbridge, Georgia.
Whereas Ruth Jackson, MD (Cervical Syndrome, 1957 & 1977 editions) drew
posterior tangents on C2 and C7, she never measured a rotation angle of
the cervical curvature with these “Physiological stress lines.” In her
texts, she only used these lines to locate a stress vertebra at the
location of their crossing in her whiplash patients. Pettibon used
Jackson’s stress lines at C2 and C7 and at points of inflection in
cervical “S”-curves and later at L1 & L5, but he measured his own
confusing Cervical Leverage Factor (CLF) and did not measure segmental
or global angles in degrees with these lines.
In 1977, my father correlated Pettibon’s CLF measures (2.5 - 5.0) with
degrees of a circle and in a copyrighted text by him (Dr. Don Harrison)
in 1979, my father began to measure the angles in degrees between
posterior tangents (C2-C7, T3-T10, & L1-L5) on lateral x-rays. In 1982,
my father began to draw posterior tangents on every vertebra in the
lateral radiographic views. His mathematics and engineering background
led him to this analysis. Engineers draw tangents, as derivatives of the
function representing the shape of a beam or column, at all points along
beams and columns. In an engineering analysis of beams with calculus,
the 1st derivative is the slope (posterior tangents), the 2nd derivative
is the bending moment, and the 3rd derivative is the shear. When using a
chain of rigid bodies, the segmental angles are relative rotation angles
(RRAs) and the global angles are absolute rotation angles (ARAs).
A few medical doctors have measured an angle at C2-C7, notably Gore
(1986 in Spine), but no one drew posterior tangents on each vertebra
until my father did.
As with most first occurrences, the person to originate the method gets
credit for it. I believe that the Harrison Posterior Tangent method, as
published in Spine, is the first chiropractic radiographic method to be
featured in a medical journal.
We are very excited that our entire lateral spine, original, x-ray line
drawing method has been reported as reliable in one of the world’s most
prestigious medical journals. Perhaps now, chiropractic radiologists (DACBRs)
will finally admit that geometric line drawing analysis has been shown
to be highly reliable and our Harrison Posterior Tangent radiographic
method is one of the best.