August 2009

Objective and reliable evidence

by Dr. Mark Payne

For years, chiropractors have been hounded for objective evidence to support our recommendations for care. More recently, there have been a number of published guidelines attempting to standardize exactly when and how field practitioners should X-ray their patients.

While I am all for genuine efforts to improve our standards of care, today's "recommendations" often have a strange way of becoming tomorrow's mandates and I would encourage everyone to remain vigilant. Your future right to examine and treat patients as you deem appropriate may well be impacted by the outcomes of such studies.

In a time when our very right to take X-rays is under assault and a structural definition of subluxation has become unfashionable, many doctors aren't aware of how much objective information can be obtained from simple radiographic analysis.

Many (possibly most) chiropractors will X-ray their typical new patient and two perpendicular views are generally considered bare minimum. In addition to the traditional diagnostic values, plane radiographs can actually yield a great deal of biomechanical information.

Let's review some of the information you can get from just a simple lateral cervical film. Note that the principles can be applied to the lateral thoracic and lumbar films as well.

***  Jackson's Angle -- first published in the '50s by Ruth Jackson, MD, in her landmark book, "The Cervical Syndrome, Jackson's Angle" -- gives us a wealth of biomechanical information with a single measurement. The method was popularized in chiropractic by Pettibon in the '70s and later by Harrison.

Measurement of Jackson's Angle generally requires the construction of only two simple lines and a measurement of their angle of intersection. Fig. 1 shows how lines are constructed along the posterior bodies of C2 and C7 and extended down and upward respectively until they intersect. A simple protractor is then used to measure the acute side of the angle.

Jackson's Angle tells us exactly how much lordosis is present in our patient. In this case, the neck has a 31 degree lordosis between C2 and C7, which we record by convention as a "negative" or "minus" number.

While there is some disagreement in the scientific literature as to how much lordosis is needed for long term spinal health, there is basically no disagreement at all regarding the validity and reliability of measuring the angle on the films. A number of studies have established the accuracy and reliability of this simple method of measurement.

Occasionally, patients will present with some sort of "S" Shaped neck configuration and the lines from C2 and C7 won't intersect. If that happens, it becomes a simple matter of just drawing a third line off one of the middle vertebrae so as to best represent the middle portion of the "S" configuration (see red line in Fig. 2). In this case, I drew the third line off of C5 and we now have three lines intersecting to form two angles.

As mentioned, degrees of lordosis are recorded by convention as negative numbers. Conversely, degrees of kyphosis are recorded as positive numbers. With this in mind, the kyphotic lower portion of the neck in Fig. 2 would be recorded as +15 degrees and the lordotic upper neck as -42 degrees. Or -42 / +15. If you are math averse, relax. That's as bad as it gets.

***  Anterior Head Carriage -- Finally, the lateral film readily yields one more important piece of information: an accurate analysis of the weight bearing status of the spine. We do this by simply extending a line straight upward from the posterior-superior corner of T1. This "vertical axis" line should intersect C1 at the junction of the posterior arch and the lateral mass.

Forward head posture, a common finding, is recorded in millimeters as a positive number. If the head is carried posterior (less common) we would likewise record the displacement as a negative number. Fig. 3 shows a patient with a very slight forward head posture (approx +5mm). Although there are other blatant problems with this neck, this slight amount of forward head posture is not a major biomechanical problem.

The next time you hear some academic "poo poo" the value of radiographs, just remember that here with just one film and a couple of quick measurements we have an accurate method of assessing the patient's sagittal spinal curves and an objective benchmark against which we can gauge the efficacy of any treatment efforts directed at restoring normal posture. Best of all, the accuracy of this measurement is well established in the scientific literature and should stand up very well if you are ever questioned about your findings.

If you would like to learn more about simple methods of X-ray analysis, call 334-448-1210 and request our new workbook on marking the lateral spinal films. The manual is part of our continuing series entitled, "The Best Corrections of Your Career," and is available free of charge to interested doctors.

(A 1979 graduate of Life Chiropractic College, Dr. Mark Payne is the president of Matlin Mfg., a manufacturer and distributor of postural rehabilitation products since 1988. For more information regarding issues, products or methods discussed in this column, or to receive the free report, "Spinal Remodeling for the Frontal Plane Postures," call 334-448-1210. Visit www.matlinmfg.com  for a free product catalog.)