Standard Posture Analysis: As simple as XYZ
by Mark R. Payne D.C.
Lost of us were taught some rudimentary method of postural analysis in college. Unfortunately, it often consisted of little more than looking for a high/low shoulder or hip, or maybe a bit of head tilt in the frontal view and perhaps a glance at the lumbar lordosis in the lateral plane. Even worse, there has been little or no standardization of the language used to describe aberrations of posture. There exists a real need for an organized approach to postural analysis and a standard way for doctors to record their findings. Fortunately, there has been some good work in this area already published in the scientific literature. All that remains now is for the profession at large to begin incorporating existing methods whenever postural analysis is performed.
In 1974, orthopedic researchers Panjabi, White, and Brand1 authored a standardized method for describing three dimensional positioning and movement of the human body, using the centuries old, and widely accepted, Cartesian Coordinate System. (Rene Descartes circa 1637) Panjabi, et al., applied three mutually perpendicular axes to the human body, as seen in Fig. 1. Once this was done, it became possible to describe ALL movements of the human frame as either 1) translations along and/or 2) rotations around, one or more of the three axes. This method has since been popularized to some degree by Harrison2, Troyanovich3, and others with an interest in postural chiropractic methods. Unfortunately, many doctors seem to find the method too technical or burdensome. Hopefully, this article will make the simplicity and practicality of the method more apparent.
In the frontal view (Fig. 1), we see the X axis, extending out the left side of the patient and the Y axis extending vertically out the top of the patient’s head. In this view, the Z axis extends forward, out the front of the patient’s body and toward the reader.
In the lateral view (Fig. 2), the Z axis is now visible extending to the anterior. The Y axis, of course, is still seen extending vertically out the top of the body while the X axis (not visible here) extends to the patient’s left and away from the reader. Note that it simply isn’t possible to observe all three axes of movement in either view. Proper analysis requires observation of the patient from both front and side.
Take just a moment to make sure you are clear about the directions of each of the three axes. Once you have done so, it now becomes very simple to describe any motion or position of the body in terms of translation along one or more of the axes, and/or rotation around one or more of the axes. Fig. 3 shows forward head carriage, a very common posture, as an example.
Using Panjabi’s method, we can describe this as translation of the head along the Z axis. Because it is theoretically possible for movement to occur along or around an axis in either direction, we will need to record the direction of movement. Translations are recorded as "positive" when they occur in the direction of arrow and "negative" when in the opposite direction. Rotational movements (not shown here) are recorded as "positive" when clockwise around an axis and "negative" when counterclockwise.
Finally, we need a concise way to record our findings in the patient’s chart. There are actually four components which must be recorded. Here they are in no particular order.
1. In which direction has movement occurred?
2. Is the movement a translation along or a rotation around an axis?
3. Which body part is involved in the movement?
4. Which axis of motion is involved?
In his original article, Panjabi abbreviated translations and rotations as "T" and "R" respectively. In more recent years, Harrison described a way to incorporate all four items into a brief notation system. The method has now been described in numerous articles by both Harrison and Troyanovich and is probably as close as we have to a standardized method of notating human posture. Fig. 4 describes how this simple method would be used to record our patient’s forward head translation posture.
Truthfully, the really important thing is just that you analyze the posture in all possible directions and accurately describe your observations. How you choose to notate it isn’t nearly so important, as long as interested third parties can understand your records. Certainly, you could just write it all down in long hand…nothing whatsoever wrong with that. In this case, "the patient presents with abnormal head carriage consisting of pronounced positive translation of the head along the Z axis." Or you just abbreviate it with a standardized system. Here’s how it would actually look on your chart.
Understanding the Cartesian Coordinate System encourages doctors to analyze posture and motion in a more systematic fashion. In addition, it allows for more accurate communication between doctors and other interested parties. Obviously, the above example is just one simple posture. I have prepared a report which describes the method in more detail. Interested doctors may call 1-334-448-1210 to request a FREE copy of "Visual Postural Analysis."