UC Technique #3
This is the final installment in the vectored adjusting debate. This article is a reprint from the November/December issue of The Digest of Chiropractic Economics. As with previous articles written by Dr. Molthen, NUCCRA refused to publish the following in their Monograph. 
 
VECTORED ADJUSTING:
FURTHER COMMENTS
By D. A. Molthen, D.C.
14742 Plaza Drive, Tustin, CA 92780

In their November/December 1980 issue Chiropractic Economics published an article which I authored titled "Vectored Adjusting: A Critique." This paper was later reviewed by doctors Gregory and Seeman. Their paper titled "A Critique of a Critique of Vectored Adjusting" appeared both in the July/August 1981 Issue of Chiropractic Economics and the June 1981 issue of the NUCCRA Monograph.

The temptation is there, of course, to use the testy word again -- thus, this article would be titled "A Critique of a Critique of a Critique of Vectored Adjusting" - but, with a sense of kindness to all concerned, the temptation was resisted.

In my paper I made two basic and very simple points:

Point #1:
It is virtually impossible for the human body to deliver a rectilinear (straight line) force; therefore, it is an inefficient adjusting machine. To illustrate this I used the analogy of a person attempting to play pool by using a pisiform contact on the pool ball with the arms as the driving force.

Point #2:
When the head is placed on the headpiece preparatory to adjusting, a slight turning of the skull in either the rotation or the laterality plane, or both, will cause the position or attitude of the atlas to change significantly with reference to the vector, or line of drive, which has been calculated. (The bulk of my article, "Vectored Adjusting..." was devoted to this last point. For further elaboration of the rectilinear vs. Curvilinear issue see "The Physics of the Upper Cervical Adjustive thrust" [Chiropractic Economics July/August 1980 issue] ) (This will be posted on the web page shortly)

NUCCRA, in its article, chose to deal with point #1 the rectilinear vs. curvilinear issue first. The following is a direct quotation from their paper: "We know in sports that it is possible to put 'English' on a cue ball which produces a curvilinear path and that it is possible to throw a straight ball in bowling if the body angles are properly aligned when delivering the ball."

Response to NUCCRA
The hand adjustment is just that--a hand adjustment. Nothing external to the human body is used to deliver the thrust. In each of their two analogies NUCCRA found it necessary to add an instrument or machine to the human body - a bowling ball and a pool cue-in order to produce a rectilinear force. They state that "...it is possible to throw a straight ball in bowling if the body angles are properly aligned when delivering the ball.'' This analogy serves to illustrate my point perfectly. As long as the bowling ball is in contact with the human body, hung on the end of the arm, it is traveling in a curvilinear path. The ball inscribed an arc as it is swung forward. The pivotal center, or axis, of this arc is the ball and socket joint formed by the head of the humerus and the glenoid cavity of the scapula. The path of the ball only becomes rectilinear when it breaks contact with the human body -- when it is released down the alley. When it is released from the fingers, two outside forces then converge to rectify its path. The force of gravity pushes it down onto the hardwood surface of the alley, and the hardwood surface then pushes back against gravity. Together these two forces collaborate to straighten, or rectify, the curvilinearity which was imparted to the ball by the bowler's arm. As it follows through, the arm continues in its curvilinear path. In this analogy rectilinearity has been achieved only by the use of an instrument (the bowling ball) and two other factors -- gravity and the surface of the bowling alley.
In the other analogy which was used by NUCCRA, a pool cue (again an instrument or machine) is employed in order to accomplish rectilinear motion. The rectilinear force results in a curvilinear path taken by the cue ball. However, this analogy is not applicable to our discussion. There is no question that an instrument or machine can influence an object to take a curvilinear path (in the internal combustion engine the rectilinear motion of the pistons is converted to curvilinearity by the crankshaft). The point in this discussion Is whether the human body can, without employing an instrument or machine, produce a rectilinear force-a very different matter.
When NUCCRA discusses point number 2 -- the issue of headpiece placement, and whether a slight turning of the head on the headpiece in the rotation or laterality plane will result in a significant error -- they make statements and quote a number of referenced sources all dealing with the mechanics of motion in the cervical spine. None of this is Germane to the argument.

The point which is made in my article "Vectored Adjusting: A Critique" was very simple; i.e., when the head turns on the headpiece the atlas moves with it, therefore a slight turning of the head causes the attitude-or position of the atlas to change with respect to the calculated vector. This turning then results in an enormous error, and this error is inherent in all vectored adjusting procedures. The following is a direct quotation from my article: "The average human skull is about 22 inches in circumference. (The skull is obviously not round in shape. It would best be described as being elliptical, with the long axis being A-P. However, when it rotates it follows a roughly circular path.) As a result, each inch of circumference represents approximately 16 degrees.
360/22 = 16.3

Since each inch contains slightly more than 16 degrees, each 1/16 of an inch equals approximately one degree. A change in the position of the skull of 1/16 of an inch will cause a corresponding one degree change in the position of the atlas" (Fig. 1 & 2).

Figure 1. In this drawing line A-B represents the central skull line; C-D is a line constructed perpendicular to A-B. If the skull/atlas unit is to reconcile with the adjusting vector in such a way that line A-B is horizontal and line C-D is vertical.

Figure 2. The attitude of the atlas changes to the extent that line C-D changes. If the skull is placed so that C-D is a vertical line, then the attitude of the atlas reconciles with the calculated adjusting vector. However, if the skull is placed so that C-D is not a vertical line (represented by C'-D' in this drawing), then the attitude of the atlas is out of phase with the calculated vector.

Doctors Gregory and Seeman answer this by stating that: "Using Molthen's example of the average skull of 22", the radius of the skull would be about 3 1/2" and a 1/16" deviation of head placement would equal 1 degree of error. This example is only correct if the skull rotates around a radius of 3 1/2" or the center of mass. The skull actually rotates around a point where the skull rests on the headpiece. This increases the radius to approximately 7". One degree of deviation would then be equal to 1/8". This amount of error would be more apparent to the adjuster. The adjuster then would either reposition the skull or accommodate the small error in measuring from the transverse tip which will be discussed later in the paper."

The following is a quotation from J. W. Fielding: "In the first part of rotation, the skull and first cervical vertebra move as a unit on the immobile second cervical vertebra below. The pivot of this rotation is the odontoid process of the second cervical vertebra. This pivot is laterally central but is anteriorly eccentric" (Journal of Bone and Joint Surgery, Dec., 1957) (Fig. 3 & 4).

Figure 3. The dot in the figure above represents the point of rotation as described by J.W. Fielding.

Figure 4. Enlargement of axis from figure 3 showing point of rotation.

For the sake of argument, however, let's accommodate our reasoning to Gregory and Seeman's statement and assume that at times the head may turn on the headpiece with the center of rotation being "a point where the skull rests on the headpiece" (Fig. 5), and at times it may turn on the headpiece around the odontoid process as stated by Fielding (Fig. 6).
 

Figure 5. Depicts the skull pivoting "around a point where the skull rests on the headpiece" as described by doctors Gregory and Seeman.
 

Figure 6. Depicts the skull pivoting around the odontoid process as described by Fielding.

Allowing that the turning on the headpiece may take place either as depicted in Figure 5 or Figure 6, the adjuster would then have to be able to eye the skull on the headpiece and determine how far it had rotated and then perceive whether it had rotated around point P in Figure 5 or point P in Figure 6. This subtle perception represents a value of one degree (or a 100 percent error factor when adjusting an anterior or posterior rotation of one degree). An 1/8 inch pivot around a point of the headpiece as depicted in Figure 5 would introduce a one degree error; an 1/8 inch pivot around the odontoid as depicted in Figure 6 would introduce a two degree error. (A two degree error would cause an anterior atlas rotation of one degree to move to the position of either anterior three degrees or posterior one degree with respect to the calculated vector -- depending on which way the skull had turned on the headpiece.)

Please keep in mind that we have been discussing just one plane, the atlas rotation plane. The atlas laterality or height plane is just as sensitive to head placement error; it too is carried from the view box to the adjusting table. If the skull is placed on the headpiece so that the skull divider line (taken from the nasium view) is not horizontal, a whole other set of errors would be produced. These would compound on the head placement errors which might have occurred in the atlas rotation plane.

Doctors Gergory and Seeman sweep aside consideration of these enormous inherent errors by simply stating that their figures, which have been developed in their office, prove that their system is accurate.
 
REFERENCES
Seeman, D.C. & Gregory, R.R., "A Critique of a Critique of Vectored Adjusting," The Upper Cervical Monograph, Vol. 3, No. 1, June, 1981.
Molthen, D. A., "Vectored Adjusting: A Critique," Chiropractic Economics Nov./Dec. issue, 1980.
Molthen, D. A., "The Physics of the Upper Cervical Adjustive Thrust," Chiropractic Economics, July/Aug. issue, 1980.
Fielding, J. W., "Cineroentgenography of the Normal Cervical Spine," The Journal of Bone and Joint Surgery, Dec., 1957. (White & Panjabi quote several references of Fielding in their book, Clinical Biomechanics of the Spine.)
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