UC Technique #2
The following is a reprint of Dr. Gregory and Seeman's response to A Critique of Vectored Adjusting. This was published in the July/August 1981 Digest of Chiropractic Economics. We have put great effort into reproducing the drawings. They are not as good as we would have liked, for that we apologize. However, the original drawings were not masterpieces. A rebuttal to this article is found at UC technique #3.
 
A CRITIQUE OF A CRITIQUE
OF VECTORED ADJUSTING

by Ralph R. Gregory, D.C. and Daniel C. Seeman, Ph.D.
National Upper Cervical Chiropractic Association, Inc. 217 West Second Street Monroe, MI 48161
In the 1980 November-December issue of Chiropractic Economics D.A. Molthen suggests that vectored adjusting may be more theoretical than plausible when some of the premises of upper cervical adjusting are examined more closely. This paper is an attempt to answer Molthen's concerns. We would like to note Molthen's article has generated considerable attention among upper cervical adjusters about the assumptions under which they operate, and this is healthy. It is healthy for chiropractors to dialogue differences of opinion openly and rationally and for this we thank Dr. Molthen.

There are three major points in Molthen's article that we want to respond to: 1. rectilinear motion, 2. head placement and rotation and 3. head placement and laterality.

Rectilinear Motion
Molthen states that the ideal force required to reduce a subluxated atlas is rectilinear and may be applied either means of an adjusting gun or manual. Molthen feels that it is virtually impossible for the human body to deliver a rectilinear force. He uses the example of a person attempting to shoot pool using the pisiform contact and the arms instead of a pool cue. 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 bodies angles are properly aligned when delivering the ball.

Perhaps it is appropriate to review a few kinesiological principles concerning motion (Gowitzke & Milner, 1980). Human body exhibits two basic types of motion which is either translator (linear) or angular. Translatory motion, the moving of the body from one location to the other either moves in straight line or in a curved line. Angular motion occurs when a body rotates around a fixed axis (Groves & Camaione, 1975). These same principles can be used to explain the conversion of curvilinear motion into rectilinear motion in manual adjusting.

Manual adjusting need not be inefficient when the triceps pull is used as the principle energy delivery system. The adjustor's ability to convert angular motion to linear motion is dependent upon the adjuster's understanding the necessary steps preparatory to the triceps pull. If the adjuster has aligned the reduction pathway (horizontal resultant) with the notch-transverse resultant, delivery of the rectilinear force to the atlas will occur. If these two planes are not coplanar the energy generated by the triceps will be curvilinear. The effect of delivering acurvilinear force is to render an improper horizontal resultant, because the final vector of the resultant will either increase or decrease the height vector. (See Figure 1.)

Figure 1. The effect of delivering a curvilinear adjustment to the transverse process.
 

If the force is delivered properly, the transverse process of the atlas will transmit this energy to the articulating surfaces of the axis along a pathway determined by the shape and size of the cervical joint facets. If the force is applied improperly the atlas will resist moving or the atlas will be driven to an out of pattern subluxation.

Frequently it is necessary to deliver both a linear and angular motion in the adjustment at the same time. The combination of directing a linear force with an angular force (torque) is required when the axis spinous has misaligned different from the axis body and the atlas. Those energy systems which only use a linear force in the adjustment preclude an important element in the successful reduction of the subluxation to the vertical axis. It is impossible to return an axis spinous that has moved outside the plane of the atlas and axis. (See Figure2).
 

Figure 2. A rectilinear force with angular torque.
 

Another important advantage that a skilled manual adjuster has is that by directly contacting the atlas the adjuster receives immediate proprioceptive feedback as to whether the vertebra moved or whether the adjustment was complete. If the vertebrae are moving in the desired direction, the adjuster should feel confident that a proper vector is being given. If the vertebrae are not moving the adjuster should then examine all the processes in the adjustment that might be in error and correct the possible errors. With an energy system that does not have this immediate feedback, the probability of compounding an error would seem likely.

Head Position and Rotation
It does not follow that "a slight rotation of the head when placed on the headpiece in the amount of 1/16" or an 1/8" will cause anterior rotations to be driven more anterior and posterior rotations to be driven more posterior." This is true both for mathematical and anatomical reasons.

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 head piece. 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.

For a vertebrae to be subluxated the vertebra must be misaligned outside its normal range of motion. Anatomically, if the skull is placed incorrectly on the headpiece it is not valid to assume that an artificial increment of rotation will be added to the existing rotation. The mere incorrect placement of the skull on the headpiece will not extend the atlanto-occipital joint outside the normal range of motion. According to White and Panjabi (1978) the normal range of motion for the atlanto-occipital joint is 0 degrees which indicates that the joint rotates as a unit. If this is true then any accommodation to rotation must be realized further down the cervical unit. This is verified by White and Panjabi (1978) and Caillet (1974) who report the normal range of motion is +/- 47 degrees. It would seem then that to increase rotation, by placing the skull on the headpiece, the head would have to be placed in a manner well outside the range of motion that Molthen suggests.

To verify that rotatory misalignment could not occur outside the normal range of motion, a series of measurements were taken on a number of patients using the vertex x-ray procedure (Dickholtz, 1980). In the vertex position, the patient's head was turned in increments from the zero plane either left or right, 1/4", 1/2" or 1". The results indicated that, in fact, the turning of the head through these three increments did not increase the rotation. Beyond 1" distortion in the x-ray film prevented accurate analysis of the film. With a 1" error an experienced adjuster should be able to detect error in the placement of the skull and take appropriate measures to correct the error.

Even without repositioning the head, slight head rotations can be accounted for when the adjuster measures for the rotation and height vector at the beginning of the adjustment. For example, if the rotation vector is 4 degrees anterior and the height vector is 4 degrees, and the transverse tip is slightly anterior because of improper head placement, the adjuster will measure anterior from the tip in the same plane as the slightly tipped transverse process. The height vector will be measured in the same plane 90 degrees distal to the rotation line. The horizontal resultant would then be directed back to the transverse tip in the same plane. (See Figure 3).

Figure 3. Measuring from the transverse tip that is slightly anterior.
 

A further clue to the adjuster that an error may exist with head placement is if the transverse tip from which the vectors were measured did not turn with the slightly rotated skull. If this is true, it is possible that a misalignment has occurred between atlas and the condyles.

Head Position and Laterality
Molthen also indicates that an error can occur with laterality if the head is improperly placed on the headpiece.
Again we feel this assumption is invalid. White and Panjabi (1978) report that the atlanto-occipital joint will tolerate 8 degrees of normal motion and the atlanto-axial joint will tolerate 0 degrees. The bulk of the lateral range of motion is exhibited in the lower cervical units. The degree of tolerance in the cervical unit is well beyond the limits suggested by Molthen.

To verify that laterality does not occur outside of the normal range of motion, a series of measurements were taken on a number of patients using the nasium x-ray procedure. The patient's head was tilted either right or left in increments of 1/4", 1/2", and 1" from the vertical plane. The results showed that the relationship between the condyles and the atlas did not change when the head was tilted either right or left up to 1". An analysis of the x-rays did show that two elements of the height vector changed: the lower angle and the atlas plane line, therefore care must be taken in head placement with these two elements in mind. The original height vector can be affected by improper head placement. Improper head placement also can change the position of the axis spinous and this would effect the torguing procedure in the adjustment. This of course, would not be a problem for adjusters who do not torque the adjustment vector.

Conclusion
It is apparent that we do not agree with Molthen's conclusions that "...no matter how much calculation is involved in determining the ultimate vector, it is physically impossible to control the placement of the head on the headpiece." This conclusion would render any type of upper cervical adjusting ineffective and an exercise in false assumptions.

Our experience has not followed Molthen's prediction. About 95% of our patients who are adjusted (using the tricep pull) show almost a 100% reduction of rotation, laterality and torque, and a return to the vertical axis (Gregory, 1981). It is also true that every head that is placed on the headpiece is not as precisely placed as we would like, yet the reductions do occur. The results would support our findings that the cervical unit is tolerant to moderate errors in head placement with regard to rotation at laterality. The adjuster should position the head so that the sagittal plane of the skull squares with the headpiece support and the Frankfort Line of the skull (line from the superior aspect of the auditory meatus and the inferior orbit of the eye). A further step in reducing her placement error is to use a headpiece which locks the head with three contacts. This type of headpiece is current being used by NUCCA adjusters.

The triceps energy system requires considerable skill in delivering a rectilinear vector. If the adjuster has not acquired this precise motor skill the possibility of a curvilinear vector will be rendered is valid. But the skill can be acquired and probably has more to do with error in the reduction of subluxation than head placement. Errors that can occur because of improper head placement are changes in atlas plane line, lower angle and the axis spinous.

REFERENCES
Caillet, R., Neck and Arm Pain, Seventh Printing, F.A. Davis Co., 1974.
Dickholtz, M., Patient Alignment for Upper Cervical X-Rays, Upper Cervical Monograph, Vol. 2, No. 8, Jan. 1980
Gregory, R.R., Biomechanics of the Upper Spine, The Upper Cervical Monograph, Vol. 2, No. 10, Jan. 1981.
Gowitzke, B.A. & Milner, M., Understanding the Scientific Bases of Human Motion, Wilkins & Wilkins Co., Baltimore, 1980.
Groves & Camione, Concepts in Kinesiology, W.B. Saunders Co., Philadephia, 1975.
Molthen, D.A., Vectored Adjusting A Critique, Chiropractic Economic November-December Issue, 1980.
White, A.A., Panjabi, M.M., Clinic Biomechanics of the Spine, J.B. Lippincott Co.: Philadelphia, 1978.