1. Tilt, either superior or inferior, is assesed on the lateral view. The reference point is the anterior tubercle. The atlas normally “sits” on a superior tilt (anterior tubercle positioned superior to the posterior tubercle). Tilt is represented in the second letter of the atlas listing (i.e. ASR). So in an ASR, the atlas anterior tubercle is more superior than it normally is. There are a number of different criteria on the lateral view for determining whether tilt is present.
2. Laterality, either left or right, is assessed on the AP open mouth and base posterior radiographs. There are also a number of different checks for laterality on the AP open mouth view, as well as a check on the base posterior view. Among the various checks on the AP open mouth view is the comparison of the distances from a vertical median line out to the lateral masses (the greater distance = the side of laterality). The vertical median line represents the vertical center of the foramen magnum, halfway between the medial inferior tips of the occipital condyles. Another check for atlas laterality on the AP open mouth view is noting if a point wedge is present. A point wedge is formed by the covergence of an atlas line and an occiput line. The occiput line is constructed simply by connecting two dots, one placed on each of the medial inferior tips of the occiput condyles. The atlas usually rides up on the condyle on the side of laterality, forming the point wedge on the side of laterality. Another check for atlas laterality consists of noting any overlap or under-lap when comparison is made to the corresponding superior articulating surface of atlas to the inferior articulating surface of the occipital condyle. The side of the overlap would represent the side of the lateral side-slip. Laterality is noted in the third letter of the atlas listing (i.e., ASR).
3. Rotation: anterior or posterior, is assessed on the base posterior radiograph, as well as on the AP open mouth radiograph. On the base posterior, an atlas line (constructed via the dotted centers of the atlas transverse foramina) is compared to a Duff’s “V” line (12). The “V” line represents the spatial orientation of the occipital condyles, and is constructed by placing dots on structures (ossification centers) on the condyles that happen to be V-shaped. One of the advantages for the Duff analysis is that it helps to prevent erroneous analysis due to occipital condyle malformations. Rotation is listed on the side of atlas laterality. One of the criteria on the AP open mouth view for atlas rotation is determining whether the lateral masses are the same size. Assuming there is no head rotation during the x-ray, and assuming there is no congenitally large lateral mass present, the rule is that the side of the smaller lateral mass would represent the side where the atlas has rotated posterior (= the side closer to the film). Consequently, an ASRP atlas would be one that is misaligned on a superior tilt, and is side-slipped to the right, and is also rotated posteriorly on the side of laterality.

In the upper cervical specific technique, there are 12 basic listings for the atlas:

ASL	ASLA	ASLP
ASR	ASRA	ASRP
AIL	AILA	AILP
AIR	AIRA	AIRP

1. Laterality (also referred to as rotation) of the body and/or spinous process, either left or right, is assessed on the AP open mouth radiograph. The vertical median line remains the reference point. Axis is analyzed according to pivot points. If for example the dens is in the center of the neural canal (derived from vertical median line) but the spinous process is lateral to the right of this line, then the x-ray listing would be body pivot, spinous right (BPSR). As another example, if C2 as a whole (dens and spinous) is misaligned to the right of the VML, then the listing would be entire segment right (ESR).
2. Anteriority/posteriority is also taken into consideration for the adjustment line-of-drive by assessing whether or not the axis is in juxtaposition relative to C3, as seen on the lateral neutral radiograph. For example, if C2’s posterior body line (George’s line) on the lateral radiograph is in juxtaposition or anterior to C3’s posterior body line, then a P-A line-of-drive would be contraindicated in the adjustic thrust.

ESL	ESR
BPSL	BPSR
SPBL	SPBR
ESL-SL	ESR-SR
ESL-BL	ESR-BR
CPBL	CPBR
PLI	PRI

References

1. Anonymous. A new era for PSC. International Review of Chiropractic. February 1956, p. 4.
2. Palmer BJ. Subluxation Specific, Adjustment Specific. The Palmer School of Chiropractic. Davenport, IA. 1934.
3. Remier PA. Modern X-ray Practice and Spinography. The Palmer School of Chiropractic. Davenport, IA, 1957, pp. 312-378.
4. Remier PA. System of spinographic analysis. In: Palmer BJ. Answers. W.B. Conkey Co. Hammond, Indiana. 1952, pp. 1-25.
5. Remier PA. Spinographic analysis. International Review of Chiropractic (ICA). February 1955, pp. 7-8, 32.
6. Remier PA. Analysing the axis and atlas. International Review of Chiropractic (ICA). August 1955, pp. 6-10, 29.
7. Bolton PS, Bolton SP. Acute cervical torticollis and Palmer upper cervical specific technique: a report of three cases. Chiropractic Journal of Australia 1996;26(3):89-93. and
8. Amalu W, Tiscareno LH. HIO: old problems, new solutions. Today's Chiropractic 1997;26(6):24-34).
9. Hyman C. The Upper Cervical Technique. Enchantment Publishing. 1996.
10. Strazewski J. The Essentials of Toggle Recoil. 1998.
11. Remier PA. Modern X-ray Practice and Spinography. The Palmer School of Chiropractic. Davenport, IA, 1957, p. 378.
12. Forest TJ. Upper cervical chiropractic in a full spine practice. Digest of Chiropractic Economics. January/February 1980, p. 89.
13. Remier PA. System of spinographic analysis. In: Palmer BJ. Answers. W.B. Conkey Co. Hammond, Indiana. 1952, p. 5.
14. Panjabi MM et al. Articular facets of the human spine. Spine 1993;18(10):1298-1310.

William G. Blair studied thousands of radiographs and osseous specimens to give rise to his biomechanical model for the upper cervical spine. He quantified the prevalence of structural asymmetries and proposed models based on the assumption that misalignments take place at the articulations between bones. Anatomical relationships determine the possible misalignments of atlas relative to occiput and axis relative to third cervical. The specialized Blair radiographs, including proctractoviews and lateral stereo views, allow for direct visualization of misalignments.

This presentation will describe the Blair models for atlas and axis misalignment, using diagrams, computer animations and radiographs to demonstrate them. The radiographic positioning for Blair protractoviews and lateral stereo films will be outlined, and listings for atlas and axis will be illustrated.

PURPOSE: Due to the anatomical shape and supporting soft tissue, the upper cervical spine is unique to all other areas of the spinal column. Other authors have adequately discussed normal biomechanics of the occipito-atlantal-axial region. The purpose of this presentation is to define biomechanics of the upper cervical spine in subluxation. These biomechanical definitions will be supported by known factors such as anatomical structure and function of supporting soft tissue along with plain view and stereo X-ray analysis.

BACKGROUND AND OBJECTIVES: The anatomical structure of the atlas, axis and occiput are known factors although there are unique differences from any one person to the next. The muscles and ligaments supporting the upper cervical spine are known and their functions have been described. These universally known factors are put together with knowledge gained through Blair Protracto views and lateral stereo analysis to arrive at a new way of looking at the biomechanics of the upper cervical region in subluxation.

CONCLUSION: The fundamental basis for upper cervical chiropractic adjusting techniques is to correct the upper cervical subluxation. Varied upper cervical techniques attempt this through methods specific to their own procedure. Facilitating the upper cervical spine into juxtaposition, thus removing neurological impediment, through an adjusting procedure is the goal. A common ground for all techniques is in the above defined fundamental basis and goal. Understanding the biomechanics of the upper cervical spine in subluxation is a foundation upon which to build further insight into what we do, why we do it, ultimately bringing us to greater application, regardless of specific upper cervical chiropractic technique utilized.

Our early work involved a large group of faculty and graduate students. That work was presented at the first government sponsored conference on spinal manipulative therapies. We had an impressive enough program to be able to attract grant money from the NIH, the first federal grant that went to support research into chiropractic.

There were two main areas in which I was involved, the development of a computerized kinematic model of the spine, and the three-dimensional distortion-free x-ray analysis. A string of graduate students worked on these projects, getting their PhD's from me. After the NIH money ran out, we continued to receive funding from the ICA and particularly Life College in the most recent decade. In this talk, I will provide my perspective on how chiropractic biomechanics research should best proceed in the coming decade.

Upper Cervical Subluxation Biomechanics

1. Architecture
2. "Normal" alignment and motion
3. How the atlas misaligns and creates various subluxation patterns

1. How to locate structures and measure subluxation
2. Research behind the validity of Grostic Procedure X-ray analysis

1. Standard pre cervical x-rays
   • sagittal
   • frontal
   • horizontal
   • a-p open mouth
2. Standard post cervical x-rays
   • frontal
   • horizontal
   • sagittal(if positive on the pre)

1. Review of anatomy. Upper Cervical anatomy as it relates to projectional geometry.
2. Central Skull Line, Atlas Plane Line, Angular Rotation, reference Horizontal and Vertical Planes.
3. Condylar and Axial arc segments
4. Description of the four basic types. Reduction pathways for each type.
5. Headpiece placement for each basic type.

If we can agree that a primary component of the chiropractic vertebral subluxation is hypomobility in a spinal joint complex, there is an immense body of research to support the ensuing degenerative process and the logical conclusion of restoring movement. Immobilization degeneration is supported by over 40 years of research. The literature notes a joint that has lost a degree of its normal movement will begin degenerating at a rate measurable within one week of onset. Notable is that this degenerative process is histologically distinct from osteoarthritis and will continue, often painlessly, until significant degeneration has occurred or sudden a significant biomechanical stress creates an acute injury.

ID alone is substantial enough to argue for the chiropractic care of a patient without back pain, but it is also important to understand why a vertebral subluxation may be present and the patient may remain asymptomatic. Nociceptors are peripheral receptors that depolarize with noxious stimuli. The impulse is carried into the spinal cord and ascends through the lateral spinothalamic tract to the thalamus. Once the signal reaches the thalamus the impulse is sent to three major cortical areas involved in the perception of pain: the postcentral gyrus, the anterior cingulated, and the insula. It is well understood that pain is perceived in the cortex. Three factors influence the perception of pain: 1) the intensity of the stimulus; 2) the duration of the stimulus; and 3) descending inhibition. It is also understood that most nociception never reaches the cortex allowing tissue damage to occur without symptoms. The spinothalamic tract sends impulses into the hypothalamus and reticular formation (spinoreticular tract) in the brain stem which accounts for more systemic autonomic changes secondary to nociceptor activity which, again, may occur without the perception of pain. This is the same neural mechanism that allows serious disease processes to progress subclinically. Additionally, nociceptors synapse on excitatory interneurons in the dorsal horn, which fire directly into the intermediolateral cell column resulting in increased firing in postganglionic sympathetic efferents. This is the connection between the musculoskeletal and non-musculoskeletal systems.

1. Lantz, C. Immobilization degeneration and the fixation hypothesis of chiropractic subluxation. Chiro Research J, 1988. 1(1): 21-45.
2. Krassioukov AV, Weaver LC. Anatomy of the Autonomic Nervous System. Phys Med Rehab-State of the Art Reviews; 1996; 10(1):1-14.
3. Ghelarducci B, Sebastiani L. Contribution of the cerebellar vermis to cardiovascular control. J Autonomic Nervous System; 1996; 56:149-156.
4. Sato A. The reflex effects of spinal somatic nerve stimulation on visceral function. J Musc Physiol Ther; Jan 1992; v15 no1.
5. DeBoer, et al. Acute effects of spinal manipulation on gastrointestinal myoelectric activity in conscious rabbits. Manual Med; 1988; v3; pp85-94.
6. Nansel D, Szlazak M. Somatic dysfunction and the phenomenon of visceral disease simulation: a probable explanation for the apparent effectiveness of somatic therapy in patients presumed to be suffering from true visceral disease. J Manip Physiol Ther; 1995; 18(6):379-397.
7. Coote JH. Somatic sources of afferent input as factors in aberrant autonomic, sensory and motor function. In: Korr IM, ed. The Neurobiologic Mechanisms in Manipulative Therapy. New York, Plenum Press, 1978:91-127.
8. Bienenstock, et al. The role of mast cells in inflammatory processes. Int Arch Allergy and Applied Immunol 1987;82:238-243.
9. Grieve G. Common Vertebral Joint Problems, 2d ed. 1988, New York, Churchill Livingstone; pp151-152.
10. Price D. Physchological and Neural Mechanisms of Pain 1988; New York, Raven Press; p100.
11. Price D. Psychological and Neural Mechanisms of Pain 1988.New York, Raven Press; p86.
12. Slosberg M. Effects of altered afferent articular input on sensation, proprioception, muscle tone and sympathetic reflex response. J Musc Physiol Ther 1988; 11:400-408.
13. Cabell J. Sympathetically maintained pain, p 141-149 In: Willis W, ed. Hyperalgesia and Allodynia. New York, Raven Press; 1992.
14. Light A. The Initial Processing of Pain and Its Descending Control: Spinal and Trigeminal Systems. New York, Karger; 1992; p28.
15. Dubner R. Neuronal plasticity in the spinal and medullary dorsal horns: A possible role in central pain mechanisms, In: Pain and Central Nervous System Disease: The Central Pain Syndromes; New York, Raven Press; 1991;pp143-155.
16. Bennett G. Neuropathic Pain, p201-224, In: Wall and Melzack, Textbook of Pain, 3rd ed., New York, Churchill Livingstone; 1994.
17. Wolf C. Physiological, inflammatory and neuropathic pain, Adv Tech Stand Neurosurg; 1987;15:39-62.
18. Bonica J. Clinical Importance, pp17-43 In: Willis, W. Hyperalgesia and Allodynia. New York, Raven Press; 1992.
19. Budgell B, et al. Spinovisceral reflexes evoked by noxious and innocuous stimulation of the lumbar spine. J Neuromusculoskel Syst 1995; 3:122-131.
20. Patterson M. The spinal cord: participant in disorder. J Spinal Manip 1993;9(3):2-11.
21. Sato A, Sato Y, Schmidt RF. The Impact of Somatosensory Input on Autonomic Functions. Reviews of Physiology, Biochemistry and Pharmacology 1997; vol 130; Springer-Verlag, Berlin and New York, as reviewed in Chapman-Smith D. The Chiropractic Report. May 1997; v11 no3.

Likewise, each of the three techniques has its own particular x-ray views and analysis to determine the extent of misalignment in the different directions. The Blair technique and HIO use particular landmarks on the occipital condyles and Atlas articulations to assess alignment, while the Grostic Procedure uses landmarks on the skull edges and posterior arch/lateral mass intersection. It would be interesting to determine which of these methods provides the most accurate assessment of Atlanto-occipital relationship.

Methods

A computer model of the base of the occiput and the Atlas vertebra has been used to generate simulated x-ray views of just those two bones. The bones can be accurately positioned with respect to each other and simulated misalignments imposed with known displacements or rotations in 3 dimensions. Next, camera views were staged to represent the viewing positions for the HIO A/P open mouth, the Base Posterior view, the Nasium view and bilateral Blair Protractoviews. Finally, high quality images are rendered with semitransparent materials applied to the bones, producing a fair likeness of a radiograph.

For purposes of this study, printed copies of renderings of a mixture of misalignment patterns, from all 5 views, will be presented blindly to practitioners for analysis. The practitioners will be provided with pencils, rulers and protractors and asked to analyze the images with their preferred technique. Analyzers will not know what misalignments are shown on each image.

Data analysis will be carried out after the session and the results will be presented for discussion at a later session during the weekend. The main parameter will be the accuracy of each technique in determining the actual displacement shown on the images. If at least two assessors of each technique are present, then interexaminer reliability can be assessed as well.

1. Whether it supports a conceptual distinction between a functional and anatomical short leg
2. Etiology
3. Clinical significance: analytic/diagnostic findings, treatable entites, outcome measures
4. Patient position in assessing LLI: sittting, standing, supine, prone
5. Measuring technology: visual, instrumented, advanced imaging
6. How it addresses signs and symptoms thought related to leg length inequality.

The results of our interdisciplinary survey of LLI concepts and clinical implemation facillitate communication between practitioners from different professions, allowing more cross-fertilization of patient assessment and treatment parameters.

In another study, Cooperstein found that padded wedges or SOT pelvic blocks could be used for lumbopelvic mechanical analysis. [2] Unger noted that pelvic block placement could be shown to affect muscle strength. [3]

In the Lisi et al study [1] they determined a pain pressure threshold of patients in a neutral position, and then with a pair of padded wedges placed under the subject in each of four different positions: (Right Short Leg - Category One) left iliac crest, right greater trochanter; (Left short Leg - Category One) right iliac crest, left greater trochanter; (SB+) left and right iliac crests; and (SB-) left and right greater trochanters.

In this current study, radiographs were taken to determine whether pelvic distortions could be demonstrated on x-ray when pelvic blocks were placed under the patient in the prone position. One patient was placed prone in a neutral position and radiographs were taken in a neutral position, and then with a pair of pelvic blocks placed under the subject in each of four different positions: (Right Short Leg - Category One) left iliac crest, right greater trochanter; (Left short Leg - Category One) right iliac crest, left greater trochanter; (SB+) left and right iliac crests; and (SB-) left and right greater trochanters. Findings indicated that pelvic block placement could create or affect distortions of the pelvis. Further studies are indicated correlating radiographic analysis, pain provocation, and muscle strength to determine if a clear pelvic block preference can be determined definitively.

1. Lisi AJ, Coopertein R, "A pilot study of provocation testing with pelvic wedges: Can prone blocking demonstrate a directional preference?" Proceedings of the ACC Conference IX, Journal of Chiropractic Education Spr 2002; 16(1): 30-1.
2. Coopertein R, "Padded Wedges for Lumbopelvic Mechanical Analysis" Journal of the American Chiropractic Association, Oct 2000: 24-6.
3. Unger JF, Jr, The Effects of a Pelvic Blocking Procedure upon Muscle Strength: a Pilot Study Chiropractic Technique Nov 1998; 10(4): 50-5.

On the other hand, upper cervical techniques have an element of progressiveness as well. Most are continually being modified and improved to reflect new discoveries and methods. There exists published research in the form of case and case series studies, reliability studies and some cohort studies that support the claims of upper cervical chiropractic's effectiveness. The fact that leaders of technique organizations are willing to come together at conferences such as this in an air of openness and curiosity to discuss their similarities and differences also points to their progressive nature.

This one-hour panel discussion will provide a forum for technique representatives to give their views on these questions: Is your technique open to progress and change? If not, why is it important to adhere to old notions? How can we best overcome the negative perception that the public seems to hold toward us?

It is expected that representatives from at least five techniques will be available for the panel. There will be time for questions and comments from the audience as well.