A Neurophysiologic approach to spine and posture

The Pettibon System: A Neurophysiologic
Approach to Spine and Posture Correction

Mark Morningstar, D.C.
Burl R. Pettibon, D.C.
Carol L. Remz, Ph.D.
The structure of the spine, and ultimately posture, are considered by some to be a
requisite to maintaining health and normal function.3 Abnormal posture can cause
alterations in some of our basic physiological processes, such as headaches, blood
pressure, emotions, lung capacity, and hormonal production.4 Yet maintaining an erect
sitting position is difficult because postural control is mainly reflexive and involuntary.
Therefore, although we can temporarily change our posture through voluntary muscular
action, inevitably our conscious control bows to our reflexive, neurological control of
posture. From this, we can logically presume that the best way to make a lasting change
to spinal structure, or posture, is to correct posture from a reflexive, involuntary
standpoint. This logic forms the foundation for a treatment protocol referred to as The
Pettibon System developed by Pettibon37,38 to correct the spine and posture through
gradual adaptation of the spinal and postural reflexes.
A fundamental difference in the overall medical education of a chiropractor is the
amount of importance placed upon restoring and maintaining the integrity of the nervous
system. Given that the nervous system controls and regulates all other body functions,12 it
is logical that it also controls spinal and postural position and movement. However,
chiropractic treatment has typically shown little success in making gross structural and
postural changes.16,29 The procedures used in The Pettibon System, in contrast to
conventional chiropractic treatment, heavily emphasize the importance of postural and
paravertebral soft tissues in making structural changes. Although most chiropractors also
incorporate physical exercises into their treatment regimens,22,23 these exercises usually
attempt to change postural through voluntary neuromotor pathways. They include mirrorimage
type exercises, where postural isotonic exercises are performed in mirror-image
fashion to the patient’s presenting posture. However, since we know that posture is under
reflexive control, it is much more difficult to change posture through voluntary means.
From a biomechanical perspective, chiropractors typically view the spine as a
series of 24 movable segments. As a result, chiropractic manipulation is typically
delivered on a segmental basis, using a variety of exams performed to locate a singular
misaligned vertebra. In contrast, The Pettibon System treats the skull as a vertebra.
Further, it is regarded as the single most important vertebra, given that most of the
reflexes that govern postural control are housed within the skull, such as the visual
system and vestibular apparatus. With these neurophysiologic capabilities, the skull is the
only vertebra that can orient itself to time and space. Many of our postural reflexes, such
as the vestibulocollic reflex,47 cervicocollic reflex,35 pelvo-ocular reflex,31 vestibuloocular
reflex,39 cervico-ocular reflex, and cervical somatosensory input,41,30,49 all serve to
maintain a level head position in relation to the visual field or to the neck and trunk.
Therefore, correcting the static structure of the cervical spine becomes a primary goal in
correcting overall spinal and postural position and movement, as the rest of the spine
orients itself in a top-down fashion.34 Once this is achieved, the rest of the spine is
corrected according to the normalized reference point.

Normal vs. Abnormal

Like any physiologic process, the spine and posture must also possess a normal
measurement. Just as blood pressure, serum cholesterol, body temperature, and blood pH
have normal values, so too must static spinal structure. The spine serves two distinct
functions: 1) provide protection for the spinal cord, and 2) provide structural support for
the bony frame. In providing this structural support, one common denominator exists for
all upright bipedal mammals: gravity. Given that gravity is a constant on Earth, a
corollary to the second spine function is that it also serves to adapt to gravity, while
allowing for a balance between support and flexibility. Various authors have attempted to
identify a normal spinal model.5,9,10,11 Most recently, Harrison et al.5,17,20,26 and
Troyanovich et al.44 outlined their definition of a normal sagittal spine by using elliptical
shell modeling. They conclude that the normal cervical curve should be a 42.5º arc of a
circle from C2-C7, the thoracic kyphosis should be a 44.2º ellipse when measured from
T1-T12, and the lumbar spine should be a 39.7º ellipse from L1-L5. According to
Kapandji27, each of these three areas should measure 45º arcs of a circle. The inherent
problem with an ellipse is the fact that an ellipse contains a stress point. The arc of a
circle, on the other hand, is radially loaded, meaning that an arc does not contain stress
points. When modeling the lumbar spine as an arc instead, as Kapandji27 does, each of the
lumbar segments bears the weight of the trunk uniformly. Therefore, it seems logical to
use the Kapandji spinal model as a clinical goal compared to sagittal ellipses. The spinal
model proposed by Pettibon,38 adapted from the parameters identified by Kapandji,27 is
pictured in Figure 1.
In discussing the concept of a normal spine, it is also important to address the idea
of clinical symptoms in spine correction. Although clinical trials have not been
conducted, theoretical models have attempted to demonstrate the inevitable result of
chronic abnormal spinal loading. For example, a forward head posture can reverse the
stresses placed upon the cervical spine. This causes degenerative changes at the anterior
portion of the mid and lower cervical spine due to increased compressive force at these
areas.19,21 It also creates traction stress along the posterior longitudinal ligament, thereby
promoting traction spur development. This concept is supported in a recent study by
Wiegand et al.,45 where abnormal changes in cervical spine configuration correctly
predicted cervical pathology 79% of the time. A significant relationship has also been
shown between cervical spine pathology and symptoms. Ironically, although cervical
pathology may be present with abnormal cervical spine structure, the relationship
between an altered cervical spinal structure and clinical symptoms is tenuous at best.36
However, it could be postulated, as in the case of scoliosis progression,48 that because the
cervical spine pathology may develop slowly over time, the body continuously adapts to
the abnormal position and advancing pathology. Therefore, symptoms do not develop
until a critical point has been reached, such as neuroforaminal stenosis or spinal canal
stenosis, eg. cauda equina syndrome.
The ultimate purpose of identifying a normal spine and posture is simply to
provide a reference point from which a clinical goal can be developed. Spinal correction
as a clinical goal and outcome is becoming more important and necessary in a society
where musculoskeletal complaints total nearly $50 billion in health care spending
annually.6 With the growing interest occurring in spinal correction, consensus on a
normal sagittal spine is desirable so that randomized trials and outcome assessments in
the clinical setting can be designed and tested.

Pettibon Manipulative Procedures

The Pettibon System uses a collection of manipulative techniques, performed both
by hand or adjustive mechanical instruments, and rehabilitative exercises not known to
the typical physiotherapeutic arsenal.39 The manipulative and rehabilitative procedures
are applied on an individual basis, so that every treatment plan can be designed according
to each patient’s needs. A brief look into the biomedical literature reveals that using a
combination of manipulation and rehabilitative exercises seems to outperform either
modality alone in achieving various clinical outcomes.2,13,24 Classically, the goal of
chiropractic manipulation is to correct misalignments within the spinal column. However,
the literature available to support this idea is limited at best. In The Pettibon System, by
contrast, spinal manipulation is performed in order to provide a temporary increase in
joint mobility so that the rehabilitative exercises can take advantage of this increased
range of motion. Central to this system is the idea that the manipulation is not the
corrective procedure; rather, the rehabilitative exercise becomes the corrective procedure.
The limited corrective ability of spinal manipulation stems from the neurophysiologic
adaptations to sudden applied mechanical forces. According to Guyton,14 when the spine
is subjected to sudden mechanical forces, the paravertebral soft tissue is stretched,
eliciting intrinsic dynamic and static stretch reflexes in the paraspinal muscles. These
reflexes cause a reflex contraction of the stretched muscle until the muscle has restored
its initial resting length. Therefore, spinal manipulation performed alone does not address
or counteract these reflex properties of the spine that are designed to protect it from
potentially injurious external mechanical forces.
Rather than addressing the spine as a series of individual segments, Pettibon37,38
addresses the spine according to the muscular attachments of the postural muscles.
Through this the spine is conceptualized as a functional entity made of six specific units,
divided by these muscular attachments. Although the individual vertebrae have
independent motion, they do not move independently within a functional confine.
Therefore, the specific goal of manipulative treatment in The Pettibon System is to
mobilize a region of vertebral segments described by its common muscle attachments.
How muscle attachments relate to Pettibon’s model of six functional units can be found
in Tables 1, 2 and 3.
The manipulations performed by hand also differ from conventional chiropractic
methods. Typically, compressive-type manipulative forces are administered in
conventional chiropractic. These forces are vectored perpendicular to the predominantly
vertical orientation of the paravertebral soft tissue, especially in the cervical spine.
Therefore, these soft tissues cannot adapt to this direction of force efficiently, and may
sustain injury from this type of manipulation. In contrast, The Pettibon System uses
distraction and accumulative type manipulative procedures. The forces applied in the
distraction procedures are vectored more cranially, thereby allowing the vertically
oriented soft tissue to better adapt to the forces with less chance of injury. The
accumulative force procedures represent the positional traction procedures.

Pettibon Rehabilitative Procedures

The heart and soul of Pettibon rehabilitative procedures is the patented (US Patent
#740087.403C1) Pettibon Weighting System™ (Fig.2). Its goal is to realign the centers of
mass of the head, trunk, and pelvis. It incorporates the use of head, shoulder, and hip
weights placed at specific areas with varying amounts of weight, depending upon the
patient’s needs. Since we know that the spine attempts to distribute body weight evenly
around the vertical axis of gravity, placing asymmetrical weights on the external body
surface causes the postural reflexes and spine to adapt to the change in weight
distribution, re-orienting this added weight around the vertical axis. In a study by
Saunders et al.,40 with 131 patients, initial neutral lateral cervical radiographs were
compared to lateral cervical radiographs with patients wearing 3 lb or 5 lb. frontal
headweights. On average, the cervical lordosis improved 34%, while the amount of
forward head posture was reduced by 14 mm in patients wearing 5 lbs. Those wearing 3
lbs. experienced a 31% improvement in cervical lordosis and 18mm reduction in forward
head posture. In a smaller study by Morningstar et al.,32 15 patients underwent a series of
three manipulative procedures, and were then fitted for a 4-lb frontal headweight.
Radiographic measures of cervical lordosis improved 9.9° and forward head posture
reduced 1.25 inches. While these studies have shown that external body weighting does
make spinal changes, their position is key to successful treatment.
Cailliet3 described adding weight to the top of the head to treat cervical
hyperlordosis. However, a previous study17 has shown that in a non-patient population,
the average cervical lordosis is 34º, less than the normal value of 42.5º identified by
Harrison et al.15 and 45º outlined by Kapandji27 and Pettibon38. Therefore, adding weight
to the top of the head to reduce cervical lordosis seems contraindicated for a majority of
the population. However, the Pettibon headweight is positioned on the patient’s forehead
just above the eyes, causing a posterior skull translation versus a superior translation. The
postural reflexes attempting to rebalance the skull’s new center of mass mediate this
posterior translation. This results in a reduction of the forward head posture and increase
in the cervical lordosis.
The Pettibon Weighting System is also considered a type of “isometric demand
exercise” where the weighting system retrains and strengthens weaknesses in the postural
muscles. Because patients vary in height, weight, shape, muscular strength, and medical
history, the practitioner cannot assume that the same abnormal posture in two different
patients will associate with the exact same muscle weaknesses. The Pettibon Weighting
System can only be accurately utilized in conjunction with radiographic measurements
because the reliability of visualizing cervical and lumbar sagittal alignment is extremely
low8. Therefore, all patients must undergo radiographic analysis while wearing the
weighting system designed specifically for them. While concerns tend to arise regarding
radiation exposure to the patient, the dosage used is always minimal. In fact, Toppenberg
et al.43 concluded that it would take 2500 cervical spine x-rays or 1250 lumbar spine xrays
to approach the radiation safety limit of 5 Rad for a fetus.
Another important aspect of the rehabilitative procedures used in The Pettibon
System is that they are intended to address the biomechanical properties of soft tissue.
Hysteresis, for example, is the stored energy in viscoelastic tissues, like muscles,
ligaments, and discs, that is decreased when these tissues are subjected to progressive
loading and unloading cycles over time.47 Since muscles, ligaments, and discs are the
structural “glue” of the spinal column, it is logical then to address these tissues when
attempting to make changes in the static structure of the spine. In The Pettibon System,
exercises are performed to decrease hysteresis in these tissues using the Wobble Chair™
(Fig.3) and the Pettibon Repetitive Cervical Traction™ (Fig.4). From a clinical
standpoint, the exercises are performed at the beginning of a patient visit prior to
manipulative intervention. This reduces the overall resistance of the soft tissues to the
manipulative force, thus allowing that force to assume a more corrective role. Once the
manipulative techniques are administered, the patient then wears the Pettibon Weighting
System while the soft tissue is less resistant. Therefore, in The Pettibon System, all of the
components of the spine are corrected and rehabilitated as a unit, using rehabilitative
procedures designed to target each type of tissue specifically.
Finally, another type of isometric exercise is used to rehabilitate normal spine
alignment. Kendall et al.28 demonstrated this exercise for the treatment of scoliosis, and
Pettibon has slightly modified the performance of these exercises by creating the Linked
Exercise Trainer™ (Fig.5) on which they are performed. The ways in which these
exercises are performed change the functional origin and insertion of the muscle. For
example, the action of a rhomboid muscle is to retract the scapula, when the spinous
processes of the mid thoracic vertebrae serve as the origin. However, when the scapula is
alternatively stabilized as the origin, the rhomboid now pulls on the thoracic spinous
processes, thus acting as a vertebral rotator muscle. Hence, this muscle can be used to
correct evidence of coronal curvatures in that region. Areas of muscle imbalance can
therefore be isolated and strengthened using the Linked Exercise Trainer, thus reinforcing
corrective spinal changes.

Pettibon Radiographic Analysis

For radiographic analysis to be reliable, the quantification of patient progress on
pre- and post-treatment x-rays must not be nullified by inconsistent patient placement.
Harrison et al.18 showed that small deviations in patient placement can alter the amount of
cervical lordosis by 6.9º. A pilot study by Stitzel et al.42 found that inconsistent bite line
positioning on lateral cervical radiographs can result in up to a 20% measurement error.
Therefore, The Pettibon System uses the bite line as a reference point for lateral cervical
radiographs.
The Pettibon System also uses seated x-ray analysis rather than the standard
standing or recumbent positions. From a theoretical standpoint, seated x-rays may reduce
the amount of potential variability in patient positioning because the lower extremity
cannot effect the overall positioning. Furthermore, a seated position increases the stress
on the lumbar spine by 25%. Studies assessing the clinical validity for seated lumbar
films in detecting and grading spondylolistheses are currently being conducted. This
method of patient positioning produces a radiographic measurement error of only onehalf
to two-thirds of a degree in the cervical spine.25
Dynamic radiographic study is also performed in The Pettibon System. Cervical
and lumbar flexion and extension studies help the practitioner locate areas of spinal
instability due to ligamentous disruption. This analysis is performed according to the
American Medical Association’s Guide to the Evaluation of Permanent Impairment1
enabling the practitioner to document soft tissue injuries commonly overlooked in
recumbent and static x-rays.

Testing Prospective Patients for Treatment

Patients presenting to a conventional chiropractic facility will typically provide a
full case history, be subjected to some type of examination including palpatory,
neurological, and orthopedic testing, and undergo special studies such as plain film
radiography, magnetic resonance imaging (MRI), ultrasound, or computerized
tomography (CT). As long as there are no contraindications to manipulative treatment,
such as fracture, malignancy, marked instability, dislocation, or prior surgical
intervention, all patients are accepted for treatment, regardless of prognosis. The Pettibon
System, in contrast, allows for individualized patient testing to help determine, before
treatment begins, whether or not benefits are likely.
This patient testing is performed by weighting the patient’s head and shoulders
according to his/her preliminary x-ray findings. While wearing weights, the patient
performs a series of exercises on the Wobble Chair, followed by specific stretching
exercises. Afterwards, the initial x-rays are retaken, but this time while wearing the head
and shoulderweights. For example, if the patient’s cervical curve improves measurably,
and the forward head posture is reduced, then the patient can be expected to achieve a
significant outcome. However, if the cervical spine measurements worsen, then the
patient does not possess adequate muscle strength and/or endurance. At this time, if the
patient “fails” this test, he/she is not accepted as a candidate for treatment. However, the
patient may elect to participate in a strengthening program for a specified time period.
Once this program is completed, the patient is re-subjected to the testing protocol, and if
improvement is obtained, the patient is then accepted for treatment.

Phase of Care

The Pettibon System is divided up into three distinct phases: acute care,
rehabilitation and correction, and maintenance and supportive care. The goals of the acute
phase, which lasts from 14 to 21 days, include reducing or eliminating the patient’s
symptoms as quickly as possible, improving joint range of motion, and beginning the
restoration of normal sagittal spine alignment. Patients receive training on home care
equipment and procedures that they must do twice daily for strengthening postural
muscles and building endurance. At the end of acute care, patients are re-x-rayed to
assess their progress and qualification for rehabilitation and correction. This phase of care
requires three treatments per week, based upon the common knowledge that muscle
strength gains are achieved when a muscle is fully exercised three times per week.
Rehabilitation and correction continues until normal sagittal and coronal spine alignments
are achieved. This typically takes from 90 days to 24 months, depending upon the extent
of injuries, age of the patient, chronicity of the presenting complaint, and patient
compliance. Finally, maintenance and supportive care focuses upon making the structural
changes long lasting, through weekly workouts using the Linked Exercise Trainer and
training in lifestyle habits to support the patient’s health goals.
Preliminary Data
Although many of the individual parts of The Pettibon System have been peerreviewed,
any treatment method should also seek to provide outcome data on the overall
method to determine effectiveness, risks, side effects, and target populations. To date,
two studies outlining two specific subsets of patient populations have been conducted. In
a progressive study by West et al.46, 200 of a possible 1936 patients met the inclusion
criteria for this study. Of these, 177 participated in the trial intervention. Each patient was
evaluated using a visual analog scale (VAS), range of motion quantification, plain-film
radiography, and CT or MRI to rule out treatment contraindications. These patients were
treated by manipulation under anesthesia (MUA) using The Pettibon System
manipulative methods. Following the full MUA protocol, patients with cervical
complaints reported an average 62.2% improvement in VAS scores, while patients with
lumbar complaints reported a similar 60.1% improvement. A 68.6% decrease in patients
out of work and 64.1% return to unrestricted activity 6 months post-MUA was achieved.
Finally, there was a 58.4% reduction in prescription pain medication usage, and 24%
required no medication six months after the MUA.
A retrospective case series by Morningstar et al.33 followed the results of 22
idiopathic scoliosis patients selected consecutively at three different U.S. chiropractic
clinics. After a maximum of six weeks of treatment using The Pettibon System, an
average 17º reduction in Cobb angle measurements resulted. Although long-term follow
up was not recorded for this study, it does provide hope for an alternative to surgical
intervention.

Conclusion

The Pettibon System is a conservative treatment approach based upon basic
anatomical and physiological processes to correct the structure of the spine. There is little
doubt, according to the literature, that postural and spinal problems play a major role in
the United States, with a large portion of health care spending devoted to musculoskeletal
treatment annually.6 Therefore, it is appropriate to evaluate both the clinical effectiveness
and cost effectiveness of any treatment option. Future studies should also compare the
cost of treatment for The Pettibon System to other treatments using the same outcome
measures.
The advantages of The Pettibon System over other postural treatment methods
center on the utilization of neurophysiology to correct and maintain postural control.
Since posture is under a well-developed network of reflexes, any system recruiting these
postural reflexes to aid in spine and posture correction inevitably addresses more than
just the mechanical components. The effects of The Pettibon System on other
physiological systems are currently being explored. Randomized clinical outcome trials
are also being designed and conducted.

References

1. American Medical Association: Guides to the Evaluation of Permanent
Impairment: 4th ed, Chicago, IL, 1995
2. Bronfort G, Evans R, Nelson B, Aker PD, Goldsmith CH, Vernon H: A
randomized clinical trial of exercise and spinal manipulation for patients with
chronic neck pain. Spine 26:798-799, 2001
3. Cailliet R, Gross L: The Rejuvenation Strategy. Doubleday & Company, Inc.,
Garden City, NY, 1987
4. Cailliet R: Neck and Arm Pain: 2nd ed, FA Davis Company, Philadelphia, PA,
1981
5. Castro WH, Sautmann A, Schilgen M, Sautmann M: Noninvasive threedimensional
analysis of cervical spine motion in normal subjects in relation to age
and sex: An experimental examination. Spine 25:443-449, 2000
6. Cox ME, Asselin S, Gracovetsky SA, Richards MP, Newman NM, Karakusevic
V, Zhong L, Fogel JN: Relationship between functional evaluation measures and
self-assessment in nonacute low back pain. Spine 25:1817-1826, 2000
7. Dulhunty J: A simplified conceptual model of the human cervical spine for
evaluating force transmission in upright static posture. J Manipulative Physiol
Ther 25:306-317, 2002
8. Fedorak C, Ashworth N, Marshall J, Paull H: Reliability of the visual assessment
of cervical and lumbar lordosis: how good are we? Spine 28:1857-1859, 2003
9. Frobin W, Leivseth G, Biggemann M, Brinckmann P: Vertebral height, disc
height, posteroanterior displacement and dens-atlas gap in the cervical spine:
precision measurement protocol and normal data. Clin Biomech 17:423-431,
2002
10. Gardocki RJ, Watkins RG, Williams LA: Measurements of lumbopelvic lordosis
using the pelvic radius technique as it correlates with sagittal spinal balance and
sacral translation. Spine 2:421-429, 2002
11. Gracovetsky S, Newman N, Pawlowsky M, Lanzo V, Davey B, Robinson L: A
database for estimating normal spinal motion derived from noninvasive
measurements. Spine 20:1036-1046, 1995
12. Gray H: Gray’s Anatomy: The Classic Collector’s Edition. Gramercy Books,
New York, NY, 1977
13. Gross AR, Hoving JL, Haines TA, Goldsmith CH, Kay T, Aker P, Bronfort G: A
Cochrane review of manipulation and mobilization for mechanical neck disorders.
Spine 29:1541-1548, 2004
14. Guyton AC, Hall JE: Textbook of Medical Physiology: 9th ed. WB Saunders
Company, Philadelphia, PA, 1996
15. Harrison DD, Harrison DE, Janik TJ, Cailliet R, Ferraentelli JR, Haas JW, et al:
Results of elliptical and circular modeling in 72 asymptomatic subjects, 52 acute
neck pain subjects, and 70 chronic neck pain subjects. Spine 29:2485-2492, 2004
16. Harrison DD, Jackson BL, Troyanovich SJ, Robertson G, DeGeorge D, Barker
WF: The efficacy of cervical extension-compression traction combined with
diversified manipulation and drop table adjustments in the rehabilitation of
cervical lordosis: a pilot study. J Manipulative Physiol Ther 17:454-464, 1994
17. Harrison DD, Janik TJ, Troyanovich SJ, Harrison DE, Colloca CJ: Evaluation of
the assumptions used to derive an ideal normal cervical spine model. J
Manipulative Physiol Ther 20:246-254, 1997
18. Harrison DE, Harrison DD, Janik TJ, Holland B, Siskin LA: Slight head
extension: does it change the sagittal cervical curve? Eur Spine J 10:149-153,
2001
19. Harrison DE, Harrison DD, Janik TJ, Jones EW, Cailliet R, Normand M.
Comparison of axial and flexural stresses in lordosis and three buckled
configurations of the cervical spine. Clin Biomech 16:276-284, 2001
20. Harrison DE, Janik TJ, Harrison DD, Cailliet R, Harmon SF: Can the thoracic
kyphosis be modeled with a simple geometric shape? The results of circular and
elliptical modeling in 80 asymptomatic patients. J Spinal Disord 15:213-220,
2002
21. Harrison DE, Jones EW, Janik TJ, Harrison DD. Evaluation of the axial and
flexural stresses in the vertebral body cortex and trabecular bone in lordosis and
two sagittal cervical translation configurations with an elliptical shell model. J
Manipulative Physiol Ther 25:391-401, 2002
22. Hawk C, Byrd L, Jansen RD, Long CR: Use of complementary healthcare
practices among chiropractors in the United States: a survey. Altern Ther Health
Med 5:56-62, 1999
23. Hawk C, Dusio ME: A survey of 492 US chiropractors on primary care and
prevention-related issues. J Manipulative Physiol Ther 18:57-64, 1995
24. Hurwitz EL, Aker PD, Adams AH, Meeker WC, Shekelle PG. Manipulation and
mobilization of the cervical spine: a systematic review of the literature. Spine
21:1746-1759, 1996
25. Jackson BL, Barker WF, Pettibon BR, Woggon D, Bentz J, Hamilton D, et al:
Reliability of the Pettibon patient positioning system for radiographic production.
J Vertebral Subluxation Res 4:1, 2000
26. Janik TJ, Harrison DD, Cailliet R, Troyanovich SJ, Harrison DE: Can the sagittal
lumbar curvature be closely approximated by an ellipse? J Orthop Res 16:766-
770, 1998
27. Kapandji IA. The Physiology of The Joints. Volume 3: The Trunk and
Vertebral Column: 5th ed. Churchill Livingstone, pp, 235-236, 1974
28. Kendall FP, McCreary EK, Provance PG: Muscles: Testing and Function: 4th
ed. Williams & Wilkins, Baltimore, MD, 1993
29. Lantz CA, Chen J: Effect of chiropractic intervention on small scoliotic curves in
younger subjects: a time-series cohort design. J Manipulative Physiol Ther
24:385-393, 2001
30. Ledin T, Hafstrom A, Fransson PA, Magnusson M: Influence of neck
proprioception on vibration-induced postural sway. Acta Otolaryngol 123:594-
599, 2003
31. Lewit K: Muscular and articular factors in movement restriction. Manual
Medicine 1:83-85, 1985
32. Morningstar MW, Strauchman MN, Weeks DA: Spinal manipulation and anterior
headweighting for the correction of forward head posture and cervical
hypolordosis: a pilot study. J Chiropr Med 2:51-54, 2003
33. Morningstar MW, Woggon D, Lawrence G: Scoliosis treatment using a
combination of manipulative and rehabilitative therapy: a retrospective case
series. BMC Musculoskelet Disord 5:32, 2004
34. Nicholas SC, Doxey-Gasway DD, Paloski WH: A link-segment model of upright
human posture for analysis of head-trunk coordination. J Vestib Res 8: 187-200,
1998
35. Peterson BW, Goldberg J, Bilotto G, Fuller JH: Cervicocollic reflex: its dynamic
properties and interaction with vestibular reflexes. J Neurophysiol 54:90-109,
1985
36. Peterson C, Bolton J, Wood AR, Humphreys BK: A cross-sectional study
correlating degeneration of the cervical spine with disability and pain in United
Kingdom patients. Spine 28:129-133, 2003
37. Pettibon BR: Chiropractic and Rehabilitation Procedures Re-invented To
Correct The Spine and Posture. The Pettibon Institute, Gig Harbor WA, 1994
38. Pettibon BR: Pettibon Spinal Biomechanics: Theory and Implications.
Pettibon Biomechanics Institute, Tacoma, WA, 1978
39. Pompeiano O, Allum JHJ: Vestibulospinal Control of Posture and
Locomotion: Progress in Brain Research: Volume 76. Elsevier Science
Publishers, 1988, pp 137-143
40. Saunders ES, Woggon D, Cohen C, Robinson DH: Improvement of cervical
lordosis and reduction of forward head posture with anterior headweighting and
proprioceptive balancing protocols. J Vertebral Subluxation Res 4:E1-5, 2003
41. Schieppati M, Nardone A, Schmid M: Neck muscle fatigue affects postural
control in man. Neuroscience 121:277-285, 2003
42. Stitzel CJ, Morningstar MW, Paone PR: The effects of bite line deviation on
lateral cervical radiographs when upper cervical joint dysfunction exists: a pilot
study. J Manipulative Physiol Ther 26:E1-7, 2003
43. Toppenberg KS, Hill DA, Miller DP: Safety of radiographic imaging during
pregnancy. Am Fam Phys 59:1813-1818, 1999
44. Troyanovich SJ, Cailliet R, Janik TJ, Harrison DD, Harrison DE: Radiographic
mensuration characteristics of the sagittal lumbar spine from a normal population
with a method to synthesize prior studies of lordosis. J Spinal Disord 10:380-
386, 1997
45. Weigand R, Kettner NW, Brahee D, Marquina N: Cervical spine geometry
correlated to cervical degenerative disease in a symptomatic group. J
Manipulative Physiol Ther 26:341-346, 2003
46. West DT, Mathews RS, Miller MR, Kent GM: Effective management of spinal
pain in one hundred seventy-seven patients evaluated for manipulation under
anesthesia. J Manipulative Physiol Ther 22:299-308, 1999
47. White AA, Panjabi MA: Clinical Biomechanics of The Spine: 2nd ed.
Lippincott, Williams & Wilkins, Philadelphia, PA, 1990
48. Wilson VJ, Boyle R, Fukushima K, Rose PK, Shinoda Y, Sugiuchi Y, Uchino Y:
The vestibulocollic reflex. J Vestib Res 5:147-170, 1995
49. Yoganandan N, Knowles SA, Maiman DJ, Pinter FA: Anatomic study of the
morphology of human cervical facet joint. Spine 28:2317-2323, 2003