A Normal Spinal Position: It's Time to Accept the Evidence

Journal of Manipulative and Physiological Therapeutics 623
Volume 23 • Number 9 • November/December 2000
0161-4754/2000/$12.00 + 0 76/1/110941 © 2000 JMPT

COMMENTARY

A Normal Spinal Position: It’s Time to Accept the Evidence

INTRODUCTION Inasmuch as Haas et al7 had many different
Recent trends in our chiropractic profes- topics in their commentary and did provide
sion seem to be leading away from well- section titles, it is convenient to respond
ness care into an exclusive focus on short- with reference to those section titles. It is
term care for relief of symptoms, especially noted that some of their section titles are
pain.1 In contrast, some recent articles obscure and certainly not mainstream (eg,
authored by CBP Nonprofit, Inc, researchers their reference to Sackett); nonetheless, the
express an interest in spinal reconstruction, titles are useful as objects for debate. First,
structural outcomes, and care beyond the mere however, we present a logical approach to move-
relief of symptoms.2-6 In a recent commentary, Haas et ments in upright posture, from which much about a nor-
al7 have taken exception to this approach. mal upright position can immediately be derived.
A commentary by Haas et al7 concerning one of our It is a basic theorem of physics and engineering that the
recent papers8 expressed a paradigm for chiropractic science movement of any object can be decomposed into rotation,
and patient treatment that is different from that expressed in translation, and deformation.20 Whereas White and Panjabi21
our recent literature reviews and original publications. Their have used this theorem to describe the 6 degrees of freedom
views on normal spinal position, radiograph usage, radi- (DOF) of individual spinal segments (rigid bodies), we have
ograph reliability, and spinal rehabilitation of normal struc- used this theorem to express all possible movements of the
ture, as expressed in their commentary, did not include human head, thoracic cage, and pelvis in 3 dimensions.10-11
mechanical engineering principles, which we believe neces- Figs 1 and 2 are reprinted from a previous article in the
sary for understanding the stresses and strains in abnormal Journal of Manipulative and Physiological Therapeutics.22
or asymmetric loading of spinal tissues. These movements will form the basis on which we illumi-
In 1998, we had discussed a number critical flaws in 8 nate a normal postural position.
commonly held beliefs espoused by some diplomate chiro- After providing a review of normal upright position in
practic radiologists.8 Thus, given the fact that the “conven- terms of the engineering principles and literature reviews to
tional wisdom” of chiropractic radiologists was challenged, be presented below, analysis of chiropractic manipulations
it was not surprising that there were a total of 8 authors and (which are mostly torsional loads) will lead the reader to con-
consultants who contributed to the rebuttal commentary of clude that diversified manipulation is inadequate for obtain-
Haas et al.7 What was not expected was the divergence into a ing a structural change in the neutral resting posture. Thus,
critical analysis of Chiropractic Biophysics (CBP) methods precise postural setups (such as those used in the CBP tech-
and the Harrison spinal model,9 which is used as an anatom- nique) are recommended for the sake of obtaining structural
ical outcome for patients receiving CBP-based treatment. correction in a patient’s spine after the relief of symptoms.
However, we are pleased to both address those raised con-
cerns and present our rebuttal to Haas et al’s misconceptions Biologic Plausibility and Validity
about the use of radiography in chiropractic clinical practice. Haas et al1 defined “biologic plausibility” for us. They
Because this normal spinal model was only self-published appear to have assumed that the only important “biologic
until 1992,10-12 some have denied the existence of the process” is back pain, and on the basis of that view they
Harrison normal spinal model and its implications for physi- assume that it is unnecessary to address the upright spinal
ology. These implications were discussed in a short review configuration under gravity. In addition, they state that our
of Wolff’s law (bone remodels to stress) and Davis’ law (soft model is “merely a mathematical description of optimal
tissue remodels to stress) for abnormal sagittal spinal config- stress on a static system”.7 We now reply that back pain is a
urations.3 Because this Harrison model has recently been multifactorial condition. The process of spinal degeneration
published in the indexed literature,13-19 its existence can no and abnormal biomechanics’ causing mechanical distor-
longer be denied or ignored. tions of the central nervous system (CNS) is better charac-
terized as a degenerative disease process. Thus, symptoms
doi:10.1067/mmt.2000.110941 appear after the disease process is well advanced (as is the

624 Journal of Manipulative and Physiological Therapeutics
Commentary • Harrison et al

Fig 1. Rotational DOF of global body parts.

case in heart disease, cancer, and hypertension). In such the entire oculovestibular, muscle spindle, and mechanore-
processes, the emphasis is placed on controlling risk fac- ceptor systems perform this function from moment to
tors. It is suggested that optimizing the spine’s position to moment in upright stance. To imply that this is an unimpor-
resist the compressive force of gravity is a logical place at tant subject regarding spinal mechanics is to ignore a major
which to address an “optimal stress” risk factor. Of course, function of the CNS.


Fig 2. Translational DOF of global body parts.

Haas et al7 believe that there is no compelling evidence to ing the spine. A model is used to predict nature; it is a tool.
indicate that subluxation exists. However, subluxation has Our model’s usefulness will be determined in future studies
been precisely deﬁned through use of deviations from normal of clinical significance. For such studies to be carried out,
upright posture and our normal spinal model.23 In addition, the parameters of the model’s usage must ﬁrst be established,
Haas et al do not appear to appreciate the concept of model- and one of these parameters is a measurement method—ie,


A B C D

Fig 3. A, Vertical position of normal AP posture as agreed on in literature. B, D, Proposed ideal lateral postures. C, Average lateral
posture. Note that differences between Fig 3, B and Fig 3, C are slight.

posture and radiography. Therefore, determining the reliabili- ciated with asymmetric muscle efforts. Numerous elec-
ty of the radiographic markings (and posture reliability) is a tromyographic studies over the past 4 decades add support
logical first step. Haas et al claim that we cannot address for this fact.24-34 Because many clinicians7 may be unfamiliar
“clinically meaningful conditions,” but they want to stop us with engineering principles and aspects of upright human
from attempting such future research by negating our stance, 2 other “proofs” are presented.
attempts to study the reliability of our methods at the begin- As a first discussion of normal posture, the readers and
ning. Clinical signiﬁcance can be determined only after one Haas et al7 are asked to consider that all chiropractic, osteo-
has precise deﬁnitions to test and only after one has reliabili- pathic, physical therapy, and medical colleges teach a plumb
ty data established for the measuring methods. line analysis and global ranges of motion, as depicted for
Because a normal postural position (outside alignment) ±Tx, ±Ry, and ±Rz in Figs 1 and 2. With regard to the AP view,
and a normal spinal position (inside alignment) are funda- the following 3 questions come immediately to mind: (1)
mental to our approach to “controlling risk factors” for spinal axial rotation to the left and to the right—from where? (2)
dysfunction, a review pertaining to each of these ideas is pro- lateral flexion to the left and to the right—from where? (3)
vided to enable the reader to determine whether Haas et al’s lateral translation to the left and to the right—from where?
paradigm matches the biomechanical/biomedical literature. Before trying to give an answer that is different from ver-
tical alignment in the AP view, recall that these main postur-
Normal Upright Posture al motions of the head and thoracic cage, ±Tx, ±Ry, and ±Rz,
There are at least 3 approaches by which one can immedi- cause spinal coupling patterns for which the movements are
ately discover a normal spinal alignment in the anteroposteri- known.22,23,35,36 These vertebral coupling patterns are
or (AP) view and the lateral view. Most rigorously, equilibri- always described as movement away from a vertical normal
um equations in the AP view can be used to prove that the spinal alignment. Our research team is the first to report
postures of ±Tx, ±Ry, and ±Rz in Figs 1 and 2 result in abnor- spinal coupling for ±Tx of the head and thoracic cage.35,36
mal asymmetric loads on the spinal tissues and lower extrem- Some authors have argued that slight deviations of the
ities when these postures are in the neutral resting posture of upper thoracic spine are correlated to the side of the domi-
the subject under investigation. These postures are also asso- nant arm37 and that a true vertical spine in the AP view there-


fore cannot be considered normal. Either sight deviations Therefore, the vertical alignment of the global centers
can be ignored because of the minimal amount of asymmet- of mass in upright posture in both the AP and lateral views
ric loading, or unilateral upper extremity exercises on the has been statistically established for young adults. Fig 3
nondominant side can be prescribed to correct these. In illustrates this alignment with some additional references
addition, Haas et al7 claim that because of the natural asym- applied to the location of the shoulders and lower extrem-
metry of the spinous processes, the sensibility of a true verti- ities.
cal spine in the AP view is questionable. However, more
than 2 decades ago, Farfan38 found that the entire vertebral Harrison Spinal Model
architecture in the lumbar spine will change and keep the Through use of multiple studies and normal distributions
lamina junction in line with the structural center of the verte- with an ideal mean normal center, normal upright posture
bral body. This means that the center of mass will remain has been deﬁned in the literature. This normal posture in the
approximately the same. Farfan38 writes (pages 34-5): “It AP view correlates with a straight (vertically aligned) spine.
would appear that in the development of the vertebra, asym- In the lateral view of upright normal posture, it is generally
metrical body growth is compensated for by asymmetric accepted that there exist a cervical lordosis, a thoracic
growth of the neural arch.” Therefore, the centers of mass in kyphosis, and a lumbar lordosis; however, neither the over-
the AP view will still be in line with vertical gravity to mini- all sagittal curvatures of the cervical, thoracic, and lumbar
mize loads on the spinal tissues and to be the origin position areas nor the segmental contributions are generally stated or
for postural movements.39-47 agreed on. Therefore, when normality is being debated, only
Recently, Kiefer et al48 showed that T1, T12, and S1 must the overall geometric shape and segmental angulation of the
be vertically aligned in the lateral view. In the lateral view, cervical, thoracic, and lumbar sagittal curvatures are open to
the previous argument can be applied to the movements of debate.
±Rx, ±Ty, and ±Tz in Figs 1 and 2. In fact, much research has This is where our normal Harrison Spinal Model enters
been conducted on sagittal posture, especially anterior head the literature. Both our average (400 subjects) and our ideal
translation (+Tz) and pelvic posture, by physical therapists.49- normal sagittal cervical spine models were published in
61
This research indicates that anterior head translation (pro- 1996.14 Our average (derived from 552 subjects) normal
trusion) is fundamentally accepted as abnormal and that, in lumbar model was published in 1997.18 Our ideal normal
general, posture evaluation is repeatable and reliable. lumbar model was published in 1998.13
For a second analysis, a statistical evaluation is present- At this point, it is important to point out that the
ed. As always, there is debate in the literature concerning Harrison Spinal Model is the normal path of the posterior
average normal and ideal normal (upright posture). longitudinal ligament along the posterior vertebral bodies.
However, the differences in these upright positions are This ideal and statistical average model has a mean and a
small. In 1973 and 1975, Beck and Killus62,63 used a com- random error component (variation around the mean). It is
puter analysis to average upright lateral and upright AP a model not of the entire anatomy of the spine but only of
postures of several hundred young adults. They reported the curvature in the sagittal plane. Models of the entire
on the reliability of their digitizing methods and showed spine require huge computer codes in which finite ele-
that posture was reproducible “even though the x-rays ments methods are used.
were taken years apart.” They critically analyzed all of the The paradigm presented by Haas et al7—that abnormal
previous reports of posture (such as those of Staffel, 64 posture has no effect on physiology—is quite puzzling. It is
Goff, 65 Leger, 66 Haglund, 67 Osgood, 68 and Wiles & well documented that abnormal spinal loads (forces and
Lond, 69 which include such terms as flat back, round moments) over time cause pathoses. This is taught in all chi-
back, and hollow back). Beck and Killus 62 found highly ropractic college physiology courses as Wolff’s law (bone
pathologic postures, small sample sizes, incorrectly remodels to stress) and Davis’ law (soft tissues remodel to
applied statistics, and lack of an origin for measurement stress).
included in previous categories of posture. Using a digi- In the light of the foregoing preceding background data
tizer, they plotted, in graphic form, the coordinates (paths) and ideas, a response to each of Haas et al’s topics7 can now
of the vertebral bodies of all subjects in the AP and lateral be presented.
views. With 1500 subjects in their 1975 report, 63 they
noted that they had “one normal distribution in every point Clinical Sensibility and Validity
of abscissa.” They write: Cervical kyphosis is not a normal variant. In their commentary,
Haas et al7 repeat the common misconception that cervi-
It follows that there is only one ideal type of spinal col-
umn. According to our findings the theory of constitutional cal kyphosis is a normal variant. In general, the studies
types (of posture) cannot be conﬁrmed.62 cited by Haas et al 7 are inadequate, being characterized
by inappropriate methods, flawed statistical analysis (if
Beck and Killus provided separate graphs of their maxi- any), and/or unsupported conclusions. It is our intent to
mum points of their normal distributions of posture. The review the 6 studies 70-75 mentioned by Haas et al and to
spine had the 3 spinal curves with vertical alignment of T1, present an updated literature review focused on cervical
T12, and S1 in the lateral view. kyphosis.


To begin, Haas et al7 refer to a 1986 study by Gore et al.70 less than 3 weeks’ duration before the past 2 months or had
In 200 randomly selected asymptomatic subjects, Gore et al pain in the 2-month period immediately before the study. In
found an average of 22 degrees of lordosis using Ruth addition, the sample size was extremely small and subjects
Jackson’s angle from C2-C7; they found that a minority in the two groups were not matched for age, weight, height,
(9%) of these subjects demonstrated the presence of a cervi- or sex.
cal kyphosis. In contrast, Harrison et al76 found that 35% of Furthermore, Haas et al7 state that “in a study of 180 sub-
250 symptomatic subjects had kyphotic deformities. These jects, Borden et al concluded that a straight cervical spine is
data indicate a dramatic increase in cervical kyphosis in abnormal only in conjunction with decreased cervical flexi-
symptomatic subjects in comparison with asymptomatic bility.” In actuality, the study by Borden et al73 found that of
subjects. An additional concern is the cross-sectional study 180 asymptomatic subjects, 3 (1.7%) had a reversed cervical
design used by Gore et al. It is common knowledge among curve and 13 (7.2%) had a straight cervical spine. Of the 13
health care providers that several life-threatening illnesses subjects with a straight cervical spine, 11 (85.0%) had con-
and diseases remain asymptomatic throughout their course comitant degenerative changes. In the 3 subjects with cervi-
or are associated with no overt signs or symptoms until the cal kyphosis, “there were generalized hypertrophic degener-
end stages. Harrison et al3 have previously reviewed the ative changes and fusion.”73 Borden et al concluded that
shortcomings of the study by Gore et al.70 “roentgenographically demonstrated loss of the cervical
The second article used by Haas et al7 in their assertion curve, combined with normal thoracic kyphosis and lumbar
that kyphosis is a normal variant is the study by Maimaris et lordosis, may be indicative of abnormality of the cervical
al,71 who retrospectively assessed 67 asymptomatic and 35 spine.”73 In the light of this information, one might wonder
symptomatic whiplash-injured patients. Follow-up was how Haas et al7 could possibly believe that this reference
attained an average of 2 years after the injury. Maimaris et al supports the position that cervical hypolordosis or kyphosis
concluded that “reversal of the cervical spine to a kyphotic is a normal variant. Perhaps they were performing secondary
position was not associated with prolonged disability." referencing and did not read the original paper.
However, there are several problems with this study. First, Likewise, Haas et al7 believe that the study by Marshall
only 39 (58%) of the 67 asymptomatic subjects were "clini- and Tuchin74 indicates “that spinal curve alteration itself
cally examined," whereas 30 (86%) of the 35 symptomatic may not require treatment.” However, there are several
subjects were examined. This is a large difference in the per- potential problems with the method used by Marshall and
centage of subjects examined in each group, and it can lead Tuchin.74 The most serious of these is their choice of the C1-
to inaccurate data analysis between the groups. Second, the C7 Cobb angle for lateral cervical curve mensuration. The 4-
lateral cervical spine radiographs were not measured and line C1-C7 Cobb angle is not a valid representation of the
quantified; they were merely classified into lordotic, straight, cervical lordosis.8,77 Therefore, without a segmental analy-
or kyphotic. Therefore, no quantifiable statistical analysis sis, no conclusions can be made concerning the shape and/or
was performed to actually address the issue of the amount or magnitude of the cervical lordosis and its clinical signifi-
type of lateral cervical curvature as it relates to the presence cance in that study.
of symptoms. As an example, on page 396, Maimaris et al Last, Haas et al7 rely on the conclusions of Gay.75 In a
present two figures, one representing a kyphotic cervical 1993 review, Gay concluded that cervical kyphosis is a nor-
curve and the other representing "loss of the normal lordo- mal variant. However, before Haas et al’s7 commentary, the
sis." If one looks at these two radiographs, it is readily vast majority of the references cited by Gay had previously
apparent that both of these are kyphotic curvatures. Last, in been critically analyzed and had been found to be inappro-
their Table III on page 395, Maimaris et al present the per- priate by us in 1998.8 Thus, no weight can be applied to
centage of subjects in each group with radiographic abnor- Gay’s75 review.
malities. Clinically significant differences are noted between Recent and past mechanical, clinical, and surgical studies
the symptomatic and asymptomatic groups, with the symp- concerning the cervical lordosis do not support the position
tomatic group having higher percentages of straight and that cervical kyphosis is a normal variant. Haas et al7 seem
kyphotic curves and the asymptomatic group having the to insinuate that the only supporting reference that we8
highest percentage of lordotic curves. offered for the clinical significance of a normal cervical lor-
Similarly, Haas et al7 make the claim that Pedersen72 dosis was by Cote et al78 (our old reference 1). This clearly
“observed that cervical hypolordsis may be a normal vari- was not the case (see references 9-17 in our original manu-
ant.” However, the study by Pedersen is of insufficient quali- script8). However, because Haas et al and many others con-
ty for the drawing of such a conclusion. Pedersen compared tinue to debate this issue, a thorough review of the literature
a “treatment” group of only 9 patients with a “control” group on cervical kyphosis and its effects is presented here.
of 17 patients. The criterion for inclusion in the control It is relevant that several studies have investigated and
group was as follows: “The subject must not have had any linked altered cervical curve configurations to the presence
history of cervical or cervico-thoracic symptoms prior to 2 of chronic headache pain.79-81 In a survey of more than 6000
months before entry (lasting continuously for more than 3 cases of chronic headache-sufferers, Braaf and Rosner79
weeks).” This designation was a poor choice, inasmuch as found that “complete or segmental loss or reversal of the
subjects in the control group could either have had pain of normal lordotic curve of the cervical spine is the most con-


sistent characteristic feature and very often is the only method is important because the standard error of measure-
abnormality found.” In 47 subjects with tension and ment (SEM) is much lower (<3) and the segmental analysis
migraine headaches, Vernon et al80 found a high incidence finds alterations within the curve—ie, it is not just evalua-
of hypolordosis, straightened cervical curve configurations, tion of the end segments.
and reversed cervical curve configurations. Nagasawa et al81 According to Haas et al,7 the surgical studies just cited,
compared 372 patients with tension headaches and 225 con- all of which indicate the clinical significance of the cervical
trol subjects matched for age and sex; they found statistical- lordosis, are not appropriate because surgical patients are
ly significant differences between the two groups, the “not typical chiropractic patients who require conservative
headache patients having straightened cervical curve config- care.” But perhaps this is merely an excuse for not accepting
urations and low set shoulders. In addition, with increasing the facts.
age, the headache patients’ cervical curve was straight more However, there are several nonsurgical studies indicating
frequently. This information contrasts nicely with the find- cervical kyphosis as a factor predictive of poor results.98-100
ings of Gore et al,70 who noted that in asymptomatic sub- In a long-term follow-up of 146 whiplash-injured patients,
jects, the cervical curve increased with age. Hohl98 identified cervical kyphosis as factor predicting a
Looking into the matter further, we note that when poor out- poor outcome. Norris and Watt99 followed 61 patients
comes after surgery are considered, several studies have found involved in motor vehicle accidents for a minimum of 6
a good cervical lordosis to be a significant factor in preventing months; they found abnormal neck curves to be “more com-
neurologic deficit and/or compromise.82-93 For example, Goto mon in patients with a poor outcome.”99
and Kita82 state that “postoperative kyphotic malalignment or In addition to clinical outcomes of pain and neurologic
angulation are factors strongly affecting the outcome of deficits, several papers focusing on cervical biomechanics
surgery.” Yamazaki et al83 compared 2 groups of patients with indicate that cervical kyphosis is abnormal.101-103 Using an
ossification of the posterior longitudinal ligament (PLL) post- engineering analysis of slope and bending moment,
operatively. Group I consisted of patients with no anterior Matsunaga et al101 proved that degeneration and consequent
“compression” of the spinal cord, and group II comprised subluxation will develop in abnormal kyphotic configura-
patients with residual cord “compression.” The investigators tions, which they termed buckling alignments. “In the case
found a lordosis of less than 10.0 degrees or cervical kyphosis of the S-shaped spine,” they write, “the spine is in a ‘buck-
correlated with the presence of postoperative spinal cord com- ling’ condition, which corresponds to an unreasonable sup-
pression; this result was statistically significant. porting function.”
Similarly, recent surgical studies have emphasized that With regard to ossification of the PLL, Matsunaga et al102
operations that leave the patients’ cervical spines with less followed 101 patients for a 5-year period. Using an engi-
lordosis are associated with increased neck, upper thoracic, neering analysis of strain, they found that ossification of
and shoulder pain and overall poorer health outcomes.94-97 PLL progressed in the areas showing uneven and abnormal
Lowry94 used the average lordosis of 22 degrees found by strain at the adjacent intervertebral disk and PLL. Spe-
Gore et al70 to gauge a successful surgical outcome; he cifically, strain in the tensile direction was found to corre-
claimed that “a fixed kyphotic posture of the mid-cervical late with ossification of the PLL. It is important to note that
spine will lead to overall sagittal imbalance manifested by the only way to increase the tensile strain in the PLL is to
axial pain in the upper to mid-thoracic region as well as in have concomitant hypolordosis or kyphosis.104
the posterior cervical spine.” Katsuura et al95 compared 44 Several other studies have indicated that loss of cervical
cases treated with anterior cervical plating (a method of lordosis or kyphosis is a cause of or is associated with a
ensuring a stable lordotic correction) to 30 patients receiv- high incidence of degenerative changes in the disk and ver-
ing anterior fusion without plating. These patients were fol- tebral bodies.70,73,98,105 Because degenerative changes of the
lowed for an average of 38 months postoperatively. The cervical spine are a known cause of morbidity,98,99,106 it can
magnitude of cervical lordosis was assessed through use of be stated with confidence that cervical kyphosis is not a nor-
Ruth Jackson’s angle (posterior tangents from C2-C7), and mal variant.
intersegmental (2-line) Cobb angles were used for the align- In a recent 1997 text on the spine, statements by
ment of the fused segments. Katsuura et al found statistical- Frymoyer et al109 are clinically significant about cervical
ly significant differences in the incidence of neck pain kyphosis as a normal variant. In fact, they assert that
between the two groups, the plated group having less neck “kyphosis, straightening, and hyperlordosis of the cervical
pain and a statistically significant increase in cervical lordo- spine may all be seen in conjunction with spondylotic
sis. Likewise, Kawakami et al96 retrospectively evaluated 60 myelopathy, whereas in other patients the normal curvature
patients postsurgically. Cervical lordosis was measured with is preserved” and that “kyphosis and hyperlordosis may
a 4-line Cobb’s method from C2-C7 and a segmental (2- coexist and thus this gives rise to an S-shaped deformity of
line) Cobb angle at the fused level. Segmental kyphosis at the spine, causing greater instability and management prob-
the level of the fusion and less lordotic curvature were found lems.”109 Furthermore, in a 1996 review on the cervical
to statistically predict which patients would develop “axial spine surgeries, Lowery94 states that “an additional feature
symptoms” (neck pain, shoulder pain, and/or stiff neck). of any plate system, whether anterior or posterior, should be
The use of 2-line Cobb methods rather than the 4-line Cobb to establish a lordotic cervical curvature.” The evidence


against76-107 cervical kyphosis as a normal variant far out- subjects, Bernhardt and Bridwell123 reported a mean Cobb
weighs the evidence to the contrary.7,70-75 for T3-T12 of ~36 degrees and a mean Cobb for T1-T12 of
Finally, with regard to the cervical spine, it is noted that ~40 degrees. Jackson and McManus124 investigated sagittal
many authors (including Haas et al) have neglected to inves- balance in 100 patients and 100 volunteers; they reported the
tigate cervical lordosis and child development. It should not same means and ranges for males and females and for
have been necessary to present the preceding review indicat- patients and volunteers (mean T1-T12: ~43 ± 9 degrees). In
ing that cervical kyphosis is not a normal variant, inasmuch 1998, Vedantam et al125 investigated standing sagittal align-
as Bagnall et al108 showed in 1977 that the cervical lordotic ment in 88 adolescents (aged 10-18 years); they reported a
curve is formed in intrauterine life (9.5 weeks). Cervical lor- “striking similarity in regional thoracic kyphosis and lumbar
dosis could thus be considered a primary curve, like the tho- lordosis between adolescents and adults.”
racic kyphosis. Any loss of cervical lordosis is due to trau- In 1980, Fon et al126 reported that in 316 subjects, thoracic
ma, repetitive play, or work postural loadings during and/or kyphosis increased with age. In 1993, Cutler et al127 reported
after birth. Importantly, using skin markers or surface visual- that hyperkyphosis in women was associated with altered
ization does not correlate with the shape, magnitude, or vertebral body shape (anterior wedging), loss of bone densi-
direction of the sagittal cervical spine.109,110 Therefore, the ty, loss of fitness, decreased muscle strength, and reduced
use of radiography for identification of any abnormal lateral survival; the investigators suggested a correlation between
cervical configuration is absolutely mandatory. abnormal upright thoracic posture and changing architecture
of the spinal column (Wolff’s law). In 1996, Kolessar et al128
Thoracic Kyphosis reported that 69 patients had kyphotic Cobb T5-T12 mea-
In addition to the work of Beck and Killus,62 whose nor- surements of >33 degrees, whereas all 24 volunteers had
mal graph used a statistical average, multiple studies have Cobb T5-T12 < 33 degrees.
investigated thoracic kyphosis. As in cervical skin contour It is interesting to note that studies on thoracic kyphosis
versus radiographic measurements, D’Osualdo et al111 found with large population groups provide nearly normal distri-
considerable disagreement between radiographic findings butions. Thus, as noted by Beck and Killus,62-63 statistically
and results obtained with an Arcometer. In 1983, Willner and there would be one ideal normal at the mean of these distrib-
Johnson112 used spinal pantographs based on skin contour to utions. With the few reported values for Cobb T1-T12 and
suggest that kyphosis varied in girls and boys. However, with ratios of values from Cobb T2-T12, T3-T12, T4-T12,
using an ISIS scanner for evaluating back shape, Carr et al113 and T5-T12, the mean thoracic kyphotic value seems to be
reported no statistically significant differences with respect between 40 and 50 degrees for a Cobb angle from the top of
to age and sex in children, no statistically significant differ- T1 to the bottom endplate of T12.
ences with respect to age and sex in adults, and no differ-
ences between children and adults. Using radiography, Lumbar Lordosis
Voutsinas and MacEwen114 reported in 1986 that “the differ- Haas et al7 have neglected a large body of literature sup-
ences between boys and girls were not significant in any porting the clinical significance of a normal lumbar lordo-
group.” sis.13,18,19,116,129-158 To date, there have been 10 separate
Some studies have reported a large range of values for studies in which a similar method was used to investigate
thoracic kyphosis—from 20 degrees to 40 degrees.115-120 the normal shape and magnitude of the human lumbar lor-
One problem in deciphering a normal average thoracic dosis.18,115-117,122,129-133 These 10 studies used strict criteria
kyphosis is the inability to see T1-T4 on most lateral tho- in categorizing men and women as normal subjects. The
racic views; this has caused different levels of Cobb angle age range for the subjects was large—between 10 and 80
analysis in the literature—with different angles of kyphosis, years of age. All 10 of these investigations used radi-
of course. For example, the following levels have been used: ographic analysis in the neutral upright posture, and total
T5-T12, T4-T12, T3-T12, T2-T12, and T1-T12. This causes as well as segmental lumbar lordotic angles were mea-
wide ranges of values. For example, Propst-Proctor and sured. In all, a total of 755 normal subjects from 10 sepa-
Bleck117 measured the inferior endplate of T5 to the superior rate studies were included in the analysis. All of these stud-
endplate of T12 in 104 normal children who were referred ies18,115-117,122,129-133 indicate that the upper lumbar curve,
for suspected screening of scoliosis; they reported a normal T12-L3, is minimally lordotic whereas the distal lumbar
distribution with a range of 21 to 33 degrees and a mean of curve, L4-S1, accounts for approximately 65.0% of the
27 degrees. lumbar lordosis.
In 22 cases, Singer et al120 reported no difference in tho- Haas et al7 claim (believe) that different patient popula-
racic kyphosis in subjects before and after death (T4-T12: tions (races) have different optimal spinal configurations and
~49 degrees).120 Milne and Williamson121 reported no sig- that “given the natural variation and asymmetry in the
nificant change in thoracic curvature on follow-up radi- human musculoskeletal system,” an ideal spinal model is not
ographs of 261 subjects aged 62-90 years. In 99 Greek men plausible.
and women, Korovessis et al122 reported that thoracic kypho- Their beliefs are not supported by recent anthropometric
sis was not gender related, though kyphosis was found to clinical and experimental data on the lumbar spine. For exam-
increase with age (mean T4-T12: ~36 ± 9 degrees). In 102 ple, several studies addressing the shape and magnitude of the


lumbar lordosis found no differences with respect to geo- adult patients with symptomatic degenerative lumbar disk
graphic location and/or ethnicity.133-137 In a radiographic disease, 30 patients with low-grade L5-S1 isthmic spondy-
study of the lumbar lordosis in 16 healthy Chinese men, lolisthesis, and 30 patients with idiopathic or degenerative
Chen133 concluded that “no obvious interracial differences scoliosis. Again, statistically significant differences
were found in the geometric data found in this study.” between the groups were found in the radiographic mea-
Mosner et al134 compared the lumbar lordotic spinal radi- surements.138
ographs of 25 black women with those of 27 white women; Adams et al142 followed 403 volunteer health care work-
no significant differences were found in the lumbar lordosis, ers for a 3-year period. A decreased lumbar lordosis was
as measured with spinal radiographs, though differences found to be one of the personal risk factors in predisposing
were found in external skin contours. This difference in skin subjects to a first-time episode of low back pain requiring
contour “gives a false impression of increased lumbar lordo- medical evaluation. Itoi143 analyzed lateral lumbar radi-
sis”134 in black versus white women. In a 1985 study of 973 ographs in 100 postmenopausal female patients with spinal
adults, Fernand and Fox135 reported that “black and white osteoporosis; a statistically significant increase in low back
populations demonstrated no significant difference in the pain was found in patients with a rounded thoracic spine
mean lumbar lordotic angle.” Korovessis et al136 studied the and lower acute lumbar kyphosis. This lower lumbar kypho-
sagittal configuration of the lumbar spine in 120 asympto- sis has been shown to cause an increase in low back pain,
matic Greek volunteers. “We have shown that there are no perhaps as a result of increased electromyographic activity
differences in the sagittal profile across geographically of the paraspinal musculature.144
and ethnically different populations,” they write. As regards Many surgical papers have identified both lumbar hyper-
the “natural variation” of human anatomy, Janik et al13 have lordosis145 and hypolordosis or kyphosis146-152 as risk fac-
shown that reported small differences in vertebral tors for low back pain requiring surgical correction. Last,
body–to–disk height ratios, found in different studies, have several investigators have found statistically significant
no effect on their elliptical model of the lumbar lordosis (ie, increases or associations between loss of lumbar lordosis
none of the segmental angles, T12-S1, were found to change and degeneration of the disk, vertebral body, and lig-
more than 1 degree). aments.152-156
As regards low back pain and lumbar lordosis, 6 separate With regard to lumbar lordosis, most experts agree that
studies have found statistically significant differences “the assessment of spinal curvature is a part of an evalua-
between patients with low back pain and matched normal tion in patients with back problems”.157 Because surface
control subjects.19,136,138-141 Korovessis et al136 compared measurement of spinal curvature represents neither seg-
homogenous groups of 120 volunteers and 120 patients with mental nor total lumbar lordotic alignment, radiographic
chronic low back pain; subjects were matched for age, sex, analysis is a mandatory part of the routine examination of
and ethnicity. Lordosis was measured through use of a 4-line the lumbar spine.134,158 We believe that Haas et al’s7 nega-
Cobb’s method from T12 to S1, and segmental angles (2-line tion of the importance of the structural alignment of the
Cobb) were measured through use of endplate lines relative spine stems from a neglect of mathematics and engineering
to horizontal. Statistically significant differences were found analysis. They seem to be reading published papers with
between the two groups, the chronic low back pain subjects just rudimentary 4-line Cobb angle geometry while ignor-
having a decreased distal lordosis, L4-S1, in comparison ing papers that analyze spinal alignment with a slightly
with the controls. higher level of mathematics. Papers that use segmental
Harrison et al19 used elliptical modeling to discriminate analysis (see the references above), some analytic geome-
between a rigorously defined normal group and 3 separate try,13,19 calculus,103,120,153 curve fitting,9,159-161 and finite
groups of patients with low back pain; that study included elements162-164 have shown the importance of normal
(1) 50 normal subjects from a pre-employment physical alignment of the spine.
screening, (2) 50 patients with acute low back pain (first
occurrence; less than 6 weeks’ duration), (3) 50 patients with Pelvis Orientation
chronic low back pain (pain of more than 6 weeks’ duration Plaugher et al165 have investigated pelvic radiographic
or a history of recurrent disabling low back pain), and (4) 24 measurements and found reproducibility in pelvic position-
subjects with low back pain and radiographically verified ing and radiographic marking. Troyanovich et al166 have
degenerative disorders or pathoses. These 4 groups were established high intraclass coefficients (ICCs) and low
matched for age, weight, height, and sex. The investigators SEMs for pelvic tilt on the lateral lumbopelvic view.
found that “of 11 angles, 2 distances, and 2 ratios, statistical Jackson et al138 have reported high Pearson correlation
analysis was significantly different across groups for 12 of coefficients for pelvic measurements (in degrees) on lateral
these measurements.”19 The chronic low back pain and lum- full spine views; they reported significant differences in
bar pathosis group had a decreased lordosis, whereas the pelvic measurements for normal subjects versus 3 patient
acute low back pain group had an increased lordosis in com- groups.
parison with the normal subjects. In 1995, Saji et al167 studied 61 adolescents with idio-
In a similar study, Jackson et al138 compared sagittal lum- pathic scoliosis and 33 normal subjects for femoral neck
bar radiographs of 50 normal volunteers with those of 50 shaft angles and asymmetry of the hips. An angle was


Table. Partial review of x-ray reliability studies: ICCs and standard errors of measurement for intraobserver error and interobserver
error (in degrees)

Standard error of measurement (degrees)
ICC 4-line Cobb 2-line Cobb Mod. Risser-Ferg Post. tangent
Area/Reference Intra Inter Intra Inter Intra Inter Intra Inter Intra Inter
AP cervical — — — — — — — — — —
Troyanovich et al >0.90 >0.90 — — — — <2.0 <1.5 — —
AP thoracic — — — — — — — — — —
Pruijs et al (1994) (Spearman > 0.98) — 3.2, 2.0* — — — — — —
Sevastikoglou, Bergquist — — — 3.1 — — — — — —
Beekman, Hall — — — 4.2* — — — — — —
Gross et al (p176) — — 3.2 2.3 — — — — — —
Morrissy et al — — 4.9, 3.8, 7.2, 6.3, — — — — — —
2.8 6.3
Carman et al — — — 3.8* — — — — — —
Goldberg et al — — 1.9 2.5 — — — — — —
Desmet et al — — — 1.1, 1.3* — — — — — —
AP lumbar — — — — — — — — — —
Troyanovich et al >0.70 >0.80 — — — — <2.0 <2.0 — —
Lateral cervical — — — — — — — — — —
Phillips et al (1999) — >0.83 — — — <2.7† — — — —
Singer et al5 — — 4.5 — — — — — — —
Plaugher et al — — 2.9† 4.2† — — — — — —
Cote et al — >0.90 — 9.1, 8.3‡ — — — — — —
Jackson et al (Pearson r > .80) — — — — — — 1.2 1.2
Harrison et alSpine >0.70 >0.80 — — 3.6, 3.2 2.2, 2.7‡ — — 2.3 2.4
Lateral thoracic — — — — — — — — — —
Carman et al — — — 3.3* — — — — — —
Voutsinas, MacEwen — — 2.2* — — — — — — —
Jackson et al (1998) (Pearson r > .82) — — — — — — — —
Lateral lumbar — — — — — — — — — —
Jackson et al (1998) (Pearson r > .73) — — — — — — — —
Polly et al (1996) >0.81 >0.83 10.0 10.0 — — — — — —
Voutsinas, MacEwen — — 2.1* — — — — — — —
Gelb et al — — — — 3.0* 3.0* — — — —
Wood et al — — — — — 1.1† — — — —
Troyanovich et al >0.70 >0.80 — — — — — — 1.5 1.7
Troyanovich et al >0.70 >0.80 — — — — — — 1.7 1.8

ICC, Intraclass coefﬁcient; Intra, intraobserver error; Inter, interobserver error.
*Only average difference was reported (not standard error of measurement).
†Standard error of measurement was reported.
‡First value is for C1-C7; second value is for C2-C7.

formed by lines through the femoral shaft and neck. Intra- ic analysis of spinal displacement.” We have published 5
observer and interobserver reliability were assessed. There radiographic line drawing analysis reliability studies and
were no significant differences between the measurements have another in review.77,166,169-172 In other chiropractic pub-
of a single observer or between the measurements of differ- lications, the reliability of line drawing analysis on the nasi-
ent observers. Standard errors of measurement were small um view and pelvis, additional AP, and lateral views have
(intraobserver, 1.6 degrees; interobserver, 1.9 degrees). Saji been reported.165,173-176 Curiously, in regard to the nasium
et al discovered that a normal femoral neck-shaft angle was and AP lumbopelvic radiographic views, Haas et al make the
approximately 135 degrees, the scoliosis subjects having a following inaccurate statement: “There are no grounds for
much higher value for this angle (straightened femur). generalizing from studies on pelvic height and the cranium
Levine and Whittle168 studied the effects of pelvic tilt on to the repeatability of analyzing spinal curves and segmental
lumbar lordosis. They reported that flexion of the pelvis displacement.”7 Perhaps Haas et al are unaware that the nasi-
increased lumbar lordosis and that extension of the pelvis um radiograph includes the cervical spine and that its align-
was associated with hypolordosis. Similarly, Harrison et al19 ment in comparison with the “cranium” has been subjected
reported that their subjects with acute low back pain had to several reliability studies.173,174
ﬂexed pelvises and lumbar hyperlordosis whereas their sub- For the various Cobb methods (2-line and 4-line), numer-
jects with chronic pain had extended pelvic positions and ous reliability studies have been done on AP lumbar, AP tho-
lumbar hypolordosis. racolumbar, and AP thoracic, lateral lumbar, lateral thoracic,
and lateral cervical views.9,159-161,177-192 Furthermore, the
Reliability measurement of pelvic rotation and sagittal segmental trans-
Haas et al7 make the following statement: “To date, there lations has been reported as reliable.193-195 In 1992, Capasso
is little convincing evidence for the reliability of radiograph- et al196 reported high Pearson correlation (r > 0.90) for both


“intra and intergroup correlations among orthopedic sur- Recently, computer-aided spinal radiographic measure-
geons” for 3 types of spondylolisthesis radiographic mea- ments have been shown to be highly reliable. For example,
surements. Similar to Tallroth et al’s194 findings for lumbar in 1996, Rosol et al207 reported a high Pearson correlation
flexion/extension, the findings of Lind et al197 for cervical for vertebral morphometry (r = 0.96) and low mean coeffi-
flexion/extension were high examiner reliability and low cients of intraobserver variability (4%) and interobserver
intraobserver error of measurement (<1.8 degrees) for later- variability (2%).
al cervical segmental flexion angles. Gross et al198 (1983) We have already mentioned the recent (1998) study of
and Goldberg et al199 (1988) revisited AP Cobb angle relia- sagittal balance with normal subjects and 3 patient groups
bility and reported smaller errors of measurement (between conducted by Jackson et al.138 They reported high Pearson
1.9 and 3.2 degrees) than most studies. Similarly, DeSmet et correlation coefficients in the vast majority of their interob-
al200 reported small interobserver errors of the differences server and intraobserver reliability measures (13 measures
(<1.2 degrees) for Cobb angles. in their Tables 8 and 9, most being greater than 0.75).138 In
The multitude of studies just cited (a total of 35) report- addition to the pelvic measurements, they also reported sig-
ing high radiographic reliability (those with ICCs report the nificant differences in the normal subjects and the 3 patient
majority of ICCs to be in the >0.75 range) is sufficient to groups for a multitude of lateral spine measurements. In
establish the “reliability of radiographic analysis of spinal 1997, Hardacker et al208 studied lateral cervical reliability
displacement” to the satisfaction of any well-informed with segmental Cobb angles and reported only 3 values of
reader. interobserver and intraoberver Pearson correlations less
Perhaps the high variability of SEM (ranging between 3 than 0.83 for 8 measurements of segmental lordosis (0.64 <
and 10 degrees) with the 4-line Cobb methods are of con- r < 0.92).
cern. Inasmuch as the Harrison posterior tangent method has In 1994, Pruijs et al209 used a Spearman correlation coef-
smaller SEMs (<2 degrees), this method is suggested to ficient for measurements of Cobb angles on AP thoracic
Haas et al7 as well as to clinicians and other researchers for radiographs. They reported high coefficients (>0.98) for
the analysis of the sagittal spine. both interobserver and intraobserver variation with small
However, until recently (the 1990s), most investigators SDs of differences (<3.2 degrees).
reported only means, SDs, and SDs of differences in read- In 1996, Levine and Whittle168 measured pelvic tilt and
ings and rereadings (Table). Because the SEM has SD in its lumbar lordosis using a television/computer system that
formula, the low means and SDs for measurement differ- obtained 3-dimensional (3-D) coordinates of markers on the
ences indicate good-to-excellent reliability. However, before pelvis and spine at 20-ms intervals. ICCs for 3 readings of
1990, authors rarely provided proper statistical analyses pelvic tilt and lumbar lordosis were 0.78 < ICCs < 0.95. The
with Pearson r, intrarater ICC, interrater ICC, 95% CI, and investigators reported that altering the pelvic tilt significant-
SEM values. The vast majority of medical investigators have ly changed the angle of lumbar lordosis.
stated that the low means and SDs for differences in drawing In 1995, Saji et al167 studied 61 idiopathic scoliosis ado-
and redrawing radiographic lines (Table) suffice for a claim lescents with 33 normal subjects for femoral neck shaft
of adequate reliability. After all, it is merely Euclidean angles and asymmetry of the hips. An angle was formed by
geometry! lines through the femoral shaft and neck. They also per-
In 1999, Phillips et al201 reported high correlation coeffi- formed Cobb angle measurements. Intraobserver reliability
cients (0.83, 0.91, 0.89, 0.91, 0.88, 0.87) and low SEMs and interobserver reliability were assessed; there were no
(2.45 degrees, 2.71 degrees, 1.69 degrees; 1.22 mm, 1.32 significant differences between the measurements of a single
mm, 1.48 mm) when measuring the occipital-C2 angle and observer or between the measurements of different
distances on neutral, flexion, and extension radiographs. For observers. SEMs were small (intraobserver, 1.6 degrees;
measuring spinal canal dimensions and cord size in a 1999 interobserver, 1.9 degrees). In addition, the investigators
review article, Rao and Fehlings202 reported that 7 studies reported a significant difference in the obtuse femoral angles
provided interobserver and intraobserver reliability of radi- in normal versus scoliotic subjects, the latter having much
ographic measurements (0.82 < ICC < 0.99). In 1997, with larger obtuse angles. In 1985, Tibrewal and Pearcy210
means and SDs for measurement differences on AP thoracic assessed measurement of disk heights from lateral radi-
views, it was reported that the rib vertebral angle could be ographs. They reported a maximum error of 0.7 mm for
reliably measured (intraobserver mean, 4.4 degrees; interob- intraobserver and interobserver measurements.
server mean, 3.6 degrees).203 Since 1990, many chiropractic studies have included sta-
In 1996, Omeroglu et al204 reported that “both intraobserv- tistical analyses that are extensive in comparison with those
er and interobserver error risks were insignificant” for use of of previous studies. For our 6 CBP radiography reliability
the Perdriolle torsionmeter to measure vertebral axial rota- studies, we consulted with Burt Holland, PhD, a professor in
tion in scoliosis on AP radiographs.204 In 1994, Gilliam et the Department of Statistics at Temple University. With his
al205 reported high ICCs for both intertester (ICC > 0.86) and aid, our studies have reported complete statistical analyses
intratester (ICC > 0.92) pelvic radiographic measurements. with a majority of intraobserver and interobserver ICCs
Also in 1993, Hamberg et al206 reported that “the x-ray mea- greater than 0.75 and small SEMs (<2 degrees). It is interest-
surements showed high reliability” for pelvic tilt analysis. ing to note that ICC > 0.60 is the set of values that Haas et


Fig 4. Four types of loads with inherent stresses.

al7 have declared to be in the good-to-excellent range for more than Euclidean geometry, which is the basis of every
chiropractic studies.211 This range is close to the excellent human-made structure in our industrial lives.
range suggested by Shrout and Fleiss212 (poor < 0.4; 0.4 <
fair to good < 0.75; excellent > 0.75). Posture Reproducibility, Reliability, and Validity
It would be a great surprise to every mathematician, There is in the literature a plethora of posture reliability
physicist, and engineer to find that radiographic line draw- and reproducibility studies performed by ergonomists, med-
ings of all types are not highly reliable. After all, it is nothing ical doctors, chiropractors, and physical therapists. Posture


A B
Fig 5. A, Diversified technique is limited; lumbar roll is a torsional load applied to lumbar segments by
twisting pelvis relative to fixed thoracic cage. B, Cervical rotary-break is a torsional load applied to head in
lateral flexed and forward flexed positions. These loads are applied to every subject; patient’s abnormal
pretreatment posture is disregarded.

has been studied with patients lying,213 sitting,214 stand- Last, inasmuch as Fialka-Moser et al255 reported that
ing,215 lifting,216 working,217 walking,218 engaging in daily adolescents’ postural faults have been established as the
routine performance,219 and running.220 Postural stress has cause of pain syndromes in adulthood, we are bewildered
been correlated with scoliosis,221 office work,222 work-relat- that chiropractic state licensing boards are being influenced
ed lifting injuries,223 driving,224 sitting,225 space flight,226 by the paradigm promoted by Haas et al7 and others, as
sports injuries,227 and back pain.228 Posture as a valid out- cited in a recent review.8 For example, in August 1999 the
come of care is universally accepted by almost all health care Nevada Board of Chiropractic Examiners told practitioners
sciences.229-231 Virtually every body part has been studied for that it was against Board ruling to take radiographs of chil-
its posture in normal subjects versus injured individuals; dren and that posttreatment radiographs were unwarranted.
included are the postures of the head,232 shoulders,233 upper The selective information (countered in our preceding
extemity,234 trunk,235 pelvis,236 lower extremity,237 and short review) generally generated and disseminated by chiroprac-
leg,238 as well as the whole body posture.239-251 The vast tic radiologists and academicians is adversely affecting chi-
majority of these studies report high interobserver and ropractic clinicians’ ability to provide the best possible ser-
intraobserver reliability. In 1990, in a study of 86 Chinese vice to the patients who seek our care.
subjects, Dai and Gu252 found no significant differences in
posture for males and females and no significant differences Clinical Utility and Appropriateness
in posture between groups of old-aged subjects and middle- Haas et al’s7 negation of structure (spinal alignment) as
aged subjects with eyes open, though they did find a differ- a clinical outcome seems to be based on a few controlled
ence in posture between groups of old-aged subjects and clinical trials that failed to demonstrate the effectiveness
middle-aged subjects with eyes closed. In a 1997 study of of chiropractic manipulation in conditions such as asth-
160 men and women, Raine and Twomey253 found no signif- ma260 and nocturnal enuresis.261 These studies used spinal
icant gender differences for each of head and shoulder pos- manipulation as the intervention (treatment). Because
ture measurements. For a review of the normal alignment of manipulation seemed to be beneficial for headaches, neck
the lower extremities, the reader is referred to the 1996 pain, and back pain but not for other diseases or spinal dis-
review by Riegger-Krugh and Keysor,254 who noted that placement, Haas et al prefer to see chiropractic as merely a
pathology of structures results from skeletal malalignment. temporary treatment regimen for the relief of spinal aches
Adolescents’ postural faults have been established as the and pains.
cause of pain syndromes in adulthood.255 Anatomical short There are many flaws in this line of reasoning, and most
leg inequality has received much attention in the literature. of these flaws are derived from a complete void in an engi-
True anatomical leg length inequality causes a recogniz- neering education. At least two topics can be applied to
able abnormal posture. For a review, the reader is referred Haas et al’s faulty reasoning: (1) exclusive use of torsional
to the 1983 review by the American Academy of Osteo- loads in spinal manipulation and (2) neglect of CNS biome-
pathy256 and to recent articles by Beaudoin et al257 and chanics. This whole discussion of posture and radiographic
Keppler et al.258 line drawing reliability/validity omits a very important clin-
In terms of validity, posture as a valid outcome in the ical factor when any of the postural rotations and transla-
health care sciences is well accepted. In fact, the editor of tions in Figs 2 and 3 are present for long periods, especially
this Journal has made the following statement: “That pos- flexed segments in the cervical and lumbar areas.
ture can lead to low back pain will come as a surprise to no Deformations of the CNS, which result from abnormal pos-
one.”259 tural loads, were recently reviewed in this Journal.262-264


A B

Fig 6. In these examples, torsional loads make subjects’ posture worse. A, Patient’s initial posture is left head lateral flexion with con-
tralateral right thoracic bending (low shoulder at right). B, Patient’s head is right laterally translated with contralateral translation of
thoracic cage. Y-axis torsional loadings (seen in Fig 5) will not correct this posture and will in fact add other abnormal postural loads.

Thus, of the two topics, only that of torsional loads in spinal loads. After being exposed to some anatomy and ranges of
manipulation needs to be presented here. motion, any engineer can visualize the stresses (forces/area)
and strains (measurements of deformation) in these postures.
Torsional Loads For example, in lateral flexion, the flexural stresses are com-
Let us revisit the postural DOF in Figs 1 and 2, which are pression on the concave fibers and tension on the convex
based on the engineering concepts of rotations and transla- fibers. For the paraspinal tissues, these stresses/strains are
tions in 3 dimensions. There are 12 single movements in 6 directly associated with Wolff’s law and Davis’ law, especial-
DOF for each of the head, thoracic cage, and pelvis. ly for the application of these abnormal loads over long peri-
Through use of permutations in probability theory, it can be ods. The previous discussion now illuminates a glaring defi-
determined that there are 728 possible postures (singles, ciency in applying diversified loadings to patients’ spines.
doubles, triples, . . . sextuples) of each of the head, thoracic The vast majority of diversified maneuvers are torsional
cage, and pelvis in 3 dimensions, for a total of 7283 or loads (Fig 5). It might seem that these loadings will have a
385,828,352 possible upright human postures!12 This is such probability of being only 11% effective (of the 18 DOF illus-
an overwhelming number that it is best to restrict our discus- trated in Figs 1 and 2, head and thoracic torsions are only 2
sion to the individual postures depicted in Figs 1 and 2. DOF). However, when considering the total permutations of
These 36 postures (12 singles each for head, thoracic cage, posture, these diversified torsional loads are 4 out of
and pelvis) can be recategorized into the 4 types of loads 385,828,352 possible human postures, which amounts to
taught in junior-level engineering courses on the mechanics approximately 0% of specificity in matching the patient’s
of materials (Fig 4). abnormal posture. Haas et al7 seemingly do not understand
In mechanics of materials, engineers study the material the necessity of matching the patient’s individual posture
properties, design, loadings, deflections, stresses, and strains because they do not have a realization that these (rotated and
of structures.265 The y-axis rotations in Fig 1 are caused by translated postures) are mathematical functions in linear
torsional loads, whereas the x-axis (flexion/extension) and z- algebra, which is fundamental to an engineering education.
axis (lateral flexion) rotations are examples of pure bending. Linear algebra is the study of linear transformations.266
The y-axis translations are examples of axial loads, whereas There are 4 important linear transformations in 3-D geometry:
the x-axis and z-axis translations are examples of transverse (1) rotations, (2) reflections, (3) projections, and (4) transla-


tions. Because of a complete void in chiropractic education, However, the complete void of mechanical engineering
clinicians and academicians are unaware that rotations, reflec- in their reasoning has led them to a paradigm of chiropractic
tions, and translations have unique inverses (ie, only one load treatment that we do not accept. Their paradigm of treat-
will correct them) and that rotations, translations, and reflec- ment, based on torsional loads, is detrimental to the
tions are the only 3-D rigid body movers (this is a theorem in patient’s well-being in the longitudinal sense. They seem to
mathematics). From linear algebra, one deduces that there be interested only in temporary “patient happiness out-
must be a normal (origin) from which to measure the displace- comes”7 of chiropractic care, whereas we are interested in
ments caused by rotations, reflections, and translations. the long-term effects of abnormal postural loads. We find it
From the study of linear algebra, it becomes apparent that paramount to measure the patient’s structure on the outside
y-axis torsional loads are inappropriate interventions in the (posture) and use radiography for the segmental alignments
vast majority of patients. Actually, in most cases (ie, most on the inside (spine). The measurements gathered are used
postural positions of the patient), y-axis torsional loads make to uniquely determine the specific interventions chosen for
the patient’s posture worse (adding a new position not pre- each individual patient. We cannot accept the paradigm of
sent in the initial posture). For the sake of brevity, we pro- applying general torsional loads to every patient.
vide only 2 examples. Deed E. Harrison, DC
Suppose the new patient has either head lateral flexion Private Practice of Chiropractic
to the right and thoracic lateral flexion to the left or con- 123 Second Street
tralateral lateral translations of the head and rib cage (Fig Elko, NV 89801
6). A cervical rotary break, as in Fig 5, A, will cause Donald D. Harrison, DC, PhD
increased lateral flexion and the addition of head rotation,
Stephan J. Troyanovich, DC
whereas a lumbar roll will not correct the thoracic lateral
bending to the left but will add a y-axis rotation posture to Stacy Harmon, DC, MD
the patient. The torsion stresses cause deformation of the
mechanoreceptors in the disks, ligaments, and muscle REFERENCES
spindles (these reflexes reduce pain), but they do not alter 1. Haldeman D, Peterson D, Chapman-Smith D. Guidelines for
the initial and ongoing postural loads on the subject’s chiropractic quality assurance and standards of practice.
paraspinal tissues. (This simple example, like the preced- Gaithersburg, Md: Aspen Publishers; 1992.
ing discussion on outside posture, neglects the configura- 2. Harrison DD, Jackson BL, Troyanovich SJ, Robertson GA,
tions of the sagittal cervical, thoracic, and lumbar curves DeGeorge D, Barker WF. The efficacy of cervical exten-
sion-compression traction combined with diversified
on the inside.) manipulation and drop table adjustments in the rehabilita-
tion of cervical lordosis. J Manipulative Physiol Ther
CONCLUSION 1994;17:454-64.
A thorough review of normal upright posture, normal 3. Harrison DD, Troyanovich SJ, Harrison DE, Janik TJ, Murphy
spinal modeling, structural spinal alignment as a clinical DJ. A normal sagittal spinal configuration: a desirable clinical
outcome. J Manipulative Physiol Ther 1996;19:398-405.
outcome, and radiograph reliability has been provided. It 4. Troyanovich SJ, Harrison DD. Chiropractic biophysics
is up to the reader to evaluate whether it is the present (CBP) technique. Chiropr Technique 1996;8:1-6.
authors or Haas et al7 who (1) have been guilty of “omit- 5. Troyanovich SJ, Harrison DE, Harrison DD. Review of the sci-
ting of relevant studies, the misrepresentation of evidence, entific literature relevant to structural rehabilitation of the spine
and the disregard of the rules of evidence”7 and/or (2) may and posture: rationale for treatment beyond the resolution of
symptoms. J Manipulative Physiol Ther 1998;21:37-50.
have presented a “‘bits and pieces’ approach to the litera- 6. Troyanovich SJ, Harrison DD, Harrison DE. Low back pain
ture, selective extracting and manipulating that which and the lumbar intervertebral disc: clinical considerations for
could be construed to be supportive of their position and the doctor of chiropractic. J Manipulative Physiol Ther
ignoring the rest.”267 The reader may compare the litera- 1999;22:96-104.
ture cited by Haas et al7 and Morgan267 (a total of 49 refer- 7. Haas M, Taylor JAM, Gillete RG. The routine use of radi-
ographic spinal displacement analysis: a dissent. J Mani-
ences) with the literature cited in this review and a 1998 pulative Physiol Ther 1999;22:254-9.
review 8 (a total of 434 references) to determine whether 8. Harrison DE, Harrison DD, Troyanovich SJ. Reliability of
published studies have been misrepresented and/or spinal displacement analysis on plane X-rays: a review of
neglected. commonly accepted facts and fallacies with implications for
A detailed response to the criticisms of Haas et al con- chiropractic education and technique. J Manipulative Physiol
Ther 1998;21:252-66.
cerning biological plausibility, clinical sensibility, and so on 9. Harrison DD, Janik TJ, Harrison GR, Troyanovich SJ,
has been provided here. Finally, Haas et al and Morgan have Harrison DE, Harrison SO. Chiropractic biophysics tech-
questioned our integrity and have become personal in their nique: a linear algebra approach to posture in chiropractic. J
attack on our credibility. For example, Morgan267 claims that Manipulative Physiol Ther 1996;19:525-35.
“the Harrison et al approach to the topic of spinal displace- 10. Harrison DD. CBP technique: the physics of spinal cor-
rection. National Library of Medicine #WE 725 4318C,
ment appears much less as research and much more as pro- 1982-97.
motion.” Science requires critique of ideas, but personal 11. Harrison DD. Spinal biomechanics: a chiropractic perspective.
attacks have no place in a scientific debate. National Library of Medicine #WE 725 4318C, 1982-97.


12. Harrison DD. Abnormal postural permutations calculated as 32. Joseph J, Nightingale A. Electromyography of muscles of
rotations and translations from an ideal normal upright static posture: thigh muscles in males. J Physiol 1954;126:81-5.
spine. In: Sweere JJ, editor. Chiropractic family practice. 33. Joseph J, Nightingale A, Williams PL. A detailed study of the
Gaithersburg, Md: Aspen Publishers; 1992. p 6-1:1-22. electric potentials recorded over some postural muscles while
13. Janik TJ, Harrison DD, Cailliet R, Troyanovich SJ, Harrison relaxed and standing. J Physiol 1955;127:617-25.
DE. Can the sagittal lumbar curvature be closely approximat- 34. Joseph J, Nightingale A. Electromyography of muscles of
ed by an ellipse? J Orthop Res 1998;16:766-70. posture: leg and thigh muscles in women, including the
14. Harrison DD, Janik TJ, Troyanovich SJ, Holland B. effects of high heels. J Physiol 1956;132:465-8.
Comparisons of lordotic cervical spine curvatures to a theo- 35. Harrison DE, Cailliet R, Harrison DD, Janik TJ, Troyanovich
retical ideal model of the static sagittal cervical spine. Spine SJ, Coleman RR. Lumbar coupling during lateral translations
1996;21:667-75. of the thoracic cage relative to a fixed pelvis. Clin Biomech
15. Harrison DD, Janik TJ, Troyanovich SJ, Harrison DE, 1999;14:704-9.
Colloca CJ. Evaluations of the assumptions used to derive an 36. Harrison DE, Cailliet R, Harrison DD, Janik TJ, Troyanovich
ideal normal cervical spine model. J Manipulative Physiol SJ. Cervical coupling during lateral translations of the head.
Ther 1997;20:246-56. Clin Biomech 2000;15:436-40.
16. Harrison DD, Janik TJ. Clinical validation of an ideal normal 37. Williams PL, Warwick R. Grays anatomy. 36th ed.
static cervical spine model. In: Witten M, editor. Philadelphia: WB Saunders; 1980.
Computational medicine, public health, and biotechnology, 2. 38. Farfan HP. Mech disorders of the low back. Philadelphia: Lea
Austin, Tex: World Scientiﬁc Publishing; 1995. p 1047-55. & Febiger; 1973. p 34-5.
17. Janik TJ, Harrison DD. Prediction of 2-D static normal posi- 39. Woodhull AM, Maltrud K, Mello BL. Alignment of the
tion of the cervical spine from mathematical modeling. In: human body in standing. Eur J Appl Physiol 1985;54:109-15.
Witten M, editor. Computational medicine, public health, and 40. Wells KF, Luttgens K. Kinesiology: scientiﬁc basis of human
biotechnology, 2. Austin, Tex: World Scientific Publishing; motion. 6th ed. Philadelphia: WB Saunders; 1976.
1995. p 1036-46. 41. Hellebrandt FA, Tepper RH, Braun CL, Elliott MC. The loca-
18. Troyanovich SJ, Cailliet R, Janik TJ, Harrison DD, Harrison tion of the cardinal anatomical orientation planes passing
DE. Radiographic mensuration characteristics of the sagittal through the center of weight in young adult women. Am J
lumbar spine from a normal population with a method to Physiol 1938;121:465-70.
synthesize prior studies of lordosis. J Spinal Disord 1997; 42. Hellebrandt FA, Hirt S, Fries EC. Centre of gravity of the
10:380-6. human body. Arch Phys Ther 1944;25:465-70.
19. Harrison DD, Cailliet R, Janik TJ, Troyanovich SJ, Harrison 43. May J. The placement of the gravity line on the human body
in the anterior-posterior plane and its relationship to posture
DE, Holland B. Elliptical modeling of the sagittal lumbar lor-
by roentgenoscopic study [unpublished thesis]. Ames, Iowa:
dosis and segmental rotation angles as a method to discrimi-
State University of Iowa; 1955.
nate between normal and low back pain subjects. J Spinal
44. Smidt GL, Day JW, Gerleman DG. Iowa anatomical position
Disord 1998;11:430-9.
system: a method of assessing posture. Eur J Appl Physiol
20. Cowin S. Bone mechanics. Boca Raton, Fla: CRC Press;
1984;52:407-13.
1989. p 37.
45. Kapandji AI. The physiology of the joints. Vol 3. New York:
21. White AA, Panjabi MM. Clinical biomechanics. Phila-
Churchill Livingstone; 1974. p 15.
delphia: Lippincott; 1978. 46. Kendall HO, Kendall FP, Boynton DA. Posture and pain.
22. Harrison DE, Harrison DD, Troyanovich SJ. Three-dimen- Baltimore: Williams & Wilkins; 1952.
sional spinal coupling mechanics, I: a review of the literature. 47. Kuchera M. Gravitational stress, musculoligamentous strain,
J Manipulative Physiol Ther 1998;21:101-13. and postural alignment. Spine: State of the Art Reviews
23. Harrison DE, Harrison DD, Troyanovich SJ. Three-dimen- 1995;9:463-89.
sional spinal coupling mechanics, II: implications for chiro- 48. Kiefer A, Shirazi-Adl A, Parnianpour M. Synergy of the
practic theories and practice. J Manipulative Physiol Ther human spine in neutral postures. Eur Spine J 1998;7:471-9.
1998;21:177-86. 49. Hanten WP, Lucio RM, Russell JL, Brunt D. Assessment of
24. Carlsoo S. The static muscle load in different work positions: total head excursion and resting head posture. Arch Phys Med
an electromyographic study. Ergonomics 1961;4:193-211. Rehabil 1991;72:877-80.
25. Klausen K. The form and function of the loaded human spine. 50. Less M, Eihelberg W. Force changes in neck vertebrae and
Acta Physiol Scand 1965;65:176-90. muscles. In: Komi P, editor. Biomechanics. Vol VA. Baltimore:
26. Nachemson A, Elfstrom G. Intravital dynamic pressure mea- University Park Press; 1976. p 530-36.
surements in lumbar discs: a study of common movements, 51. Ferguson D. Posture aching and body build in telephonists. J
maneuvers and exercises. Scand J Rehabil Med 1970;1 Hum Ergol 1976;5:183-86.
(Suppl):1-40. 52. Biraune W, Fischer O. On the center of gravity of the human
27. Andersson BJG, Ortengren R, Nachemson A, Elfstrom G. body. New York: Springer-Verlag; 1985.
Lumbar disc pressure and myoelectric back muscle activity 53. Vital JM, Senegas J. Anatomical bases of the study of the
during sitting, I: studies on an experimental chair. Scand J constraints to which the cervical spine is subject in the sagit-
Rehabil Med 1974;6:104-14. tal plane: a study of the center of gravity of the head. Surg
28. Basmajian JV, Bentzon JW. Electromyographic study of cer- Radiol Anat 1986;8:169-73.
tain muscles of the leg and foot in the standing position. Surg 54. McKenzie RA. The cervical and thoracic spine: mechanical
Gynecol Obstet 1954;98:662-6. diagnosis and therapy. Waikanae, New Zealand: Spinal
29. Basmajian JV. Electromyography of iliopsoas. Anat Rec Publications, Ltd; 1990.
1958;130:267. 55. Garrett TR, Youdas JW, Madson TJ. Reliability of measuring
30. Floyd WF, Silver PHS. The function of the erector spinae forward head posture in a clinical setting. J Orthop Sports
muscles in certain movements and postures in man. J Physiol Phys Ther 1993;17:155-60.
1955;129:184-203. 56. Lundstrom F, Lundstrom A. Natural head position as a basis
31. Joseph J, Nightingale A. Electromyography of muscles of for cephalometric analysis. Am J Orthod Dentofacial Orthop
posture: leg muscles in males. J Physiol 1952;117:484-91. 1992;101:244-7.

A Normal Spinal Position: It's Time to Accept the Evidence

A Normal Spinal Position: It's Time to Accept the Evidence

Recomendados

Recomendados

Más contenido relacionado

La actualidad más candente

La actualidad más candente (20)

Destacado

Destacado (7)

Similar a A Normal Spinal Position: It's Time to Accept the Evidence

Similar a A Normal Spinal Position: It's Time to Accept the Evidence (20)

Último

Último (20)

A Normal Spinal Position: It's Time to Accept the Evidence