Robert Anderson

Department of Anthropology, Mills College, Oakland, California 94613, U.S.A.

Received 27 December 1983 and accepted 10June 1984

Keywords: Leg length discrepancy, pelvic rotation, sacral tilting, scoliosis.

Misalignments in the Human Pelvis Measured on Radiographs

Antero-posterior, 14" x 36" X-ray views of the upper femoral shafts, pelvis, spine and craniovertebral articulation were obtained for 200 patients with spinal pain in a public clinic. Intrapelvic and spinal asymmetries were measured. Twenty per cent showed rotation of the pelvis at the public symphysis-sacral tubercle axis of 1 cm or more. A physiologic leg discrepancy of 1 cm or more was identified in 19"5%. Lateral tipping of the sacral platform of 5 ~ or more occurred in 18"0%. In 5"0% of all patients, asymmetries on these levels of magni tude occurred in a pattern of pelvic shifting in which the low sacral base and short leg occurred on the side opposite to the side of pelvic rotation. The vertebra prominens near the cranial end of the spine deviated 1 cm or more laterally from the gravitational center in the sacrum in 40"0% of all radiographs. In 37"5%, at least 10 ~ ofscoliosis was seen. Misalignments in the foundation structures of the pelvis show a tendency to correlate with misalignments in the spinal superstructure, and thus to be associated with soft-tissue stress. The implications of these findings for human health need to be explored.

1. Introduct ion

Long after he had distinguished himself as the discoverer of Australopithecus, Raymond A. Dart published several provocative papers in which he drew attention to what he termed the pandemic condition ofmalposture (Dart, 1946a, 1947). He cited well-known contemporaries in orthopedics (J. E. Goldthwait) and paleoanthropology (W. E. LeGros Clark) to argue that 80% of the American and British populations exhibit poor body mechanics which leave them deficient in co-ordinated movement. Above all, Dart drew attention to lateral and rotational deviations in human neuromusculoskeletal mechanisms which anatomists and physicians customarily think of as bilaterally symmetrical.

The massive sheets of muscle that strengthen and move the trunk, specifically the musculi obliquus externus, internus and transversus abdominis, were identified as contributing to rotational imbalances. Every adult, Dart argued, "suffers to a greater or lesser extent as the result of having acquired a mild, moderate or even a serious degree of permanent postural obliquity, rotation or twis t . . . " . Indeed, he concluded, "this condition ofpostural twist is a fundamental factor to be taken into account in clinical conditions as widely separated as night terrors, spasticity and scoliosis . . ." (1946a, p. 9). Quite independently of Dart, a small number of investigators contributed more recently to our understanding of these phenomena. Ingebright Dalseth (1974), a Norwegian radiologist, documents extensive left-right asymmetries in the osseous structures of the craniovertebral joints. He notes differences in the size, shape and location of the occipital condyles and the lateral masses of the atlas, as well as lateral deviations of the dens. These asymmetries, he speculates, may well result in postural faults, dysfunction, and degenerative disease.

Another radiologist, J anJ i rou t of Czechoslovakia, has also explored asymmetries in the craniocervical area (1980). J irout found in a radiographic study that left-right positional asymmetries could be identified in the area of the occiput and the cervical spine in 94% of 600 human subjects. More precisely, he found that in 70% of these subjects, the occiput was rotated to the right of the posterior tubercle of the atlas.

Journal of Human Evolution (1984) 13, 593 600

0047-2484/84/070593 + 08 $03.00/0 �9 1984 Academic Press Inc. (London) Limited

594 R. ANDERSON

Inspired by Jirout, measurements carried out on dry specimens in the osteological laboratory of the Lowie Museum (University of California, Berkeley) identified a related shift in the basilar portion of the occiput (Anderson, 1983). It had moved to the left in slightly over half of 156 crania. From the same laboratory, an investigation of 215 American Indian skulls revealed that the sphenoid was rotated away from the central axis in one-third of the specimens (Anderson, 1982).

Comparable findings have been published for the pelvic area. From an examination of 132 skeletons, Radomir Cihak (1970) reports that in 37% of his specimens, the left and right sides of the sacrum differ in the inclination of the articular surfaces. This agrees with other studies, including a review of 3000 radiographs, in which approximately one-third of all spines display left-right asymmetries in the lumbosacral facets (Badgley, 1941; Hadley, 1950).

Two Harvard University anthropologists, E. Reynolds and Earnest A. Hooton, undertook a radiographic study of the pelvis in relation to upright posture nearly half a century ago. They reported intense frustration. "Obviously, the x-ray oilers the only possibly successful approach to this problem", they wrote. "With this unoriginal idea in mind, we some years ago undertook an investigation which has nearly brought clown our gray hairs in sorrow to the grave" (Reynolds & Hooton, 1936).

The present study is equally unoriginal. It does, however, report on rotation of the innominates, functional lowering of the height of the head of the femur, and lateral tipping of the sacrum, together with scoliosis and lateral deviation from the center of gravity of the vertebra prominens.

These findings are relatively direct and uncomplicated. No effort is made to investigate the far more difficult problem of identifying the harmful implications' lateral and rotational asymmetries may have for human health, although the creation of soft-tissue stress will be noted. Health was the issue that concerned Dart. It is the issue to which we ultimately must address ourselves. When we do, we may well echo the lamentations of Reynolds & Hooton, who spoke of "... hoping by trial and error we might eventually emerge from a morass in which we had become bogged". For the present, however, we are content merely to document the presence of pelvic asymmetries and their correlations with misalignments in the spinal column.

2. Methods

The first 100 adult patients of each sex to present with back pain in a new public clinic comprise the population of 200 whose radiographs were measured in this study. All patients were caucasoid and resident in a medium-sized town in Calitbrnia. They ranged in age from 20 to 81, with a mean of 34'9 and a standard deviation of 27-4. The examination of each included an unusual kind of X-ray exposure in the form of a full-spine view of the complete pelvis and upper femur shafts, together with the whole spinal column and the base of the cranium, all on a'single film.

These radiographs were not done for research purposes. They constitute part of the customary diagnostic procedure carried out in this clinic, and were undertaken solely for diagnostic and therapeutic purposes. Permission to examine them for this study was granted subsequent to, and independently of, their clinical use.

The following standardized format structured the taking of these X-ray films. Patients were positioned with their feet oriented to floor lines marking transverse and sagittal

M I S A L I G N M E N T S OF T H E H U M A N P E L V I S 595

direct ions. T h e y were ins t ruc ted to s tand in a way that felt normal to them, but with the heels of their s tockinged feet carefully posi t ioned agains t the transverse line while the media l aspects of their feet were kept equ id i s tan t from the sagi t ta l line. Ante ro-pos te r io r rad iographs , 14" X 36", were taken at a focal fi lm dis tance of 80" with the central ray focused at the m i d p o i n t between the base of the occiput and the ischial tuberosi t ies , both of which were inc luded on the film.

Six measu remen t s were per formed on each film by the invest igator or an assistant . Pelvic rota t ion was measu red in mil l imeters of r ight or left deviat ion of the pubic symphys is from

a vert ical l ine descend ing from the second sacral tubercle. La te ra l angula t ion of the sacral p la t form was measu red by d rawing a line through the sacral notches. Degrees of devia t ion from the b o t t o m of the film, which was hor izonta l to the ground, were recorded.

The extent to which one femur stood higher than the other was noted by d rawing a hor izonta l line across the top of each femur head and calcula t ing any differences between the two in mil l imeters . Rober t E. K a p p l e r (!982) points out tha t an ana tomica l ly shor t leg can be ident if ied in this manner . Such differences are uncommon, however, while our findings on many r ad iog raphs documen t the posi t ioning of one femur head lower than the other. I t is clear tha t in near ly all such cases the X - r a y films under considera t ion demons t r a t e a phys io logica l ly short leg ra ther than a s t ructura l deformity. In these pat ients , one leg appea r s shor ter than the other on film because shifts in pelvic or ientat ions result in differences in the degree of pe rpend icu la r i t y of the femur shafts. In such pat ients , the legs are ana tomica l ly equal in length, but funct ional ly unequal .

La te ra l cu rva tu re or scoliosis in any pa r t of the spine was measured using the technique ofJ . R. C o b b (1948). By this method , devia t ion in the coronal p lane is identif ied as an angle formed by the in tersect ion of lines d r a w n pe rpend icu la r to the rostral surface of the top ver tebra tha t is most angled at the p rox ima l end of the curve and the cauda l surface of the bo t tom v e r t e b r a tha t is most angled distal ly. Al though some prefer the R i s se r -Fe rguson method of ident i fying such curves, we chose the C o b b method as that now most commonly in use (George & Ripps te in , 1961).

As a measu re of the a l ignment of the spinal co lumn with grav i ta t iona l forces, la tera l d i sp lacements of the ve r t eb ra p rominens (C7) were identif ied by d rawing a pe rpend icu la r line from the center of tha t ve r tebra l body down to the level of the second sacral tubercle. Any la tera l d i sc repancy be tween the center of the sacrum and the center of C7 was recorded in mi l l imeters to the r ight or left.

3 . R e s u l t s

A str iking a m o u n t of pelvic misa l ignment is documen ted (Table 1). In 91-5% of all cases, ro ta t ion of the pelvis is demons t r a t ed at the pubic symphys is -sacra l tubercle axis. A total of

Table 1 P e l v i c and sp ina l n o n - a l i g n m e n t s

N % Range )T S.D.

Rotation 183 91 "5 (~29 ~ 5"93 ~ 14-16 ~ Short leg 190 95"0 0-22mm 5"44mm 13"45mm Tilted sacrum 175 87.5 0-10 ~ 2"23 ~ 6'6 ~ Scoliosis 130 65'0 (>43 ~ 7'53 ~ 10.48 ~ Lateral deviation of C7 193 96"5 0-49mm 7"06mm 17'89mm

N = 200. For explanations of the terms and measures, see the section on methods.

596 R. ANDERSON

20-0% are rotated 1 cm or more. A max imum rotation of 29 ~ is recorded, with a mean of 5"9 ~ and a s tandard deviation of 14"2 ~ Of all those demonstra t ing rotation, 55'2% were rotated to the left and 44'8% to the right. Since the handedness of patients was not recorded, the possible role of hand dominance in these frequencies could not be calculated.

A short leg is recorded in 95"0% of the X-rays. In 19"5% of all cases a leg inequality of 1 cm or more is found, with a maximim of 22 mm. The mean inequality is of 5"4 m m with a s tandard deviation o f 13-5 mm. Sacral tilting is identified in 87'5% of all subjects. Eighteen per cent are angled 5 ~ or more. The max imum recorded angulat ion is 10 ~ with a mean of 2"2 ~ and a s tandard deviation of 6"6 ~

A number of clinicians have drawn attention to a common pattern of intrapelvic asymmetry (Bourdillon, 1973; Grieve, 1981). Opposite the side on which the ilium is rotated forward, as demonstra ted by movement of the pubic symphysis across the midline, they note that the sacral platform tends to angulate downward and the leg tends to be physiologically short. This form of pattern shift proves to be quite common.

We record it in 56"5% of all patients. In 5 '0% the pat tern involves a t leas t 1 cm of pelvic rotation, 1 cm of leg length discrepancy, and 5 ~ of sacral base angulation.

Deviations laterally of the vertebra prominens are found in 96-5% of all radiographs. In 40"0%, the deviation is 1 cm or more. These deviations range as high as 49 m m , with a mean of 7"1 m m and a s tandard deviation of 17"9 mm.

Scoliosis is measurable in 65"0% of the population. Cobb ' s angles of 10 ~ or more are seen in 37 ~ 5%. The most scoliotic patient demonstrates an angle of 43 ~ The mean is 7"5 ~ with a s tandard deviation of 10'5 ~ .

In order to explore possible relationships between foundation distortions in the form of intrapelvic asymmetries and superstructure misalignments in the form of scoliosis or gravitational deviations, we looked for correlations between the two (Table 2). The u correction formula was used in calculating the chi-square values.

Distortions in the pelvic girdle on the order of at least 1 cm of rotation, 1 cm of leg length discrepancy or 5 ~ of sacral angulat ion consistently show a correlation with the presence of a scoliosis of 10 ~ or more, or a deviation of the vertebra prominens of 10 ~ or more, or both. The phi-coefficients reveal that these correlations are significant, but of a low order (Table 2). The highest correlation involves the pat tern shift in which all three foundat ion misalignments occur simultaneously. A phi-coefficient of +0'521 for this condition of pat tern shift coexisting with spinal deviation or scoliosis, or both, would indicate that about 27" 1% of the variance of the pelvic foundation in these cases is associated with the variance that coexists in the spinal superstructure. Al though all correlations are of a low magnitude, pelvic rotation, leg length discrepancy and tilted sacrum separately also tend to vary with spinal deviation and /or scoliosis.

4. Discussion

Dart was right to draw attention to the prevalence of"pos tura l twist" in modern people. As noted above, this s tudy documents high frequences of pelvic rotation, functional short leg and sacral tilting together with lateral inclinations of the spinal column and scoliosis.

The populat ion under study here is distinguished by presenting to a clinic with either back or neck pain or both. In terms of skeletal alignments, it is probable that it is not representative of the populat ion at large, since back or neck pain may well influence joint relationships. I t is also possible, however, that this populat ion is not greatly different

Tab

le 2

C

orre

lati

ons

betw

een

foun

dati

on d

isto

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ns a

nd s

uper

stru

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e m

isal

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ents

Ro

tati

on

S

ho

rt l

eg

Til

ted

sa

cru

m

Pat

tern

>

~10

mm

0

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m

>~1

0 m

m+

0

-3 m

m

>15 ~

0

-1 ~

sh

ift

Fu

ll

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gn

me

nt

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No

sco

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sis

un

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ign

ific

ance

23

25

)~2

=

p =

~

=

17

21

25

28

13

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16

43

g

36

1 5"

48

X ~

=

5"10

Z

2 =

18

"11

X ~

=

6"00

>

0'0

2

P =

>

0"0

5

P =

>

0"0

01

P

=

>0

"02

+

0"2

19

OO

=

+0

"22

1

e~

=

+0

"46

2

�9

=

+0

-44

7

Dev

iati

on

/> 1

0 ~

No

dev

iati

on

un

de

r 5 ~

S

ign

ific

ance

19

21

X2

=

p =

~

=

31

21

21

22

21

6 4

4

17

46

14

28

4

13"1

5 Z

2 =

5"

83

X z

=

2'7

8

X ~

=

2.5

6

>0

"00

1

P =

>

0"0

2

P =

>

0"1

0

P =

>

0"2

0

+0

"33

8

�9

=

+0

"23

6

q)

=

+0

"18

2

�9

=

+0

'30

0

11 9

Sco

lios

is a

nd

/or

dev

iati

on

N

eith

er s

coli

osis

no

r d

evia

tio

n

Sig

nif

ican

ce

ll

p =

c

)=

29

45

33

37

35

30

6 29

1

21

0 9-

56

X s

=

10"5

8 )~

2 =

12

-89

X a

=

8"13

>

0"0

1

P =

>

0-0

1

P =

>

0"0

01

P

=

>0

"01

+

0"2

88

�9

=

+

0'3

18

q)

=

+

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90

�9

=

+

0"5

21

Dev

iati

on

ref

ers

to l

ater

al d

isp

lace

men

ts o

f C

7

fro

m t

he

cen

ter

of

the

sac

rum

. P

atte

rn

shif

t re

fers

to

th

e co

mb

inat

ion

of

rota

tio

n,

sho

rt l

eg,

and

sac

ral

tilt

as

des

crib

ed i

n t

he

tex

t, w

ith

all

th

ree

me

asu

res

in t

he

hig

her

ran

ges

. In

ful

l al

ign

men

t, r

ota

tio

n,

sho

rt l

eg a

nd

til

ted

sa

cru

m a

re a

ll at

th

e m

inim

al

fig

ure

s o

f th

is

tab

le.

"M

598 R. ANDERSON

because of spinal pain. The relationship of these measures to symptoms is not known (Nichols, 1960) .J .D.G. Troup (1975), an orthopedist, makes a telling point in this regard. "Almost every pathological change to which back pain has been attributed has subsequently been demonstrated in the symptom-free population".

It is not possible from this study to comment upon the possible effects upon health of either pelvic rotation or sacral tilt, since all patients were symptomatic whether they were characterized by these misatignments or not. Leg length inequalities are another matter. Two previous studies give reason to think that a discrepancy of 10 mm or more has clinical significance.

Physiologic short leg is reported by Alan Stoddard (1969) to be correlated with back pain. "In a series of 100 consecutive cases of backache, 60 per cent were found to have 1/4 in. [6-35 mm] or more of femoral discrepancy as compared with 28 per cent of fifty patients who had no backache symptoms". A closer examination of these figures reveals a phi-coefficient of +0"356, which is the same significant but low level of correlation that we find relates short leg to scoliosis and/or spinal deviation.

Giles & Taylor (1982) finds that a leg discrepancy of 10 mm or more correlates with degeneration in the lumbar spine measured on radiographs. Comprising 50 patients with a leg length difference greater than 9 mm and postural scoliosis with 50 patients evincing no leg length difference (0-3 mm) and straight spines, they report striking findings. Asymmetric concavities in the end-plates are found in 28% of those with short legs and in only 2% of controls. Asymmetric wedging of the fifth lumbar vertebra is found in 10% of those with short legs and in none of the controls. Finally, they document bilateral traction spurs and osteophytes in 83% of patients with leg length differences and in only 25% of the controls.

It should be noted that by including the presence or absence ofscoliosis as an additional variable, this study obscures the role of the short leg as such in vertebral degeneration. Be that as it may, however, re-evaluation of their findings reveals correlations that are significant, but limited. Phi is +0"232, +0'365 and +0-581 respectively for the above cited percentages. These correlations, again, are of the same order of magnitude as those found in our radiographs when leg length discrepancies are compared with spinal deviation or scoliosis. The orthopedic and rheumatological literature provides a basis, then, for assuming that the pelvic misalignments recorded in this study tend to correlate with painful symptomatology or spinal pathology.

We document a tendency for pelvic misalignments to correlate with misalignments in the spinal column. This correlation may well be associated with clinical musculoskeletal stress.

The amount of stress that is associated with spinal laterality from the center of gravity, as measured by the displacement of the C7 vertebra, is unknown. John J. Triano (1983) has demonstrated that lateral deviations correctable by the prescription of heel lifts designed to level the pelvis result in equalizing electromyographic activity in the paraspinal musculature on both sides of the spinal column. Before treatment, his patients showed a dominance of muscular activity on one side. Paraspinal dominance is statistically correlated with the frequency of low-back pain, according to Triano (1980). By extrapolation, then from the findings of Triano, we may conclude that deviations from gravitational balance can be expected to result in muscular imbalances between the two sides of the trunk, and that these may result in back pain. The amount of deviation that is

MISALIGNMENTS OF THE HUMAN PELVIS 599

necessary to cause clinically meaningful stress, however, is not known. Although 40"0% of the patients in the present study show a deviation of 1 cm or more, we cannot know that the muscular stress implied by that much deviation is associated with symptoms.

Orthopedists consider a scoliosis measuring 10 ~ or more to be clinically significant (Brooks, 1980; Willner & Ud6n, 1982). I n Minnesota, angulations of 5 ~ or more are recorded as representing identifiable scoliosis (Lonstein, 1977). The clinical implications of a 10 ~ Cobb ' s curve are not great, however. Such a curve merely alerts practitioners to the possibility that a larger and more dangerous condition may evolve. "The aim of early detection of scoliosis is p rompt diagnosis and the institution of appropriate orthotic treatment, thus reducing the need for surgical t reatment" (Lonstein et al., 1982.) Even small curves, however, result in e lectromyographic imbalances (Anonymous, 1982). To the extent that muscles on the concave side o f a scoliotic curve are contractured relative to those on the convex side, musculoskeletal stress is clearly present.

To conclude, then, functional asymmetries in pelvic and spinal structures prove in this study to be very common. The various misalignments show a tendency to vary co-ordinately. They result in conditions that appear to induce musculoskeletal stress into the system, and other investigators give reason to think that some back pain may have its origin in this process. Al though limited, these findings are sufficient to justify the allocation of research energies to explorations that go in a different direction from the study of structural relationships as these have been customary in physical anthropological research. Research is also needed to elucidate functional relationships. Physiologic asymmetries appear to be very common in Homo sapiens, and we need to know more about them.

References

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Anderson, R. T. (1983). Angulation of the basiocciput in three cranial series. Current Anthropology 24 (2), 226-228. Anonymous (1982). Electrical stimulation of muscles replaces braces for scoliosis. `journal of the American Medical

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600 R. ANDERSON

Jirout, J. (1980). Einfluss der einseitigen Grosshirndominanz aufdas R6ntgenbild der Halswirbels~iule. Radiologe 20, 466-469.

Kappler, R. E. (1982). Postural balance and motion patterns. Journal of the American Osteopathic Association 81 (9), 598-606.

Lonstein, J. E. (1977). Screening for spinal deformities in Minnesota schools. Clinical Orthopaedics and Related Research 126, 33-42.

Lonstein, J. E., Bjorklund, S. et al. (1982). Voluntary school screening for scoliosis in Minnesota. The Journal of Bone and Joint Surgery 64A (4), 481-488.

Nichols, P. J. R. (1960). Short-leg syndrome. British Medical Journal, 18 June, 1863. Reynolds, E. & Hooton, E. A. (1936). Relation of the pelvis to erect posture. American Journal of Physical

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spinae of low back pain subjects. Proceedings of the Eleventh Annual Biomechanics Conference on the Spine. Boulder, Colorado: Biomechanics Laboratory, University of Colorado.

Triano, J. j . (1983). Objective electromyographic evidence for use and effects of lift therapy. Journal of Manipulative and Physiological Therapeutics 6 (1), 13-16.

Troup, J. D. G. (1975). The biology of back pain. New Scientist 65, 17-19. Willner, S. & Ud~n, A. (1982). A prospective prevalence study ofscoliosis in southern Sweden. Acta Orthopaedica

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