Ernest Eckford Tucker
SACRUM LIMITATIONS TO MOTION: Lesions: Correction
The study of the limitations to motion in the joints
of the body is important for several reasons; first among them this, that
beyond that limitation is the danger of lesion; second, that since, for
correction, tension must be gotten on the bones in lesions, and since to
get tension on them they must be carried to the limit of their normal motion,
therefore this knowledge is essential to a scientific technic.
There is no proper motion at all in the sacrum.
If it moves at all it is in excess of the limitations of its motion, and
with danger of lesion. Normally there is a mere elastic yielding
of the ligaments of the sacrum, with possibly a slight grinding of the
articular surfaces. In view of the fact that many statements on this
subject have been made of an opposite character, this statement requires
In the first place I challenge anyone to show where
Dr. Still has said that the sacrum normally moves on or between the innominates
in mature persons. That the sacrum is found in lesion, having been
moved abnormally, he has said; and the fact is proven daily in Osteopathic
experience. But this is not to attribute normal motion to the sacrum.
Tests made in the classes above referred to at the
A. S. O. seemed at first to give positive results in many cases.
First the diameter between dorsum of sacrum and symphysis pubis seemed
to be increased in flexion of the body, decreased in extension. A
moment’s thought will reveal the interesting fact that this is motion in
the wrong direction, if it is motion at all. Second, the interval
between the posterior iliac crests seemed to decrease with flexion and
to increase with extension. This again is the wrong motion, if the
sacrum moves as above indicated. A moment’s thought will reveal the
interesting fact that to accomplish this motion either the bones at the
symphysis pubis must be absolutely separated from each other and by several
times as ;much as they are approximated at the posterior superior spines—being
much the longer arm of the lever; or else the sacrum must slide forward
far enough to allow this approximation—a very great distance, because the
sacro-iliac surfaces are not beveled in and back at all points of the surface,
but are uneven and actually slope out and back at some points, which points,
small though they be, would absolutely determine a separation instead of
an approximation of these spines if the sacrum glided downward and forward
in flexion of the trunk within the area oaf the articular surface.
This seeming motion was then found to be due to the
tensing of the fibrous mass at the root of the erector spine muscle, both
over the dorsum of the sacrum and between the iliac spines. It was
found impossible to make satisfactory measurements of body movement in
active emotions of the body on account of this fact; and in passive movements
t here was to some extent the same difficulty, and also little or no force
leading to movement of the sacrum in any case.
We then have resource to anatomical examination of
the parts for evidence of movement or the lack of it. All evidence
points to lack of it. We find that the sacro-iliac joint is not smooth,
as it would have to be to permit of actual normal motion; that fibrous
adhesions are the rule between the opposing surfaces. Why then the
articular membranes, or the remains of them? Examining the surfaces
with the eyes closed, the fingers are able to outline in practically all
sacra an uneven groove about the width of the ends of the fingers describing
a fairly accurate curve, concentric about a point which proves to be the
point of attachment of the sacro-iliac ligament—the great ligament by which
the sacrum is suspended. It may be supposed then that the sacrum
did move about this center in early life or in foetal life; perhaps chiefly
at the time when the child is learning to walk upright, before the bone
is fully developed. This groove should define whatever motion might
be normal to the sacrum; which would be a turning about this center with
a freer movement of the caudal end; but at the caudal end this motion is
checked by the great sacro-sciatic ligament, and is probably no greater
than is allowed by the stretching of this ligament. (In the immature,
before the sacral vertebrae became ossified, motion might have occurred
with bending of the sacral vertebrae on each other.)
Why would not motion occur in the opposite direction,
that is with depression of the caudal end and relaxation of the sacro-sciatic
ligament? Because every normal force that applied to the sacrum forces
it in the opposite direction. On the front end the full weight of
the body together with the force of its muscular action pressed down; on
the caudal end the great tension of the erector spinae muscle pulls up.
Of the other muscles, the gluteus maximum and pyriformis pull out, and
the muscles of the pelvic floor, small and delicate, are the only ones
that pull down.
The sacro-iliac joint is a spring joint, a safety
joint, without normal functional movement.
The limitations to motion in this joint are those
of the uneven (as though dove-tailed) joint, the great sacro-iliac ligament,
largest in the body (sometimes an inch in diameter); the sacro-sciatic
ligament, scarcely less strong, and the suspensory ligament on the ventral
aspect. Sometimes there is a further limitation formed by actual
contact of the posterior superior spine of the ilium with the dorsum of
the second sacral vertebra, making another pseudo joint in the horizontal
plane. Except for the elasticity of these ligaments and the cartilage
of the joint, these limitations are absolute.
Although the sacrum does not move, it yields in elastic
fashion to foraces of movement. The direction of the fibres of ligaments
is the key to the direction of lines of tension. Some of the fibres
of the sacro-iliac ligament incline inward, from iliac crest to sacral
spines, indicating that there is often tension in this direction; which
tension would incline the articular surface to gap open on the dorsal side,
with leverage at the ventral side of the articular surface; as in walking
when the opposite leg is lifted. Advantage is taken of this in the
correction of lesions. The greater proportion of the fibres of this
ligament extend directly down, in the line of the weight of the body.
MECHANICS OF SACRAL LESIONS
More than ninety per cent of the lesions of the sacrum
present a slipping of that bone ventrally on its articulation with the
ilium (the so-called posterior innominate). This may be unilateral, the
axis of rotation being of course the opposite side; or as in probably fifty
per cent of the cases, bilateral.
This lesion would seem to involve a direct stretching
of the great sacro-iliac ligament. The size of this ligament is tremendous,
such that production of lesions would seem to require overwhelming force.
This, however, is not the case. Lesion does not involve direct stretching
of this great ligament, but on the contrary stretches only a few of its
outer fibres. Examining the mechanics of the part we find that as
the sacrum slips forward it first turns so as to lie at a more acute angle
with the iliium, and that then the tension on the fibres of this ligament
draw down the crest and the posterior superior spine closer to the dorsum
of the sacrum; draw it down by as much as the fibres are tensed, so that
only those fibres closest to the ilium itself are unduly stretched, while
those farthest from it (those passing to the sacral spines) may be actually
relaxed; the intervening ones being neutral, or slightly stretched or slightly
relaxed, according to position. The articulation itself is then gapped
at the bottom and under heavy pressure at its top edge, where an indentation
is made in the soft tissue of the periosteum and the articular membranes
by the upper corner of the sacral articular surface; the whole bone on
that side being found slightly forward of its normal position.
This change is, of course, reflected to the opposite
articulation. If on the depressed side there is a gap below, then
on the sound side there must be a corresponding gap above, with tensing
of the ligaments along the upper edge. Wherefore we often find that
there is more tenderness along the inside of the iliac crest of the sound
side than there is on the side in lesion; except that at the point where
the sacrum emerges from between the ilia (the sacro-iliac “X”) there is
always more pain on the lesion side.
Nature always distributes equally the tension on
ligaments so far as possible; indeed that is a ;mechanical result
in any structure not absolutely rigid. That brings about secondary
changes in position of these bones. The ligaments involved here are
the two sacro-iliac ligaments, the one tensed, the other partly tensed
and partly relaxed, and the suspensory ligaments, the one tensed (on affected
side) the other relaxed. We have also the joint gapped below on the
affected side and gapped above on the sound side. The natural effect
therefore is to so swing the whole pelvis that these tensions are balanced.
Being hinged only at the symphysis, this shift of position is easy.
The first shift swings both articulations to the side opposite the
lesion. But this leaves the gaps still greater. To more or
less close those the second shift occurs, which is a rotation, forward
on the sound side, backward on the lesion side. Experimenting with
the actual bones in the position of sitting one quickly realizes to what
this leads—a tilting of the two innominata so that the posterior superior
spine of the affected side is lower or nearer the table than its fellow.
It is this secondary result that gave rise to the diagnosis of “rotated
ilium.” But the sound side being shifted forward there is a natural
tendency to force this ilium backward—to cause lesion also on this side.
There is usually a perceptible difference in the
tension of the sacro-sciatic ligaments, it being less on the sound side.
The relative height of the posterior superior spines
from the table in sitting is altered by difference in thickness of the
cartilaginous pads, in tension of muscles, in habits of sitting, etc.,
which make that an unreliable basis for diagnosis. In general all
measurements that involve other joints or other factors than the actual
bones in lesion and at the very points where lesions occurs, are unreliable.
Diagnosis should be made at the very point where lesion actually exists,
or as near to it as possible.
Diagnosis of sacro-iliac lesion should be made at
the only points where the bones are in actual contact that is reachable
by the examining finger—at the points where the sacrum emerges from between
the two ilia, the sacro-iliac “X,” just below and in contact with the posterior
superior spines of the ilia.
Patient seated on table; operator seat ed on stool
behind; places two thumbs on posterior superior spines and notes corresponding
points of the two; passes thumbs downward until they com into contact with
the dorsum of the sacrum. The thumbs should then lie with the balls
pressing on the dorsum, the upper edges pressing against the inferior margins
of the posterior superior spines. Difference may be noted on the
two sides. On the side in lesion there will be greater depth between
posterior superior spine and sacrum, possibly a definite gap; possibly
the edge of the ilium below the spine may be flelt as it turns forward
and grows more sharp. More or less sensitiveness should be noted
on the affected side. There is rarely so much fat here as to make
CORRECTION OF ANTERIOR SACRUM
The lesion above described is usually defined as
a “rotated ilium” or “posterior innominate,” but in reality is much more
accurately defined as a sacrum anterior on one or both sides.
Patient lying on side on table, lesion side uppermost.
Assume that lesion is on right side. Patient lies on left side.
Extend left leg; draw right knee in front and place in contact with table.
Operator stands facing patient. With left hand outlines the crest
of ilium, places forearm along crest so as to bring pressure on whole anterior
and upper edge thereof, especially over the anterior superior spine.
(Caution: Operator must not allow elbow to
come into contact with patient at any point, as it causes exquisite pain;
operator must not allow forearm to slip down from upper edge of crest so
as to bring pressure on the fibres of the glutei muscles which are here
raised from the bone in tented fashion; as this both defeats the purpose
of the technic and causes much pain to patient.)
With forearm thus placed operator is in position
to produce pressure downward and forward over iliac crest and particularly
over anterior superior spine, the effect of which is to bend the ilium
down in front and up in the back around an axis passing through the symphysis
and the points in contact in the lesion, so as to reverse the gapping in
the lesion; to cause, that is, gapping behind and to prize up the engaged
corner of the lesions from its indentation.
Operator then places right forearm in the hollow
of the patient’s right shoulder (grasping for convenience the fat of the
patient’s forearm, being careful that the sharp olecranon process does
not hurt patient’s pectoral muscles). He rotates the shoulder back
and slightly down, and rotates the ilium forward and slightly down, both
at the same time, until all of the intervening joints are at the limit
of their normal tension, making sure that the patient’s muscles are all
relaxed. This position alone with practically no tension is sufficient
to correct many lighter lesions, proving the correctness of the technic.
Pressure is then exerted backward and downward on the shoulder, forward
and downward on the ilium, until the articulation yields and is restored.
Force must be adjusted to the stubbornness of the lesion. A quick
and shallow thrust is better than a gradual one which requires to be much
heavier, as will be explained later.
Mechanics: The student should follow the effect
of the force that he applies from the point where he applies it, through
all intervening joints, ligaments or muscles, to its actual effect in correcting
the lesion. The force applied to the shoulders tenses pectoral and
serratus muscles, passes to ribs, thence to transverse processes and the
spine as a whole, which it carries back over the fulcrum of the right shoulder
and also rotates, as far as the sacrum, which is being held. At the
sacrum it is effective in drawing back the base, through traction, and
drawing back the upper articular surface through rotation over the lower
articular surface as fulcrum.
The effect of the force applied to the anterior superior
spine is as noted.
Criticisms. This technic as practiced especially
by beginners shows usually certain typical faults. The operator forgets
and leans his weight on the pelvis without making sure that it is applied
at the anterior superior spine. Or he makes jerky motions without
first getting the patient relaxed and his spinal joints all at the limit
of their motion—in which case the whole effect of the energy is used up
in them, and not in correction of the lesion. Or, before making the
quick and shallow thrust, he releases, draws back as it were, however slightly,
when of course the patient’s muscles follow him and the effect is lost
because the joints are not at the limit of motion before the corrective
pressure is applied.
Some straining of the pectoral muscles is usually
felt, but is not so severe as to make the treatment painful, with care
and practice. Poppings at various points along the spine may be noted,
which may or may not have significance. Usually it is very easy to
correct lesions and very hard to produce them, so that unless specially
indicated these poppings may be ignored, as they are probably corrective
in themselves. In some patients, especially in females with large
pelvis and short waists, this technic puts such a strain upon the tissues
about the twelfth rib that it cannot be used.
OTHER LESIONS OF THE SACRUM
In rarer cases the sacrum is found deviated not at
all ventrally but caudally—the articulation having slipped in its longitudinal
axis. Diagnosis of this lesion is very difficult. When it is
suspected, have patient on side with lesion uppermost, as before, his back
near to back edge of table; extend left leg; lift right leg, carry backward
beyond edge of table, and allow it to hang down as far as possible.
Operator now fixes shoulder of patient with his right arm or axilla, while
with right hand (if possible) he presses up and forward on affected tissues,
and with left hand lifts patient’s right leg and then carries it smartly
downward behind table to full limit, so as to spring the right ilium away
from the sacrum, which is being held by traction through the spine.
The practical success of this technic seems to depend on keeping the pelvis
in such position of balance, that the downward thrust takes effect at the
articulation, and not on the muscles in front of or behind it; and on keeping
the spine in such alignment that it exerts firm traction on the sacrum.
Mechanics: The lower articular surface becomes
the fulcrum, traction through the spine over this fulcrum draws upper surface;
force applied to leg finds its fulcrum at the symphysis and the sacro-iliac
X and so gaps open the whole joint and draws down on lesion.
In still rarer cases the sacrum is found displaced
dorsally. These cases give a history usually of some unusual form
of violence, as wrenches in foot ball games, railroad wrecks, etc.
Diagnosis is difficult, may even be said to be presumptive and by exclusion.
The correction is, however, extremely easy, so easy in fact that there
is danger of over-correction, or of producing lesion where none exists.
Patient seated on table, operator stands behind.
Assuming that the sacrum is displaced dorsally on the right:
Operator places fingers of right hand along crest of ilium with enough
pressure to secure a hold for the fingers; the thumb extending over the
crest and bringing pressure ventrally on the dorsum of the sacrum by means
of the hold with his fingers. Operator then passes his left arm under
patient’s left axilla and grasps patient’s right shoulder, carrying patient
slightly forward and partly supporting his weight. With the left
arm he then rotates the patient’s shoulders, the right forward, the left
slightly backward until the spinal joints are all at the limit of their
motion and on tension, then brings extra tension to bear in the same direction,
with pressure from the right thumb. The lesion is usually felt to
Merchanics: Elastic yielding is prevented by
thumb and finger pressure so that joint is gapped by the rotation and slid
forward by the thumb pressure.
Many other forms of technic are in vogue. Many
of them are open to criticism on this very simple mechanical ground—that
they do not consider the necessity of having tension on both of the bones
involved in the lesion. To break a stick it is necessary to have
hold of both ends. For instance the following very simple form of
technic for right anterior sacrum which looks at first sight very simple
and correct, is yet found to be not effective, and for the reason that
will be pointed out. Patient lying on face on table; operator stands
on side opposite to lesion (left side); draws patient’s shoulders from
table until patient’s axilla rests over operator’s right thigh; grasps
shoulder on side of lesion with left hand and lifts until all spinal joints
are at limit of motion. With right hand reaching across table he
presses down on posterior superior spine of ilium in lesion; then with
extra pressure and lifting-rotation-traction of shoulder he endeavors to
This technic is rarely successful for the reason
that the pelvis is not fixed; so that the only effect of the effort is
to turn the pelvis around the axis made by pressing the anterior superior
spine against the table. The effort is not focused on the lesion
and is wasted. Sometimes, however, it is successful (where pelvis
is heavy enough to fix left ilium against table).
The same criticism may be made of the technic which
lifts the leg of the side in lesion while pressing down on the posterior
superior spine. There is nothing to hold the sacrum. Except in patients
with very large chests and relatively stiff spines, the effort is wasted.
Two forms of technic which depend for success on
a sudden jar rather than on well directed tensions may be described.
Patient prone on table. Operator stands at side of lesion.
Lifting heels and sliding knees from table toward side of lesion (toward
himself), with turning of pelvis, he carries knees well up (while chest
remains flat on table). Operator then hooks pisiform bone of other
hand under posterior superior spine of lifted ilium, prepared to follow
it with pressure as it rotates toward prone position in next phase.
Then grasping and lifting ankles until tension is complete, and keeping
ankles well in air so as to lift knees above level of table, he swings
legs back to prone or median position and beyond, with pressure always
over posterior superior spine of affected side.
Mechanics: At moment of correction there is
tension caudally (through legs) and ventrally (through pressure of hand)
on ilium; and tension upward and dorsally on sacrum (through spine).
The value of coming suddenly to limit of motion in this way is that patient’s
muscles are all relaxed and that the quick tension in the right direction
more easily overcomes the elastic “set” of the parts.
The other form of using this same principle is applied with
patient prone, assistant maintaining continuous heavy pressure over posterior
superior spine of affected side; operator grasps ankle and lifts leg of affected
side, and without allowing it to touch table, cracks it downward as though cracking
a whip—a downward and an upward jerk, with traction.