Sacrum

Question 1

Sacrum anatomy

Answer 1

The sacrum consists of 5 fused vertebral segments.
It articulates with the lumbar spine, ilia, and coccyx.
It’s anterior surface is concave and posterior surface is convex
In its center is the sacral canal with the caudaequina and 4 sacral spinal nerves which exit from the foramina.
The top of the sacrum is the sacral base (wide and flat like the top of home plate)
The bottom is known as the apex
The sacral promontory is the anterior portion of S1

Question 2

Anatomy (weight bearing)

Answer 2

The weight of the upper body is transmitted through the sacrum and its ligamentous attachments to the pelvis via the iliolumbar, sacrospinous, &sacrotuberous ligaments.
The anterior and posterior sacroiliac ligaments are extremely strong and connect the sacrum to the pelvis.

Question 3

Muscles of the Sacrum

Answer 3

Piriformis: 2nd-4th sacral segments (anterior attachment)
Iliacus: superolaterally
Pelvic diaphragm (particularly coccygeous): Anteriorly to sacrotuberous &sacrospinous ligaments
Aponeurosis of the erector spinae and Latisimus dorsi: Posterior-medial surface
Gluteus Maximus: Inferior Lateral Angle

Question 4

Lumbosacral angle

Answer 4

also called Ferguson’s angle

The angle is generally between 25-35 degrees
An increase in this angle can increase lumbosacral strain

Question 5

Landmarks for diagnosis of the sacrum

Answer 5

The sacral sulci may be found moving medial and slightly superior to the PSIS bilaterally.

Physician places the palm of his/her hand on the sacrum. The most posterior/inferior aspect of the sacrum is the level of the Inferior Lateral Angles. The thumbs are then placed on each ILA.

Question 6

The axes of sacral motion

Answer 6

The sacrum has SEVEN axes of motion
1 vertical: allows for left/right rotation
1 Anterior-posterior: allows for sidebending
3 Transverse: Allows for flexion and extension.
2 oblique axes: Combines rotation, sidebending, and flexion/extension.

Question 7

transverse axes of the sacrum

Answer 7

Superior transverse / (thoracic) Respiratory axis. (S2)
- Flexion and Extension occurs with respiration.
- The sacrum flexes with exhalation
- The sacrum extends with inhalation
Middle transverse / Postural/Sacroiliac axis. (S2)
- At the anterior convexity of the upper and lower limbs of SI joint
- Flexion and extension occurs with motion of the sacrum on the ilium.
Inferior transverse / Iliosacral axes. (S3)
- At the posterior-inferior part of the inferior limb of SI joint.
- Flexion and extension occurs with motion of the ilium on the sacrum.
BOTTOM LINE: All 3 axes allow flexion & extension.

Question 8

Oblique sacral axes

Answer 8

Named for the SUPERIOR aspect.
The axis that runs from the right superior aspect of the sacrum (right sulcus) to the left inferior aspect of the sacrum (left ILA) is the right oblique axis.
The axis that runs from the left superior aspect of the sacrum (left sulcus) to the right inferior aspect of the sacrum (right ILA) is the left oblique axis.

Question 9

Dynamic sacral motion

Answer 9

During the gait cycle:

With walking, sacrum alternates: right-on-right, neutral, left-on-left, neutral, etc.
In stance phase, an ipsilateral oblique axis is created, and the sacrum moves anteriorly (obliquely) about this axis.
The lumbar spine sidebends ipsilateral to the weighted foot because of quadratus lumborum contraction.
This motion is physiologic (normal), however, when this motion is limited or fixed in a non-neutral position dysfunction occurs.

Question 10

Gait from the osteopathic viewpoint: SI joint dysfunction

Answer 10

Can lead to inhibition of the glut max and medius
- This shortens the stride
- The hamstrings are the recruited and overused to help extend the hip and leg
- The erector spinae are also recruited and overused
The QL (stabilizer of the L-spine)
- This muscle will spasm causing low back pain
- It can also be activated by standing on the same leg constantly or by jumping and landing on the same leg multiple times
The “jammed butt syndrome”
Remember the fascial connection from the foot into the TL region
- Any disruption in this chain can cause gait abnormalities

Question 11

Why is this important?

Answer 11

Gait abnormalities can cause up to a 300% increase in energy expenditure
The average adult completes 2500 stance-swing cycles per day
Ave 80 minutes of weight bearing activity per day
So athletes do quite a bit more
This is about 1,000,000 steps/year for each limb
Any minor dysfunction is magnified by 1,000,000

Question 12

L5 “rule”

Answer 12

in a sacral torsion, the sacrum and L5 rotate opposite each other.
Forward sacral torsions occur with NEUTRAL mechanics in the lumbar spine. (Type 1)
Backward sacral torsions occur with NON-Neutral mechanics in the lumbar spine. (Type 2)

So, in a Left on Left sacral torsion, it is expected that L5 is rotated to the RIGHT, and sidebent left.

Question 13

AGR

Answer 13

The Area of Greatest Restriction screen will determine if the sacrum/pelvis is the best place to begin treatment.
Decreased motion over the SI area (often accompanied by increased paraspinal tension in the lumbars) is a clue to evaluate the SI area further.

Question 14

Seated flexion test

Answer 14

Seated flexion test determines the motion of the sacrum upon the ilium. This test is performed in the seated position to take away pelvis and lower extremity muscle influences.
The side which moves first and farthest is the positive side.
The side which is positive is usually the side of dysfunction. False positives exist due to muscle influences.
In sacral torsions the side of the positive test is ipsilateral to the dysfunction, but contralateral to the oblique axis.
In sacral sheers, (flexions/extensions) the side of the positive test is ipsilateral to the dysfunction.

This is a lateralizing test—it determines left or right.

Question 15

ASIS Compression Test

Answer 15

This procedure will test the three transverse axes of the SI joint.
Attempt to disengage the ilium from the sacrum and drive the innominate posterior.
To evaluate the middle transverse axis: Direct force straight posterior to the PSIS. This evaluates the postural axis—the motion of the sacrum on the ilium. A positive test indicates sacral dysfunction. This should correlate to the seated flexion test.
A negative test will have a small amount of free motion of the ilium with respect to the sacrum before the entire pelvis begins to rotate. In addition, there will be a ligamentous (firm but not bony) end-feel.
A positive test will have NO motion of the ilium with respect to the sacrum, and the pelvis will rotate immediately. Repeat the procedure on both sides.
This is a lateralizing test—it determines left or right.

Question 16

Spring Test

Answer 16

Backward bending introduces extension of the lumbar spine and flexion of the sacrum (relative to the lumbar spine). (Sphynx or “TV watching” position)
Pressure applied from posterior to anterior on the sacral base, near the lumbosacral junction should initiate FORWARD sacral base motion. (spring)
The test is POSITIVE if there is a LACK of spring—i.e. the sacrum will not move forward, but instead is “stuck” backward.

This test determines anterior or posterior

A board like resistance or “lack of spring” to the LS junction determines that the sacrum is stuck BACKWARDS.
This is a positive Spring Test.
Able to move sacral base forward with pressure = normal response/negative spring test.
Unable to move sacral base forward with pressure = abnormal motion response/positive spring tes

Question 17

Static examination of sacral landmarks

Answer 17

(patient prone)

Palpation of the sacral sulci: Physician places thumb pads on the inferior aspects of the gluteal tubercles (dimples). The thumb that is more anterior by palpatory and visual observation is the side of the deep sulcus (anterior sacral base). The sacral sulci may also be found moving medial and slightly superior to the PSIS bilaterally.

Palpation of the Inferior Lateral Angle (ILA’s): Physician places the palm of his/her hand on the sacrum. The most posterior/inferior aspect of the sacrum is the level of the ILA’s. The thumbs are then placed on each ILA. The side on which the thumb is more anterior, according to palpatory and visual observation, is the anterior ILA. Because of sacral biomechanics, the more anterior ILA is usually the more superior.

*note: in discussing specific dysfunctions, I will describe the dysfunctional landmark as either being anterior or posterior

Question 18

Backward bending (sphynx) test

Answer 18

Contact all four sacral landmarks at once (thumb and index finger of both hands)
Patient prone, comes up on elbows (sphinx position). Backward bending introduces extension of the lumbar spine and flexion of the sacrum (relative to the lumbar spine).
Observe for change in landmark asymmetry.
Deceased asymmetry indicates any of the flexion-type dysfunctions (the sacral base prefers anterior motion).
Increased or unchanged asymmetry indicates any of the extension-type dysfunctions (the sacral base prefers posterior motion).

Question 19

Motion testing

Answer 19

With the patient prone, the DO applies a posterior to anterior pressure over all four corners of the sacrum (bilateral ILA’s and sulci)
Note which corner moves anterior the easiest.
Test each of the possible diagnoses.
Motion testing, along with landmarks, can confirm your sacral diagnosis.

*Motion testing is considered to most reliable of all the diagnostic test.

Question 20

Naming a sacral torsion

Answer 20

ALL dysfunctions are named for their ease of motion. The reference point for motion is ALWAYS the anterior-superior component.
We diagnose the sacrum based on the position of ease with the anterior superior aspect of S1 (sacral promontory) as our reference point.
Rotation is stated first with the axis stated 2nd.
For example, a right rotation on a right axis
R on R

Question 21

Sacral torsions

Answer 21

Seated flexion test and ASIS compression test determine dysfunctional side—opposite oblique axis
Sphinx/Spring test determines anterior posterior
Landmarks (and motion testing give final diagnosis)

Question 22

Sacral torsion example (find a diagnosis):

Positive seated flexion test on the RIGHT
Denotes a LEFT oblique axis
Negative spring test (there is good, easy anterior spring)
Denotes and anterior dysfunction
Landmarks
Anterior (deep) sulcus right
Posterior ILA left

Answer 22

Diagnosis:

Left on Left sacral torsion.

Question 23

Unilateral sacral flexion

Answer 23

The slippage of one sacroiliac joint about a vertical axis with translation of the sacral base (the sacrum appears to be side bending on an A-P axis).
Positive seated flexion test (usually) on dysfunctional side.
Spring test NEGATIVE (forward motion present)
Sulcus deep on same side as positive seated flexion test
ILA posterior on same side as positive seated flexion test

Question 24

Unilateral sacral extension

Answer 24

The slippage of one sacroiliac joint about a vertical axis with translation of the sacral base (the sacrum appears to be side bending on an A-P axis).
Positive seated flexion test (usually) on dysfunctional side.
Spring test POSITIVE (forward motion ABSCENT)
Sulcus shallow (posterior) on same side as positive seated flexion test
ILA anterior (deep) on same side as positive seated flexion test

Question 25

Bilateral sacral shear

Answer 25

Negative (or equivocal) seated flexion test.
Exaggeration of normal flexion or extension.
Sacral sulci equal but excessively deep or shallow.
ILA’s are equal but excessively deep or shallow.
The sphinx/spring test will determine flexion or extension.

Positive spring test (spring is absent) = Extension
Negative spring test (spring is present) = Flexion

Question 26

Different names for diagnoses

Answer 26

Right on Right
Left on Right
Left unilateral flexion
Left unilateral extension
Left on Left 
Right on Left
Right unilateral flexion
Right unilateral extension
Bilateral Flexion
Bilateral Extension