The Sacrum - SS Flashcards
•The weight of the upper body is transmitted through the sacrum and its ligamentous attachments to the pelvis via what ligaments?
the iliolumbar, sacrospinous, &sacrotuberous ligaments.
What ligaments connect the sacrum to the pelvis? Characterize their strength.
•The anterior and posterior sacroiliac ligaments are extremely strong and connect the sacrum to the pelvis.
What is the fist ligament to spasm when there is sacral dysfunction?
Iliolumbar ligament
What ligament is the fascia of the biceps femoris continuous with?
Sacrotuberous ligament
What does nutation mean?
Old term for sacral flexion
(this is opposite of cranial nutation - which is extension there)
What muscles attach to the sacrum?
Piriformis
Iliacus
Diaphragm
Erector spinae and latisimus dorsi (via aponeurosis)
Gluteus maximus
What muscles move the sacrum directly?
None
Where does the piriformis attach to the sacrum?
SV2-SV4 - anterior surface
How does the diaphragm attach to the sacrum?
Anteriorly to the sacrotuberous and sacrospinous ligaments
What is the normal lumbosacral angle?
25-35 degrees
What does an increas in Ferguson’s angle cause?
(Lumbosacral angle)
can increase lumbosacral strain
What are the landmarks for sacral diagnosis?
Sacral sulci
Inferior lateral angles
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What are the seven axes of motion of the sacrum?
- 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.
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What is the respiratory axis of the sacrum? What movements correspond with inhalation/exhalation?
•Superior transverse / (thoracic) Respiratory axis. (S2)
- The sacrum flexes with exhalation
- The sacrum extends with inhalation
Describe the
•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.
Describe the
•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.
All 3 transverse axes allow?
Flexion and extension
Identify the indicated axes
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The oblique sacral axes are named for?
The superios axis
With walking, what happens with sacral motion?
•sacrum alternates: right-on-right, neutral, left-on-left, neutral, etc.
What axis is created in stance phase?
•In stance phase, an ipsilateral oblique axis is created, and the sacrum moves anteriorly (obliquely) about this axis.
right on right sacral torsion, and lumbar sidebending to the right - would be due to what stance?
left stance
What can SI joint dysfunction lead to?
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”
To what degree may a gait abnormality increase energy expenditure?
300%
What is the L5 “rule”?
- It is a “rule” (meaning it always occurs on board exams, and sometimes occurs in practice too.) that 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 and side bent in what directions?
rotated to the RIGHT, and sidebent left. (follows neutral mechanics)
How do you perform the seated flexion test?
Describe what we see in sacral torsions and in sacral sheers.
- 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.
What type of test is the seated flexion test?
Lateralizing (determines left or right)
•In sacral sheers, (flexions/extensions) the side of the positive test is where?
ipsilateral to the dysfunction.
•In sacral torsions the side of the positive test is where?
ipsilateral to the dysfunction, but contralateral to the oblique axis.
Describe the sphinx/spring test
- Backward bending introduces extension of the lumbar spine and flexion of the sacrum (relative to the lumbar spine). (Sphynx 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.
What does the combined sphinx/spring test determine?
Anterior/posterior
Does a negative spring test have spring?
Yes, which is a normal result
Does a positive spring test have spring?
No (abnl result)
•A board like resistance or “lack of spring” to the LS junction determines that the sacrum is stuck in what direction?
BACKWARDS.
What do we do in static examination of sacral landmarks?
- 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.
How do we do motion testing of the sacrum?
- 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.
- Motion testing, along with landmarks, can confirm your sacral diagnosis.
How are sacral torsions named?
- 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 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
Based on position of sacral promontory
A positive spring test indicates a?
Posterior problem
Negative spring test indicates what direction of the sacrum?
Anterior
Describe unilateral sacral flexion
•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).
What test results indicate unilateral sacral flexion?
- 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
Describe unilateral sacral extension
•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).
What test results indicate unilateral sacral extension?
- 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
What do we see in bilateral sacral shear?
•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
Positive right flexion test can have what diagnoses?
If you have a positive spring test what is left?
Sulcus is posterior on the left and ILA is anterior right?
1.
•Left on Left
•Right on Left
•Right unilateral flexion
•Right unilateral extension
2.
Right on left or right unilateral extension
3.
right rotation on left axis
L5FRSR
What is sacrum doing?
Type II mechanics
Sacrum is going backward (type II mechanics)
Sacrum is rotated left on right
L5NSLRR
Sacrum is doing what?
Type I mechanics
Anterior sacrum
Sacrum is left on left
+ seated flex test on left
Spring test -
Deep left sacral sulcus and deep left ILA
What is sacral Dx?
Right on Right
Deep left ILA is relative to the right ILA - same thing as saying a right posterior ILA
This is where they will get tricky on the TQ’s. Beware language and remember the landmarks are judged relative to one another.
+ seated flex test on left
back bending of the lumbar spine = improved symptoms
deep left sacral sulcus
deep right ILA
Left unilateral sacral flexion