INTERNAL MEDICINE SERIES OMM LECTURE Sacrum and Innominates Julia Faller, D.O., PGY1

ANATOMY Innominate: 3 bones; ilium, ischium and pubis Sacrum: 5 fused vertebrae Sacral base: top part of the sacrum Sacral promontory: anterior portion of 1st segment Sacral apex: bottom part of the sacrum Sacral sulci: superior lateral part of sacrum Inferior lateral angles (ILA’s): inferior lateral part of sacrum

ANATOMY

ANATOMY

LIGAMENTS True pelvic ligaments: sacroiliac ligaments that surround and help stabilize the SI joint Anterior Posterior Interosseous

LIGAMENTS Accessory pelvic ligaments Sacrotuberous—originates at ILA and attaches to ischial tuberosity Sacrospinous—originates at sacrum and attaches to ischial spines Iliolumbar—originates from transverse processes of L4 and L5 and attaches to medial side of iliac crest

LIGAMENTS

LIGAMENTS

Board Points The sacrospinous ligament divides the greater and lesser sciatic foramen The iliolumbar ligament is often the first ligament to become painful in lumbosacral decompensation

MUSCLES Primary pelvic muscles: levator ani and coccygeus (pelvic diaphragm) Secondary: muscles that have partial attachment to the true pelvis Iliopsoas Obturator internus Piriformis

Clinical Point Approximately 11% of the population will have the entire peroneal portion of the sciatic nerve running through the belly of the piriformis. Piriformis hypertonicity can cause buttock pain that radiates down the thigh, but not usually below the knee.

MECHANICS Innominates: rotate about an inferior transverse axis of the sacrum during the walking cycle. Sacrum: four types of motion Respiratory Craniosacral Postural Dynamic

AXIS

RESPIRATORY AXIS Respiratory motion occurs about the superior transverse axis of the sacrum. Located at S2 During inhalation the sacral base moves posterior. During exhalation the sacral base moves anterior

RESPIRATORY AXIS

CRANIOSACRAL AXIS Motion occurs about the superior transverse axis of the sacrum AKA inherent motion During craniosacral flexion the sacral base rotates posteriorly, counernutation During craniosacral extension the sacral base rotates anteriorly, nutation

CRANIOSACRAL AXIS

POSTURAL AXIS Motion occurs about the middle transverse axis of the sacrum. As a person begins to bend forward, the sacral base moves anteriorly. At terminal flexion the sacrotuberous ligaments become taut and the sacral base will move posteriorly.

POSTURAL AXIS

OBLIQUE AXIS Motion that occurs during ambulation. Dynamic motion As weight bearing shifts from one side to the other while walking, the sacrum engages two sacral oblique axes. Stepping forward with the right leg will cause a left sacral axis to be engaged.

OBLIQUE AXIS

INNOMINATE DYSFUNCTION The side of the positive standing flexion test is the side of the dysfunction. Types: Anterior/posterior rotation Superior/inferior innominate shear Superior/inferior pubic shear Inflare/outflare

INNOMINATE DYSFUNCTION Anterior innominate rotation: one innominate will rotate anteriorly Inferior transverse axis Tight quadriceps ASIS inferior/PSIS superior Longer leg ipsilaterally ASIS restricted to compression

ANTERIOR INNOMINATE

INNOMINATE DYSFUNCTION Posterior innominate rotation: one innominate will rotate posteriorly Inferior transverse axis Tight hamstrings ASIS superior/PSIS inferior Shorter leg ipsilaterally ASIS restricted to compression

POSTERIOR INNOMINATE

INNOMINATE DYSFUNCTION Superior innominate shear: one innominate will slip superiorly ASIS and PSIS superior Pubic rami superior Short leg ipsilaterally ASIS restricted to compression

SUPERIOR INNOMINATE SHEAR

INNOMINATE DYSFUNCTION Inferior innominate shear: one innominate will slip inferiorly ASIS and PSIS inferior Pubic rami inferior Long leg ipsilaterally ASIS restricted to compression

INFERIOR INNOMINATE SHEAR

INNOMINATE DYSFUNCTION Superior pubic shear: one pubic bone is displaced superiorly compared to the other Trauma or tight rectus abdominus ASIS/PSIS level Pubic bones superior ipsilaterally ASIS restricted to compression

SUPERIOR PUBIC SHEAR

INNOMINATE DYSFUNCTION Inferior pubic shear: one pubic bone is displaced inferiorly compared to the other Trauma or tight abductors ASIS/PSIS level Pubic bones inferior ipsilaterally ASIS restricted to compression

INFERIOR PUBIC SHEAR

INNOMINATE DYSFUNCTION Innominate inflare: innominate rotates laterally ASIS more lateral ipsilaterally therefore the distance between the ASIS and umbilicus is greater on the affected side Ischial tuberosity more medial ipsilaterally ASIS restricted to compression ipsilaterally

INNOMINATE DYSFUNCTION Innominate outflare: innominate rotates medially ASIS more medial ipsilaterally therefore the distance between the ASIS and umbilicus is less on the affected side Ischial tuberosity more lateral ipsilaterally ASIS restricted to compression ipsilaterally

SACRAL DYSFUNCTION Three types of dysfunction Sacral torsion on an oblique axis Sacral shear (unilateral sacral flexion/extension) Bilateral sacral flexion/extension

SACRAL TORSION Sacral rotation about an oblique axis along with somatic dysfunction at L5 The axis is named for the side of the superior pole it runs through

SACRAL TORSION RULES When L5 is sidebent, a sacral oblique axis is engaged on the same side as the sidebending When L5 is rotated, the sacrum rotates the opposite way on an oblique axis The seated flexion test is positive on the opposite side of the oblique axis

Board Points Know the rules of L5 on the sacrum

MOTION OF TORSIONS Motion present over the part of the sacrum that moved anteriorly Motion restricted over the part of the sacrum that moved posteriorly Motion restricted over the poles that make up the oblique axis

SACRAL TORSION Forward sacral torsion AKA anterior sacral torsion. Rotation is on the same side of the axis. Left on left/right on right Negative lumbosacral spring test

SACRAL TORSION: L on L Left on left Right sulcus deeper Left ILA posterior and inferior Lumbar curve convex to the right Motion at right base only

SACRAL TORSION: R on R Right on right Left sulcus deeper Right ILA posterior and inferior Lumbar curve convex to the left Motion at left base only

SACRAL TORSION Backward sacral torsion AKA posterior sacral torsion Rotation is on the opposite side of the axis Right on left/left on right Positive lumbosacral spring test Positive backward bending test L5 will be non-neutral

SACRAL TORSION: R on L Right superior sulcus moves posterior and the left ILA moves anterior Right sulcus shallow Left ILA anterior and superior Lumbar curve convex to the right Motion at left ILA only

SACRAL TORSION: L on R Left superior sulcus moves posterior and the right ILA moves anterior Left sulcus shallow Right ILA anterior and superior Lumbar curve convex to the left Motion at right ILA only

BILATERAL SACRUM Bilateral flexion and extension The entire sacral base moves anterior or posterior about a middle transverse axis Common in the postpartum female

BILATERAL SACRAL FLEXION Right and left sulci deep ILA’s shallow bilaterally Increased lumbar curve False negative seated flexion test Motion at base Negative spring test

BILATERAL SACRAL EXTENSION Right and left sulci shallow ILA’s deep bilaterally Decreased lumbar curve False negative seated flexion test Motion at both ILA’s Positive spring test

SACRAL SHEARS AKA unilateral sacral flexion/extension The sacrum will shift anteriorly or posteriorly around a transverse axis

UNILATERAL SACRAL FLEXION Ipsilateral deep sulcus Ipsilateral inferior ILA Ipsilateral ILA posterior Ipsilateral positive seated flexion test Ipsilateral motion at sulcus Ipsilateral restriction at ILA Negative lumbosacral spring test

UNILATERAL SACRAL EXTENSION Ipsilateral shallow sulcus Ipsilateral superior ILA Ipsilateral ILA anterior Ipsilateral positive seated flexion test Ipsilateral motion at ILA Ipsilateral restriction at sulcus Positive lumbosacral spring test

Question 1 Which structure divides the greater and lesser sciatic foramen? a. Sacrotuberous ligament b. Sacrospinous ligament c. Sacroiliac ligament d. Tendon of the obturator internus e. Tendon of the piriformis

Question 1 Which structure divides the greater and lesser sciatic foramen? a. Sacrotuberous ligament b. Sacrospinous ligament c. Sacroiliac ligament d. Tendon of the obturator internus e. Tendon of the piriformis

Question 2 Which of the following movements will cause the sacral base to move anterior? a. Cranial extension b. Counternutation c. Exhalation d. Weight bearing on right leg e. Weight bearing on left leg

Question 2 Which of the following movements will cause the sacral base to move anterior? a. Cranial extension b. Counternutation c. Exhalation d. Weight bearing on right leg e. Weight bearing on left leg

Question 3 Which of the following findings is present in a left innominate anterior rotation? a. PSIS inferior on left b. PSIS superior on right c. PSIS superior on left d. ASIS superior on left e. PSIS and ASIS posterior on left

Question 3 Which of the following findings is present in a left innominate anterior rotation? a. PSIS inferior on left b. PSIS superior on right c. PSIS superior on left d. ASIS superior on left e. PSIS and ASIS posterior on left