Osteopathic Evaluation of the Pelvis

• Osteopathic Evaluation of the Pelvis

Objectives

• Students will have a working knowledge of the basic anatomy of the pelvis and sacrum including neurovascular structures
• Students will have a working knowledge of pelvis and sacrum motion and biomechanics
• Students will identify the superior, middle and inferior transverse sacral axes
• Students will understand the characteristics and diagnostic criteria of pelvic somatic dysfunctions
• Students will explain the pelvic and lumbar mechanics during gait

Definition (Functional Anatomy)

• False Pelvis refers to the part of lower abdomen which is walled laterally by ilia
• True Pelvis is inferior and posterior to the abdomen
• True Pelvis contains the sacral promontory, arcuate line, pectinate line, pubic bones, and inferior fascia of the pelvic diaphragm

Bones

• There are 2 innominate bones: ilium, ischium, and pubis
• Sacrum is composed of 5 fused vertebrae
• Sacrum includes a base, apex, and transfers weight

The Pelvis

• Embryologically it is a single cartilaginous element for the entire innominate
• Complete fusion happens by late Teens or early 20s
• Each innominate functionally consists of 3 bones: Illium, Ischium, and Pubis

The Sacrum

• It is a large inverted triangle formed by the fusion of five sacral vertebrae with the superior aspect being the base and the inferior aspect being the apex
• It articulates superiorly to L5 forming the LS junction (Ferguson's angle)
• It articulates bilaterally with the innominates forming the complete ring of the pelvis
• The anterior superior portion of S1 is the sacral promontory
• The anterior surface is concave and the posterior surface is convex with palpable spinous tubercles
• The Medial row of tubercles is formed by the fusion of the sacral articular processes
• The Lateral row is formed by the fusion of sacral transverse processes and ends inferiorly in a curve called the ILA
• Sacral canal and four bilateral sacral foramina exist for the ventral and dorsal rami of the first four sacral spinal nerves
• Sacral hiatus is a defect near the apex and the location for sacral epidural nerve blocks
• The Coccyx attaches to the sacral apex via the sacrococcygeal joint
• Ganglion impar (where R and L sympathetic chains join) rests on the anterior surface of the coccyx

Transverse Sacral Axis

• Superior: At PRM
• Middle: At Sacroiliac motion (sacral motion)
• Inferior: At Iliosacral motion (walking)

Transverse Sacral Axes

• Superior: Above S2, the cranial primary respiratory mechanism creates motion around this axis
• Middle: At S2, Sacroiliac motion, Forward and backward bending
• Inferior: Below S2, Iliosacral motion rotates the innominates

Accessory Ligaments

• There are 3 accessory ligaments: iliolumbar, sacrotuberous, and sacrospinous

• The Sacrospinous Ligament forms the lesser and greater sciatic foramen

• Iliolumbar ligament attaches from the anterior surface of the iliac crest and anterior surface of the sacral base to the transverse processes of L4 and L5

  • Lower fibers integrate with anterior SI ligament integrating SI mechanics with the L-spine
  • Prone to irritation by LS instability
  • Pain may be referred to the groin via the ilioinguinal nerve, mimicking the pain felt in an inguinal hernia
  • Implicated in nerve entrapment syndrome

• Sacrotuberous ligament runs from inferior medial border of sacrum and insert on the ischial tuberosites and posterior margins of the sciatic notches

• Sacrospinous: anterior to sacrotuberous ligaments and attach to the ischial spines, dividing this space into a greater and lesser sciatic foramen

  • SS and ST ligaments restrain anterior movement of the sacrum within the pelvic bones
  • In weight bearing position without strong pelvic ligaments the sacral base tends to rock anteriorly
  • Stress on these ligaments can create lumbosacral imbalance, chronic back pain, and joint degeneration

Neurovascular System

• Abdominal Aorta branches into the Right and Left common Iliac Arteries
• The Right and Left common Iliac Arteries branch into the External and Internal Iliac Arteries
• The Internal Iliac artery has anterior and posterior trunks and supplies the pelvis

Arterial Supply

• Abdominal Aorta becomes R & L common Iliac arteries
• Bifurcation of the abdominal aorta happens at L3 (umbilicus), and R and L common iliac arteries diverge to the LS junction where they divide into the internal and external iliac arteries
• External iliac artery goes to lower extremity
• Internal iliac artery splits into Anterior & posterior trunks to and the pelvis
• Internal iliac arteries have two trunks that supply the pelvic viscera, perineum and gluteal region
  • Posterior trunk: iliolumbar artery, lateral sacral arterires, and the superior gluteal artery
  • Anterior trunk: Umbilical, superior vesical, inferior vesical / vaginal, middle rectal, obturator, internal pudendal, inferior gluteal (terminal branch)

Somatic Plexus

• Sacral (L4-S4)
• Sciatic n. (L4-S3)
• Pudendal n. (S2-S4)
• Coccygeal (S4-C0)

Autonomic NS

• SANS:T12-L2

• PANS: S2-S4

• Sacral plexus (ventral rami of L4-S4): Gray rami communicants from the sympathetic trunk connect with anterior rami and carry postganglionic SANS fibers

  • Pelvic splanchnic nerves carry PANS fibers from S2-4

• Sciatic Nerve (L4-S3)

  • Common fibular (peroneal) n. (L4-S2) and Tibial n.(L4-S3)
  • Innervates muscles of thigh (post. Compartment), leg, and foot
  • Sensation from foot and lateral leg

• Pudental (S2-4): Goes through Lr. sciatic foramen, inferior to piriformis, and enters gluteal region, innervates skin and muscles of perineum

• Other branches

  • Superior gluteal (L4-S1): Glut med & min, TFL
  • Inferior gluteal (L5-S2): Glut max
  • Obturator n. (L2-L4)
  • Perforating cutaneous nerve passes through ST ligament

• Coccygeal plexus: (S4-CO) – S5 & CO penetrate coccygeus m. & ss & st ligaments, join s4, forms anococcygeal nerves and innervate skin in anal triangle

Autonomic Innervation of Pelvic Viscera

• Lower GI and GU
• SANS: T12 – L2: paravertebral trunk and sacral splanchnics
• PANS: S2- S4

Muscles

• No specific muscles move the SI Joint
• Primary muscles include the Pelvic Diaphragm
• Secondary muscles have partial attachment to the true pelvis (rectus abdominis, transverse abdominis, obliques, QL, piriformis, obturator internus)

Muscles: Primary

• Intrinsic Pelvic Diaphragm

• Levator Ani (iliococcygeus, pubococcygeus, puborectalis)

• Coccygeus

• Moves synchronously with the abdominal diaphragm and aids in lymphatic return

• Primary muscles (muscles of the perineum) provide support during defecation, inhibit bladder activity, and assist in providing lumbosacral pelvic support and are innervated by the pudental nerve

• Divided into a urogential triangle and the anal triangle

• Intrinsic to the pelvic floor

• Urogenital diaphragm (Urogenital triangle) spans the area between the ischiopubic rami and is filled by a thick fibrous sheet (the perineal membrane)

  • Contains a layer of skeletal muscle and neurovascular elements

• Pelvic diaphragm:

  • Formed by:
  • Levator ani (iliococygeus, pubococcygeus, puborectalis)
  • Coccygeus muscles posteriorly overlie the sacrospinous ligaments, and attach to the ischial spine

• Works synchonously with the abdominal diaphragm and aids in lymphatic return

Muscles: Secondary

• Rectus Abdominis
• Transverse Abdominis
• Obliques
• Quadratus Lumborum
• Lower Extremities - piriformis and obturator internus

Anterior Landmarks

• Iliac Crest
• ASIS
• Pubic Symphysis
• Pubic Tubercle
• Medial Malleoli

Posterior Landmarks

• PSIS
• Sacral Sulcus
• Sacral Base
• ILA
• Sacrotuberous Ligament
• Ischial Tuberosity
• Iliac Crest
• Piriformis Muscle
• Iliolumbar Ligament

Pelvic Diagnosis (Somatic Dysfunction)

• Innominate
• Anterior Rotation
• Posterior Rotation
• Superior Shear
• Inferior Shear
• Outflare
• Inflare
• Pubic Bone
• Superior
• Inferior
• Abduction
• Adduction

Standing Flexion Test

• Positive: side that moves 1st and furthest
• Iliosacral Somatic Dysfunction happens on the ipsilateral side
• Name based of landmarks on the side of a positive SFT

ASIS Compression Test

• Iliosacral Somatic Dysfunction happens on the ipsilateral side
• Positive: side that moves the least/restricted and does not compress

Superior Innominate Shear (upslipped)

• Shear happens between innominate & sacrum and subluxed superiorly
• Often associated with pelvic or low back pain
• May elicit history of fall on one ischial tuberosity

Inferior Innominate Shear (downslipped)

• Shear happens between the innominate and sacrum and subluxed inferiorly
• This is rare and walking tends to reduce it
• May be associated with pelvic or low back pain

L Supererior Innominate Shear (upslipped)

• Left ASIS is superior
• Left medial malleolus is superior
• Left PSIS is superior
• Left ischial tuberosity is superior
• Left sacrotuberous ligament is lax
• Positive on the Left Standing Flexion Test

R Innominate Inferior Shear (downslipped)

• Right ASIS is inferior

• Right medial malleolus is inferior

• Right PSIS is inferior

• Right ischial tuberosity is inferior

• Right sacrotuberous ligament is tight

• Positive on the Right Standing Flexion Test

• Left Innominate Posteriorly Rotated

• Left + standing flexion test

• Left ASIS is superior

• Left medial malleolus superior

• Left PSIS is inferior

• Left sacral sulcus is deep

Posterior Rotators

• Gluteus maximus muscle
• Semitendinosis muscle
• Biceps Femoris muscle
• Semimembranosus muscle
• Piriformis muscle (weak)
• Iliopsoas
• External abdominal oblique muscle

Anterior Rotators

• TFL muscle
• Quadraceps muscles
• Quadratus lumborum
• Iliocostal muscles
• Internal abdominal oblique muscles
• Latissimus dorsi muscle

Innominate Flares

• Flare is apparent when the ASIS is more medial on one side than the other
• Standing Flexion Test can assess for this
• Measure from the umbilicus (or xyphoid) to each ASIS

Inflares

• (+standing forward bending test)
• ASIS is closer to the midline (medial)

Outflares

• (+standing forward bending test)
• ASIS is further from the midline (lateral)

Right Innominate Medial (inflare)

• Right standing flexion test is positive
• Right ASIS is medial
• Right PSIS is lateral
• Right sacral sulcus is wide

Left Innominate Lateral (outflare)

• Left standing flexion test is positive
• Left ASIS is lateral
• Left PSIS is medial
• Left sacral sulcus is narrow

Pubic Symphysis

• Motion happens around a transverse axis during normal gate

• Dysfunctions are common during pregnancy and childbirth

• It is a Fibrocartilaginous joint with motion determined by its anatomic shape, ligaments, and muscular attachment

• Muscular forces acting on each pubic ramus can cause rotation upon each other at the symphysis, about a transverse axis

• Synarthrosis - interpubic disc covered in hyaline cartilage

• Surface is not flat, but has crests and pappili to resist shearing forces

• Inguinal Ligament is a surgical landmark for palpation

• Dysfunctions common during pregnancy and childbirth include Abduction

• Has three planes of motion: inferior/superior, anterior/posterior, and rotation

• Pubic Shears cause uneven tension on the pelvic diaphragm with these associated symptoms

• Constipation, Urinary Symptoms, Dyspareunia, Supra-pubic pain, low back pain, and anterior thigh pain

Left Superior Pubic Shear

• Left standing flexion test is positive
• Left pubic tubercle is superior
• Left inguinal ligament is tense and tender
• The Superior Pubic Symphysis Muscles includes the Rectus abdominus and the Pyramidalis muscle

Right Inferior Pubic Shear

• Right standing flexion test is positive
• Right pubic tubercle is inferior
• Right inguinal ligament is tense and tender

Steps to diagnose *Pelvis/Innominate somatic dysfunction

1. Lateralization test - Standing Flexion test or ASIS compression test

• Perform hip flop maneuver prior to checking the following landmarks

2. Check levels of ASIS's (in supine position)
3. Check levels of medial malleoli (in supine position)
4. Check levels of PSIS's (in prone position)

• Based on this information above, determine the somatic dysfunction Note: Innominate dysfunction diagnoses that can be determined here include Anterior and Posterior rotation, Superior shear, and Inferior shear

Pelvic Mechanics During the Walking Cycle

• Walking induces neutral oblique axis mechanics in the sacrum with every step

• It induces side bending of the lumbar spine towards the side of the weight bearing leg.

• It causes anterior rotation of the weight bearing ilium and posterior rotation of the opposite ilium.

• Walking induces reversible neutral oblique axis mechanics in the sacrum with every step and induces side bending of the lumbar spine towards the side of the weight bearing leg

• It causes anterior rotation of the weight bearing ilium and posterior rotation of the opposite ilium.

• To move the right foot the body must shift to the left

• SLRR motion occurs in the lumbar spine

• A left oblique axis occurs in the sacrum

• Sacrum rotates left on its oblique axis as right innominate rotates posterior

• This explains why the sacrum moves opposite in relation to L5