Orthopaedic Evaluation of Pelvic Ring

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Orthopaedic Evaluation of Pelvic Ring
Acetabulum Fractures

• Department of Orthopaedics
• Garden City Hospital
• James M. Steinberg, D.O.

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Clinical Evaluation

• Immediate life-threatening problems addressed
  first
• ATLS protocols (ABCs)
• Team approach
• General surgery, Neurosurgery, Vascular surgery
• Rule out life threatening injuries
• Head, chest and abdominal injuries
• Examine for an open pelvic fx
• Inspect the perineum carefully

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Associated Injuries

• Hemorrhage - 75
• Urogenital - 12
• Lumbosacral plexus - 8
• Other associated musculoskeletal - 60-80
• Mortality rate is about 15-25
• Important to distinguish b/t stable and unstable
  pelvic injuries

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Physical Signs of Pelvic Instability

• Massive flank or buttock contusions and swelling
• Significant bleeding
• Deformity of lower extremity that is not
  fractured
• Leg length discrepancy
• Markedly internally or externally rotated pelvis

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Testing for Pelvic Stability

• AP-Lateral compression test
• Performed by one person
• First clot is the best clot
• Subsequent clotting of retroperitoneal hemorrhage
  difficult due to IV dilution exhaustion of
  clotting factors
• Palpation of the symphysis
• widening
• Palpation of posterior aspect of the pelvis
• Large hematoma
• Gap through the disrupted fx area
• Dislocation of SI joint

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Radiographic Evaluation

• AP
• Anterior lesions pubic rami and symphysis
• SI joint sacral fxs
• Iliac fxs
• L5 transvers process fxs
• Landmarks
• Iliopectineal line (limit of anterior column)
• Ilioischial line (limit of posterior column)
• Ant posterior lips
• teardrop

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Radiographic Evaluation

• Inlet
• X-ray taken in supine position with the tube
  directed 60 degrees caudally
• Determine posterior displacement of SI joint,
  sacrum or iliac wing
• Determine internal rotation deformities of ilium
  and sacrum

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Radiographic Evaluation

• Outlet
• Taken in supine position with the tube directed
  45 degrees cephalad
• Determine vertical displacement of hemipelvis
• Visualize sacral formina

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Radiographic Evaluation

• Iliac Oblique
• 45 degree external rotation view
• Posterior column (ilioischial line) anterior
  wall

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Radiographic Evaluation

• Obturator Oblique
• 45 degree internal rotation view
• Anterior column (iliopectineal line) posterior
  wall

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Radiographic Evaluation

• CT Scan
• Allows visualization of posterior structures of
  the pelvis
• Assess impacted fxs of the acetabular wall, bone
  fragments in the joint, and degree of comminution
• 3-D reconstruction permits direct visualization
  of the acetabular articular surface by
  subtracting the femoral head

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Radiographic MeasurementsAcetabulum

• Roof arc
• Formed by angle betw a line drawn vertically thru
  the geometric center of the acetabulum from the
  fx line to the geometric center
• Limited usefulness for both column fxs
  posterior wall fxs
• Medial roof arc AP view
• Anterior roof arc obturator oblique
• Posterior roof arc iliac oblique
• All three roof arcs should be gt 45 degrees

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Radiographic Lines Review
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Pelvic Anatomy

• Three bones Sacrum and two innominate bones
• Three ossification centers Ilium, ischium, and
  pubis coalesce at triradiate cartilage
• Two major joints Two SI and the symphysis pubis
• The three bones and three joints have no inherent
  stability without ligaments
• Strongest most important ligaments are the
  Posterior SI Ligaments

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Pelvic Anatomy

• Posterior SI ligaments are divided into two
  components short and long
• Short oblique running from the posterior ridge
  of the sacrum to the PSIS and PIS of the ilium
• Long run longitudinally from lateral sacrum to
  PSIS and merge with the sacro-tuberal ligaments
• The long ligaments cover the short

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Pelvic Anatomy

• Anterior SI ligaments
• span across the sacrum to the ilium
• provide some stability but less than posterior
• SI joints have two parts
• inferior has articular surfaces and is synovial
• upper more dorsal part is fibrous
• 5 degree tilt of SI joints to accommodate the
  upright position

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Pelvic Anatomy

• Symphysis pubis
• synovial with hyaline cartilage
• covered by fibrocartilage then surrounded by a
  thick fibrous band
• reinforced inferiorly by muscle and the arcuate
  ligament
• thickest portion of the joint is superior and
  anterior

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Pelvic Anatomy

• Sacrotuberous ligament
• runs from the sacrum to the ischial tuberosity
• thickens to form the falciform tendon that blends
  with the obturator membrane and the posterior
  origin of the gluteus maximus
• Along with the posterior SI ligaments the
  sacrotuberous ligament provides vertical
  stability

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Pelvic Anatomy

• Sacrospinous ligament
• triangular and runs from the sacrum and coccyx to
  the sacrotuberous ligament to insert into the
  iliac spine
• divides posterior column into the greater and
  lesser sciatic notch and is covered by the pelvic
  floor
• The sacrospinous ligaments helps provide
  rotational control

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Pelvic Anatomy

• Iliolumbar ligaments
• secure the pelvis to the lumbar spine from the
  L4,5 transverse process to the posterior iliac
  crest
• Lumbosacral ligaments
• run from the transverse process of L5 to the
  sacral ala
• Transversely placed ligaments resist rotational
  forces
• short posterior SI, anterior SI, iliolumbar
  sacrospinous ligaments
• Vertically placed ligaments resist vertical shear
• long posterior SI, sacrotuberous, lateral
  lumbarsacral ligaments

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Pelvic Ligaments
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Pelvic Anatomy

• Intact pelvis is divided into the true and false
  pelvis by the pelvic brim (iliopectineal line)
• False pelvis is lined by the iliacus muscle and
  contains abdominal contents
• True pelvis floor consists of
• coccyx, coccygeal and levator ani muscles
• urethra, rectum and vagina that pass through it
• obturator membrane the greater and lesser
  sciatic notches

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Pelvic Anatomy

• Obturator vessels exit in the superior portion of
  the foramen
• Superior and inferior gluteal vessels, piriformis
  muscle and sciatic nerve exit through the greater
  sciatic notch
• L5 root exits under the L5 transverse process to
  cross the sacral ala 2 cm medial to the SI joint
• The median sacral artery lies on the anterior
  midline of the sacrum

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Pelvic Anatomy

• Superior rectal artery is midline and posterior
• Common iliac divides into the internal and
  external iliacs at the pelvic brim
• Bladder is superior to the pelvic floor
• Weak link in the urethra is below the pelvic
  diaphram at its bulbous portion

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Acetabular Anatomy

• Acetabulum is regarded as a socket contained
  within 2 arms of an inverted Y
• Two-column pelvis
• Posterior column ilioischial component
• Anterior column iliopubic component

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Stability

• McBroom Tile sequentially sectioned pelvic
  ligaments to determine the spectrum pelvic
  stability
• Symphysis sectioned diastasis was no greater
  than 2.5 cm due to intact anterior SI ligaments
  and sacrospinous ligaments
• Symphysis and sacrospinous ligaments sectioned
  greater than 2.5 cm of diastasis was noted
  (rotationally unstable)

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Stability

• Sectioning of the symphysis, sacrospinous,
  sacrotuberous, and posterior SI ligaments the
  pelvis was unstable in rotation and vertically
• Bony equivalents to ligament disruptions
• SI dislocation
• Vertical pubic rami fractures
• L5, L4 transverse process fractures
• Avulsions of the iliac spine and ischial
  tuberosity

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AP Force PatternPelvic Fractures

• External rotation of the hemipelvis
• Pelvis springs open, hinging on the intact
  posterior ligaments
• Force applied to the ASIS will externally rotate
  both hemipelvi
• Often seen in pedestrian vs auto and MCA

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Lateral Compression ForcePelvic Fractures

• Most common pattern
• Creates impaction through cancellous bone of the
  sacrum and SI joint
• Force thru posterior half of ilium
• Classic lateral compression with min soft tissue
  disruption (stable)
• Force directed over anterior half of iliac wing
• Rotation of hemipelvis inward with poss
  disruption of posterior SI ligament complex
• Force through the greater trochanter
• Poss transverse acetabular fx
• Often due to MVA
• High incidence of brain and visceral injuries but
  less incidence of pelvic vascular injuries

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Anterior Lateral CompressionPelvic Fractures

• Rotates the hemipelvis inward pivoting around the
  SI joint
• Anterior portion of the sacrum will be crushed
  followed by disruption of the posterior SI
  ligaments
• Sacrospinous and more importantly the
  sacrotuberous are intact therefore vertically
  stable and rotationally unstable
• If force continues it will externally rotate the
  opposite hemipelvis

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External Rotation AbductionPelvic Fractures

• Common in MCA
• Force is through femoral shaft and head
• Tends to tear the hemipelvis from the sacrum
• Completely tears the posterior ligamentous
  structures

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Shear ForcePelvic Fractures

• High energy applied perpendicular to the bony
  trabecular pattern
• Will lead to triplanar instability
• Disrupts the sacrospinous and sacrotuberous
  ligaments
• Ligament avulsions in the young and bony
  fractures in the elderly
• Vertical shear injuries result from falls

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Mechanism of InjuryAcetabular Fractures

• Femoral head acts as a hammer
• Direct Force
• Direct blow to greater troch
• Hip in neutral position transverse fx
• Hip externally rotated ant. column
• Hip internally rotated posterior column
• Indirect Force
• Dashboard injury to flexed knee
• As hip flexion increases, inf portion of
  posterior wall fx
• As hip flexion dec below 90 degrees, sup portion
  of posterior wall fx

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Pelvic Fracture Classifications

• Letournel
• Young-Burgess
• Tile

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LetournelAnatomic

• A. Iliac wing
• B. Ilium into SI joint
• C. Transsacral
• D. Unilateral sacral fracture
• E. SI fracture-dislocation
• F. Acetabular fractures
• G. Pubic rami fractures
• H. Ischial fractures
• I. Symphysis diastasis

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Young-BurgessMechanism of Injury

• Alerts the surgeon to the potential resuscitation
  problems associated with pelvic fractures
• Three major components
• Lateral compression force
• Anterior-posterior compression force
• Vertical shear force

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Lateral Compression Force

• Type I posterior-lateral force causes sacral
  impaction transverse rami fxs (stable injury)
• Type II more anterior-lateral force causes
  disruption of posterior ligaments but is
  vertically stable (may have an anterior sacral
  impaction)
• Type III lateral force continues across the
  pelvis to produce external rotation injury to
  contralateral hemipelvis (windswept pelvis)

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AP Compression Force

• Type I lt2.5cm of pubic diastasis or vertical
  fxs of one or both pubic rami no posterior
  injury
• Type II gt2.5cm of pubic diastasis with opening
  of the anterior SI joints but is vertically
  stable
• Type III complete disruption anteriorly and
  posteriorly with significant sacral diastasis or
  displaced vertical rami fxs (completely unstable
  fx)

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Vertical Shear Force

• Hemipelvis is torn from the sacrum
• Completely unstable fx
• Associated with significant retroperitoneal
  hemorrhage and other major injuries

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Tile Classification

• Type A Stable
• A1 - Fxs outside of the pelvic ring
• A2 - Stable, minimal displacement
• A3 - Transverse fxs of sacrum and coccyx

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Tile Classification

• Type B Rotationally Unstable, Vertically
  Posteriorly Stable
• B1 - External rotation (open book)
• B2 - Internal rotation unstable (lateral
  compression injury)
• B3 - Bilateral rotationally unstable injury

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Tile Classification

• Type C Rotationally, Posteriorly and
  Vertically Unstable
• C1 - Unilateral injury
• C2 - Bilateral injury, one side vertically
  unstable and the other rotationally unstable
• C3 - Bilateral injury, both hemipelvi are
  completely unstable

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Acetabulum Fracture Classification

• Judet-Letournel
• Based on trauma and resultant damage to the two
  columns
• Ten fracture patterns five elementary five
  associated

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Elementary FracturesAcetabulum

• Posterior Wall
• Marginal impaction
• Fx-dislocations
• Posterior Column
• Typically detaches in one fragment
• Femoral head often dislocates centrally
• Anterior Wall
• Iliopectineal line disrupted
• Teardrop displaces inward
• Anterocentral displacement of femoral head

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Elementary FracturesAcetabulum

• Anterior Column
• Break in iliopectineal line
• Anteromedial displacement of femoral head
• Transverse
• Ilioischial teardrop keep normal relationship
• Innominate bone in two fragments
• Articular surface divided in one of three ways
• Thru the roof (transtectal)
• At the junction of roof acetabuli (juxtatectal)
• Thru the fossa acetabuli (infratectal)

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Associated FracturesAcetabulum

• Posterior Wall Column
• Wall is usually markedly displaced rotated
• Posterior hip dislocation often associated with
  sciatic nerve injury
• Transverse Posterior Wall
• 2/3 femoral head dislocates posteriorly
• 1/3 femoral head dislocates centrally

• T-shaped
• Combines tranverse fx (transtectal, juxtatectal
  or infratectal) with a vertical fx that divides
  the ischiopubic fragment into 2 parts

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Associated FracturesAcetabulum

• Anterior Column Posterior Hemitransverse
• Ant wall/column with a fracture line that divides
  the posterior column
• Both Column
• Central acetabular fracture
• Floating acetabulum
• Wing sign
• Most complex of all acetabular fxs