Classification of Pelvic Fractures: A Mechanistic Approach
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Classification of Pelvic Fractures: A Mechanistic Approach Allison Moriarty December 16, 2006. Outline Epidemiology Anatomy Imaging Classification Complications Treatment. Epidemiology Only 2-3% of all skeletal fractures Most result from high energy trauma

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Classification of Pelvic Fractures: A Mechanistic Approach Allison Moriarty December 16, 2006

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Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Classification of Pelvic Fractures: A Mechanistic Approach

Allison Moriarty

December 16, 2006


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Outline

  • Epidemiology

  • Anatomy

  • Imaging

  • Classification

  • Complications

  • Treatment


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Epidemiology

  • Only 2-3% of all skeletal fractures

  • Most result from high energy trauma

  • Severity of fracture depends on mechanism of injury

    >Minor pelvic fractures (fractures of individual bones or single breaks in the pelvic ring; lower energy) – elderly patients after simple falls

    >Complex pelvic fractures (higher energy) – younger patients (50% <30yo, 77% <50yo), M:F = 3:1

  • Severe pelvic injury usually due to high-velocity MVA, industrial

    accidents, falls of a significant distance


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Epidemiology

Complex Pelvic Fxs

Etiology % Patients Mortality Rate

MVA43 26%

Farm accident18 0%

Pedestrian accident17 41%

Motorcycle accident8 38%

Falls6 17%

Other8 0%


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Anatomy

Pelvic Ring

  • Consists of 2 innominate

    bones (ilium, ischium,

    pubis) and sacrum that

    are connected posteriorly

    at the SI joints and

    anteriorly at the symphysis

    pubis

  • The acetabulum is located

    where the ilium, ischium,

    and pubis meet laterally

    Source: Berquist


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Anatomy

  • Posterior Arch

    >Extends superiorly and posteriorly from one acetabulum to the other

  • Anterior / Tie Arch

    >Extends inferiorly and

    anteriorly from one

    acetabulum to the other

    through the pubic bones

    >Weaker than posterior

    arch and more likely to

    fracture


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Anatomy

Bony Pelvis

Source: Berquist

  • Composed of 2 innominate bones (ilium, ischium, pubis), sacrum, coccyx

  • SI joint – predominately amphiarthroidal (connected by fibrocartilage) and partially diarthroidal (synovial)

  • Pubic symphysis (articulation of bodies of pubic bones) – amphiarthroidal


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Anatomy

Source: Berquist

  • Stability of these joints depends entirely on strong ligamentous support -> limited motion

  • Pubic symphysis is only a “strut” and pelvis can still be stable if ligaments in posterior portion are intact

  • Sacrum – 5 fused vertebral segments; 4 foraminal pairs, both A&P; alae (wings) laterally

  • Coccyx – 4 rudimentary segments


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Anatomy

Ligaments

Supraspinous l.

Iliolumbar l.

Long post. sacroiliac l.

Sacrospinous l.

Sacrotuberous l.

Lateral sacrococcygeal l.

Sacrospinous l. Tendon of biceps femoris

Source: Berquist Source: Berquist

  • Anterior SI ligaments – extend from anterior sacrum to ilium

  • Posterior SI ligaments (both originate from PSIS and PIIS) –

    >Short – travels laterally to sacrum

    >Long – travels inferiorly to lateral portion of inferior sacrum

  • Interosseous SI ligaments – connect tuberosities of ilium and sacrum

  • Sacrospinous ligaments – extend from lateral border of sacrum to ischial spine


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Anatomy

Ligaments

Supraspinous l.

Iliolumbar l.

Long post. sacroiliac l.

Sacrospinous l.

Sacrotuberous l.

Lateral sacrococcygeal l.

Sacrospinous l. Tendon of biceps femoris

Source: Berquist Source: Berquist

  • Sacrotuberous ligaments – extend from lateral border of sacrum to ischial tuberosity

  • Iliolumbar ligaments – extend from L5 transverse process to superior ilium

  • Lumbosacral ligaments – extend from L5 transverse process to superior sacrum

  • Anterior, superior, inferior pubic ligaments

    *Posterior SI ligaments stronger than anterior SI ligaments


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Anatomy

Vascular

Veins

>Internal iliac veins join external iliac

veins to form common iliac veins

that then join to form IVC at the

L5 level

>Branches are similar to arterial branches

Arteries Source: Berquist

  • Abdominal aorta bifurcates at level of L4 to form common iliac arteries

  • Common iliac arteries divide anterior to SI joints to form external and internal iliac arteries

  • External iliac artery travels under the inguinal ligament where it forms the common femoral artery


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Anatomy

Vascular

  • Internal iliac artery (major blood supply to pelvis) has several branches

    Posterior Division

    >Iliolumbar artery – travels

    superiorly along wing of ilium

    >Superior gluteal artery – travels

    posteriorly, just inferior to the SI joint

    >Lateral sacral arteries

    Anterior Division

    >Obturator artery

    >Inferior gluteal artery Source: Berquist

    >Many visceral branches (including, but not limited to): superior vesical arteries, inferior vesical artery (male), uterine artery (female), internal pudendal artery, middle rectal artery


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Anatomy

Nervous

  • Lumbosacral plexus (ventral rami of L1-S2 with contributions from T12 and S3) supplies the pelvis and hips

  • Sciatic Nerve (L4-S3) – exits greater

    sciatic foramen and travels posterior

    to femoral head

  • S2-4 supply the GU tract

    Source: Berquist


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Imaging

  • X-ray is the primary method of initial evaluation

  • Standard view is the AP view; inlet and outlet views can be obtained for clarification

  • SI joint should be no more than 2-4mm wide; superior or inferior offset of 1-2mm is normal

  • Symphysis pubis should be no more than 5mm wide


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Imaging

Source: Berquist

Source: Berquist

  • AP

    >Patient supine with feet internally rotated 15˚

    (helps clearly visualize greater trochanter and

    femoral neck in light of natural neck

    anteversion) Source: Berquist

    >Beam centered on and perpendicular to cassette that is 1.5 inches above the iliac crests


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Imaging

  • Inlet

    >Patient supine

    >Beam centered on umbilicus

    and angled 40˚ toward the feet

    >Midpoint of cassette should

    intersect the beam

    *Good for examining the internal Source: Berquist

    structure of the pelvic ring,

    displaced fracture fragments

    Source: Berquist


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Imaging

  • Outlet

    >Patient supine

    >Beam centered on symphysis

    pubis and angled 25˚ (males)

    and 40˚ (females) towards the

    head

    >Midpoint of cassette should Source: Berquist

    intersect the beam

    *Good for examining the anterior

    pelvis, ventral foramina and

    margins of the sacrum, superior

    and inferior displaced fracture

    fragments

    Source: Berquist


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Classification

  • The Young and Burgess system classifies pelvic fractures based on the direction of the applied force. This allows recognition of likely associated injuries as well as assisting with planning of treatment.


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Classification

Source: Pearson Source: Young

  • Lateral compression – 49% of pelvic fractures; caused by a force delivered from the side; horizontal or oblique orientation of pubic rami fractures

    >Type 1 – Force delivered across the posterior part of the pelvis. Findings include: pubic rami fractures, possible crush injury of the sacrum or SI joint. Stable because ligaments remain intact.


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Classification

Source: Pearson

>Type 2 – Force delivered across the posterior part of the pelvis, but more anterior than in Type 1. There is internal rotation of the ipsilateral anterior hemipelvis and potential external rotation of the posterior hemipelvis with the anterior SI joint acting as the pivot. Findings include: pubic rami fractures, possible disruption of the posterior SI ligaments, possible crush injury of the sacrum. Unstable.


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Classification

Source: Pearson

>Type 3 – Force delivered across the posterior part of the pelvis, but more anterior than in Type 1. It is so severe that there is external rotation of the contralateral hemipelvis as well as internal rotation of the ipsilateral hemipelvis (this pattern appears as lateral compression on the ipsilateral side and AP compression on the contralateral side). Findings include: pubic rami fractures; rupture of the ipsilateral posterior SI ligaments; rupture of the contralateral sacrospinous, sacrotuberous, and anterior SI ligaments; possible crush injury of the sacrum. Unstable.


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Classification

Source: Pearson

Source: Young

  • AP Compression – 21% of pelvic fractures; caused by an AP or PA force; vertical orientation of pubic rami fractures

    >Type 1 – Findings include: <2.5cm of pubic symphysis diastasis, possible fracture of one or more pubic rami. Stable because posterior ligaments are intact.


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Classification

Source: Pearson Source: Young

>Type 2 – Findings include: >2.5cm of pubic symphysis diastasis; possible fracture of one or more pubic rami; disruption of the sacrospinous, sacrotuberous, and anterior SI ligaments. Unstable.


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Classification

Source: Pearson Source: Young

>Type 3 – Findings include: possible fracture of one or more pubic rami, total disruption of the pubic symphysis and SI joint. Unstable.


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Classification

Source: Pearson

Source: Young

  • Vertical Shear – 6% of pelvic fractures; caused by a force delivered over one or both sides of the pelvis lateral to the midline such as that to an extended lower extremity (fall or jump from height) or impact from above; vertical orientation of pubic rami fractures

    >Findings include: possible fractures of the pubic rami, sacrum, SI joint, or iliac wing; usually complete disruption of the symphysis pubis, anterior and posterior SI, sacrospinous, and sacrotuberous ligaments. Unstable.


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Classification

  • Combination

    >Usually due to a crush mechanism. Source: Young

    Most often vertical shear and lateral compression.


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Complications

  • Hemorrhage / Vascular Injury

    >Usual source of retroperitoneal hemorrhage is venous plexus disruption in the posterior pelvis; can also be caused by large artery injury

  • GI / GU Injury

    >Perforation of the rectum or anus with bony fragments or entrapment of a portion of the bowel in the fracture site

    >Ureters (posterior pelvic fractures; infrequent); bladder, urethra (symphysis and pubic rami injury; urethra injured more often in males)

  • Neurologic Injury

    >Lumbosacral plexus and nerve root (especially with sacral fractures) injuries are the most common

    >Sciatic nerve at particular risk with posterior pelvic injury


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Treatment

  • Initial treatment involves general trauma evaluation / resuscitation and hemorrhage control (can include angiography and embolization if bleeding persists)

  • Further treatment can involve external and/or internal fixation with particular attention paid to possible open fractures that involve associated injury to the GI or GU systems

  • Other postoperative measures include: aggressive pulmonary toilet, thromboembolic prophylaxis (heparin as allowed), slowly advancing weight-bearing status


Classification of pelvic fractures a mechanistic approach allison moriarty december 16 2006

Sources

1. Berquist TH, Coventry MB. Chapter 5: The Pelvis and Hips. Imaging of Orthopedic Trauma. 1992.

2. Koval KJ, Zuckerman JD. Handbook of Fractures. 2002.

3. Moore KL, Dalley AF. Clinically Oriented Anatomy. 1999.

4. Pearson, JM. “Pelvic Fractures” handout.

5. Young JWR, et al. Pelvic Fractures: Value of Plain Radiography in Early Assessment and Management. Radiology 1986;160:445-451.


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