Transcript Classification of Pelvic Fractures: A Mechanistic Approach

Classification of Pelvic Fractures: A
Mechanistic Approach
Allison Moriarty
December 16, 2006
Outline
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Epidemiology
Anatomy
Imaging
Classification
Complications
Treatment
Epidemiology
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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
Epidemiology
Complex Pelvic Fxs
Etiology
% Patients Mortality Rate
MVA
43
26%
Farm accident
18
0%
Pedestrian accident
17
41%
Motorcycle accident
8
38%
Falls
6
17%
Other
8
0%
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
Anatomy
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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
Anatomy
Bony Pelvis
Source: Berquist
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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
Anatomy
Source: Berquist
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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
Anatomy
Ligaments
Supraspinous l.
Iliolumbar l.
Long post. sacroiliac l.
Sacrospinous l.
Sacrotuberous l.
Lateral sacrococcygeal l.
Tendon of biceps femoris
Sacrospinous l.
Source: Berquist
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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
Anatomy
Ligaments
Supraspinous l.
Iliolumbar l.
Long post. sacroiliac l.
Sacrospinous l.
Sacrotuberous l.
Lateral sacrococcygeal l.
Tendon of biceps femoris
Sacrospinous l.
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
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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
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
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
Imaging
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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
Imaging
Source: Berquist
Source: Berquist
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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
Imaging
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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
structure of the pelvic ring,
displaced fracture fragments
Source: Berquist
Source: Berquist
Imaging
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Outlet
>Patient supine
>Beam centered on symphysis
pubis and angled 25˚ (males)
and 40˚ (females) towards the
head
>Midpoint of cassette should
intersect the beam
*Good for examining the anterior
pelvis, ventral foramina and
margins of the sacrum, superior
and inferior displaced fracture
fragments
Source: Berquist
Source: Berquist
Classification
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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
Source: Pearson
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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
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
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
Source: Pearson
Source: Young
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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
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
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
Source: Pearson
Source: Young
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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
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Combination
>Usually due to a crush mechanism.
Source: Young
Most often vertical shear and lateral compression.
Complications
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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
Treatment
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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
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.