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

2. Outline Epidemiology Anatomy Imaging Classification Complications
Treatment

3. 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

4. Epidemiology Complex Pelvic Fxs Etiology % Patients Mortality Rate
MVA %
Farm accident 18 0%
Pedestrian accident %
Motorcycle accident 8 38%
Falls %
Other 8 0%

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. Imaging 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

16. 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

17. 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

18. 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.

19. 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.

20. 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.

21. 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.

22. 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.

23. 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.

24. 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.

25. 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.

26. Classification Combination
>Usually due to a crush mechanism Source: Young
Most often vertical shear and lateral compression.

27. 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

28. 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

29. Sources
1. Berquist TH, Coventry MB. Chapter 5: The Pelvis and Hips. Imaging of Orthopedic Trauma
2. Koval KJ, Zuckerman JD. Handbook of Fractures
3. Moore KL, Dalley AF. Clinically Oriented Anatomy
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: