Background

Bony anatomy

 

Pelvic AnatomyPelvis Outlet

 

Soft tissue anatomy

 

Pelvis anatomy 1LIgaments pelvis posterior

 

Anterior sacroiliac ligaments Resist external rotation
Posterior sacroiliac ligaments Strongest in the body
Sacrospinous ligaments

Lateral sacrum to ischial spine

Resist external rotation

Sacrotuberous ligaments

Posterior sacrum to ischial tuberosity

Resist vertical shear

Iliolumbar ligaments Iliac crest to transverse process of L5

 

Young and Burgess Classification

 

AP COMPRESSION

Diastasis of the pubic symphysis without anterior fracture

APC 1 Pubic diastasis < 2.5 cm Stable
  APC 2

Pubic diastasis > 2.5 cm

Anterior SI joint widening

Posterior SI ligaments intact

Rotationally unstable

Vertically stable

  APC 3

Pubic diastasis > 5 cm

Anterior and posterior SI joint widening

Globally unstable

 

LATERAL COMPRESSION

Transverse overlapping obturator ring fractures

LC1 Sacral impaction fracture Stable
  LC2 Iliac wing fracture

Rotationally unstable

Vertically stable

  LC3

Lateral compression fracture one side

AP compression fracture other side

Globally unstable

VERTICAL SHEAR FRACTURE

Fractures of the pubis and SI joint with vertical displacement

 

Vertical displacement of hemipelvis

Fractures of pubis and SI joint

Unstable

COMBINED

  Complex fractures with combined elements of ACP / LC / Vertical shear

 

 

APC / Anterior Posterior Compression

 

APC-1

 

Pelvic Fracture APC 2

< 2.5 cm diastasis with no anterior SI joint widening

 

APC-2

 

Pelvic Fracture APC 2Pelvis APC 2

Pubic diastasis with anterior SI joint widening on the right

 

APC-3

 

APC 3Complete SI joint disruption

Pubic diastasis > 5 cm with complete SI joint disruption

 

LC / Lateral Compression

 

Mechanism

 

Compressive force to lateral aspect of the pelvis

Results in internal rotation and medialisation of the hemipelvis

 

LC-1

 

Pelvic Lateral Compression Fracture LC1LC1 sacral fractures

Pubic rami + sacral compression left side

 

LC-2

 

Pelvic Fracture LC2

Pubic rami + iliac wing fracture

 

LC-3

 

Wind swept pelvis

Lateral compression + contralateral open book

 

LC-3LC-3 b

 

Vertical Shear

 

APC or LC fractures with vertical displacement

 

Vertical shearVertical shear xray

Vertical shear fracture through sacrum                        Vertical shear fracture through ilium

 

CM / combined mechanism

 

Tile Classification

 

Type A: pelvic ring stable A1

Fractures not involving the ring

iliac crest or wing, avulsions

  A2 Stable minimally displaced fractures of the pelvic ring
Type B:  Pelvic ring rotationally unstable, vertically stable B1 Open Book
  B2 Lateral compression ipsilateral
  B3

Lateral compression contralateral or bucket handle type injury

Type C:  Pelvic ring rotationally and vertically unstable C1 Unilateral
  C2 Bilateral
  C3 Associated with acetabular fracture

 

X-rays

 

Inlet view

- 40o caudal

- shows AP displacement of sacrum and anterior ring

- anterior and posterior sacral borders

 

Pelvis Inlet viewPelvis Inlet

 

Outlet view

- 40o cephalad

- vertical displacement of sacrum relative to ilium

 

Pelvis Outlet ViewPelvis Outlet

 

CT scan

 

Associated injuries

 

Pelvic vascular injury - arterial / venous

Injuries to urethra / rectum / vagina

Nerve injury

Compound / Morel Lavallee

 

Pelvic vascular injury

 

Incidence

 

Dyer et al 2006

- 60% lateral compression

- 52% APC

- 40% vertical shear

 

Injury pattern

- 15% arterial

- 85% venous

 

Arterial bleeders

 

Internal pudendal artery most common

Iliolumbar / SGA / IGA / lateral sacral / internal iliac

 

Retroperitoneal veins / bone bleeding

 

85% of bleeding

 

Visceral injury

 

Urethra / rectum / vagina / rectum / peroneum

- vaginal and rectal examinations

- looks for blood at urethral meatus

 

Retrograde urethrogram indicated for blood at meatus +/- retropubic catheter

 

Pelvic Fracture Retrograde Urethrogram Normal

Retrograde urethrogram in setting of APC pelvic fracture

 

Neurological Damage

 

Denis classification of sacral fractures

 

Sacral fractures

  Site of fracture Incidence of neurological deficit Nerve injury
Zone 1 Lateral to foramen < 7% L5 nerve root which is superior to sacral alar
Zone 2 Through foramen 30%

S1 / S2

Difficulties with voiding

Pudenal nerve numbness

Zone 3 Spinal canal 60%

Cauda equina

Loss of bladder and bowel function

Sexual dysfunction

Sacral Fracture Transforaminal

 

Denis Zone 2 sacral fracture

 

Morel - Lavallee Lesion

 

Definition

 

Skin degloving

- predisposes to infection

- found on the thigh in lateral compression fractures

- found in the lumbar area in APC or vertical shear

 

Morel Lavalle

Morel-Lavallee

 

Beckmann et al Emerg Radiol 2016

- ML lesions seen in 12% of pelvic fractures based on CT

- most common in vertical shear (34%)

- occur in 12% of APC and LC fractures

 

Compound wounds

 

Compound pelvis 2Compound Pelvis 1