Background

Bony anatomy

 

 

Soft tissue anatomy

 

 

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

 

< 2.5 cm diastasis with no anterior SI joint widening

 

APC-2

 

Pubic diastasis with anterior SI joint widening on the right

 

APC-3

 

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

 

Pubic rami + sacral compression left side

 

LC-2

 

Pubic rami + iliac wing fracture

 

LC-3

 

Wind swept pelvis

Lateral compression + contralateral open book

 

 

Vertical Shear

 

APC or LC fractures with vertical displacement

 

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

- 40^o caudal

- shows AP displacement of sacrum and anterior ring

- anterior and posterior sacral borders

 

 

Outlet view

- 40^o cephalad

- vertical displacement of sacrum relative to ilium

 

 

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

 

Retrograde urethrogram in setting of APC pelvic fracture

 

Neurological Damage

 

Denis classification of 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

 

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-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