Pelvic Fractures

Introduction

The majority of pelvic fractures are the result of high-energy blunt injures
Patients require emergent and thorough evaluation
As compared to the extremities, the pelvis has greater soft tissue constraints, as well as vital non-musculoskeletal structures
Treatment of pelvic fractures requires techniques different from those used in the extremities
Treatment can be surgical or nonsurgical, but emphasize the re-establishment of a stable ring structure that allows appropriate transfer of weight from the torso to the hips and legs

Anatomy

Bony Anatomy

Pelvis is composed of 3 bones, 1 sacrum and 2 innominate bones
Innominate bone forms from the fusion of the immature
- Ischium (infero-posterior)
- Illium (superior)
- Pubis (infero-anterior)
The acutabulm forms at the junction of these 3 bones
Important bony prominences and landmarks include
- The anterior superior illiac spine (ASIS)
- The anterior inferior illiac spine (AIIS)
- Iliac crest
- Iliac fossa
- Posterior superior illiac spine (PSIS)
- Ischial spine
- Ischial tuberosity
- Inferior and superior pubic rami
- Pectineal eminence
- Pubic tubercle
Figure to show landmarks via lateral view of inominate bone and anterior view of the pelvis

Ring stability

The bony pelvis is stabilized primarily by
- Symphysis pubis
  - Forms the anterior part of the pelvic ring
  - Composed of a complex of
    - Hyaline cartilage
    - Fibrocartilage
    - Fibrous tissues
- Sacroilliac (SI) joints
  - Forms the posterior part of the pelvic ring
  - Composed of both hyaline and fibro-cartilage
  - Stabilized via posterior, anterior and interosseous ligaments; the latter are the strongest ligaments in the body
  - Not a true synovial joint, as it does not originate from an anlage of condensed mesanchyme
The elements of the pelvis are further stabilized relative to each other through
- Sacro-spinous ligament (anteroposterior and rotational vectors)
- Long and short sacro-tuberous ligament (vertical vector)
From a superior view with the pubis facing down, the sacrum forms an upside down keystone (or suspension bridge) that does not have inherent stability; with loss of bony or ligamentous constraints, the sacrum tends to displace anteriorly (the bridge will fall)
From an anterior view the sacrum forms the keystone of an arch that transfers weight from the spine to the acetabuli

Non-musculoskeletal structures

Knowledge of this anatomy is critical to complete evaluation of the patient, as well as for uncomplicated surgical management
The pelvis has an intimate and constrained relationship with a number of structures including
- Branches of the lumbosacral plexus
- Main and terminal branches of the iliac vascular system
- Lower gastrointestinal tract
- Genitourologic structures including the bladder and urethra
Figures to show these relationships--one for nervous, one for vascular, one for GI and one for urologic

Pathogenesis

Direct impact to the pelvis with indirect transfer of forces to anterior and posterior ring elements
Mechanisms of Injury
- Lateral compression
- Antero-posterior compression
- Vertical shear
- Combination of the above
Impact forces cause rotation-translation of a hemipelvis fragment relative to the sacrum in the axial plane or translation in the coronal plane
Settings
- Most commonly motor vehicle and pedestrian-vehicle crashes
- Motorcycle crashes, fall from heights and crush injuries are less common

Natural History

Mortality 5 - 20% (up to 42% for open fractures)
Increasing mortality with increased age
> 70 years old has 50% mortality
Pedestrian injury has 50% mortality
Pregnant cases have 33% fetal loss
20 - 40% of females subsequently need caesarean section

Clinical Presentation

Comorbidities
- The risk of additional injuries approaches 40-50%
- Significant injuries to the viscera, great vessels (highest in APC-III) and head (highest in LC-II) are common with high energy mechanisms
- APCs have the highest rate of blood loss and death
  - APC-III has a mortality rate as high as 37%
  - Newer studies, however, have called into question these particular associations with specific fracture patterns
Associated injured
- Arteries
  - Internal pudendal : the most frequent cause of active bleeding
  - Iliolumbar artery
  - Superior gluteal artery
  - Lateral sacral artery
  - Internal iliac artery
- Neurologic
  - L5, S1 are the most commonly injured spinal nerve roots
  - The degree of displacement of the posterior elements rather than specific location appears to be more important determinant of injury
- GU
  - Bladder
  - Urethra
  - Vagina
- GI
  - Rectum
  - Distal colon

Imaging and Diagnostic Studies

Patients with significant pelvic ring injuries should receive a full trauma evaluation according to American College of Surgeon's Advanced Trauma Life Support
Evaluation includes assessment of Airway, Breathing, Circulation

Radiographic evaluation

Initial radiographic evaluation includes
- AP view
  - Provides initial assessment of the anterior and posterior portions of the ring
  - May show concomitant acetabular injuries
- Inlet (40 degree caudal) view; provides information regarding
  - Rotation of each hemipelvis
  - Translation of the ilium relative to the sacrum
- Outlet (40 degree cephalad) view; shows
  - Sagital plane rotation
  - Vertical displacement
  - Sacral fractures
- Judet views are not typically needed, unless
  - There is a concomitant acetabular fracture
  - A better view of a ramus rootlet fracture is sought
  - Recommended in preparation of an anterior column screw
Anterior ring injuries are often easily seen
- Symphysis diastasis
- Pubic rami fractures
Posterior injuries can be more subtle
- Sacral fractures
- Sacroiliac (SI) joint injuries
Signs of posterior injury or instability
- Irregularities of the SI joint
- Fracture of the L5 transverse process
- Inferior pubic ramus fracture
Horizontal translation most often appears as posterior translation of ilium in SI dislocations /fracture-dislocations; also known as crescent fracture
Vertical displacement is commonly identified as cephalad migration of ilium; complete separation and migration is called Malgaign fracture

CT Scan

With any significant pelvic injury, a CT scan with fine cuts should be obtained
Allows for measurement of
- "Safe zone" in the bodies of S1 or S2, if iliosacral screws are indicated
- Degree of antero-posterior sacral alar comminution
- SI gapping with hemipelvis rotation
- Sacral foraminal involvement on coronal images
Special attention should be paid to the posterior elements, as sacral fractures can be missed on plain radiographs

Classification

Anatomic

The Letournel system is based purely on the location of the fracture
show Figure

Mechanism

Penal first introduced a mechanistic classification system in 1961
- Lateral compression (LC)
- Anterior-posterior compression (APC)
- Vertical shear (VS)
Young and Burgess (1986)
- LC fractures were subdivided into 3 types:
  - Type I : pubic rami fractures with impaction of the SI joint
  - Type II
    - Pubic rami fractures with internal rotation, posterior disruption
    - Posterior disruption can take 2 forms :
      - Iliac wing fracture
      - Varying degrees of anterior SI impaction and posterior SI disruption depending on location of impact on ilium
  - Type III : LC fracture on one side with APC fracture on the other side
- APC fractures were divided into 3 types:
  - Type I : Anterior ring widening with intact posterior elements
  - Type II
    - SI anterior widening
    - External rotation of the ilium
    - Disruption of sacro-tuberous and sacro-spinous ligaments
  - Type III : Complete posterior/SI disruption
- Strength of this system is that it is predictive of associated injuries and may aid in the initial evaluation and stabilization of the patient

Stability

Bucholtz in 1981 and Tile in 1988 created a system based on stability
The Tile classification
- Type A, stable
  - A1 : avulsion
  - A2 : minimally displaced ring
- Type B, rotationally unstable
- Type C, rotationally and vertically unstable
The OTA/AO scheme presents a variation where
- Type A is stable
  - A1 : Avulsion
  - A2 : Impaction
  - A3 : Transverse sacral/coccygeal fracture
- Type B is partially stable
  - B1 : Unilateral/partial in external or internal rotation
  - B2 : Bilateral/partial
- Type C is unstable
  - C1 : Unilateral/complete
  - C2 : Bilateral/incomplete
  - C3 : Bilateral/complete

Treatment

Resuscitation

Fluid replacement
Antishock garment
Embolisation
Direct surgical intervention
Application of external fixator can significantly reduce venous and bony bleeding

Provisional stabilisation

For fractures that increase pelvic volume, i.e. open book (B1) or vertical shear (C3), apply external fixator or pelvic clamp percutaneously in emergency room
External fixator placement :
- 2 pins placed percutaneously in each Ileum
- 1 at ASIS, 1 at iliac tubercle, at 45 degrees to each other
- Complete frame as anterior rectangle

By Type

A
- Symptomatic
- Mobilisation
B
- B1 : no stabilization
- B2 : stabilise with external fixator or anterior plate
- B3 (bucket handle)
  - If LLD < 1.5 cm : accept
  - If LLD > 1.5 cm or pelvic deformity excessive : reduce with pins in the iliac crest, maintain with anterior frame
C
- Anterior frame and skeletal traction (supracondylar femoral pin)
  - Safe
  - Indicated if :
    - There is adequate reduction of posterior sacroiliac complex
    - When posterior injury is a iliac fracture rather than an SI dislocation or a sacral fracture
  - Disadvantage is traction for 8-12 weeks
- ORIF
  - Risks
    - Bleeding
    - Loss of tamponade
    - Coagulopathy
    - Infection
    - Wound necrosis, esp. in posterior wounds
    - Nerve damage
  - Indications
    - Inadequate reduction of posterior injury, esp. SI dislocation
    - Open posterior wound
    - Associated with acetabular fracture

Indications for External Fixator

B : to aid and maintain reduction
C
- To produce partial stability
- Decreases bleeding
- Decreases pain
- Aids nursing
If ORIF is to be performed, it should be delayed, but no more than 7 days, until
- Patient is stable
- All investigations completed
- Operation planned

Complications

ORIF delayed more than 3 weeks would limit accuracy of reduction, because of callus formation
Non-union / malunion
- High incidence in Malgaine type 90%
- Usually symptomatic
- High incidence of nerve, bladder complications at revision surgery
Infection
- 6% incidence
- Increased incidence of infection associated with open bowel injury
- Increased incidence with ilio-inguinal approach
- Avoid operations in febrile patients
- Use prophylactic antibiotics
- Manage by draining wounds
Nerve palsy
- 11.2% incidence
- 17.4% in posterior fractures
- Usually peroneal component of sciatic nerve
Ectopic bone formation
- 20% incidence
- Indomethicin useful
- Radiation is also an option
Thrombo-embolic problems
- Give anticoagulation for 6 - 8 weeks after open operation
- 3500 units heparin tds starting at 72 hours post-injury or surgery and adjusted according to APTT (aim for APTT 31-36)
- Warfarinise after one week post-injury or operation (INR 2 - 2.5)
Urethral injury
- Occurs in 1/3 of unstable fractures (13% overall)
- Perform retrograde urethrogram prior to IDC
- Cystogram
- IVP may be indicated
Bladder rupture is usually extra-peritoneal and may lead to vesico-colic or vesical fistulas
Impotence 40%
Post-traumatic osteoarthritis in 4 - 15%; depends on quality of reduction