Open Book Pelvic Injuries

Open book pelvic injuries (APC injuries) result from external rotation forces that "open" the pelvis like a book at the symphysis pubis. Symphysis widening greater than 2.5cm is the surgical threshold, indicating anterior SI ligament disruption (APC-II). Critical emergency: the open book increases pelvic volume by up to 4L, causing life-threatening hemorrhage. Apply pelvic binder IMMEDIATELY - do not wait for imaging. 80% of bleeding is venous and responds to mechanical closure. Definitive treatment depends on posterior stability: symphysis plating alone if posterior ligaments intact (APC-II), or combined anterior and posterior fixation for APC-III.

Introduction

"Open book" is the colloquial term for anteroposterior compression (APC) pelvic injuries, specifically APC-II pattern. The name derives from the appearance of the pelvis on AP radiograph - the two hemipelves externally rotate and separate anteriorly at the symphysis, like opening a book where the symphysis represents the spine.

This injury pattern is critical because it produces the highest hemorrhage risk of all pelvic fracture patterns. The external rotation mechanism dramatically increases pelvic volume, eliminating the tamponade effect of the intact ring and allowing massive retroperitoneal bleeding.

The Book Analogy

Understanding the "book" concept:

• Spine of book: Pubic symphysis
• Pages: The two hemipelves
• Opening the book: External rotation force
• Closing the book: Pelvic binder (internal rotation)

Clinical Significance

Why Open Book Injuries Matter:

1. Hemorrhage: Volume expansion allows liters of blood loss
2. Instability: Rotational instability affects function
3. Associated injuries: Urological, vascular, neurological
4. Time-critical: Hemorrhage control is lifesaving
5. Recognizable pattern: Classic radiographic appearance

Epidemiology

Incidence:

• Most recognized pelvic injury pattern
• Classic presentation of APC mechanism
• Common in motorcycle accidents

Mechanism:

• Motorcycle collision (handlebar impact to pelvis)
• Pedestrian struck anteriorly
• Frontal MVA with AP compression
• Crush injuries

Demographics:

• Young males predominate
• High-energy mechanism
• Associated polytrauma common

Pelvic Ring Biomechanics

Normal Anatomy

Pubic Symphysis:

• Fibrocartilaginous joint
• Normal width approximately 5mm (range 3-8mm)
• Increases physiologically in pregnancy
• Limited mobility normally

Stability Hierarchy:

• Posterior structures provide 60% of stability
• Anterior structures provide 40% of stability
• Symphysis disruption alone does NOT cause complete instability

Open Book Pathoanatomy

The external rotation force causes sequential failure:

Stage 1 (less than 2.5cm diastasis - APC-I):

• Symphysis stretched/partially disrupted
• Anterior SI ligaments intact
• Mechanically stable
• Conservative management usually appropriate

Stage 2 (greater than 2.5cm diastasis - APC-II/Open Book):

• Complete symphysis disruption
• Anterior SI ligaments disrupted
• Sacrospinous ligament torn
• Posterior SI ligaments INTACT (KEY)
• Rotationally unstable, vertically stable

Stage 3 (Complete disruption - APC-III):

• All anterior structures disrupted
• All posterior structures disrupted
• Complete hemipelvic instability

Hemorrhage Mechanism

Volume Expansion:

• Normal pelvic volume approximately 1.5 liters
• Open book can expand to greater than 4 liters
• No tamponade from intact ring
• Retroperitoneal space fills with blood

Bleeding Sources:

• Venous (80%): Presacral plexus, internal iliac veins
• Arterial (20%): Superior gluteal (most common), internal iliac branches
• Bone surfaces: Cancellous bleeding

Associated Soft Tissue Injuries

Urological (Common):

• Bladder injury (15-25%)
• Urethral injury (males)
• Mechanism: Symphysis disruption tears attached structures

Vascular:

• Presacral venous plexus
• Internal iliac branches
• Corona mortis (variant vessels)

Neurological (Less Common):

• L5 nerve root
• Lumbosacral plexus
• Less common than VS injuries

Young-Burgess APC Classification

The Anteroposterior Compression (APC) classification system is essential for understanding open book injuries and guiding treatment.

Key Radiographic Measurements

Symphysis Width:

• Normal: approximately 5mm (3-8mm range)
• Suspicious: greater than 10mm
• APC-I: under 2.5cm
• APC-II/III: greater than 2.5cm

SI Joint Widening:

• Anterior SI widening suggests ligament disruption
• Posterior SI widening indicates APC-III
• CT imaging essential for accurate assessment

Inlet View Assessment:

• Best view for assessing symphysis diastasis
• Shows rotational deformity
• Evaluates anterior SI joint

Primary Survey

Open book injuries present in major trauma context. Assessment follows ATLS principles.

Mechanism History

Classic Mechanisms:

• Motorcycle vs car (handlebar impact)
• Pedestrian struck from front
• Frontal vehicle collision
• Direct AP compression

Physical Examination

Inspection:

• Leg external rotation (both limbs)
• Perineal swelling/ecchymosis
• Scrotal/labial hematoma
• Blood at urethral meatus (urological injury)
• Obvious widening of pubic area

Palpation (Once Only):

• Palpable symphysis gap
• Tenderness over symphysis
• SI joint tenderness
• Avoid repeated manipulation

Signs of Hemorrhage:

• Tachycardia (early sign)
• Hypotension
• Reduced consciousness
• Poor capillary refill
• Ongoing transfusion requirements

Urological Assessment

CRITICAL Before Catheterization:

• Blood at urethral meatus
• Perineal hematoma
• High-riding prostate (DRE in males)
• Scrotal hematoma

If Urethral Injury Suspected:

• Do NOT attempt urethral catheterization
• Retrograde urethrogram first
• Suprapubic catheter if complete rupture

Stability Assessment

Clinical Signs of Instability:

• Bilateral leg external rotation
• Palpable symphysis gap greater than 2 finger widths
• Hemodynamic instability
• Ongoing resuscitation requirements

Radiographic Correlation:

• greater than 2.5cm symphysis widening
• Anterior SI widening
• Assess posterior integrity on CT

Differential Diagnosis

The widened or painful symphysis on an AP pelvis has several mimics. The key discriminators are the mechanism, the degree and symmetry of widening, and the posterior ring on CT.

Imaging Protocol

Plain Radiography

AP Pelvis (First-Line):

• Immediate in trauma bay
• Can be done with binder in place
• Measure symphysis width

Measurement Technique:

• Measure at superior aspect of symphysis
• Normal: approximately 5mm
• greater than 10mm: Suspicious
• greater than 25mm (2.5cm): Surgical threshold

Associated Findings:

• External rotation of hemipelves
• Pubic rami fractures
• SI joint widening
• Sacral fracture

Inlet View:

• Best demonstrates AP displacement
• Shows symphysis widening clearly
• Evaluates SI joint anteriorly

Outlet View:

• Evaluates vertical displacement
• Distinguishes from VS component
• Sacral fracture visualization

CT Imaging

Indications:

• All hemodynamically stable patients
• Surgical planning
• Assess posterior injury

Key Findings:

• Symphysis diastasis measurement
• Anterior SI ligament status
• Posterior SI ligament integrity (CRITICAL)
• Associated fractures
• Hematoma extent

CT Angiography:

• Active arterial bleeding
• Guides angioembolization
• Contrast extravasation

Retrograde Urethrogram

Indications:

• Blood at urethral meatus
• High-riding prostate
• Perineal hematoma
• Before urethral catheterization if suspicious

Technique:

• 20-30mL water-soluble contrast
• Gentle injection
• Look for extravasation

Cystogram

Indications:

• Gross hematuria with pelvic fracture
• After urethral integrity confirmed

Findings:

• Extraperitoneal rupture: Flame-shaped extravasation
• Intraperitoneal rupture: Contrast around bowel

Algorithm

View larger

Treatment Algorithm

Symphysis Plating - Step by Step

Posterior SI Screw Fixation (APC-III)

Indications

• APC-III with posterior SI disruption
• Posterior SI widening on CT
• Vertical instability

Technique Overview

• Percutaneous iliosacral screw preferred
• Patient prone or lateral
• Entry point: Posterior iliac crest
• Trajectory: Across SI joint into S1 body
• Guide with AP, inlet, outlet views
• 6.5mm or 7.3mm cannulated screws
• One or two screws depending on stability

Key Safety Points

• L5 nerve root at risk (stays superior)
• S1 foramen must be avoided
• Stay in "safe zone" of S1 body
• Outlet view ensures screw below L5

Early Complications

Hemorrhagic Shock:

• Primary cause of early mortality
• Requires aggressive resuscitation
• Binder is lifesaving intervention

Urological Injury:

• Bladder rupture (15-25% incidence with open book)
• Extraperitoneal more common (symphysis tears bladder)
• Intraperitoneal rupture with full bladder at impact
• Urethral injury (male predominance, longer urethra)
• Membranous urethra at risk
• Blood at meatus is cardinal sign

Management:

• Bladder extraperitoneal: Catheter drainage 10-14 days
• Bladder intraperitoneal: Surgical repair required
• Urethral: Retrograde urethrogram before catheterization
• Suprapubic catheter if complete urethral rupture
• Delayed primary repair vs immediate realignment

Vascular Injury:

• Superior gluteal artery most common arterial source (exits greater sciatic notch)
• Corona mortis (aberrant obturator vessels, present in 30%)
• Can cause significant bleeding during anterior approaches
• Angioembolization effective for arterial injuries

Morel-Lavallee Lesion:

• Closed degloving injury
• Subcutaneous fat separates from fascia creating fluid-filled cavity
• Typically over greater trochanter or iliac crest
• Delays surgical fixation
• Infection risk if not addressed
• May need debridement before surgery

Thromboembolic Events:

• Very high DVT risk
• Early prophylaxis when safe
• May need IVC filter

Infection:

• Especially with open injuries
• Morel-Lavallee lesion increases risk
• Surgical site infection

Late Complications

Malunion:

• Residual diastasis
• Gait abnormality
• Chronic pubic symphysis pain

Hardware Failure:

• Plate loosening
• Screw pullout
• May indicate unrecognized posterior instability

Sexual Dysfunction:

• Erectile dysfunction (vascular or neurological)
• Dyspareunia
• Counseling important

Chronic Pain:

• Symphysis pain
• SI joint pain (if posterior injury)
• May need plate removal

Functional Outcomes

APC-II (Open Book) - Good Prognosis

Expected Outcomes:

• 70-80% return to pre-injury function
• Most patients ambulate independently by 6 months
• Return to work: 4-6 months for sedentary, 6-12 months for physical
• Sports: 9-12 months for high-impact activities

Factors Predicting Better Outcome:

• Younger age
• Anatomic reduction achieved
• No posterior injury
• Early appropriate fixation
• No major associated injuries

APC-III - More Guarded Prognosis

Expected Outcomes:

• 50-60% return to pre-injury level
• Longer recovery (12-18 months)
• Higher residual pain rates
• More likely to have permanent limitations

Complications More Common:

• Chronic SI pain
• Residual instability
• Gait abnormalities
• Need for revision surgery

Mortality and Morbidity

Mortality:

• APC-II: 5-8% (mostly from hemorrhage if uncontrolled)
• APC-III: 15-20%
• Early deaths: Hemorrhagic shock
• Late deaths: Multi-organ failure, PE

Major Morbidity:

• DVT/PE: 20-30% without prophylaxis
• Sexual dysfunction: 10-15%
• Chronic pain: 20-30%
• Gait abnormality: 10-20%

Long-Term Issues

Pelvic Pain:

• Symphysis pain common initially
• Usually improves by 12 months
• Persistent pain in 15-20%
• May benefit from plate removal

Sexual Function:

• Males: Erectile dysfunction (vascular or neurological)
• Females: Dyspareunia, altered sensation
• Counseling important
• May improve with time

Pregnancy Considerations:

• Future pregnancy generally possible
• May have pelvic pain during pregnancy
• Consider elective caesarean section
• Discuss with patient before fixation

Arthritis:

• SI joint arthritis long-term risk if APC-III
• Symphysis arthritis rare with good reduction
• Monitor for late degenerative changes

Return to Activity

Desk Work: 3-4 months

Light Manual Work: 6 months

Heavy Manual Work: 9-12 months

Running: 9-12 months

Contact Sports: 12+ months (if ever)

Driving: When off narcotics and can perform emergency stop (usually 8-12 weeks)

Global Epidemiology

According to PubMed (Balogh et al., J Trauma 2007, DOI), a population-based study of an inclusive trauma system found the overall incidence of pelvic ring fractures was 23 per 100,000 persons per year, split evenly between high-energy (10 per 100,000) and low-energy (10 per 100,000) mechanisms, with 3 per 100,000 dying pre-hospital. High-energy fractures occurred predominantly in younger men, and pelvic-fracture-related mortality was always attributable to bleeding. Demonstrated arterial bleeding was rare (1.3 per 100,000 per year), reinforcing that most haemorrhage is venous and amenable to mechanical control.

In the original Young-Burgess series (Burgess et al., J Trauma 1990, PMID 2381002), anteroposterior compression (open book) injuries had the highest transfusion requirement (mean 14.8 units) and the highest mortality (20%) of all force-vector patterns. Type A (stable) and type B (rotationally unstable, including open book) patterns together account for 70-80% of all pelvic ring injuries (Tile, JAAOS 1996, DOI).

Guideline Comparison (Side-by-Side)

There is broad international concordance: all major bodies (WSES, NICE NG37, BOA/BOAST, AAOS/OTA, AO Foundation, EFORT) endorse immediate circumferential compression, early tranexamic acid, and posterior-ring-led decision making for definitive fixation. The principal practice variation is in the haemorrhage-control adjunct - North American and Northern European centres with hybrid theatres favour early angioembolisation, whereas systems without immediate interventional radiology (and most military doctrine) favour preperitoneal packing first. The WSES classification and guidelines (Coccolini et al., World J Emerg Surg 2017, DOI) integrate haemodynamic status with anatomical pattern and are the most widely adopted contemporary algorithm.

Registry Evidence

National and regional registries (German Pelvic Trauma Registry / TraumaRegister DGU, UK Trauma Audit and Research Network [TARN], and the Victorian Orthopaedic Trauma Outcomes Registry [VOTOR] in Australia) consistently report that bleeding remains the dominant early cause of death in unstable pelvic ring injury, and that mortality is driven more by associated injuries and haemodynamic status than by the anterior diastasis itself. TARN data have been used to quantify the small subset of exsanguinating pelvic patients potentially amenable to REBOA in England and Wales (Barnard et al., Emerg Med J 2015, DOI).

Pharmacological and System Considerations

Practice variation: pharmacological VTE prophylaxis timing also differs - earlier initiation in some European protocols versus more conservative North American thresholds - reflecting the tension between bleeding and thrombosis risk in the polytrauma pelvis. Drug availability, reimbursement and trauma-network maturity differ by jurisdiction and should be checked against local formularies and guidelines.

High-Yield Concepts

Critical Numbers

• 5mm: Normal symphysis width
• 10mm: Suspicious for injury
• 25mm (2.5cm): Surgical threshold (APC-I vs APC-II)
• 80%: Proportion of bleeding that is venous
• 1.5L to 4L: Pelvic volume increase with open book

Surgical Decision-Making

Symphysis Fixation Alone (APC-II):

• Posterior SI ligaments intact on CT
• Symphysis widening is the primary pathology
• Single anterior approach, symphysis plate

Add Posterior Fixation (APC-III):

• Posterior SI widening on CT
• SI ligament disruption
• Complete hemipelvic instability
• Need anterior AND posterior fixation

Binder Positioning

Correct: Greater trochanters Incorrect: Iliac crests (too high, doesn't close book effectively)