Anteroposterior Compression (APC) Pelvic Injuries

Young-Burgess APC Classification

The Young-Burgess classification stratifies APC injuries by severity and stability based on progressive ligamentous disruption.

View larger

APC-I (Stable)

Definition: Symphysis widening less than 2.5cm

Structures Disrupted:

• Symphysis pubis (partial)
• Anterior SI ligaments (sprained, not torn)

Structures Intact:

• Sacrospinous ligament
• Sacrotuberous ligament
• Posterior SI ligament complex
• Interosseous SI ligaments

Clinical Features:

• Mechanically stable
• Moderate hemorrhage risk
• Usually ambulatory with weight-bearing restrictions
• Conservative management often appropriate

The 2.5cm threshold is the key differentiator for APC-I injuries.

APC-II (Rotationally Unstable, Vertically Stable)

Definition: Symphysis widening greater than 2.5cm with intact posterior SI ligaments

Structures Disrupted:

• Symphysis pubis (complete)
• Anterior SI ligaments (complete)
• Sacrospinous ligament (torn)
• Pelvic floor widened

Structures Intact:

• Posterior SI ligament complex
• Sacrotuberous ligament (partially intact)
• Interosseous SI ligaments (partially intact)

Clinical Features:

• "Open book" appearance on imaging
• Rotationally unstable (external rotation)
• Vertically stable (no cephalad migration)
• Significant hemorrhage risk
• Surgical fixation usually required

APC-III (Rotationally and Vertically Unstable)

Definition: Complete SI disruption with hemipelvic external rotation

Structures Disrupted:

• All anterior structures
• All posterior SI ligaments
• Sacrospinous ligament
• Sacrotuberous ligament
• Complete hemipelvic instability

Clinical Features:

• Grossly unstable pelvis
• Life-threatening hemorrhage
• Hemodynamic instability common
• Urgent surgical stabilization mandatory
• Highest mortality of all pelvic patterns

The posterior SI ligament status differentiates APC-II from APC-III.

Tile Classification Equivalent

• APC-I = Tile B1 (partially stable)
• APC-II = Tile B1 (rotationally unstable)
• APC-III = Tile C (rotationally and vertically unstable)

Classification guides management decisions and predicts hemorrhage risk.

Acute Hemorrhage Control

Pelvic Binder Application

Principles:

• Applies internal rotation force
• Closes the "open book"
• Reduces pelvic volume
• Restores tamponade effect
• Temporary measure (not definitive)

Technique:

• Position at level of greater trochanters (NOT iliac crests)
• Apply circumferential compression
• Commercial binder or sheet wrap acceptable
• Do not over-tighten (skin necrosis risk)
• Re-evaluate after 24-48 hours maximum

Contraindications:

• LC injuries (already internally rotated - binder makes worse)
• Acetabular fractures (may displace)

Damage Control Resuscitation

Principles:

• Permissive hypotension (SBP 80-90mmHg)
• Balanced transfusion (1:1:1 ratio)
• Avoid crystalloid overload
• Early TXA administration
• Correct coagulopathy aggressively

Early mechanical stabilization combined with damage control resuscitation saves lives.

External Fixation

Indications:

• Hemodynamically unstable with APC injury
• Binder alone insufficient
• Allows better access for abdominal surgery

Techniques:

• Anterior frame (iliac crest or supra-acetabular pins)
• Provides rotational stability
• Does NOT address posterior injury
• Temporizing measure

Angioembolization

Indications:

• Ongoing hemodynamic instability despite mechanical stabilization
• CT angiography showing arterial extravasation
• Contrast blush on imaging

Timing:

• Should not delay definitive surgical stabilization
• Hybrid theater ideal (IR + surgery)
• Superior gluteal artery most common target

REBOA

Role in APC:

• Zone III deployment (infrarenal)
• Bridge to definitive hemorrhage control
• Buys time for intervention
• Requires trained personnel

Adjuncts complement but do not replace mechanical stabilization.

Definitive Surgical Management

APC-I Management

Conservative:

• Weight-bearing as tolerated
• Protected mobilization
• Analgesia
• Serial X-rays to ensure no progression

Surgical indications (rare):

• Failure of conservative treatment
• Progression of diastasis
• Symptomatic instability

APC-II Management

Anterior Fixation:

• Symphysis plating (indicated when widening greater than 2.5cm)
• Open reduction, plate fixation
• 2-hole or 4-hole plate
• May need two plates for rotational control

Approach:

• Pfannenstiel incision
• Protect bladder
• Reduce symphysis with reduction clamps
• Apply plate to superior pubis

APC-III Management

Anterior AND Posterior Fixation Required:

Anterior:

• Symphysis plating as above

Posterior Options:

• SI screw fixation (percutaneous or open)
• Anterior SI plating
• Sacral bars
• Lumbopelvic fixation (severe instability)

Timing:

• Day 1-2 for hemodynamically stable patients
• Delayed for polytrauma/damage control

Surgical Approaches:

For SI Joint:

• Percutaneous: 7.3mm cannulated screws
• Lateral position, fluoroscopic guidance
• S1 body is target (not ala)
• Risk: L5 nerve root, iliac vessels

Anterior SI Plate:

• Pfannenstiel extended laterally
• Retroperitoneal approach
• 2-3 hole plate across SI joint

Management complexity increases with injury grade - APC-III requires comprehensive stabilization.

Anterior Symphysis Fixation

Indications:

• APC-II injuries (symphysis widening over 2.5cm)
• APC-III injuries (combined with posterior fixation)
• Symphysis diastasis over 2.5cm with rotational instability

Pfannenstiel Approach:

1. Transverse skin incision 2cm above symphysis
2. Incise linea alba vertically
3. Protect bladder (retract inferiorly)
4. Expose symphysis and superior pubic rami
5. Reduce symphysis with clamp
6. Apply superior pubic plate (3.5mm reconstruction plate)
7. 4-6 hole plate preferred for stability

Technical Pearls:

• Reduce symphysis before plating
• Superior plate position (strongest)
• Protect bladder throughout
• Consider second inferior plate for APC-III

The Pfannenstiel approach provides excellent access with minimal soft tissue damage.

Posterior SI Joint Stabilization

Indications:

• APC-III injuries with SI joint disruption
• Posterior instability on stress views
• Combined with anterior fixation for complete instability

Percutaneous Technique:

1. Lateral decubitus position (injured side up)
2. Fluoroscopy: inlet, outlet, lateral views
3. Entry point: posterior iliac crest
4. Target: S1 body (avoid neural foramen)
5. Guide wire placement under fluoro
6. 7.3mm partially threaded cannulated screws
7. Consider second screw for increased stability

Critical Anatomy:

• S1 neural foramen: avoid anterior-superior
• L5 nerve root: runs across ala
• Iliac vessels: anterior to SI joint
• Safe zone: S1 body centered

Meticulous fluoroscopic guidance prevents neurological complications.

Temporary Stabilization

View larger

Indications:

• Hemodynamically unstable patients
• Damage control orthopedics
• Bridge to definitive fixation
• Contaminated open pelvic wounds

Anterior Frame Technique:

1. Supra-acetabular pin placement
2. 5mm Schanz pins into iliac crest
3. Connect with anterior bar
4. Apply compression to close symphysis

Advantages:

• Rapid application (15-20 minutes)
• No C-arm required for basic frame
• Allows access for laparotomy
• Reversible and adjustable

Limitations:

• Does not address posterior instability
• Pin site infection risk
• Not definitive for APC-III

External fixation is a temporizing measure, not definitive treatment for unstable APC injuries.

Associated Injuries

Urological Injuries

Bladder Injury:

• 15-25% of APC injuries
• Extraperitoneal more common (symphysis disruption)
• Intraperitoneal with full bladder at impact
• Hematuria is key finding

Management:

• Extraperitoneal: Catheter drainage 10-14 days
• Intraperitoneal: Surgical repair required

Urethral Injury:

• More common in males (long membranous urethra)
• Blood at meatus, high-riding prostate
• Do NOT blind catheterize
• Retrograde urethrogram first
• Suprapubic catheter if complete disruption

Vascular Injuries

Arterial:

• Superior gluteal artery most common
• Internal iliac branches
• Corona mortis (variant obturator vessels)

Venous:

• Presacral venous plexus (major source)
• Internal iliac veins
• Low pressure but high volume bleeding

Neurological Injuries

Lumbosacral Plexus:

• L5 nerve root most vulnerable
• Foot drop, sensory loss
• S2-4 sacral roots: Bladder, bowel, sexual function

Documentation Essential:

• Motor function L2-S1
• Sensory examination
• Perineal sensation
• Rectal tone

Open Pelvic Fractures

Faringer Classification:

• Type I: Iliac wing (low risk)
• Type II: Perineum/buttock (moderate)
• Type III: Rectum/vagina (high mortality)

Management:

• Fecal diversion for rectal involvement
• Wound debridement
• Broad spectrum antibiotics
• High mortality (up to 50%)

Early Complications

Hemorrhagic Shock:

• Most common cause of early death
• Massive transfusion requirements
• Coagulopathy compounds bleeding

Thromboembolic Events:

• High DVT risk (venous stasis, injury)
• PE can be fatal
• Early prophylaxis when safe

Infection:

• Open fractures: High mortality
• Surgical site infections
• Osteomyelitis rare with closed injuries

Late Complications

Malunion:

• Residual diastasis
• SI joint malreduction
• Affects gait and pain

Nonunion:

• Rare with adequate fixation
• Symphysis nonunion: Painful instability
• SI nonunion: May need fusion

Hardware Issues:

• Symphysis plate loosening (activity related)
• Screw pullout
• May need removal if symptomatic

Chronic Pain:

• SI joint arthritis
• Symphysis pain
• May benefit from SI fusion

Sexual and Urological:

• Dyspareunia
• Erectile dysfunction
• Chronic urethral stricture

Immediate Postoperative (Days 0-14)

ICU Management:

• Continued hemodynamic monitoring
• Serial hemoglobin checks
• DVT prophylaxis (LMWH when hemostasis achieved)
• Early removal of pelvic binder (once fixation stable)

Mobility:

• Bed rest initially for severe injuries
• Toe-touch weight-bearing when hemodynamically stable
• Log-roll precautions for posterior fixation

Wound Care:

• Monitor surgical incisions
• Pin site care for external fixation
• Watch for infection signs

Early mobilization improves outcomes but must be balanced against injury stability.

Rehabilitation Phase (Weeks 2-12)

Weight-Bearing Progression:

• APC-I: Weight-bearing as tolerated
• APC-II: Partial weight-bearing 6 weeks, then advance
• APC-III: Protected weight-bearing 8-12 weeks

Physical Therapy:

• Core strengthening
• Gait training with aids
• Hip and lumbar ROM exercises
• Pelvic floor rehabilitation if indicated

Radiographic Follow-up:

• 6 weeks: Check implant position
• 12 weeks: Assess union

Regular clinical and radiographic assessment guides rehabilitation progression.

Return to Function (3-6 Months)

Expected Timeline:

• APC-I: Full activity by 3 months
• APC-II: Full activity by 4-6 months
• APC-III: May require 6+ months

Hardware Removal:

• Symphysis plate: Rarely removed
• SI screws: Remove if symptomatic after union
• External fixator: Convert to definitive fixation or remove

Long-term Considerations:

• Annual review for first 2 years
• Address chronic pain syndromes
• Fertility counseling for women if concerned

Most patients return to near-normal function with appropriate treatment and rehabilitation.