PELVIC RING INJURIES
Ring Injury Concept | LC vs APC vs VS | Hemorrhage Control First
YOUNG-BURGESS CLASSIFICATION
Critical Must-Knows
- Pelvis is a ring - injury in one place means injury elsewhere
- Hemorrhage is the killer - venous plexus bleeds profusely (90% of bleeding)
- Binder at greater trochanters - reduces volume and tamponades bleeding
- Posterior ring = stability - assess SI ligaments on CT
- Vertical shear = worst stability - complete posterior disruption
Examiner's Pearls
- "LC injuries often stable (impaction posteriorly)
- "APC diastasis greater than 2.5cm = posterior injury
- "Preperitoneal packing for venous bleeding
- "L5 transverse process fracture = unstable injury
Clinical Imaging
Imaging Gallery
Critical Pelvic Ring Injury Points
Ring Concept
Pelvis is an osseo-ligamentous ring. A break in one place implies a break elsewhere. Always assess entire ring on CT.
Hemorrhage Control
Venous plexus = 90% of bleeding. Control with pelvic binder then preperitoneal packing then angioembolization.
Young-Burgess
LC = lateral compression (most common). APC = open book (external rotation). VS = vertical shear (worst).
Stability
Posterior ring = stability. VS and APC III have complete posterior disruption = globally unstable.
At a Glance: Quick Decision Guide
| Clinical Scenario | Diagnosis | Urgency | Action |
|---|---|---|---|
| Stable BP, isolated pubic rami fracture | LC I (Stable) | Routine | Mobilize WBAT, analgesia |
| Rotationally unstable, symphysis widened | APC II / LC II | Urgent | ORIF symphysis, assess posterior ring |
| Vertical displacement, L5 TP fracture | Vertical Shear | Urgent | Skeletal traction, posterior fixation |
| Unstable BP, open book on X-ray | APC III (Unstable) | Emergent | Pelvic binder, MTP, OT/Angio |
POSTPelvic Stability
Memory Hook:POSTerior ring determines stability - assess the back of the ring!
GAPRadiographic Signs of Instability
Memory Hook:Mind the GAP - it means instability!
BINDHemorrhage Control
Memory Hook:BIND the pelvis to save the life.
FABCOpen Pelvic Fracture
Memory Hook:FABC - the ABCs of open pelvis come after stopping the bleed!
Overview and Epidemiology
Why This Topic Matters
Pelvic ring injuries are life-threatening emergencies. The pelvis can hold 4+ liters of blood. Understanding classification, stability, and hemorrhage control is essential for the trauma component of orthopaedic exams.
Demographics
- Young adults: High-energy (MVA, fall from height)
- Elderly: Low-energy falls, osteoporotic bone
- Polytrauma: 20% have associated pelvic injury
- Pedestrians vs car: High-energy mechanism
Associated Injuries
- Urological: 10-15% (bladder, urethra)
- Neurological: 10-15% (lumbosacral plexus)
- Vascular: Life-threatening hemorrhage
- GI: Rectal tears (open fracture)
Anatomy and Biomechanics
The Ring Concept
The pelvis is a TRUE RING structure. A break in one location always implies a second break elsewhere. The ring can break through bone (fracture) or ligament (dislocation). Always assess the ENTIRE ring on CT.
Key Ligamentous Stabilizers
Pelvic Ligaments and Function
| Ligament | Location | Function | Injury Pattern |
|---|---|---|---|
| Interosseous SI | Between sacrum and ilium | STRONGEST - resists vertical shear | Disrupted in VS, APC III |
| Dorsal SI | Posterior to SI joint | Resists posterior translation | Disrupted in APC II-III |
| Ventral SI | Anterior to SI joint | Resists external rotation (weakest) | First to fail in APC |
| Sacrospinous | Sacrum to ischial spine | Resists external rotation | Torn in APC II-III |
| Sacrotuberous | Sacrum to ischial tuberosity | Resists vertical shear, external rotation | Torn in VS |
| Pubic Symphysis | Anterior ring | Provides 10-15% stability only | Widened in APC |
Vascular Anatomy
Venous Plexus (90% of Bleeding)
- Presacral plexus: Extensive, low pressure
- Prevesical plexus: Around bladder
- Tamponaded by packing: Direct pressure works
- Source of most hemorrhage
Arterial (10% of Bleeding)
- Superior Gluteal Artery: Most common
- Internal Pudendal Artery: Perineal injuries
- Obturator Artery: Anterior ring
- Corona Mortis: Anastomosis at risk in Stoppa approach
Vertical Stability
Vertical stability depends on the interosseous sacroiliac ligaments - the strongest ligaments in the body. If disrupted (VS or APC III), the hemipelvis migrates superiorly and the patient is globally unstable.
Classification Systems
Young-Burgess Classification
Young-Burgess Classification
| Type | Mechanism | Deformity | Posterior Injury | Stability |
|---|---|---|---|---|
| LC I | Lateral | Internal rotation | Ipsilateral sacral impaction | Stable |
| LC II | Lateral | Internal rotation | Crescent (iliac wing) fracture | Rotationally unstable |
| LC III | Lateral + contralateral APC | Windswept | Contralateral SI disruption | Globally unstable |
| APC I | AP compression | Diastasis less than 2.5cm | Intact | Stable |
| APC II | AP compression | Diastasis greater than 2.5cm | Anterior SI disrupted | Rotationally unstable |
| APC III | AP compression | Complete diastasis | Complete SI disruption | Globally unstable |
| VS | Vertical | Cephalad displacement | Complete disruption | Most unstable |
The 2.5cm Rule
Symphysis diastasis greater than 2.5cm indicates disruption of the sacrospinous ligament (APC II) and posterior ring injury. This is the threshold for surgical intervention.
Clinical Assessment
History
- Mechanism: MVA, fall from height, crush
- Energy level: High-energy = high suspicion
- Symptoms: Pelvic pain, inability to walk
- Red flags: Blood at meatus, gross hematuria
Examination
- Look: Leg length discrepancy, rotation
- Feel: Symphysis gap, SI tenderness
- DO NOT rock pelvis - disrupts clot
- PR/PV exam: Rule out open fracture
Open Pelvic Fracture
A rectal or vaginal tear communicating with a pelvic fracture = Open Fracture. Mortality up to 50%. Requires fecal diversion (colostomy), aggressive debridement, and broad-spectrum antibiotics.
Specific Examination Findings
Examination Findings by Injury Pattern
| Finding | Injury Pattern | Clinical Significance |
|---|---|---|
| Leg length discrepancy (shortened) | Vertical Shear | Hemipelvis migrated superiorly |
| External rotation deformity | APC injury | Open book pattern |
| Internal rotation (windswept) | LC injury | Contralateral side in external rotation |
| Scrotal/labial hematoma | Urethral injury | Do NOT insert Foley - needs urethrogram |
| Blood at meatus | Urethral injury | Contraindication to blind catheterization |
| Morel-Lavallée lesion | Degloving injury | Avoid incision through for surgery |
Neurological Assessment
- L5: Ankle dorsiflexion (Tibialis Anterior), sensation dorsal webspace
- S1: Ankle plantarflexion (Gastrocnemius), sensation lateral foot
- S2-S4: Perianal sensation, sphincter tone, bulbocavernosus reflex
Investigations
Imaging Protocol
Standard trauma radiograph. Assess symmetry, rami fractures, symphysis width, SI joints. Look for L5 transverse process fracture (indicates unstable injury).
Inlet (40° caudad): AP displacement, sacral impaction. Outlet (40° cephalad): Vertical displacement, sacral foramina.
Mandatory for surgical planning. Defines posterior ring injury, sacral fractures, acetabular involvement. 3D reconstruction for complex patterns.
Arterial blush indicates active arterial bleeding requiring embolization. Performed in hemodynamically stable patients.
L5 Transverse Process Fracture
A fracture of the L5 transverse process indicates avulsion of the iliolumbar ligament - a strong marker of unstable pelvic ring injury (vertical shear pattern).
Additional Investigations
Urological Assessment
- Retrograde urethrogram: If blood at meatus
- Cystogram: If gross hematuria
- CT urogram: Ureteric injury assessment
- Suprapubic catheter: If urethral injury confirmed
Laboratory Studies
- FBC: Baseline Hb (expect drop)
- Coagulation: INR, fibrinogen (TXA consideration)
- Crossmatch: 6 units PRBC minimum
- Lactate: Marker of shock severity
Management Algorithm
Pelvic Hemorrhage Algorithm
- Pelvic Binder - at greater trochanters, NOT iliac crests
- Massive Transfusion Protocol - 1:1:1 ratio (PRBC:FFP:Platelets)
- FAST Scan - if positive, laparotomy first
- Preperitoneal Packing - venous bleeding (90%)
- Angioembolization - arterial bleeding (10%)
Sequential approach for hemodynamically unstable patient:
- Immediate: Pelvic binder at greater trochanters, internal rotation of legs
- Concurrent: MTP with 1:1:1 ratio, permissive hypotension (SBP 80-90), TXA within 3 hours
- Assessment: FAST scan - positive means laparotomy, negative suggests pelvic source
- Intervention: PPP for venous bleeding (90%), angioembolization for arterial (10%)
This structured approach optimizes hemorrhage control.
Surgical Management
Operative vs Non-Operative
Management by Injury Pattern
| Pattern | Stability | Treatment |
|---|---|---|
| LC I, APC I | Stable | Non-operative: WBAT, analgesia |
| LC II, APC II | Rotationally unstable | Operative: Anterior +/- posterior fixation |
| LC III, APC III, VS | Globally unstable | Operative: Anterior AND posterior fixation |
Absolute Indications for Surgery:
- Hemodynamic instability requiring stabilization
- Open pelvic fracture
- Symphysis diastasis greater than 2.5cm
- Posterior ring disruption (SI dislocation, displaced sacral fracture)
- Vertical shear injury
Surgical indications are based on instability patterns and associated soft tissue injuries.
Sequence of Fixation
Posterior First
In combined injuries (anterior + posterior), fix the posterior ring FIRST. Restoring the posterior ring restores hemipelvic height and rotation, making anterior reduction easier.
Complications
Complications Overview
| Complication | Incidence | Risk Factors | Management |
|---|---|---|---|
| Hemorrhage/death | 8-15% mortality | Open fracture, VS pattern | Binder, packing, embolization |
| DVT/PE | 35-60% DVT | Immobility, pelvic vein injury | Mechanical + chemical prophylaxis |
| Infection | Up to 50% (open) | Open fracture, Morel-Lavallée | Antibiotics, debridement, colostomy |
| Neurological injury | 10-15% | Zone II-III sacral, VS | Decompression, observation |
| Urogenital injury | 10-15% | APC pattern, anterior ring | Urology consult, suprapubic catheter |
| Chronic pain | Up to 60% | Posterior ring injury | Multimodal analgesia, PT |
| Sexual dysfunction | Up to 40% | Pudendal nerve injury | Counseling, medication |
| Malunion | Variable | Inadequate reduction | Osteotomy if symptomatic |
Morel-Lavallée Lesion
Closed degloving injury - subcutaneous tissue sheared from fascia, fills with blood/fat. High infection risk if operated through. Aspirate or debride if infected. Avoid direct incision through the lesion.
Postoperative Care
Postoperative Protocol
ICU monitoring if polytrauma. DVT prophylaxis (mechanical + LMWH when safe). Wound checks. Pain control.
Stable patterns (LC I, APC I): Weight-bear as tolerated (WBAT). Unstable patterns: Toe-touch weight bearing (TTWB) 6-12 weeks.
Wound check, suture removal. Check X-rays for hardware position. Assess neuro status.
Repeat X-rays. Advance weight-bearing if healing. Continue PT.
Full weight-bearing if radiographic healing. Return to activities. Monitor for chronic pain, sacroiliac dysfunction.
Weight-Bearing Protocol
Weight-Bearing by Pattern
| Pattern | Immediate | 6 Weeks | 12 Weeks |
|---|---|---|---|
| LC I, APC I (stable) | WBAT | Full WB | Return to activity |
| LC II, APC II (partially unstable) | TTWB | PWB | Full WB |
| VS, APC III (globally unstable) | NWB | TTWB | PWB to Full WB |
Outcomes and Prognosis
Mortality
Mortality by Injury Pattern
| Group | Mortality Rate | Key Factors |
|---|---|---|
| Stable (LC I, APC I) | Less than 5% | Isolated injury, hemodynamically stable |
| Unstable (LC II-III, APC II-III) | 10-20% | Hemorrhage, associated injuries |
| Vertical Shear | 20-30% | Highest energy, most associated injuries |
| Open Pelvic Fracture | 20-50% | Infection, hemorrhage, rectal/vaginal tears |
Functional Outcomes
Return to Function
- 60-80% return to pre-injury employment
- 70-80% walk without aids at 1 year
- Up to 60% report chronic pelvic pain
- Higher function with stable patterns
Quality of Life
- Chronic pain: Most common long-term issue
- Sexual dysfunction: Up to 40%
- Sitting intolerance: With malunion
- Psychological impact: PTSD common after major trauma
Prognostic Factors
Predictors of Poor Outcome
Poor prognostic factors:
- Open pelvic fracture
- Vertical shear mechanism
- Associated head injury
- Increasing age
- High ISS (Injury Severity Score)
- Neurological deficit at presentation
- Requirement for massive transfusion
Evidence Base
Pelvic Binder Efficacy
- Early pelvic binding reduced transfusion requirements and mortality in unstable pelvic fractures. Most effective when applied in pre-hospital or ED setting.
Preperitoneal Packing (PPP)
- PPP achieved hemorrhage control in 85% of patients, faster than angioembolization. Secondary angio required in only 13%.
Early vs Late Fixation
- Fixation within 24 hours reduced complications (ARDS, pneumonia, MOF) and length of stay compared to delayed fixation.
Iliosacral Screw Safety
- Defined safe corridors for S1 and S2 screws. Sacral dysmorphism (30-40%) narrows safe zones, requiring careful preoperative CT planning.
CT vs Plain Radiographs
- Plain radiographs (AP, Inlet, Outlet) missed 30% of posterior ring injuries compared to CT scan.
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Hemodynamically Unstable Pelvic Fracture
"32-year-old pedestrian struck by car. BP 70/40, HR 130. AP pelvis shows open book injury with 6cm symphysis diastasis. FAST scan is positive."
Vertical Shear Injury
"25-year-old male fell 4 meters from scaffolding. X-ray shows cephalad migration of left hemipelvis by 4cm. L5 transverse process fracture noted. Hemodynamically stable."
Morel-Lavallée Lesion with Acetabular Fracture
"45-year-old motorcyclist with acetabular fracture. On examination, there is a large, boggy, fluctuant area over the greater trochanter. The skin is intact but mobile over underlying tissue."
MCQ Practice Points
Classification Question
Q: What is the most common mechanism of pelvic ring injury?
A: Lateral compression (LC) - accounts for approximately 60% of pelvic fractures. The internal rotation of the hemipelvis often causes impaction of the sacrum posteriorly.
Stability Question
Q: What is the primary determinant of pelvic ring stability?
A: Posterior ring integrity - specifically the interosseous sacroiliac ligaments. The posterior ring provides 60% of pelvic stability. Complete posterior disruption (VS, APC III) results in global instability.
Technical Question
Q: At what level should a pelvic binder be applied?
A: At the level of the greater trochanters - NOT at the iliac crests. This level provides optimal reduction of pelvic volume and internal rotation of the hemipelvis.
Threshold Question
Q: What symphysis diastasis indicates posterior ring injury?
A: Greater than 2.5cm - this threshold indicates disruption of the sacrospinous/sacrotuberous ligaments (APC II pattern) and mandates assessment of the posterior ring.
Anatomy Question
Q: What is the significance of an L5 transverse process fracture?
A: Indicates avulsion of the iliolumbar ligament - a strong marker of vertical shear injury and globally unstable pelvic ring.
Hemorrhage Question
Q: What percentage of pelvic hemorrhage is venous vs arterial?
A: 90% venous (from presacral and prevesical plexus), 10% arterial (from internal iliac branches). This explains why preperitoneal packing is effective.
Australian Context
Trauma Systems
- Level 1 Trauma Centers: 24/7 IR and trauma surgery
- Transfer protocols: Early activation for pelvic trauma
- Prehospital: Binder application by paramedics
- MERT/RSQ: Retrieval services for remote areas
Australian Epidemiology
- Pelvic fractures account for approximately 3% of all skeletal injuries
- Bimodal age distribution: young MVA, elderly falls
- Mortality rate ranges from 5-20% depending on injury severity
- Higher incidence in rural and remote areas due to MVA patterns
ACSQHC Guidelines
- Early surgery within 48 hours for hip fractures (applies to pelvic trauma principles)
- Orthogeriatric models of care for elderly trauma patients
- VTE prophylaxis protocols
PELVIC RING INJURIES
High-Yield Exam Summary
Young-Burgess Classification
- •LC: Lateral compression (internal rotation) - 60% of fractures
- •APC: AP compression (external rotation, 'open book')
- •VS: Vertical shear (vertical displacement) - worst pattern
- •Diastasis greater than 2.5cm = posterior injury (APC II+)
Stability Assessment
- •Posterior ring = stability (60%)
- •LC I, APC I = stable
- •LC II, APC II = rotationally unstable
- •LC III, APC III, VS = globally unstable
Hemorrhage Control
- •Binder at greater trochanters FIRST
- •90% bleeding is venous (packing works)
- •MTP with 1:1:1 ratio + TXA
- •Positive FAST = laparotomy
Fixation Principles
- •Fix POSTERIOR ring first (restores height)
- •IS screws = gold standard for SI disruption
- •Lumbopelvic fixation for VS and U-sacral fractures
- •Assess sacral dysmorphism before IS screws
Key Numbers
- •Symphysis greater than 2.5cm = posterior injury
- •L5 TP fracture = VS pattern marker
- •Mortality 20-50% for open pelvic fractures
- •Sacral dysmorphism in 30-40%