ACETABULAR FRACTURES
Column Concept | Judet-Letournel Classification | Approach Selection
JUDET-LETOURNEL CLASSIFICATION
Critical Must-Knows
- Two-column concept - anterior and posterior columns meet at iliac crest
- 3 Judet views - AP, obturator oblique, iliac oblique
- Dome concept - weight-bearing 10cm arc must be reduced
- Approach dictated by column - KL for posterior, IL/Stoppa for anterior
- Anatomic reduction (under 2mm step) = 80% good outcomes
Examiner's Pearls
- "Both-column = 'spur sign' on obturator oblique
- "Posterior wall = most common pattern
- "Sciatic nerve at risk in posterior approaches
- "Delay surgery 3-5 days to reduce blood loss
Clinical Imaging
Imaging Gallery
Critical Acetabular Fracture Points
Two-Column Concept
Anterior column: Pubis to iliac crest via pelvic brim. Posterior column: Ischium to iliac crest via greater sciatic notch. They meet at the iliac crest like an inverted Y.
Judet Views
Obturator oblique (45° toward injured hip): Shows anterior column and posterior wall. Iliac oblique (45° away): Shows posterior column and anterior wall.
Dome Concept
Weight-bearing dome = superior 10cm arc. Must be anatomically reduced. Peripheral fractures may be treated conservatively.
Approach Selection
Kocher-Langenbeck: Posterior column/wall. Ilioinguinal/Stoppa: Anterior column. Extended iliofemoral: Both columns (rarely used).
At a Glance: Quick Decision Guide
| Pattern | Approach | Key Structures at Risk | Priority |
|---|---|---|---|
| Posterior wall | Kocher-Langenbeck | Sciatic nerve | Urgent if dislocated |
| Posterior column | Kocher-Langenbeck | Sciatic nerve, SGA | Urgent |
| Anterior column | Ilioinguinal/Stoppa | LFCN, femoral vessels | Semi-urgent |
| Transverse | Based on displacement | Column-specific | Assess dome |
| Both column | Usually ilioinguinal | Corona mortis, LFCN | Complex - delay OK |
PAPATElementary Patterns
Memory Hook:PAPAT - 5 elementary patterns, Posterior Wall is most common!
BATTPAssociated Patterns
Memory Hook:5 Associated patterns combine elements - Both Column is the hallmark!
OAPJudet Views
Memory Hook:OAP - Obturator sees Anterior column, iliac oblique sees Posterior column
SAFESciatic Nerve Protection
Memory Hook:Keep the hip SAFE during posterior approaches!
Overview and Epidemiology
Why This Topic Matters
Acetabular fractures are complex injuries requiring detailed anatomical understanding. The Judet-Letournel classification is the gold standard and must be known for the exam. Approach selection is directly tied to fracture pattern.
Demographics
- Young adults: High-energy MVA, falls from height
- Elderly: Low-energy falls, osteoporotic bone
- Male predominance: 3:1 ratio
- Associated injuries: 80% have hip dislocation
Mechanism
- Dashboard injury: Knee strikes dashboard, force through femur
- Position determines pattern: Flexed hip = posterior wall
- Lateral compression: Direct blow to trochanter
- Force magnitude: Determines comminution
Historical Context
Judet and Letournel revolutionized acetabular surgery in the 1960s-1980s. Before their work, most acetabular fractures were treated non-operatively with poor results. Their classification and surgical approaches remain the foundation today.
Anatomy and Biomechanics
The Two-Column Concept
Column Anatomy
The acetabulum is supported by two columns that meet at the iliac crest like an inverted Y:
- Anterior column: Anterior half of iliac wing + pelvic brim + superior pubic ramus
- Posterior column: Posterior half of iliac wing + greater/lesser sciatic notches + ischial tuberosity + inferior pubic ramus
Key Anatomical Landmarks
Radiographic Landmarks
| Landmark | Location | Clinical Significance |
|---|---|---|
| Iliopectineal line | Anterior column | Disruption = anterior column fracture |
| Ilioischial line | Posterior column | Disruption = posterior column fracture |
| Acetabular roof/dome | Superior 10cm arc | Weight-bearing - must reduce |
| Anterior wall | Medial curve on AP | Anterior wall outline |
| Posterior wall | Lateral curve on AP | Posterior wall outline |
| Teardrop | Floor of acetabular fossa | Medial wall/quadrilateral plate |
Neurovascular Anatomy
Posterior Approach Dangers
- Sciatic nerve: Courses 1cm inferior to piriformis
- Superior gluteal artery: Above piriformis
- Inferior gluteal artery: Below piriformis
- Piriformis: Key landmark
Anterior Approach Dangers
- Lateral femoral cutaneous nerve: Medial to ASIS
- Femoral nerve/vessels: In iliac fossa
- Corona mortis: Anastomosis on pubic ramus
- External iliac vessels: Medial retraction risk
Corona Mortis
Corona mortis ("crown of death") is an aberrant obturator vessel crossing the superior pubic ramus. Present in 30-70% of patients. Must be identified and ligated during Stoppa or ilioinguinal approaches.
Classification Systems
Elementary Patterns (5)
Elementary Acetabular Fracture Patterns
| Pattern | Frequency | Key Feature | Approach |
|---|---|---|---|
| Posterior wall | 25% (most common) | Fragment from posterior rim | Kocher-Langenbeck |
| Posterior column | 4% | Through greater sciatic notch to obturator foramen | Kocher-Langenbeck |
| Anterior wall | 2% (rare) | Anterior rim fragment | Ilioinguinal/Stoppa |
| Anterior column | 4% | Through pelvic brim | Ilioinguinal/Stoppa |
| Transverse | 8% | Divides acetabulum horizontally | Based on displacement |
Posterior Wall - Most Common
Posterior wall fractures are the most common elementary pattern (~25%). They typically occur with dashboard injuries when the hip is flexed. The sciatic nerve is at risk in up to 30% of cases.
Clinical Assessment
History
- Mechanism: Dashboard injury, fall from height, lateral blow
- Position at impact: Determines fracture pattern
- Associated injuries: Head, chest, abdomen, pelvis
- Pre-injury function: Critical for decision-making
Examination
- Inspection: Hip position (posterior dislocation = flexed, adducted, IR)
- Palpation: Tenderness over greater trochanter
- ROM: Limited and painful
- Neurovascular: Sciatic nerve (dorsiflexion, plantarflexion, sensation)
Sciatic Nerve Assessment
30% of posterior wall/column fractures have sciatic nerve injury. Always document:
- Peroneal division (more common): Ankle/toe dorsiflexion, foot eversion, sensation dorsal foot
- Tibial division: Ankle/toe plantarflexion, sensation plantar foot Document BEFORE and AFTER reduction/surgery!
Associated Injuries
Associated Injuries to Exclude
| Injury | Incidence | Assessment |
|---|---|---|
| Hip dislocation | Up to 80% | Hip position, urgent reduction |
| Sciatic nerve injury | 30% (posterior) | Motor/sensory exam |
| Femoral head fracture | 10% | CT scan |
| Knee ligament injury | Dashboard mechanism | Examine knee |
| Ipsilateral femur fracture | 10% | Full femur X-ray |
Investigations
Imaging Protocol
AP Pelvis: Assess both columns, dome, teardrop. Obturator oblique (45° toward): Anterior column + posterior wall. Iliac oblique (45° away): Posterior column + anterior wall.
Mandatory for all acetabular fractures. Defines fracture pattern, comminution, impaction, loose bodies. 3D reconstructions show pattern clearly. Subtract femoral head for better visualization.
MRI: Labral injury, femoral head cartilage. CTA: If vascular injury suspected (rare).
Radiographic Lines
Six Lines on AP Pelvis
6 key lines to assess on AP pelvis:
- Iliopectineal line = anterior column
- Ilioischial line = posterior column
- Acetabular roof = dome
- Anterior wall = medial curve
- Posterior wall = lateral curve
- Teardrop = medial wall/quadrilateral plate
Management Algorithm
Indications for Non-operative Treatment
Non-operative Criteria
| Criterion | Threshold | Rationale |
|---|---|---|
| Displacement | Less than 2mm | Acceptable articular congruity |
| Roof arc | Greater than 45° | Dome not involved in fracture |
| Both column | Secondary congruence | Head moves with medial fragment |
| Low anterior column | Below sourcil | Non-weight bearing area |
Low anterior column fractures that exit below the weight-bearing dome may be treated non-operatively if stable.
Protocol: Traction (4-8 weeks) or touch-down weight bearing with close radiographic follow-up.
Surgical Technique
Kocher-Langenbeck Approach
Indications: Posterior wall, posterior column, transverse with posterior displacement
Surgical Steps
Lateral decubitus with hip flexed 20-30°, or prone with bolsters. Knee flexed to relax sciatic nerve.
From PSIS curving over greater trochanter, extending distally along femoral shaft, or straight for Gibson approach.
Split gluteus maximus in line with fibers. Identify and protect sciatic nerve inferior to piriformis.
Detach piriformis, obturator internus, gemelli from greater trochanter (leave quadratus femoris to protect MFCA). Capsulotomy to access joint.
Reduce fragments under direct vision. Buttress plate for posterior wall (spring plate). Reconstruction plate for column.
Sciatic Nerve Protection
Knee flexion reduces tension on sciatic nerve. Limit hip flexion beyond 60°. External rotation relaxes piriformis. Use retractors carefully - avoid persistent traction.
Complications
Complications Overview
| Complication | Incidence | Risk Factors | Management |
|---|---|---|---|
| Post-traumatic arthritis | 20-30% | Malreduction, cartilage damage | THA when mature |
| AVN femoral head | 5-10% | Dislocation duration, posterior injury | Core decompression, THA |
| Heterotopic ossification | 20-50% | Posterior approach, head injury | Prophylaxis (indomethacin or XRT) |
| Sciatic nerve injury | 10-15% | Posterior approach, retraction | Observation, most recover |
| DVT/PE | Variable | Pelvic surgery, immobility | Thromboprophylaxis |
| Infection | 3-5% | Open fracture, prolonged surgery | Debridement, antibiotics |
Heterotopic Ossification (HO)
HO Prophylaxis
Brooker Grade III-IV HO occurs in 20-50% of posterior approaches. Prophylaxis options:
- Indomethacin 25mg TDS for 6 weeks (most common)
- Radiation therapy: Single fraction 700cGy within 72 hours Both reduce severe HO to under 5%.
Post-Traumatic Arthritis
The most significant long-term complication. Risk factors:
- Articular step greater than 2mm
- Femoral head cartilage damage
- Delayed reduction of dislocation
- Age at injury
THA after acetabular fracture is technically challenging with higher complication rates. Delay at least 3-6 months for fracture healing.
Postoperative Care
Postoperative Protocol
DVT prophylaxis (mechanical + LMWH). Monitor sciatic nerve function. Drain management. Pain control.
Touch-down weight bearing (TDWB) with frame/crutches. PT for ROM and strengthening.
X-rays to assess healing. Continue TDWB. Remove sutures/staples.
Partial weight bearing if healing. Repeat X-rays. Continue PT.
Full weight bearing when radiographic union. Return to activities. Monitor for HO, arthritis.
HO Prophylaxis Protocol
- Indomethacin 25mg TDS for 6 weeks (start within 48h)
- Or single-dose radiation 700cGy within 72h post-op
- Continue DVT prophylaxis for 4-6 weeks
Outcomes and Prognosis
Radiographic Outcomes
Outcome by Reduction Quality
| Reduction | Grade | Good/Excellent Outcome |
|---|---|---|
| Anatomic (0-1mm) | Excellent | 80-85% |
| Imperfect (2-3mm) | Satisfactory | 65-75% |
| Poor (over 3mm) | Poor | 40-50% |
Functional Outcomes
Good Prognostic Factors
- Anatomic reduction (under 2mm)
- Simple fracture pattern
- Short dislocation time (under 6 hours)
- Young age
- No femoral head damage
Poor Prognostic Factors
- Articular comminution
- Femoral head impaction (Gull sign)
- Posterior dislocation over 12 hours
- Age over 60
- Both-column fractures (complex)
Matta Criteria
Matta's criteria for outcome assessment:
- Excellent: No pain, normal ROM, no limp
- Good: Mild pain with activity, slight limp
- Fair: Moderate pain, limp, uses cane
- Poor: Severe pain, marked limp, disability
Anatomic reduction = 80% excellent/good outcomes
Evidence Base
Reduction Quality and Outcome
- 810 acetabular fractures with mean 6-year follow-up. Anatomic reduction (0-1mm) achieved 83% excellent/good radiographic outcomes vs 68% for imperfect (2-3mm) and 50% for poor (over 3mm).
Timing of Surgery
- Surgery between 3-10 days post-injury had lower blood loss and similar outcomes compared to surgery within 48 hours.
HO Prophylaxis
- Indomethacin 25mg TDS for 6 weeks reduced Brooker III-IV HO from 35% to 7%. COX-2 inhibitors were less effective.
Sciatic Nerve Recovery
- 70% of sciatic nerve palsies associated with acetabular fractures showed significant recovery. Peroneal division had worse prognosis.
Both-Column Secondary Congruence
- Both-column fractures with 'secondary congruence' (femoral head remains congruent with medial acetabular fragment) can have acceptable non-operative outcomes.
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Posterior Wall Fracture with Dislocation
"28-year-old driver in MVA. X-ray shows posterior hip dislocation with posterior wall fracture. Sciatic nerve intact. How do you manage this?"
Both-Column Fracture
"45-year-old fell from roof. CT shows both-column acetabular fracture with spur sign visible. No dislocation. How do you approach this?"
Transverse + Posterior Wall
"32-year-old motorcyclist with acetabular fracture. CT shows transverse pattern with associated posterior wall fragment. Which approach?"
MCQ Practice Points
Classification Question
Q: What is the most common elementary acetabular fracture pattern?
A: Posterior wall - accounts for approximately 25% of all acetabular fractures. Typically caused by dashboard injury with hip in flexed position.
Radiographic Question
Q: Which radiographic line represents the anterior column on AP pelvis?
A: Iliopectineal line - the ilioischial line represents the posterior column. Remember: "Pectineal = Anterior, Ischial = Posterior"
Approach Question
Q: What approach is used for posterior column fractures?
A: Kocher-Langenbeck - this posterior approach gives direct access to posterior column and wall. The ilioinguinal/Stoppa is used for anterior column.
Classification Question
Q: What is pathognomonic for a both-column acetabular fracture?
A: Spur sign - a fragment of intact ilium "floating" above the acetabulum visible on obturator oblique view. Indicates both columns separated from axial skeleton.
Complication Question
Q: What is the most important factor for good outcome in acetabular fractures?
A: Anatomic reduction (under 2mm) - Matta's studies showed 83% excellent/good outcomes with anatomic reduction vs 50% with poor reduction greater than 3mm.
Technical Question
Q: What is the corona mortis?
A: Aberrant obturator vessel crossing the superior pubic ramus. Present in 30-70% of patients. Must be ligated during ilioinguinal/Stoppa approaches to prevent catastrophic hemorrhage.
Australian Context
Referral Patterns
- Tertiary referral: Major trauma centers only
- Subspecialist surgery: Pelvic/acetabular trained surgeons
- Transfer protocols: Early transfer if complex pattern
- AOA Pelvic SIG: Special interest group for education
Key Points for Australian Practice
- Acetabular fractures should be managed at tertiary trauma centers
- Preoperative CT is mandatory and usually done at referring hospital
- 3D reconstructions aid in pattern recognition and planning
- Subspecialty training beyond general orthopaedic fellowship recommended
ACETABULAR FRACTURES
High-Yield Exam Summary
Classification
- •5 Elementary: PW, PC, AW, AC, Transverse
- •5 Associated: Both-column, T-type, Trans+PW, PC+PW, AC+PHT
- •Posterior wall = most common (25%)
- •Both column = spur sign pathognomonic
Radiographic Lines
- •Iliopectineal = anterior column
- •Ilioischial = posterior column
- •Obturator oblique: anterior column + posterior wall
- •Iliac oblique: posterior column + anterior wall
Approach Selection
- •Kocher-Langenbeck: Posterior wall/column
- •Ilioinguinal/Stoppa: Anterior wall/column
- •Extended iliofemoral: Both column (rare)
- •Sciatic nerve at risk in KL approach
Key Numbers
- •Under 2mm step = acceptable reduction
- •Greater than 40% wall = needs fixation
- •3-5 days delay = less blood loss
- •80% good outcome with anatomic reduction
Complications
- •HO: 20-50% (indomethacin prophylaxis)
- •Sciatic nerve: 10-15%
- •Post-traumatic arthritis: 20-30%
- •Corona mortis: ligate in anterior approaches