Complete pelvic ring disruption with vertical/cephalad hemipelvic displacement
- VERTICAL displacement distinguishes VS from LC/APC patterns
- Always Tile C - completely unstable rotationally AND vertically
- Highest energy mechanism - fall from height or MVA with axial load
- ALL ligaments disrupted - no inherent stability remains
- Both anterior AND posterior fixation MANDATORY
- “Limb length discrepancy is pathognomonic (hemipelvis migrates cephalad)
- “Look for 'Destot sign' - perineal/scrotal hematoma from hemorrhage
- “Neurological injury common - L5, lumbosacral plexus
- “Combined patterns exist (VS + LC, VS + APC) - look for rotation too
- “Often associated with acetabular fractures
Vertical shear injuries are the HIGHEST ENERGY pelvic injuries with COMPLETE instability. The hemipelvis displaces VERTICALLY (cephalad), not just rotationally. This distinguishes VS from LC-III and APC-III, which have rotational instability but limited vertical displacement. VS injuries ALWAYS require both anterior AND posterior fixation - there is no conservative option for true VS patterns.
- LC-III
- Rotational
- APC-III
- Rotational
- VS
- Vertical (cephalad)
- LC-III
- Internal rotation
- APC-III
- External rotation
- VS
- Axial load
- LC-III
- Variable
- APC-III
- Variable
- VS
- Always present
- LC-III
- Yes
- APC-III
- Yes
- VS
- May be minimal
- LC-III
- Minimal
- APC-III
- Minimal
- VS
- Significant
- LC-III
- C1
- APC-III
- C1
- VS
- C1-C3
- LC-III
- Moderate
- APC-III
- Highest
- VS
- Moderate (less than APC)
- LC-III
- Lower
- APC-III
- Moderate
- VS
- Highest
VERTICALVERTICAL - VS Injury Features
Hook:VS injuries cause VERTICAL displacement - remember the complete instability and mandatory surgical fixation
Overview
Introduction
Vertical shear (VS) pelvic injuries represent the most severe form of pelvic ring disruption. Unlike lateral compression (LC) and anteroposterior compression (APC) injuries, which have components of rotational instability, VS injuries have complete disruption of all stabilizing structures allowing the hemipelvis to migrate vertically (cephalad) relative to the sacrum.
These injuries result from high-energy axial loading mechanisms and are characterized by the complete loss of the weight-bearing function of the pelvic ring. The term "vertical shear" refers to the direction of the displacing force and resultant displacement pattern.
Epidemiology
- 5-10% of all pelvic ring injuries
- Least common of the major injury patterns
- Most severe subtype
- Fall from height landing on extended leg (most common)
- Motor vehicle collision with axial load
- Motorcycle ejection
- Pedestrian struck
- Young adults predominate
- Often high ISS scores
- Polytrauma almost universal
- Occupational (falls from scaffolding, construction)
Clinical Significance
Why VS Injuries Are Most Severe:
- Complete instability: No residual ligamentous support
- High energy: Greater associated injuries
- Weight-bearing lost: Cannot transmit load
- Neurological injury: Traction on lumbosacral plexus
- Hemorrhage: Significant (though less than APC typically)
Anatomy and Pathophysiology
Pelvic Ring Stability
The pelvis functions as a ring structure. When disrupted, the injury cannot occur at a single location - there must be a second break in the ring (or a combination of bone and ligament injuries).
Stabilizing Structures
- Posterior SI ligaments (strongest)
- Interosseous SI ligaments
- Sacrotuberous ligament
- Sacrospinous ligament
- Iliolumbar ligaments
- Pubic symphysis
- Pubic rami
- Anterior SI ligaments
VS Injury Pathoanatomy
In vertical shear injuries, BOTH anterior and posterior structures fail completely:
- Symphysis diastasis, OR
- Pubic rami fractures (ipsilateral), OR
- Combined symphysis and rami injury
- Sacral fracture (Denis zone I-III), OR
- SI joint diastasis (complete), OR
- Iliac wing fracture (crescent pattern)
Force Vectors
- Axial load through extended lower extremity
- Force transmitted through femur to acetabulum
- Hemipelvis driven cephalad
- Sequential failure: anterior then posterior, or vice versa
- Vertical (cephalad) translation
- May have rotational component (combined injury)
- Shortening of affected lower limb
Associated Soft Tissue Injuries
- Superior gluteal artery
- Internal iliac branches
- Presacral venous plexus
- Less severe bleeding than APC (closed ring effect)
- L5 nerve root (exits under ala)
- Lumbosacral trunk
- S1-S4 roots (sacral fractures)
- Overall neurological injury rate: 30-50%
SHEARSHEAR - Posterior Injury Patterns
Hook:VS injuries SHEAR the posterior structures - sacral fractures are most common
Classification
Classification
Vertical Shear (VS)
- Complete anterior AND posterior pelvic ring disruption
- Vertical (cephalad) displacement of hemipelvis
- No rotational component (distinguishes from LC-III, APC-III)
- Axial load mechanism
- Complete ligamentous disruption posteriorly
- Tile C equivalent
- Always surgically treated
Combined Mechanical Injury (CMI)
- VS pattern combined with LC or APC component
- Also known as "complex" pelvic injuries
- VS + LC: Vertical displacement with internal rotation
- VS + APC: Vertical displacement with external rotation (windswept)
- More complex surgical planning
- May need combined approaches
- Higher complication rates
These combined patterns require careful preoperative planning and may necessitate multiple surgical approaches.
DENISDENIS - Sacral Fracture Zones
Hook:DENIS classification for sacral fractures - zones go lateral to medial with increasing neuro risk
When the posterior injury runs through the ilium rather than the sacrum or a pure SI joint, the pattern is the crescent fracture - a posterior iliac wing fracture-dislocation of the SI joint in which the posterior SI ligaments stay attached to a crescent-shaped postero-superior iliac fragment while the anteroinferior SI joint dislocates. Because the strong posterior tension band remains with the crescent fragment, reducing and fixing the iliac fracture restores stability. The Day classification grades it by how much of the SI joint the intact crescent fragment still covers: Type I - a large crescent with only the anteroinferior third of the SI joint dislocated (fix the iliac fracture, e.g. with anterior-column/iliac screws or a plate); Type II - an intermediate fragment with one-third to two-thirds of the joint involved (combined iliosacral screw plus iliac fixation); Type III - a small crescent with most of the SI joint dislocated (behaves like a pure SI dislocation, fixed with an iliosacral screw). So name the crescent fracture, grade it by Day, and let the fragment size choose between iliac fixation and an SI screw.
Clinical Assessment
Primary Survey
VS injuries occur in major trauma context. Assessment follows ATLS principles.
Mechanism History
High-Risk Mechanisms:
- Fall from height greater than 3 meters
- Motorcycle ejection
- Pedestrian vs vehicle
- Industrial crush injury
- Landing on extended leg
Physical Examination
Inspection:
- Limb length discrepancy (SHORT LEG on affected side)
- Asymmetric iliac crest heights
- Destot sign: Scrotal/labial hematoma
- Perineal ecchymosis
- External rotation or internal rotation component
TRUE LIMB LENGTH DISCREPANCY with a pelvic fracture indicates VERTICAL SHEAR until proven otherwise. The affected limb appears shortened because the hemipelvis has migrated cephalad. This is NOT the same as apparent shortening from hip pathology.
- Iliac crest height asymmetry
- SI joint tenderness
- Symphysis gap or step-off
- Single pelvic spring test (ONCE only)
- Measure ASIS to medial malleolus bilaterally
- True shortening indicates vertical displacement
- Document amount of leg length discrepancy
Neurological Examination (CRITICAL)
- Hip flexion (L1-2)
- Knee extension (L3-4)
- Ankle dorsiflexion (L4-5) - L5 most vulnerable
- Great toe extension (L5)
- Ankle plantarflexion (S1-2)
- L5 dermatome: Dorsum of foot
- S1 dermatome: Lateral foot
- Perineal sensation: S2-S4
- Ankle jerk (S1)
- Bulbocavernosus reflex (sacral roots)
- Rectal tone
- ASIA score if complete injury
- Detailed motor/sensory documentation
- Serial examinations (may evolve)
Associated Injuries
Common Associations:
- Acetabular fractures
- Proximal femur fractures
- Lumbar spine fractures
- Intra-abdominal injuries
- Head injuries
Differential Diagnosis of a Shortened Limb with Pelvic Trauma
True limb shortening with a pelvic injury is highly suggestive of vertical shear, but several conditions can mimic the presentation and must be distinguished.
- Displacement pattern
- True cephalad migration of hemipelvis
- Key distinguishing feature
- Asymmetric iliac crest heights, true ASIS-to-malleolus shortening, complete ring disruption
- Confirming investigation
- AP/inlet/outlet pelvis + CT showing anterior AND posterior disruption
- Displacement pattern
- Rotational external rotation, ring widening
- Key distinguishing feature
- Symphysis and SI widening with SYMMETRIC iliac crest heights, no true shortening
- Confirming investigation
- AP pelvis showing symphyseal diastasis without cephalad migration
- Displacement pattern
- Internal rotation one side, external rotation other
- Key distinguishing feature
- Rotational deformity, minimal vertical translation
- Confirming investigation
- CT showing impaction/overlap pattern
- Displacement pattern
- Limb shortened, flexed, adducted, internally rotated
- Key distinguishing feature
- Hip held in fixed flexion/adduction; intact pelvic ring
- Confirming investigation
- AP pelvis: femoral head out of acetabulum, ring intact
- Displacement pattern
- Shortened, externally rotated limb
- Key distinguishing feature
- Tenderness localised to hip, intact pelvic ring
- Confirming investigation
- AP pelvis and lateral hip radiographs
- Displacement pattern
- Limb may appear shortened
- Key distinguishing feature
- Femoral head protrusion into pelvis; posterior ring often intact
- Confirming investigation
- Judet views and CT of acetabulum
Investigations
Imaging Approach
Plain Radiography
- First-line in trauma bay
- Assess for vertical displacement
- Compare iliac crest heights
- Compare obturator foramen size (smaller on elevated side)
- Cephalad migration of hemipelvis
- Asymmetric iliac crest heights
- Different sized obturator foramina
- Superior displacement of ischial tuberosity
- Posterior displacement
- SI joint widening
- Rotational component
- Vertical displacement best seen
- Sacral fracture visualization
- Foraminal involvement
CT Imaging
- Defines posterior injury precisely
- Sacral fracture pattern (Denis zone)
- SI joint injury morphology
- Associated acetabular injury
- Soft tissue hematoma
- Sacral fracture location and comminution
- SI joint widening and displacement
- Anterior injury pattern
- Vertical displacement measurement
- Surgical planning
- Demonstrates displacement clearly
- Communication with patient/team
MRI (Selective Use)
- Neurological deficit
- Suspected cauda equina injury
- Soft tissue planning for complex reconstruction
- Nerve root compression
- Disc herniation (traumatic)
- Ligament integrity
Management Algorithm
Treatment Decision-Making
Hemorrhage Control
- Apply as per protocol
- Less effective for VS than APC (vertical, not rotational displacement)
- Still provides some stabilization
- Does NOT reduce vertical displacement
- May help with vertical reduction
- Distal femoral pin preferred
- 10-15kg initial weight
- Temporizing measure
Damage Control
Principles:
- External fixation if hemodynamically unstable
- Does NOT address vertical displacement
- Bridge to definitive fixation
- May need skeletal traction additionally
Damage control is a temporizing measure only - definitive fixation required once stable.
FIXFIX - VS Surgical Principles
Hook:VS injuries need complete FIX - anterior AND posterior fixation is mandatory
Surgical Technique
Percutaneous Iliosacral Screw Fixation
Indications
- SI joint dislocation
- Sacral ala fractures (Denis Zone I-II)
- Most common posterior fixation method
Positioning
- Supine on radiolucent table (allows anterior access if needed)
- Alternative: Prone or lateral decubitus
- C-arm positioned for inlet, outlet, and lateral sacral views
Anatomical Safe Zones
- Primary target zone
- Widest safe corridor
- Parallel to S1 superior endplate
- Anterior: Iliac vessels, L5 nerve root
- Lateral: L5 nerve in ala
- Superior: L5-S1 disc
- Inferior: S1 foramen
Understanding the safe corridor within the S1 body is essential for safe SI screw placement.
Complications
Early Complications
- Significant but typically less than APC
- Retroperitoneal hemorrhage
- Presacral venous plexus
- Most common complication (30-50%)
- L5 root most vulnerable
- Sacral root injuries with sacral fractures
- Cauda equina syndrome with Zone III
- Very high DVT risk
- Early prophylaxis essential
- May need IVC filter if anticoagulation contraindicated
- Open fractures: High risk
- Surgical site infection
- Higher with extensive approaches
An open pelvic fracture (a pelvic ring injury communicating with a perineal, rectal, vaginal, groin or buttock wound, or with a degloving/Morel-Lavallée injury) is a distinct, far more lethal entity - historically quoted mortality up to 30-50%, driven by uncontrolled haemorrhage and later pelvic sepsis. The examinable musts: always perform a rectal and (in females) vaginal examination and inspect the perineum and gluteal/sacral skin in any high-energy pelvic injury - an occult rectal or vaginal laceration makes the fracture open. Management adds to the standard ring algorithm: early broad-spectrum antibiotics and tetanus cover, aggressive haemorrhage control (binder, packing, angioembolisation), repeated wound debridement, and - for a rectal or perineal wound contaminating the fracture - a diverting (defunctioning) colostomy with distal rectal washout to prevent faecal soiling and pelvic sepsis. The Faringer anatomical zones (anterior perineum, posterior perineum/buttock, iliac wing) help predict which wounds mandate diversion. Recognising the wound is the whole point - a "closed" vertical shear injury and an open one are managed very differently.
Late Complications
- Residual vertical displacement
- Limb length discrepancy
- Gait abnormality
- Painful weight bearing
- Sacral nonunion (more common with vertical pattern)
- SI joint nonunion
- May need revision fixation or fusion
- Footdrop (L5)
- Bladder/bowel dysfunction (sacral roots)
- Sexual dysfunction
- May require long-term management
- SI screw loosening
- Screw migration
- Symptomatic hardware
- SI joint arthritis
- Sacral pain
- Low back pain
Postoperative Care
Immediate Postoperative Management
- Non-weight bearing for 8-12 weeks minimum
- Bilateral VS injuries: May need 12-16 weeks
- Gradual progression based on healing
- Bed to chair with walker assistance
- Upper extremity strengthening
- Core stability exercises (non-weight bearing)
- Essential given immobility
- LMWH or direct oral anticoagulants
- Sequential compression devices
- Continue until mobile
- Multimodal analgesia
- Regional techniques if available
- Minimize opioids when possible
Monitoring
- Daily for first week
- Document any changes
- May see delayed deficits
- AP pelvis at 2, 6, 12 weeks
- Inlet/outlet views as needed
- CT if concern for loss of reduction
- Monitor for infection
- Percutaneous wounds typically heal quickly
- Open approaches need standard care
Rehabilitation Protocol
- Non-weight bearing
- Upper body conditioning
- Hip isometrics
- Core strengthening
- Progressive weight bearing if healing confirmed
- Gait training with assistive devices
- Hip strengthening
- Balance exercises
- Full weight bearing
- Advanced strengthening
- Proprioceptive training
- Return to activities
Long-term Follow-up
- Gait pattern
- Leg length discrepancy (persistent)
- Neurological status
- Pain levels
- Independent ambulation
- Return to work (variable timeline)
- Activities of daily living
- SI joint arthritis symptoms
- Hardware symptoms
- Chronic pain
Outcomes/Prognosis
Functional Outcomes
Overall Results
- 60-70% with appropriate treatment
- Depends heavily on:
- Neurological injury
- Associated injuries
- Quality of reduction
- Fixation stability
- Neurological injury (30-50% incidence)
- Bilateral injuries
- Zone III sacral fractures
- Delayed fixation
- Malunion/nonunion
Neurological Recovery
- L5 nerve: 50-60% recovery rate
- S1 nerve: 60-70% recovery rate
- Sacral roots: Variable, often partial
- Footdrop requiring AFO: 15-20%
- Bladder dysfunction: 5-10% (Zone III injuries)
- Sexual dysfunction: Variable
- Improvement may continue 12-24 months
- Peak recovery typically 6-12 months
Return to Activities
- Independent walking: 3-6 months
- Normal gait pattern: 6-12 months
- May have permanent limp
- Sedentary: 3-6 months
- Physical labor: 6-12 months
- May need modifications
- Low-impact: 6-9 months
- High-impact: 9-12+ months
- Some activities may be permanently limited
Mortality
- Around 11% at 30 days for high-energy pelvic ring fractures in population data, with reported ranges of 6-35% depending on injury severity (Mann et al., Injury 2018)
- Mortality is driven by associated injuries and total injury burden (ISS), not by the ring fracture pattern alone
- Importantly, in complete ring disruption the APC (open-book) mechanism carries a HIGHER haemorrhage and mortality risk than VS (Whitbeck/Burgess, JOT 1997) - the long-held view that VS is the most lethal pattern is not supported
- Most survivors achieve independent function
- Quality of life depends on neurological recovery and is measurably reduced versus the general population after pelvic ring injury (Banierink et al., Arch Orthop Trauma Surg 2019)
- Chronic pain is common
Radiographic Outcomes
- SI joint: 85-90%
- Sacral fractures: 80-85%
- Symphysis: Greater than 95%
- Residual displacement common
- Affects long-term outcomes
- May need corrective surgery
- Removal rarely needed (10-15%)
- SI screws typically well-tolerated
Guidelines, Registries & Global Practice
Global Epidemiology
- Figure
- 2-3%
- Source
- Mann et al., Injury 2018
- Figure
- 7-20%
- Source
- Mann et al., Injury 2018
- Figure
- approx 4.6 per 100,000 per year
- Source
- Mann et al., Ontario Trauma Registry 2018
- Figure
- 5-10% (least common major pattern)
- Source
- Young-Burgess literature
- Figure
- approx 11% (range 6-35%, ISS-driven)
- Source
- Mann et al., Injury 2018
VS injuries arise from high-energy axial loading - falls from height onto an extended limb, motorcycle ejection, pedestrian-versus-vehicle and crush mechanisms - and so cluster in young men in polytrauma worldwide. The mechanism is universal and not region-specific.
Major Guidance, Side by Side
- Region
- International
- Position on unstable pelvic ring / VS
- Tile/AO and Young-Burgess classifications; vertically unstable (Tile C) patterns require posterior reduction and fixation; reduce before fixing; SI screws into the S1 body
- Region
- UK
- Position on unstable pelvic ring / VS
- Suspected pelvic ring injury managed in a network with early non-invasive binder, CT, and transfer to a specialist pelvic unit for definitive fixation
- Region
- US / International
- Position on unstable pelvic ring / VS
- Algorithmic haemorrhage control in haemodynamically unstable pelvic fracture: binder, then preperitoneal packing and/or angioembolisation, with external fixation as adjunct
- Region
- US
- Position on unstable pelvic ring / VS
- Trauma evidence summaries emphasise early definitive stabilisation of unstable patterns; no VS-specific clinical practice guideline
Evidence level: the operative principles above rest largely on Level III-IV evidence (retrospective series such as Matta 1989, Routt 1997, Schildhauer 1998); there is no randomised trial defining VS fixation strategy, which is a genuine area of uncertainty.
Registry and Cohort Evidence
- Population trauma registries (e.g. Ontario Trauma Registry) show stable incidence and stable approx 11% 30-day mortality despite rising injury severity, indicating improving systems of care (Mann et al., Injury 2018).
- Long-term patient-reported outcomes after pelvic ring injury (SMFA, EQ-5D) remain significantly worse than the general population regardless of operative versus non-operative treatment, reflecting the burden of associated and neurological injury (Banierink et al., 2019).
- There is no dedicated implant/joint registry for pelvic fixation comparable to arthroplasty registries; evidence is from trauma registries and surgical series.
Global Practice Variation
- Typical practice
- Early CT, percutaneous SI screw fixation under triplanar fluoroscopy or navigation, combined anterior + posterior fixation, angioembolisation available
- Typical practice
- Greater reliance on traction, external fixation and open techniques; navigation and embolisation often unavailable; longer immobilisation
Across all settings the non-negotiable principle is the same: a vertically unstable injury needs both anterior and posterior stabilisation, and the posterior lesion is the primary problem.
Thromboprophylaxis and Rehabilitation (global principles)
- Pelvic ring trauma carries high venous thromboembolism risk from immobility and vascular injury; mechanical prophylaxis plus pharmacological prophylaxis (low-molecular-weight heparin, or a direct oral anticoagulant where appropriate) once haemostasis is secured is standard, continued until mobile.
- Rehabilitation follows protected weight-bearing with graduated progression; persistent L5 foot-drop may require an ankle-foot orthosis, and neurological recovery determines long-term function.
Exam Focus Points
High-Yield Concepts
The KEY distinguishing feature of VS injuries is VERTICAL (cephalad) displacement of the hemipelvis. This causes TRUE leg length discrepancy - measure ASIS to medial malleolus bilaterally. LC-III and APC-III have rotational instability but minimal vertical displacement.
Quick Differentiation
- VS: Vertical displacement, axial mechanism, high neuro risk
- LC-III: Internal rotation, lateral mechanism, windswept pelvis
- VS: Vertical displacement, limb shortened
- APC-III: External rotation, open book, highest hemorrhage
Surgical Principles
Non-Negotiables:
- BOTH anterior AND posterior fixation
- Reduce vertical displacement first (traction)
- Posterior fixation is primary stabilization
- SI screws into S1 BODY (not ala)
- Document neurology before and after surgery
Denis Zone Significance
- Zone I: L5 at risk, 5-10% neuro injury
- Zone II: S1 at risk, 25-30% neuro injury
- Zone III: Cauda equina, up to 60%, often permanent
Viva Scenarios
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A 32-year-old construction worker fell 8 meters from scaffolding, landing on his feet. He has a shortened right leg and cannot bear weight. AP pelvis shows right hemipelvic cephalad displacement with symphysis diastasis and right sacral fracture. Describe your assessment and management.”
“Explain the difference between vertical shear injuries and APC-III injuries. Why is this distinction important for management?”
“Describe your technique for percutaneous iliosacral screw fixation. What are the key anatomical considerations and how do you avoid complications?”
MCQ Practice Points
Q: What is the KEY distinguishing feature of vertical shear pelvic injuries compared to LC-III and APC-III injuries?
A: VERTICAL (cephalad) displacement of the hemipelvis causing TRUE limb length discrepancy (shortened limb on affected side). Compare iliac crest heights which are asymmetric in VS. LC-III and APC-III have rotational instability but minimal vertical displacement.
Q: What is the neurological injury rate in vertical shear injuries and which nerve root is most vulnerable?
A: 30-50% neurological injury rate (highest of all pelvic patterns). L5 nerve root is MOST vulnerable, running anteriorly through the sacral ala. Denis Zone III (central) has highest risk at 60%, Zone II (transforaminal) has 25-30%, and Zone I (alar) has 5-10% risk.
Q: A patient with a vertical shear pelvic injury has good reduction achieved with external fixation anteriorly. Can you leave the posterior pelvis untreated if the reduction is maintained?
A: NO - this is a critical exam trap. VS injuries ALWAYS require BOTH anterior AND posterior fixation. Anterior fixation alone is inadequate. The posterior injury is the PRIMARY stability problem. Never leave a VS injury with only anterior stabilization - no exceptions.
Q: Where should the iliosacral screw be placed in VS injuries and what is the most serious complication of improper placement?
A: Target the S1 BODY (not the ala), placing the screw parallel to the S1 superior endplate. Three fluoroscopic views required: inlet, outlet, and lateral. L5 nerve injury is the most serious complication from screw placement through the sacral ala. Stay within S1 body to avoid the L5 nerve.
Q: A patient fell 10 meters and presents with a shortened right leg and pelvic fracture. What classification is this and what treatment is required?
A: This is a vertical shear injury (Young-Burgess VS, Tile C). Treatment requires BOTH anterior AND posterior fixation. Next steps: detailed neurological exam (especially L5 and sacral roots), CT pelvis with 3D reconstruction to define fracture pattern, and surgical planning for combined fixation.
Q: What is the role of pelvic binders in vertical shear injuries compared to APC injuries?
A: Pelvic binders are LESS effective for VS than APC injuries. While binders help with hemorrhage control, they do NOT reduce vertical displacement effectively. VS injuries primarily displace vertically (cephalad), whereas binders work by closing the pelvic ring rotationally. Skeletal traction is more useful for vertical reduction in VS.
Quick Facts
- Mechanism: Axial load on extended leg (fall from height)
- Key finding: VERTICAL hemipelvic displacement
- Clinical sign: True limb length discrepancy (shortening)
- Destot sign: Scrotal/labial hematoma
- Neuro risk: 30-50% (highest of all patterns)
- Tile equivalent: Always Tile C (complete instability)
- Treatment: BOTH anterior AND posterior fixation
- SI screw target: S1 BODY (not ala - L5 nerve risk)
Critical Actions
- VS injury identified → Detailed neuro exam, skeletal traction, plan both anterior and posterior fixation
- Denis Zone III sacral fracture → High neurological risk, may need lumbopelvic fixation
- Bilateral VS injury → Consider lumbopelvic fixation (triangular osteosynthesis)
- SI screw placement → Target S1 body, confirm on inlet/outlet/lateral views, avoid ala
Exam Day Tips
- VS = VERTICAL displacement = TRUE limb shortening = Tile C
- 30-50% neurological injury rate - document before surgery
- BOTH anterior AND posterior fixation is mandatory
- SI screw goes in S1 BODY - ala is danger zone (L5)
- Denis Zone III = cauda equina risk = may need lumbopelvic fixation
Common Pitfalls
- Treating with anterior fixation alone (must fix posterior)
- Missing vertical displacement (compare iliac crest heights)
- SI screw in ala instead of S1 body (L5 nerve injury)
- Not documenting neurology preoperatively
- Relying on binder alone (doesn't address vertical displacement)
Evidence and Guidelines
Mechanism Predicts Resuscitation, Morbidity and Mortality (Landmark VS vs APC Study)
- In 38 patients with complete anterior and posterior ring disruption (innominosacral dissociation), outcome was driven by mechanism. The anteroposterior compression (APC) group had significantly greater transfusion requirement, multiorgan failure (11/18 versus 2/14) and mortality (39 percent versus 0 percent) than the vertical shear (VS) group. VS patients were more likely to receive fewer than 10 units of blood.
Posterior Fixation is Mandatory for Vertically Unstable Patterns
- Comparison of skeletal traction/sling, anterior external fixation and internal fixation for unstable pelvic ring fractures showed that anterior frame fixation alone failed to control the posterior injury in vertically unstable patterns. Reduction and stable fixation, addressing the posterior ring, were required to achieve union in a satisfactory position.
Percutaneous Iliosacral Screw Fixation: Early Complications
- In 177 consecutive unstable pelvic ring injuries treated with percutaneous iliosacral screws, only 5 screws were misplaced (surgeon error) and just one produced a transient L5 neurapraxia. There were no posterior pelvic infections and minimal blood loss. Adequate triplanar fluoroscopy of an accurately reduced posterior ring is essential; reduction must precede fixation.
Denis Sacral Fracture Classification (Landmark, 236 cases)
- Retrospective analysis of 236 sacral fractures defined three zones with characteristic neurological risk: Zone I (ala) occasionally damages the L5 root; Zone II (transforaminal) commonly causes sciatica but rarely bladder dysfunction; Zone III (central canal) frequently produces saddle anaesthesia and loss of sphincter function. Plain radiographs were almost useless; CT was crucial.
Triangular (Lumbopelvic) Osteosynthesis for Vertically Unstable Sacral Fractures
- In 34 patients (28 polytraumatised) with vertically unstable sacral fractures, triangular osteosynthesis (vertical vertebro-pelvic distraction plus transverse iliosacral or trans-sacral fixation) allowed early progressive weight-bearing (mean full weight-bearing at 23 days). Hardware loosening occurred in 3 of 34 (9 percent), with 2 (6 percent) needing reintervention.
Population Epidemiology and Mortality of High-Energy Pelvic Fractures
- In a 10-year Ontario Trauma Registry cohort of 3915 high-energy pelvic fractures, incidence was stable at about 4.6 per 100,000 population per year and 30-day mortality remained constant at 11 percent despite rising injury severity. Pelvic ring fractures account for 2-3 percent of all fractures but are present in 7-20 percent of high-energy polytrauma; reported mortality for high-energy patterns ranges 6-35 percent and is driven mainly by associated injuries (ISS).