Sacral Fractures

Location:

• Lateral to sacral foramina
• Sacral ala region (wing)

Neural Structures at Risk:

• L5 nerve root (runs on anterior ala surface)

Neurological Injury Rate:

• 5-10%

Clinical Presentation:

• Foot drop (L5 weakness)
• Weak great toe extension
• Sensory loss dorsum of foot
• Usually stable fracture

Management:

• Often conservative if minimally displaced
• SI screws if unstable or displaced

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Location:

• Through one or more sacral foramina
• Most common traumatic pattern

Neural Structures at Risk:

• S1, S2, S3, S4 nerve roots

Neurological Injury Rate:

• 25-30%

Clinical Presentation:

• S1: Weak plantarflexion, absent ankle jerk
• S2: Sensory loss posterior thigh
• S3-S4: Variable bowel/bladder dysfunction
• Variable stability

Management:

• SI screws common
• May need decompression if foraminal compromise
• Address neurological deficit

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Location:

• Medial to foramina
• Involves sacral canal
• Highest risk pattern

Neural Structures at Risk:

• Cauda equina
• All sacral roots

Neurological Injury Rate:

• Up to 60%

Clinical Presentation:

• Cauda equina syndrome
• Bowel dysfunction
• Bladder dysfunction
• Sexual dysfunction
• Saddle anesthesia
• Variable lower extremity weakness
• Usually unstable

Management:

• Urgent decompression if canal compromise
• Lumbopelvic fixation often needed
• Surgical emergency if progressive deficit

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Indications:

• Zone I with minimal displacement (less than 5mm)
• Stable pelvic ring
• No neurological deficit
• Insufficiency fractures (first line)

Protocol:

• Initial bed rest (2-4 weeks)
• Progressive mobilization
• Weight-bearing as tolerated
• Analgesia (paracetamol, NSAIDs, opioids)
• DVT prophylaxis (LMWH)
• Serial radiographs (1, 2, 6 weeks)
• Physiotherapy for mobilization

Expected Outcomes:

• Most heal at 6-12 weeks
• Return to function gradual
• Monitor for late complications

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Absolute Indications:

• Neurological deficit with canal compromise
• Unstable pelvic ring
• Spinopelvic dissociation (U-type, H-type)
• Progressive neurological deterioration
• Zone III with cauda equina syndrome

Relative Indications:

• Significant displacement (greater than 1cm)
• Zone III fractures even without deficit
• Associated pelvic ring injury requiring stabilization
• Failure of conservative management
• Polytrauma requiring early mobilization

Surgical Options:

• Percutaneous SI screws
• Lumbopelvic fixation
• Sacral decompression
• Sacroplasty (insufficiency fractures)

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Immediate Surgery Required:

• Cauda equina syndrome with canal compromise
• Progressive neurological deterioration
• Spinopelvic dissociation with instability
• Zone III fracture with neurological deficit

Timing:

• Decompression within 24-72 hours for best results
• Earlier decompression associated with better neurological recovery

Approach:

• Posterior sacral decompression
• Lumbopelvic fixation
• Combined procedure often needed

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Percutaneous Sacroiliac Screws

Indications:

• Zone I and II fractures
• Longitudinal sacral fractures
• SI joint instability
• Stable to moderately unstable patterns

Patient Positioning:

• Supine on radiolucent table
• Lateral decubitus alternative

Equipment:

• 7.3mm or 7.0mm cannulated screws
• Fluoroscopy (inlet, outlet, lateral views)
• Guidewires, cannulated instruments

Technique Steps:

1. Imaging Setup:

   • Obtain true AP pelvis (inlet view)
   • Obtain outlet view (40 degrees caudal)
   • Obtain lateral sacrum view
   • Mark S1 body corridor

2. Entry Point:

   • Posterior ilium lateral to SI joint
   • Approximately 1cm superior to greater sciatic notch
   • Avoid L5 nerve anteriorly

3. Guidewire Insertion:

   • Advance under fluoroscopic guidance
   • Check all three views continuously
   • Target S1 body (safe zone)
   • Avoid sacral canal medially
   • Avoid anterior cortex breach

4. Screw Placement:

   • Measure guidewire depth
   • Insert cannulated screw over wire
   • Ensure bicortical purchase
   • Final confirmation all views

5. S2 Screw (Optional):

   • For greater stability
   • Enter more cephalad
   • Similar technique

Dangers:

• L5 nerve anterior to ala
• Sacral canal medially
• Anterior vascular structures
• Dysmorphic sacrum variants

Lumbopelvic Fixation (Triangular Osteosynthesis)

Indications:

• Spinopelvic dissociation
• Bilateral sacral fractures
• Zone III fractures
• U-shaped or H-shaped patterns
• Failed SI screw fixation

Concept:

• Bypasses unstable sacrum entirely
• Creates stable construct from spine to pelvis
• "Triangular" fixation pattern

Technique:

1. Patient Positioning:

   • Prone on radiolucent frame
   • Arms tucked or out on boards

2. Exposure:

   • Posterior midline incision L3/L4 to sacrum
   • Bilateral paraspinal muscle dissection
   • Expose L4/L5 pedicles
   • Expose bilateral posterior ilium

3. Lumbar Pedicle Screws:

   • L4 and/or L5 pedicle screws
   • Standard freehand or navigated technique
   • Usually 6.5mm or 7.0mm polyaxial screws

4. Iliac Screws:

   • Enter posterior ilium
   • Directed toward ASIS
   • Between inner and outer tables
   • Long screws (70-90mm)
   • Bicortical fixation ideal

5. Rod Contouring:

   • Measure and contour rods
   • Connect lumbar to iliac screws
   • Bilateral rods
   • Apply compression or distraction as needed

6. Final Construct:

   • Tighten all set screws
   • Confirm stable construct
   • Fluoroscopic confirmation

Advantages:

• Very stable fixation
• Bypasses sacral fracture
• Allows early mobilization
• Good results in dissociation injuries

Disadvantages:

• Large exposure
• Longer operative time
• Implant prominence possible
• Adjacent segment degeneration risk

Lumbopelvic fixation provides excellent stability for complex sacral injuries.

Sacral Decompression

Indications:

• Zone III with neurological deficit
• Canal compromise on CT/MRI
• Cauda equina syndrome
• Progressive neurological deterioration

Technique:

1. Imaging:

   • Preoperative MRI essential
   • Identify level of compression
   • Plan extent of decompression

2. Exposure:

   • Posterior midline approach
   • Expose affected sacral levels
   • May extend to L5 if needed

3. Decompression:

   • Sacral laminectomy
   • Remove bone fragments
   • Decompress neural elements
   • Avoid excessive retraction

4. Stabilization:

   • Usually combine with fixation
   • Lumbopelvic fixation common
   • Prevents further instability

Timing:

• Earlier decompression better outcomes
• Aim for less than 72 hours if possible
• Incomplete injuries better prognosis

Early decompression within 72 hours optimizes neurological recovery.

Sacroplasty

Indications:

• Insufficiency fractures
• Persistent pain despite 6 weeks conservative treatment
• Osteoporotic bone
• Elderly patients

Technique:

• CT-guided percutaneous approach
• PMMA cement injection
• Bilateral usually
• Similar to vertebroplasty
• Pain relief primary goal

Outcomes:

• Significant pain reduction
• Low complication rates
• Good functional improvement

Sacroplasty provides excellent pain relief for insufficiency fractures.

Immediate Postoperative Period

Monitoring:

• Neurological observations (especially if decompression performed)
• Motor and sensory function q4h initially
• Bowel and bladder function
• Wound checks
• DVT prophylaxis

Pain Management:

• Multimodal analgesia
• IV opioids initially
• Transition to oral medications
• Neuropathic pain agents if needed (gabapentin, pregabalin)

Early pain control is essential for neurological recovery and patient comfort.

Weight-Bearing Protocol

After SI Screw Fixation:

• Touch weight-bearing for 6 weeks
• Progressive weight-bearing weeks 6-12
• Full weight-bearing at 12 weeks if radiographic healing

After Lumbopelvic Fixation:

• Usually allows earlier mobilization
• Touch to partial weight-bearing immediately
• Progressive weight-bearing as tolerated
• More stable construct than SI screws alone

Conservative Management:

• Initially bed rest 2-4 weeks
• Progressive mobilization with walking aids
• Weight-bearing as tolerated
• Pain-guided progression

Weight-bearing protocols must be individualized based on fracture pattern and fixation method.

Neurological Monitoring

Critical Assessments:

• L5 motor: Great toe extension, ankle dorsiflexion
• S1 motor: Ankle plantarflexion, ankle jerk reflex
• S2-S4: Bowel and bladder function
• Serial examinations first 48-72 hours
• Document any deterioration immediately

Bladder Management:

• Intermittent catheterization if retention
• Avoid prolonged indwelling catheter
• Urology consultation if persistent dysfunction

Bowel Management:

• Bowel regimen (stool softeners, fiber)
• Monitor for constipation
• Colorectal consultation if severe dysfunction

Close neurological monitoring is critical for detecting complications early.

Rehabilitation

Early Phase (0-6 weeks):

• Bed mobility training
• Transfer training
• Gait training with assistive devices
• Core strengthening (gentle)

Intermediate Phase (6-12 weeks):

• Progressive weight-bearing
• Strengthening exercises
• Proprioception training
• Return to ADLs

Late Phase (greater than 12 weeks):

• Advanced strengthening
• Return to sport/work
• Functional training

Follow-Up Schedule

Radiographic Follow-Up:

• 2 weeks: First post-op check
• 6 weeks: Assess healing, adjust weight-bearing
• 12 weeks: Evaluate union
• 6 months: Final assessment
• Additional imaging if symptoms persist

Clinical Follow-Up:

• Regular neurological assessments
• Pain evaluation
• Functional status
• Implant-related concerns

Structured follow-up ensures optimal healing and early detection of complications.

Union Rates

Operative Management:

• SI screw fixation: Greater than 90% union rate
• Lumbopelvic fixation: Greater than 85% union rate
• Higher union rates with stable fixation
• Nonunion rare with adequate fixation

Conservative Management:

• Most heal with conservative treatment
• Takes longer (12-16 weeks)
• Insufficiency fractures: Good healing rates
• May have residual pain even with union

Union typically occurs within 12-16 weeks with appropriate management.

Neurological Recovery

Zone I (L5 nerve):

• 50-70% recovery if incomplete deficit
• Foot drop may be permanent
• AFO may be needed long-term
• Better prognosis than central zones

Zone II (S1-S2 roots):

• Variable recovery
• Plantarflexion weakness often persistent
• Sensory deficits common
• Functional outcomes usually acceptable

Zone III (Cauda equina):

• Poorest neurological prognosis
• Complete injuries rarely fully recover
• Bowel/bladder dysfunction often permanent
• Sexual dysfunction may persist
• Early decompression improves outcomes
• Incomplete injuries have better prognosis

Factors Affecting Recovery:

• Severity of initial deficit
• Timing of decompression (if performed)
• Zone of injury (I better than III)
• Complete vs incomplete injury
• Age (younger better)

Neurological recovery is highly variable and depends on multiple factors.

Functional Outcomes

Return to Work:

• Sedentary work: 3-6 months
• Physical labor: 6-12 months
• May require job modification
• Neurological deficits impact timeline

Return to Sport:

• Low-impact activities: 4-6 months
• High-impact sports: 6-12 months
• Contact sports: 12 months minimum
• Depends on fracture healing and stability

Quality of Life:

• Most patients have good functional recovery
• Chronic pain common (30-40%)
• Neuropathic pain can be challenging
• Sexual dysfunction impacts quality of life
• Psychological support important

Multidisciplinary support optimizes functional outcomes and quality of life.

Long-Term Complications

Chronic Sacroiliac Pain:

• Occurs in 30-40% of patients
• May require SI joint injections
• Rarely needs SI joint fusion
• Multidisciplinary pain management

Implant-Related Issues:

• Prominence in lumbopelvic fixation
• May require implant removal (10-15%)
• Usually after fracture union (greater than 12 months)

Post-Traumatic Arthritis:

• SI joint arthritis possible
• Usually develops years later
• Managed conservatively initially

Neurological Sequelae:

• Permanent deficits in 20-30% Zone III
• Chronic neuropathic pain
• Bowel/bladder dysfunction management
• Sexual dysfunction counseling

Long-term complications require ongoing multidisciplinary management.