What is the step-by-step procedure for treating a right SI joint fracture with a cannulated screw?

Step-by-Step Procedure for Fracture Right SI Joint Fixation with Cannulated Compression Screws

The optimal surgical treatment for right sacroiliac (SI) joint fractures involves percutaneous fixation with cannulated compression screws under fluoroscopic guidance, which significantly reduces morbidity and mortality compared to other fixation methods.

Preoperative Planning

1. Imaging Assessment

   • Obtain CT scans of the pelvis with 2D multiplanar reformation
   • Plan the starting point and safe screw trajectory using CT 1
   • Evaluate fracture pattern, displacement, and bone quality
   • Identify safe corridors for screw placement to avoid neurovascular structures

2. Patient Positioning

   • Position patient supine on a radiolucent table
   • Place a small pillow under the ipsilateral hip for better access
   • Prepare and drape the surgical field with sterile technique

Surgical Procedure

Step 1: Anesthesia and Initial Setup

• Administer appropriate anesthesia (general or local with sedation)
• Position C-arm for inlet, outlet, and lateral views of the pelvis
• Ensure adequate visualization of anatomical landmarks

Step 2: Identification of Entry Point

• Under fluoroscopic guidance, identify the starting point on the lateral view according to preoperative planning 1
• Make a small skin incision (1-2 cm) at the planned entry point
• Use blunt dissection to reach the ilium

Step 3: Guidewire Placement

• Insert a 2.0-2.5 mm guidewire through the entry point
• Advance the guidewire under fluoroscopic control using inlet and outlet views according to the planned trajectory 1
• Confirm proper guidewire position in all views (inlet, outlet, lateral)
• Ensure the guidewire traverses the fracture site and enters the sacral body without breaching the sacral foramina

Step 4: Drilling and Screw Placement

• Measure the appropriate screw length using the guidewire
• Drill over the guidewire with a cannulated drill bit
• Select appropriate cannulated screw (typically 6.5-7.0 mm diameter)
• Insert the cannulated screw over the guidewire under fluoroscopic guidance
• Advance the screw until adequate compression is achieved across the fracture site
• Consider placing a second screw if needed for additional stability

Step 5: Final Assessment and Closure

• Verify final screw position with fluoroscopy in multiple views
• Remove the guidewire
• Irrigate the wound
• Close the incision in layers
• Apply sterile dressing

Postoperative Management

1. Immediate Care

   • Obtain postoperative CT scan to confirm proper screw placement
   • Monitor for neurological complications - immediate CT scan if neurological impairment develops 1
   • Implement multimodal analgesia including peripheral nerve block 2

2. Mobilization Protocol

   • Allow weight-bearing as tolerated using crutches 1
   • Begin early mobilization to improve oxygenation and respiratory function 2

3. Complication Prevention

   • Administer thromboembolic prophylaxis for 4 weeks postoperatively 2
   • Monitor for complications including infection, hardware failure, and non-union
   • Remove urinary catheters as soon as possible to reduce infection risk 2

4. Follow-up Schedule

   • Radiographic evaluation at 6 weeks, 3 months, 6 months, and 1 year
   • Assess fracture healing, implant position, and potential complications
   • Evaluate functional recovery and need for rehabilitation

Technical Pearls and Pitfalls

Pearls:

• Use intraoperative fluoroscopy in multiple planes to ensure accurate screw placement
• Pre-drill cortices, especially in young patients with strong bone, to prevent screw unraveling 3
• Consider navigation systems for complex cases or sacral dysmorphism

Pitfalls to Avoid:

• Inadequate visualization of anatomical landmarks can lead to screw malpositioning 1
• Failure to identify sacral dysmorphism may result in nerve injury
• Excessive screw length can cause neurovascular injury
• Insufficient compression may lead to nonunion

This procedure has shown excellent outcomes with radiological evidence of fracture consolidation achieved on average at 63 days and low complication rates 4.