Surgical Treatment of Tibial Tuberosity Avulsion Fracture with Cannulated Screws
The optimal treatment for a 3-month-old tibial tuberosity avulsion fracture is open reduction and internal fixation with cannulated screws combined with tension band wiring to ensure stable fixation, promote healing, and allow for early rehabilitation.
Preoperative Assessment
Confirm diagnosis with radiographic evaluation, including:
- Standard AP and lateral radiographs
- CT scan to assess fragment size, comminution, and displacement
- MRI to evaluate for associated soft tissue injuries (patellar ligament avulsion)
Classify the fracture using Ogden classification:
- Type I: Avulsion of distal portion of ossification center
- Type II: Upward angulation of lip fragment
- Type III: Fracture propagating into knee joint
- Each type subdivided into A (no comminution) and B (comminution)
- Type C: With patellar ligament avulsion
Surgical Technique
Step 1: Patient Positioning and Preparation
- Position patient supine on operating table
- Apply tourniquet to upper thigh
- Prepare and drape the affected limb in sterile fashion
- Ensure fluoroscopic imaging is available
Step 2: Surgical Approach
- Make a lateral parapatellar incision (preferred over midline to avoid injury to infrapatellar branch of saphenous nerve) 1
- Extend the incision to expose both tibial tuberosity with patellar tendon and, if needed, Gerdy's tubercle 2
- Carefully dissect down to the fracture site
- Identify and protect the patellar tendon
Step 3: Fracture Reduction
- Remove any interposed soft tissue or hematoma
- Reduce the avulsed fragment anatomically
- Temporarily secure with K-wires
- Confirm reduction with fluoroscopy
Step 4: Internal Fixation
- Use cannulated screws for primary fixation:
- Select appropriate size screws (typically 4.0-6.5 mm)
- Insert guide wires under fluoroscopic guidance
- Measure for appropriate screw length
- Insert cannulated screws over guide wires
- Typically requires 2-3 screws depending on fragment size 2
Step 5: Tension Band Wiring
- Add tension band wiring to neutralize tensile forces from the quadriceps 3
- Pass a tension band wire through the patellar tendon near its insertion
- Create a figure-of-eight configuration around the screws
- Secure the wire distally in the tibia
- Tighten the wire with appropriate tension
Step 6: Final Assessment
- Verify stable fixation by gently moving the knee through range of motion
- Confirm final position with fluoroscopy
- Irrigate wound thoroughly
- Close in layers with attention to repair of soft tissues
- Apply sterile dressing
Postoperative Management
Immediate Postoperative Care
- Immobilize knee in extension with hinged knee brace
- Elevate limb and apply ice to control swelling
- Administer appropriate pain management
Rehabilitation Protocol
Week 1-2:
- Non-weight bearing with crutches
- Begin gentle passive range of motion exercises (0-30°)
Week 3-4:
- Progress range of motion (0-60°)
- Begin isometric quadriceps exercises
Week 5-6:
- Advance to partial weight bearing
- Increase range of motion as tolerated
Week 6-8:
- Remove tension band wire (if used) 4
- Progress to full weight bearing
- Continue strengthening exercises
Week 8-12:
- Full range of motion exercises
- Progressive resistance training
Week 12 onward:
- Return to sports activities as tolerated
Potential Complications and Management
- Hardware irritation: May require removal after fracture healing
- Knee stiffness: Aggressive physical therapy
- Quadriceps atrophy: Strengthening exercises
- Growth disturbance: Monitor limb length
- Nonunion: May require revision surgery with bone grafting
- Patellar alta or baja: May require additional procedures if symptomatic
Special Considerations
- For older adolescents near skeletal maturity, interfragmental transphyseal screws can be used safely 4
- In younger patients or with extensive comminution, tension band wiring should be the primary fixation method 4
- The combination of internal fixation with tension band wiring allows for earlier rehabilitation and return to sports activities 3
- Avoid external immobilization when possible to prevent quadriceps atrophy
This surgical approach provides stable fixation, allows early mobilization, and optimizes functional outcomes, particularly important for athletic patients who need to return to their previous activity level.