Criteria for Acute Docking in Ilizarov Technique
Acute docking should be considered as the primary approach for tibial defects less than 5 cm, with good soft tissue coverage and when the patient is hemodynamically stable. 1
Decision Algorithm for Acute Docking vs. Bone Transport
Indications for Acute Docking:
- Defect size: Optimal for defects less than 5 cm 1, 2
- Soft tissue status: Adequate soft tissue coverage without significant defects 3
- Patient stability: Hemodynamically stable patients 2
- Fibula status: Divided fibula (facilitates compression) 3
- Infection control: Well-controlled infection after thorough debridement 1, 3
Contraindications for Acute Docking:
- Large defects: Defects exceeding 5 cm (increased risk of neurovascular compromise) 1, 2
- Soft tissue problems: Significant soft tissue defects requiring coverage 3
- Intact fibula: May prevent adequate compression at docking site 3
- Poor vascularity: Compromised blood supply to the limb 2
- Active infection: Uncontrolled infection at the docking site 1
Technical Considerations for Acute Docking
Pre-docking Requirements:
- Complete excision of pseudarthrosis/infected tissue 1
- Sufficient autogenous bone grafting at docking site 1, 2
- Proper alignment of bone ends 1
- Assessment of neurovascular status before compression 2
Docking Procedure:
- Bone end preparation: Freshen bone ends to achieve healthy bleeding surfaces 1
- Compression technique: Apply gradual compression (typically 0.25-1mm per day) 4
- Monitoring: Regular neurovascular checks during compression 2
- Bone grafting: Consider prophylactic bone grafting at docking site to reduce non-union risk 1, 5
Outcomes and Complications
Expected Outcomes:
- Union rates: 84-100% final union rate with combined Ilizarov and intramedullary fixation 1
- Union time: Average of 8.3 months for primary union with Ilizarov method 1
- Functional results: 87.94% excellent functional results reported 6
Potential Complications:
- Non-union at docking site: 5-12.3% with Ilizarov method 1
- Need for additional surgery: Docking site surgery required in 5% of acute shortening cases vs. 66.7% in bone transport 3
- Pin tract infections: Most common complication (61.3% of cases) 6
- Axial deviation: Occurs in 43.2% of cases, more common in middle 1/3 defects 6
- Delayed union: Occurs in 25.13% of cases, more common with distal 1/3 defects 6
Optimization Strategies
To Improve Docking Success:
- Combined techniques: Use Ilizarov with intramedullary fixation to reduce refracture rates by over 50% 1
- Prophylactic bone grafting: Consider at docking site to enhance union 5
- Soft tissue management: Address soft tissue defects concurrently 3
- Monitoring for complications: Regular follow-up to detect early complications 6
Risk Factors for Complications:
- Defect length: Longer defects increase complication risk 6
- Number of previous surgeries: More prior surgeries increase pin tract infection risk 6
- External fixation time: Longer treatment duration increases complication rates 6
- Defect location: Middle and distal 1/3 defects have higher complication rates 6
Clinical Pearls and Pitfalls
Pearls:
- Consider combining external fixation with intramedullary fixation for better stability and lower refracture rates 1
- Acute shortening with relengthening has fewer unplanned surgeries compared to bone transport (15% vs. 55.6%) 3
- Thorough debridement of necrotic tissue is essential before docking 1
Pitfalls to Avoid:
- Excessive acute shortening can cause neurovascular compromise 3
- Inadequate bone end preparation leads to higher non-union rates 1
- Neglecting soft tissue management increases infection risk 3
- Underestimating the importance of docking site preparation and bone grafting 1, 5
Acute docking with the Ilizarov technique offers excellent results when applied appropriately, with union rates of 84-100% and good functional outcomes. The decision between acute docking and bone transport should be based primarily on defect size, soft tissue status, and patient stability.