What is the management approach for a patient with an infected non-union tibia?

Management of Infected Non-Union Tibia

The optimal management of infected tibial non-union requires aggressive surgical debridement with complete excision of infected tissue and necrotic bone, followed by skeletal stabilization (preferably external fixation to reduce reinfection risk), combined with prolonged pathogen-specific antimicrobial therapy for at least 6 weeks. 1

Surgical Management Principles

The cornerstone of treatment involves addressing three critical components simultaneously: eradicating infection, achieving bony stability, and restoring soft tissue coverage 2.

Debridement and Infection Control

• Radical debridement is mandatory, removing all infected and necrotic bone, soft tissue, and any retained hardware 1, 3
• Obtain at least 5 deep tissue specimens intraoperatively using separate instruments from sites around the fracture and adjacent to any implants 1
• Tissue specimens should be inoculated in blood culture bottles for maximum diagnostic yield 1
• Stop antimicrobials at least 2 weeks before sampling to avoid false-negative cultures, then restart immediately after specimen collection 1
• Swab cultures are inadequate and should never be used; only deep tissue cultures are acceptable 1

Fixation Strategy Selection

External fixation is strongly preferred over internal fixation as it carries significantly lower risk of recurrent infection 2. The choice depends on the bone defect size and complexity:

For Defects 2.5-8 cm:

• Circular external fixator with bone transport achieves union in 84-88% of cases with mean healing time of 6.8 months 3, 4
• Bone transport via corticotomy and callus distraction eliminates the need for bone grafting in most cases 3
• This technique produces significantly less limb-length discrepancy compared to conventional bone grafting approaches 4

For Distal Tibial Involvement:

• Single-stage Ilizarov external fixation after complete debridement and implant removal achieves 100% union rates with median healing time of 4.5 months 5
• Local antibiotic delivery using vancomycin and gentamicin-impregnated bone graft or cement is highly effective 5
• Early protected weightbearing and ankle range-of-motion exercises should begin immediately postoperatively 5

Internal Fixation Considerations:

• Intramedullary nailing may be considered in highly selected cases where external fixation is not feasible, but carries higher reinfection risk 2, 6
• If used, combine with aggressive open wound management and plan for potential nail removal after union 6
• Union rates of 95% are achievable but with persistent drainage in up to 21% of cases 6

Antimicrobial Therapy

Timing and Duration

• Minimum 6 weeks of pathogen-specific antimicrobial therapy is required after definitive surgical treatment 1
• Initial phase: 2-6 weeks of intravenous therapy targeting identified organisms 7
• Continuation phase: oral antimicrobials to complete total treatment course 7

Organism-Specific Regimens

• For Staphylococcal infections (the most common pathogens, including MRSA): rifampin 300-450 mg orally twice daily PLUS a companion drug (fluoroquinolone or doxycycline) 7, 5
• All bacteria should be tested for antibiotic sensitivity; vancomycin and gentamicin provide broad coverage for most tibial infections 5

Critical Microbiological Considerations

• Methicillin-resistant Staphylococcus aureus is the most common pathogen (52% of cases), followed by methicillin-sensitive S. aureus (28%) 5
• Mixed bacterial flora occurs in approximately 20% of cases 5
• If initial cultures are negative despite clinical infection, specifically request mycobacterial cultures as atypical organisms may be present 1, 7

Adjunctive Therapies

• Hyperbaric oxygen therapy should be considered for cases with reinfection or compromised soft tissue healing 3
• Bone grafting is rarely needed when bone transport techniques are employed, but may be required in 16% of cases treated conventionally 3, 4

Expected Outcomes and Follow-Up

• Overall success rate of 88-97% for infection eradication and fracture union when treated by multidisciplinary teams 2
• Mean time to union: 6-9 months depending on defect size and technique used 3, 2
• Recurrent infection occurs in approximately 9% of cases, typically manageable with additional debridement 2
• Amputation rates of 10-12% are expected, reserved for cases with necrotizing infection, massive bone loss, or treatment failure 2

Critical Pitfalls to Avoid

• Never attempt definitive fixation without complete debridement of all infected tissue—this guarantees treatment failure 1, 2
• Avoid internal fixation when external fixation is feasible, as internal hardware significantly increases reinfection risk 2
• Do not rely on swab cultures or sinus tract cultures—these are contaminated and unreliable 1
• Never start antimicrobials before obtaining adequate tissue specimens unless life-threatening sepsis is present 1
• Inadequate antimicrobial duration (less than 6 weeks) leads to treatment failure and recurrence 1, 7