Congenital Pseudoarthrosis of the Tibia with Missing Toes: Associated Conditions, Causes, and Treatment
Combined fixation techniques with external fixation (Ilizarov) and intramedullary fixation are the most effective treatment for congenital pseudoarthrosis of the tibia (CPT), achieving 84% primary union rates with lower refracture risks compared to single fixation methods. 1
Associated Conditions and Causes
Primary Associations
- Neurofibromatosis Type 1 (NF1): CPT is strongly associated with NF1, which is present in a significant percentage of cases 2
- Fibrous Hamartoma: Characterized by fibrous tissue interposition between bone fragments and sclerotic bone ends with narrowing of the medullary canal 1
- Fibular Involvement: Concurrent pseudarthrosis of the fibula is common and affects treatment outcomes 3
Pathophysiology
- Abnormal tumor growth due to neurofibromatosis and impaired bone healing caused by dysplasia lead to abnormal bone growth and bowing of the tibia 3
- The affected bone is biologically and mechanically inferior, even after healing, explaining the high risk of refracture 1
- Missing toes may represent a more severe phenotype of the developmental abnormality affecting the lower limb
Treatment Options
Surgical Management
Combined Fixation Technique (Recommended - 84% consensus)
- External fixation (Ilizarov) combined with intramedullary fixation
- 84% primary union rate with 5.62 months mean union time
- 22.3% refracture rate, significantly lower than single fixation methods 1
Cross-Union Technique
NOT Recommended Techniques:
Surgical Principles
- Complete excision of the pseudarthrosis site is essential (100% consensus) 1
- Sufficient autogenous bone grafting is required 1
- Surgery is indicated for all patients over 2 years old 3, 1
- Intramedullary devices should be retained as long as possible to prevent refracture 2
Adjunctive Therapies
- Recombinant human bone morphogenic proteins (rhBMP7 and 2): Current evidence doesn't support routine use (89% expert disagreement) 1
- Bisphosphonates: Evidence inconclusive (84% neutral expert opinion) 1
- Vascularized fibular grafting: 45% refracture rate, considered a substitute for autogenous bone graft rather than a fixation technique 3
Complications and Long-Term Management
Common Complications
- Refracture: Most serious complication, can occur up to 18 years after initial fusion 1
- Non-union: Rates vary by treatment technique 1
- Limb length discrepancies: Common, especially with IMR alone 1
- Ankle stiffness: More common with IMR alone 1
- Ankle valgus deformity: Reported in multiple studies 4
Long-Term Management
- Follow-up until skeletal maturity is crucial due to risk of late refracture 1
- Monitoring should include:
- Ankle function
- Limb length discrepancies
- Deformity correction
- Signs of refracture 1
Treatment Algorithm
For patients >2 years old with CPT and missing toes:
- Complete excision of pseudarthrosis site
- Autogenous bone grafting
- Combined fixation with external fixator (Ilizarov) and intramedullary fixation
- Consider cross-union technique for younger patients or those with high-risk features
For persistent non-union or refracture:
- Repeat surgical intervention with combined fixation technique
- Consider vascularized fibular grafting as an alternative bone graft source
For severe cases with multiple failed reconstructions:
- Amputation may be considered for recalcitrant fractures, severe limb length discrepancy (>6cm), or gross deformities of leg and ankle 5
The presence of missing toes suggests a more complex developmental abnormality, which may require more aggressive surgical management and closer monitoring for complications.