Congenital Pseudarthrosis of the Tibia (CPT)
Key Points
- Rare condition (1:140,000 to 1:250,000 births)
- 50% associated with Neurofibromatosis Type 1 (NF1)
- Usually presents in early childhood
- High risk of refracture and non-union
- Multiple surgeries often required
- Challenging condition with guarded prognosis
Pathophysiology
- Genetic Associations:
- NF1 gene mutations
- Abnormal periosteal tissue
- Fibrous hamartoma formation
- Decreased osteogenic potential
- Local Factors:
- Vascular dysplasia
- Increased osteoclast activity
- Mechanical factors
- Growth disturbance
- Associated Conditions:
- Neurofibromatosis Type 1 (50%)
- Fibrous Dysplasia
- McCune-Albright Syndrome
Natural History
- Pre-fracture Phase:
- Anterolateral bowing
- Progressive deformity
- Cortical thinning
- Fracture Phase:
- Usually occurs before age 4
- Minimal trauma
- Poor healing potential
- Post-fracture Phase:
- Non-union
- Progressive deformity
- Limb length discrepancy
Clinical Features
Presentation
- Early Signs:
- Anterolateral tibial bowing
- Café-au-lait spots (in NF1)
- Limb length discrepancy
- Normal at birth in some cases
- Advanced Features:
- Pathological fracture
- Mobile pseudarthrosis
- Progressive deformity
- Ankle valgus
- Foot deformities
Physical Examination
- General Assessment:
- Growth parameters
- Skin examination (café-au-lait spots)
- Neurological screening
- Musculoskeletal examination
- Local Examination:
- Deformity assessment
- Limb length measurement
- Joint mobility
- Neurovascular status
- Adjacent joint function
Diagnosis & Classification
Crawford Classification
- Type I:
- Anterior bowing + medullary sclerosis
- Best prognosis
- Type II:
- Anterior bowing + hourglass constriction
- Higher risk of fracture
- Type III:
- Cystic lesion + fracture
- Poor prognosis
- Type IV:
- Frank pseudarthrosis
- Worst prognosis
Imaging Studies
- Radiographs:
- AP/Lateral tibia-fibula
- Standing alignment views
- Contralateral comparison
- MRI:
- Soft tissue evaluation
- Neurofibroma detection
- Pre-operative planning
- CT Scan:
- Bone architecture
- Union assessment
- 3D reconstruction
Management Approach
Pre-fracture Management
- Prophylactic Measures:
- Bracing
- Activity modification
- Regular monitoring
- Prophylactic surgery in selected cases
Surgical Management
- Intramedullary Fixation:
- Telescopic rods
- Solid rods
- Combined techniques
- Biological Enhancement:
- Autologous bone grafting
- BMP (Bone Morphogenetic Protein)
- Periosteal grafting
- Vascularized fibular graft
- External Fixation:
- Ilizarov technique
- Taylor Spatial Frame
- Compression-distraction
Current Treatment Strategies
- Combined Approaches:
- Intramedullary rod + external fixation
- Biological augmentation
- Staged procedures
- Novel Techniques:
- Induced membrane technique
- Stem cell therapy
- Growth factors
Complications
- Early Complications:
- Infection
- Hardware failure
- Soft tissue problems
- Late Complications:
- Non-union
- Refracture
- Limb length discrepancy
- Angular deformity
- Ankle valgus
Long-term Follow-up
- Monitoring:
- Regular radiographs
- Growth assessment
- Functional evaluation
- Quality of life assessment
- Additional Procedures:
- Rod exchange
- Limb length equalization
- Deformity correction
- Ankle stabilization
