Congenital Pseudoarthrosis of Tibia (CPT)

Origin of Pathology

Periosteum

• The periosteum could create a fibrous band causing an increase in local pressure around the bone resulting in reduced vascularization as well as bone atrophy

Clinical features

Mnemonic: ABCDeF

1. Age of onset:
   • Early (<4 years old) – majority present with bowing in 1st year of life
   • Late (>4 years old)
2. Bowing: Antero-lateral (junction of middle 1/3 and distal 1/3)
3. Cafe-au-lait spots and Neurofibromatosis type 1 (in 55% cases)
4. Deformity
5. Fractures; Fibrous dysplasia (in 15% cases)

Boyd Classification

Mnemonic: B-2C-2D-E

I – Bowing

II – Constriction (hourlgass)

• Most common type
• Poorest prognosis
• More often associated with NF1

III – Cyst

IV – Dense (Sclerotic)

V – Dysplastic fibula

VI – “Endosseous” (Intraosseous) neurofibroma or schwannoma

Paley Classification

Type	Bone ends	Pseudoarthrosis mobility	Previous surgical intervention
1	Atrophic	Mobile	Absent
2	Atrophic	Mobile	Present
3	Hypertrophic	Stiff	Absent/Present

Treatment

Differential Diagnoses

1. Osteofibrous dysplasia of long bones

2. Congenital angulation of tubular bones

3. Monostotic fibrous dysplasia

Poor Prognostic Factors

1. Markedly progressed disease
2. Early fractures
3. Inferior metaphyseal location of pseudoarthrosis
4. Atrophy of bone
5. Extensive sclerotic lesions with a smaller diameter bone
6. Significant shortening
7. Associated fibular involvement