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Congenital pseudoarthrosis of the tibia (CPT) is a rare, severe orthopedic condition typically presenting in infancy or early childhood, characterized by anterolateral bowing of the tibia and a high risk of developing a non-union fracture (pseudoarthrosis).

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It is frequently associated with Neurofibromatosis 1 (NF1) and has a poor prognosis for spontaneous healing.

Etiology

Factor	Description
Congenital	Present at birth or becomes evident in early childhood
Association with NF1	Seen in ~50–55% of cases; CPT may be the first manifestation
Genetic Factors	NF1 gene mutation on chromosome 17q11.2
Vascular Theory	Poor periosteal blood supply → failure of normal bone remodeling

Pathophysiology

Anterolateral bowing of the tibia leads to a pathological fracture, typically between 1–3 years.
Instead of healing with callus, the fracture site develops fibrous tissue.
Bone ends become atrophic or sclerotic, resulting in a false joint (pseudoarthrosis).

Clinical Features

Feature	Description
Anterolateral tibial bowing	Usually visible at birth or soon after
Pathologic fracture	Often follows minor trauma
Persistent non-union	Failure to heal even with immobilization
Shortening of the limb	Due to growth inhibition
Instability/deformity	False joint movement at fracture site
Possible fibular involvement	Often coexisting fibular dysplasia or absence

![Clinical and radiological presentation of anterolateral bowing in congenital pseudarthrosis of the tibia (CPT); (A,B) anterior-posterior (a.p.) view; (C,D) lateral view.

Laufer A, Frommer A, Gosheger G, Roedl R, Schiedel F, Broeking JN, Toporowski G, Rachbauer A, Antfang C, Vogt B. Reconstructive Approaches in Surgical Management of Congenital Pseudarthrosis of the Tibia. Journal of Clinical Medicine. 2020; 9(12):4132. https://doi.org/10.3390/jcm9124132](attachment:01e9cc81-5002-4e13-80fb-db3a3d68fd90:jcm-09-04132-g001.png)

Clinical and radiological presentation of anterolateral bowing in congenital pseudarthrosis of the tibia (CPT); (A,B) anterior-posterior (a.p.) view; (C,D) lateral view.

Radiology

Modality	Imaging features
XR	• Tapered or narrowed bone ends: “Pencil-point” appearance (atrophic type)
• Cystic lucencies: At fracture ends
• Sclerotic margins: Indicating chronicity and failed healing
• Anterior bowing: Pre-fracture deformity, pathognomonic
• Pseudoarthrosis: Radiolucent cleft with lack of bridging bone
MR	• Soft-tissue evaluation: Identifies fibrous tissue, marrow status
• Neurofibroma detection: If NF1 is suspected or confirmed
CT	• Bony detail: Preoperative planning
• Cortical continuity: Assesses bone end geometry and sclerosis

![Clinical (A) and radiographic (B) heterogeneity of congenital pseudarthrosis of the tibia (CPT) with anterolateral bowing of the leg and atrophic pseudarthrosis of the lower third of the leg (C).

Pannier S. Congenital pseudarthrosis of the tibia. Orthopaedics & Traumatology Surgery & Research. 2011;97(7):750-761. doi:https://doi.org/10.1016/j.otsr.2011.09.001](attachment:a5422efb-1ebd-470f-878e-c8037ead0c2a:1-s2.0-S1877056811001885-gr1.jpg)

Clinical (A) and radiographic (B) heterogeneity of congenital pseudarthrosis of the tibia (CPT) with anterolateral bowing of the leg and atrophic pseudarthrosis of the lower third of the leg (C).

Pannier S. Congenital pseudarthrosis of the tibia. Orthopaedics & Traumatology Surgery & Research. 2011;97(7):750-761. doi:https://doi.org/10.1016/j.otsr.2011.09.001

4 stage Crawford classification of CPT: