Congenital Pseudoarthrosis of the Tibia

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Synonyms

CPT,

Overview

Congenital Pseudoarthrosis of the Tibia (CPT) is a rare disorder where the shin bone (tibia) has a weak spot, leading to spontaneous fractures or breaks from minor injury, failing to heal into a solid bone and forming a “false joint” (pseudoarthrosis) instead, often with bowing, shortening, and instability. It typically appears in infancy, is sometimes linked to Neurofibromatosis Type 1 (NF1), and presents challenges due to poor bone quality, requiring complex surgical treatments like bone grafting, internal fixation, or distraction osteogenesis (Ilizarov method) to achieve union, correct deformity, and equalize leg length. 

Symptoms

Congenital Pseudoarthrosis of the Tibia (CPT) symptoms often appear as a bowing or abnormal movement in the lower leg, leading to instability, leg length differences, and difficulty walking, with the bone prone to repeated fractures (pseudoarthrosis), even from minor trauma, often developing gradually from birth. Key signs include anterolateral bowing, fracture/non-union, instability/abnormal movement, limb shortening, and potential associated signs like cafe-au-lait spots if linked to Neurofibromatosis (NF1). 

Causes

Congenital Pseudarthrosis of the Tibia (CPT) is a rare condition where the lower leg bone (tibia) doesn’t heal after a fracture, forming a false joint (pseudoarthrosis), with causes still unclear but strongly linked to genetic factors like Neurofibromatosis Type 1 (NF1), abnormal bone tissue (hamartoma) replacing the periosteum (healing layer), poor blood supply, and potentially issues with bone-forming cells (osteoblasts) and bone-resorbing cells (osteoclasts). It’s a failure of normal bone regeneration, often presenting as a bowing leg at birth or early childhood. 

Prevention

Preventing Congenital Pseudarthrosis of the Tibia (CPT) focuses on managing the pre-fracture stage with aggressive bracing (like clamshell splints) and sometimes preventative surgery, such as McFarland bypass grafting or guided growth (hemiepiphysiodesis), to correct deformity, relieve stress, and delay or stop fractures from occurring, especially in children with associated conditions like Neurofibromatosis type 1 (NF1). 

Diagnosis

Diagnosing congenital pseudoarthrosis of the tibia (CPT) involves clinical assessment of leg bowing or fracture, often noted at birth or when a child starts walking, alongside characteristic X-ray findings showing bone deformity and nonunion, sometimes requiring MRI for detail and evaluation for associated conditions like Neurofibromatosis Type 1 (NF-1). 

Prognosis

The prognosis for congenital pseudoarthrosis of the tibia (CPT) is guarded, as it’s a difficult condition to treat, often requiring multiple surgeries, with a high risk of refracture and residual deformity, including leg length discrepancy and bowing, leading to potential long-term disability, though advanced techniques like vascularized fibular grafts and cross-union offer better outcomes, aiming for stable union and functional limb preservation. Early diagnosis and aggressive management are crucial for the best results, often involving surgical excision of the problematic tissue and bone grafting. 

Treatment

Treatment for Congenital Pseudoarthrosis of the Tibia (CPT) is primarily surgical, focusing on removing the non-union site, grafting bone, and stabilizing the limb, using techniques like intramedullary nailing, Ilizarov fixation, or vascularized fibular transfer to achieve union, correct alignment, and address limb length discrepancies, sometimes combined with pre-operative bisphosphonates or bone growth factors, though severe cases might require amputation.