Congenital segmental tibial dysplasia and late onset pseudarthrosis of the tibia.

Background: Congenital pseudarthrosis of the tibia represents a continuum of dysplasia. Most cases develop pseudarthrosis during the first two years of life. Only a few cases with tibial dysplasia present after the age of two years, with or without pseudarthrosis. This under-reported form of Congenital segmental Tibial Dysplasia (CSTD) was investigated to evaluate its distinctive features and possibly predict the disease progression.

Methods: Of the 46 cases presented to our institute over a 20-year period, 17 patients had CSTD. 13 patients developed pseudarthrosis after the age of two years, the average follow up period was four years. Four patients did not break their tibiae until the time of last follow up. Radiological criteria were evaluated by plain x-rays.

Results: According to the radiological criteria, late-presenting CSTD was divided into resolving CSTD (R-CSTD), and pre-pseudarthrosis-CSTD (P-CSTD). In all cases of the R-CSTD group, the tibia had a canalized medullary cavity with anterolateral bowing and segmental cortical sclerosis. While in the P-CSTD group, there was anterolateral bowing, segmental cortical sclerosis, and any of the following: 1) medullary obliteration, 2) cystic changes, 3) hour-glass appearance, 4) Impending fracture, and 5) progressive deformity.

Conclusion: A simple classification of prognostic value has been proposed for cases that did not sustain a fracture until after the age of two years. This differentiation would assist in decision making, and in preoperative counseling for patients.

Level of evidence: IV, Retrospective case series.