Femoral overgrowth in children with congenital pseudarthrosis of the Tibia

BACKGROUND Having observed a tendency towards femoral overgrowth (FO) of the affected limb in children with atrophic-type congenital pseudarthrosis of the tibia (CPT), we aimed to identify the incidence of, contributors to, and patterns of FO among such children. METHODS We retrospectively evaluated 55 children with CPT, 22 with prepseudarthrosis and 33 with atrophic-type CPT from 1989 to 2012. FO was defined as an affected femoral segment ≥10 mm longer than the contralateral segment. We investigated FO incidences in prepseudarthrosis versus atrophic-type CPT. Sex, laterality, coexistence of neurofibromatosis type 1, development of frank pseudarthrosis, extent of tibial shortening, shortening in foot height, deformity severity, distraction osteogenesis (DO) treatment, refracture, increased femoral neck-shaft angle, tibiofemoral angle, and ankle valgus angle were investigated to identify potential contributors to FO. Patterns of FO were also determined. RESULTS At initial presentation, 11 patients exhibited a mean of 13 mm (10-23) of FO. However, the nature of FO changed over time during the follow-up period (mean, 10.8 years; range, 4.3-19.3). At the last follow-up, 14 patients presented with a mean of 12 mm (10-18) of FO. With the exception of one patient, all patients with FO presented with atrophic-type CPT. Frank pseudarthrosis, DO treatment, and increased femoral neck-shaft angle were significantly associated with FO (p = 0.016, p = 0.001, and p = 0.005, respectively). Diverse patterns of FO were observed. CONCLUSIONS FO of the affected limb is frequently encountered in patients with atrophic-type CPT. A compensatory response to frank pseudarthrosis, DO treatment, and neurofibromatosis may play a role in the diverse patterns of FO.