Evolution of the angular deformity and limb length discrepancy of congenital posteromedial bowing of the tibia over time

Abstract

This study aims to assess the natural history of congenital posteromedial bowing of the tibia (CPMBT) deformity during growth and to evaluate the outcomes of lengthening by an Ilizarov frame in CPMBT patients with limb length discrepancy (LLD). Between January 2000 and December 2019, a total of 22 patients (12 males, 10 females; mean age: 10.5±4.4 years; range, 6 to 19 years) with the diagnosis of CPMBT and followed closely from birth until skeletal maturity were retrospectively analyzed. The radiographic evaluation included the anteroposterior and lateral interphyseal angle and full leg standing radiographs. Limb lengthening by an Ilizarov frame was performed for an estimated LLD over 40 mm. The age of the patients ranged from six days to 10 months at the time of presentation, while the mean age at the final follow-up was 10.5±4.4 years. Posterior medial bowing was satisfactorily remodeled in 13 (59%) patients those were not operated either for deformity or LLD. The mean LLD was 21±4.1 mm in 13 nonoperated CPMBT patients. Nine of 22 (41%) patients underwent lengthening for LLD. Five of the nine CPMBT patients were operated under the age of 10 years, while four were operated over the age of 10 years. According to the results of the current study, CPMBT was satisfactorily remodeled in more than half of the patients, and the majority of patients did not undergo surgery for angular deformity and LLD within 10 years of their lives. Based on these findings, although most of the patients' deformities remodeled, it should be kept in mind that some may require lengthening surgery.