Deformity progression in congenital posteromedial bowing of the tibia: a report of 44 cases.

Abstract Background Congenital posteromedial bowing of the tibia (CPMBT) is an ultra-rare defect present at birth, characterized by shortened bowed leg, and ankle deformity. We described a single institution experience in the management of CPMBT Methods We identified 44 CPMBT in 44 children. The age at presentation was 5.5 ± 5.6 years and the mean age at the final review was 10.1 ± 4.8 years. Radiographic evaluation included the antero-posterior and lateral inter-physeal angle (AP-IPA and L-IPA), the limb length discrepancy (LLD), the morphology of the distal tibia and the lateral distal tibial angle (LDTA). During the study period, 26 children underwent surgical treatment. Results The estimated curves showed a progressive spontaneous correction of both AP-IPA and L-IPA during growth, but a progressive increase of the LLD. The L-IPA showed a more predictable behaviour while the AP-IPA showed a scattered correction, with a wider variation of the estimated final angle. The final LDTA was 83.4° ± 5.2° and was correlated with the L-IPA. Among the 26 children which underwent surgical treatment, 23 cases had limb lengthening, 1 case had contralateral epiphysiodesis, 1 child underwent tibial osteotomy, 1 patient was treated by hemiepiphysiodesis of the distal tibia to address ankle valgus deformity. Conclusions To date, we reported the largest case series of CPMBT. Nevertheless, further studies are needed to understand which is the best strategy to address this ultra-rare deformity during childhood.