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

Backgroundcongenital posteromedial bowing of tibia (CPMBT) is a very rare birth defect, characterized by shortened bowed leg and ankle deformity. We described a single institution experience in the management of CPMBT.Methodswe identified 44 CPMBT in 44 children. The age at presentation was 5.55.6years and the mean age at the final review was 10.14.8years. 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.Resultsthe 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 85.3 degrees 4.2 degrees and was correlated with the L-IPA (r=0.5; p=0.02). Among the 26 children who 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 correct ankle valgus deformity.Conclusions our study described the largest case series of CPMBT. A combination of surgical treatments, in a staged surgical process, should be tailored to the developmental characteristics of this abnormality. An experience-based algorithm of treatment is also proposed. Further studies are needed to understand which is the best strategy to correct this deformity during childhood.Level of evidence level IV prognostic study.