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

Giovanni Luigi Di Gennaro,Giovanni Trisolino,Giovanni Gallone,Leonardo Marchesini Reggiani,Edgar Alejandro Martinez Vazquez,Costantina Racano,Stefano Stilli,Eleonora Olivotto

doi:10.1186/s12891-020-03408-w

Giovanni Luigi Di Gennaro, Giovanni Trisolino + Show 6 more

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https://doi.org/10.1186/s12891-020-03408-w

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Abstract

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 5.5 ± 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.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° ± 4.2° 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.Conclusionsour 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 evidencelevel IV prognostic study.

Highlights

Congenital posteromedial bowing of the tibia (CPMBT) is a very rare birth defect, firstly fully described in 1949 by Heyman and Herndon [1]
Concerning the predictive model of spontaneous correction, we found that the best fitting curve was loglinear for the anteroposterior interphyseal angle (AP-IPA) and LLDcm, exponential for the lateral interphyseal angle (L-IPA) and linear for the limb length discrepancy (LLD)%
We found almost perfect correlation between AP-IPA and L-IPA, and substantial correlation between AP-IPA and LLD%. the lateral distal tibial angle (LDTA), measured at the latest follow-up, was 85.3° ± 4.2° and was correlated with the L-IPA (r = 0.5; p = 0.02)

Summary

Introduction

Congenital posteromedial bowing of the tibia (CPMBT) is a very rare birth defect, firstly fully described in 1949 by Heyman and Herndon [1]. It has been generally considered a benign, self-solving condition, in contrast to the anterolateral bowing, associated with congenital pseudarthrosis of the tibia, and the anteromedial bowing, associated with fibular hemimelia [2]. The cause of CPMBT remains unknown, a potential role of amniotic strains has been hypothesized [6] This condition is generally unilateral and not associated with other abnormalities [1, 7]. Several therapeutic options have been proposed for the management of CPMBT, but the treatment of choice remains controversial

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