Lengthening in congenital posteromedial bowing of tibia: a follow-up series at skeletal maturity.

PURPOSE: Congenital posteromedial bowing (CPMB) of tibia is a rare, usually self-resolving condition that is present at birth. The data on the long-term outcome of lengthening, choice of fixator, outcome in early and late age groups, and complications is sparse, hence the need for this study.

METHODS: This retrospective study included 93 patients with 94 affected legs from 1991 to 2023. The patients were categorized into early (under 10 years) and late (10 years or above) intervention groups. Eighteen patients with nineteen lengthening episodes who attained skeletal maturity made the basis of this study and will be discussed in detail.

RESULTS: The outcome for the lengthening group at maturity was satisfactory, with 5.53 cm of average length gained per lengthening episode, a mean LLD of 0.31 cm at final follow-up, a mean age of 23.63 years (range 14-38 years), and an average follow-up of 12.51 years (range 3-28 years) post-lengthening, but the procedure was associated with difficulties like ankle stiffness, tibial valgus, pin tract infections, and fractures through regenerate.

CONCLUSION: This study represents a large single-centre series on CPMB. We recommend that surgery for lengthening should be done at an older age, close to skeletal maturity, wherever possible to reduce the risk of repeat lengthening procedures. Based on our experience, we recommend the use of a circular fixator. Uniplanar distractors should have an adequate number and spread of Schanz screws in each segment to reduce the risk of valgus malalignment of distracting segments of bone.