What’s the Diagnosis – Case 128
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What’s the Diagnosis – Case 128
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Findings At birth there is deformity of both the left tibia and fibula where there is a bowing deformity. The apex of the bowing is directed posterior and medially. Over the time interval, there is marked degree of remodeling with the bowing almost completely resolved (without any intervention) but with a limb length discrepancy precipitated.
What’s the Diagnosis – Case 128
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What’s the Diagnosis – Case 128
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Diagnosis: Congenital Posteromedial Tibial Bowing Tibial bowing can be related to many underlying etiologies. The key is to recognize the direction of the apex of the bow which is how the bowing is described. Posteromedial bowing is a congenital codition, thought to be related to intrauterine positioning or a packing abnormality. It can be seen with another packing abnormality of a calcaneovalgus foot but can occur in isolation. Posteromedial bowing is considered benign because although it does frequently yield a limb length discrepancy as in this case, the bowing resolves and the overall course is much less difficult than the other causes of bowing. Anterolateral bowing is seen in congenital pseudoarthrosis either alone or in the setting of neurofibromatosis. This process is notoriously difficult to treat. Anteromedial bowing is seen in the setting of fibular hemimelia which is then associated with many other orthopedic abnormalities. Anterior bowing can be seen in a very rare syndrome called Weissman Netter syndrome or in the setting of some congenital infections or metabolic disorders such as rickets. As in this case there is frequently a marked decrease in the bowing in the first year and them a limited degree of remodeling after 4-5 years. As the proportionate difference of leg lengths remains stable through growth accurate estimates can be made to the final limb length discrepancy. Surgery is frequently performed if and when limb length discrepancies reach 2-5cm.
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References Limb lengthening in congenital posteromedial bow of the tibia. S. D. Kaufman, J. A. Fagg, S. Jones, M. J. Bell, M. Saleh, and J. A. Fernandes. Strategies Trauma Limb Reconstr. 2012 Nov; 7(3): 147–153. Posteromedial bowing of the tibia: a benign condition or a case for limb reconstruction? Wright J, Hill RA, Eastwood DM, Hashemi-Nejad A, Calder P, Tennant S. J Child Orthop. 2018 Apr 1;12(2):187-196. doi: 10.1302/18632548.12.170211. Special thanks to Roger Widmann, MD for his assistance in the understanding of this process.
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