Posteromedial bowing spontaneously and markedly corrects in the first 6 months of life, with essentially normal tibial angulation noted by the age of 2 years. Surgical deformity correction is rarely needed and should not be considered until 3 to 4 years of age in those with severe residual bowing. Pseudarthrosis and increased fracture frequency are not associated with posteromedial bowing. The main orthopaedic concern tends to be limb-length discrepancy, typically ranging between 3 and 7 cm. Epiphysiodesis of the contralateral tibia is typically the mainstay treatment, but limb-lengthening procedures may also be considered in large (>5 cm) limb-length discrepancies.
ANTERIOR OR ANTEROLATERAL BOWING
Anterior or anterolateral bowing of the tibia, in association with congenital dysplasia, is highly associated with increased risk for fracture and pseudarthrosis and represents one of the most difficult and challenging treatment issues in orthopaedics. There is a high correlation of anterolateral tibial bowing and pseudarthrosis with neurofibromatosis type 1, with approximately half of all cases showing an association. Fibrous dysplasia also has a strong correlation with anterolateral bowing.
Prognosis and treatment is best guided by the presence or absence of fracture and by the age of the child at which the first fracture occurs. The bowing generally occurs in the mid-diaphysis, usually with concurrent fibular bowing. Radiographs should be carefully scrutinized for dysplastic changes in the tibia (widened medullary canal, thickened cortices, cystic or sclerotic changes, fibular pseudarthrosis, hourglass constriction) because those patients with anterolateral bowing in the setting of a nondysplastic tibia may be observed without prophylactic bracing, because the risk of fracture is markedly lower.
In the setting of dysplastic changes, the prognosis for tibial dysplasia with anterolateral bowing is very poor, with minimal chance for spontaneous fracture healing once a fracture has occurred. Prevention of fracture is a vital part of the treatment algorithm, with the mainstay of prophylactic treatment being orthotics. Bracing should be instituted as early as possible, with an ankle-foot orthosis (prior to walking) or a knee-ankle-foot orthosis (with weight bearing) being some examples. Bracing should be continued until skeletal maturity or until a fracture occurs. Once a fracture occurs, union with brace management is rarely successful.
Numerous surgical options for pseudarthrosis have been described. Intramedullary fixation is typically attempted early, although vascularized free grafts and external fixation with distraction osteogenesis are recent techniques that have been reported. New approaches are being developed using osteoinductive materials, such as bone morphogenetic protein. This remains an off-label use, with noted variability in union rates within small sample populations. Refracture, valgus malunion, and nonunion are major complications of pseudarthrosis with a high degree of prevalence, and amputation may be a final option that allows the patient to return to functional levels the quickest, utilizing new orthotic technology.
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