Type 1

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Type 1 Tibial Hemimelia. © Paley Foundation 2017
These patients have intact stable knees and ankles. The proximal fibula is overgrown and may articulate with the side of the femur. The ankle joint is well formed and stable. There may be valgus malalignment in the tibia. If treated when the physes are open, the valgus can be corrected using hemi-epiphysiodesis. In adulthood, the valgus can only be treated by osteotomy.

If bilateral, the biggest complaint of these patients is mesomelid disproportion and short stature. If unilateral, there is a limb length discrepancy. In both cases, the treatment involves simultaneous deformity correction with lengthening either uni- or bilateral. The overgrown proximal fibula can either be pulled down to station with differential lengthening of the tibia relative to the fibula or left in place while lengthening both the tibia and fibula together the same amount. Pulling down the fibula risks creating a knee flexion contracture through tightening of the biceps tendon.