Lindsey
Since ankle valgus is almost always a secondary deformity, there is no role for correction of only the ankle valgus. This correction should be part of a reconstruction of a whole problem, which usually includes the planovalgus foot, equinus ankle, and sometimes the external tibial torsion. Indications for correction are more than 10 degrees of ankle joint valgus relative to the long axis of the tibia. If the external tibial torsion is being corrected as well, no more than 5 degrees of valgus should be tolerated at the ankle joint. If more valgus is present on the postoperative radiograph, the cast should be wedged to correct the deformity. Recognizing the presence of the ankle valgus is important when correcting the hindfoot because it is important to avoid over correction of the hindfoot valgus. If no tibial derotation is required, then correction of the ankle valgus can usually be obtained with a screw epiphysiodesis of the medial malleolars if there is adequate growth remaining. The ankle has to be monitored with radiographs every four to six months, and when the valgus has corrected, the screw needs to be removed. For the individual with a closed growth plate, up to 15 degrees of valgus can be accepted if the foot is corrected close to a neutral position below the ankle. This residual ankle valgus causes the foot to fall into external rotation and valgus with increased dorsiflexion, but tends to be less of a problem in individuals who are dependent on orthotics for ankle stability. Having the ankle valgus corrected is more important in individuals who are high functioning community ambulators without orthotics or assistive devices. Lindsey, a 10- year-old girl with moderate diplegia, developed a significant internal tibial torsion that was cosmetically objectionable to her. She and her family desired this to be corrected with a tibial osteotomy. A percutaneous osteotomy was performed with the application of a short-leg cast and a proximal tibial pin. The x-ray in the operating room showed a significant valgus deformity of the ankle, Image 13-5.1 so the cast was wedged while she was still under anesthesia to get her ankle in neutral position. Image 13-5.2 In general, a little valgus is better than varus because the subtalar joint can better accommodate the valgus, however, significant valgus may place an external rotation valgus moment on the foot causing progressive valgus collapse of the foot. The goal should be to have 0 to 5 degrees of valgus at the ankle joint. If there is more than 10 degrees of valgus or more than 5 degrees of varus after the cast is applied the cast should usually be wedged and the angulation corrected. The technique for doing the wedge is to make two lines down the middle of the fragments to be aligned. This intersection point A Image 13-5.3 is the level at which the cast wedge is to be placed. The triangle B Image 13-5.3 defines the size of the angular correction that needs to be made.
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