Numerous techniques have been described for posttraumatic ankle arthritis with or without an associated lower extremity deformity in the adult population. These surgical procedures may include, but are not limited to, ankle exostectomy with joint resurfacing, ankle arthrodiastasis, ankle arthroplasty, and ankle arthrodesis. Associated deformities may also be addressed with supramalleolar osteotomies, tibia or fibular lengthening, and calcaneal osteotomies. In juvenile patients, surgical treatment options for posttraumatic ankle arthritis can be challenging, especially when an associated deformity is present. This article describes a combined supramalleolar osteotomy and ankle arthrodiastasis for a juvenile patient with posttraumatic ankle arthritis and valgus deformity.