An ankle arthrodesis is placed in 0-5 degrees valgus because it ______.

• A. Allows for greater motion of the foot
• B. Reduces chance of scarring
• C. Improves ankle dorsiflexion
• D. Reduces hindfoot valgus

Answer: (A)

Positioning the ankle fusion in a small degree of valgus is chosen because it helps keep the hindfoot aligned in a balanced, plantigrade position during weight-bearing after the joint is fused. With the tibiotalar joint immobilized, the hindfoot and midfoot must absorb and adapt to function together; a slight valgus alignment of the fusion offsets the natural tendency toward hindfoot malalignment and promotes more favorable subtalar and hindfoot mechanics. This is distinct from believing the fusion would increase motion or improve dorsiflexion, which isn’t the case since the ankle joint is fused and loses motion. Scarring isn’t driven by the alignment angle, so it isn’t the purpose of placing the fusion in mild valgus.