Analysis of foot position in ankle arthrodesis and its influence on gait.

This study was carried out on 24 patients who underwent 25 ankle fusions. Twenty-four of 25 ankles operated upon by eight different surgeons achieved a solid fusion. A review showed that when the ankle was fused in a neutral position, the patient would, on the average, have 10 degrees of plantar flexion occurring in the midfoot. This motion allowed him to wear most normal foot gear. In gait, the plantar flexion in the foot approximated the plantar flexion in the normal ankle, giving little difficulty. In contrast, those individuals whose ankle was fused in 10 degrees of plantar flexion who also had 10 degrees of plantar motion in the midfoot and no dorsiflexion motion in the midfoot were, in effect, in 10 degrees of equinus. These patients showed a vaulting pattern while ambulating barefoot, but were usually able to accommodate this position while wearing shoes. The patient with a neutral position of the foot and ankle showed a very satisfactory gait in shoes and a much improved barefoot gait. It is concluded that fusion in a neutral position is indicated and that midtarsal motion occurs in the plantar direction but that no dorsiflexion is present in the midtarsal area.