Hindfoot Fusion Nail - operative indications


The three main features to be considered when planning an ankle & subtalar fusion are :

1) Can you be sure both joints are involved in the arthritic process and are symptomatic? CT, and occasionally localising injection into a joint under question, is useful.

2) Deformity is frequently present in these cases, varus or valgus. It can be difficult clinically in severe deformity to determine at which level the deformity lies. Again a CT is a useful pre-operative measure. In the severe varus deformity it is not uncommon for the calcaneus to lie in relative valgus once the ankle is fully corrected. Factors causing this need to be addressed if a hindfoot fusion nail is to be used. The calcaneal valgus will otherwise prevent safe intraosseous placement of the guide pin. These factors are medial malleolar hypertrophy, resulting in lateral translation of the talus and underlying calcaneus. This is dealt with by adequate medial gutter excision. Also a co-existant valgus deformity of the subtalar joint may be unmasked once the ankle is corrected. This is dealt with by a lateral wedge bone block (from the excised fibula) or correction of the medial wall of the subtalar joint.

3) The position of the midfoot to the ankle/hindfoot is particularly important to note. In particular whether the Midfoot is fixed and might therefore be placed into a non weight bearing position after a successful corrective ankle/hindfoot fusion. In this scenario the Choparts joint may also need to be correctively fused.