Position of Fusion: Subtalar Fusion
- traditionally, subtalar arthrodesis has been performed w/ ankle in neutral dorsiflexion / plantarflexion & neutral or slight valgus;
- by placing calcaneus in 5 degrees of valgus, transverse tarsal joint remains supple and provides mobility to the forefoot;
- in presence of fixed forefoot equinus, however, which often occurs following trauma, subtalar fusion may need to be placed in relative dorsiflexion to accommodate for the forefoot position;
- fusion in slight plantarflexion is necessary only in the presence of quadriceps weakness;
- it never should be done to accommodate for heel ht in female pts;
- Excessive Varus:
- if subtalar joint is placed into varus, transverse tarsal joint is locked & forefoot is rigid, resulting in vaulting type of gait;
- any degree of varus is poorly tolerated and excessive varus can lead to painful callosities under 5th MT head;
- Excessive Valgus:
- excessive hindfoot valgus will cause too much pronation in forefoot and may lead to calcaneo-fibular impingement;
- most common problem following fusion of subtalar joint w/ excessive pronation is hallux valgus deformity;
- patient may develop stress along medial side of ankle or knee joint.
- patient also may note arch pain
Original Text by Clifford R. Wheeless, III, MD.
Last updated by Data Trace Staff on Tuesday, September 4, 2012 3:47 pm