Subtalar fusion (arthrodesis) is an operation to permanently join the talus and calcaneus bones beneath the ankle, eliminating the painful subtalar joint. It is performed for severe subtalar arthritis, commonly following a calcaneal fracture or inflammatory arthritis.
An incision is made on the outer side of the hindfoot. The remaining cartilage is removed from the subtalar joint surfaces. The bones are positioned in the optimal alignment and fixed with screws. Bone graft may be used. The operation takes one to one and a half hours.
Subtalar fusion is recommended for severe subtalar arthritis causing pain with walking on uneven ground, post-traumatic arthritis (particularly after calcaneal fractures), inflammatory arthritis, and certain congenital or acquired foot deformities.
Supportive footwear, orthotics, ankle-foot orthosis, corticosteroid injection into the subtalar joint, pain medication, and activity modification.
CT scan for planning. Smoking cessation is critical for bone healing.
Good pain relief in over 85% of patients. The subtalar joint no longer moves, but the ankle joint and midfoot joints compensate partially. Walking on flat ground is usually comfortable; walking on uneven terrain requires more adaptation.
Expected — this is the purpose of the operation. Foot adaptability on uneven ground is reduced.
Prolonged foot swelling.
Subtle changes in walking pattern.
Failure to fuse. Risk approximately 5–10%. Significantly higher in smokers.
Numbness on the outer side of the foot.
Increased stress on the ankle and midfoot joints over time.
Wound or deep infection.
Particularly in patients with prior surgery or poor blood supply.
General or spinal anaesthesia with ankle block.
Non-weight-bearing in a cast for six to eight weeks. Weight-bearing in a boot for a further four to six weeks. Physiotherapy for ankle strengthening. Full recovery takes six to nine months.
Regular X-rays at six weeks and three months to monitor fusion progress.
Most patients walk comfortably on flat ground. Walking on uneven surfaces, hills, and slopes requires more adaptation.
Low-impact jogging may be possible for some patients. High-impact running is generally not recommended.