Subtalar fusion is a surgical procedure designed to join two bones in the foot: the talus and the calcaneus. Also known as subtalar arthrodesis, this operation permanently eliminates motion within the subtalar joint. The surgery’s purpose is to alleviate pain and enhance stability in the hindfoot. It is considered when non-surgical treatments have not provided adequate relief for persistent symptoms.
Understanding the Subtalar Joint and When Fusion is Performed
The subtalar joint is located beneath the ankle joint, connecting the talus (ankle bone) and the calcaneus (heel bone). This joint allows the foot to move side-to-side, enabling inversion and eversion. These movements are important for walking on uneven surfaces, helping the foot adapt and maintain balance.
Subtalar fusion is considered when conditions severely affect the joint’s function and comfort. A common reason is severe arthritis, including post-traumatic arthritis, osteoarthritis, or inflammatory conditions like rheumatoid arthritis. These can lead to cartilage breakdown, causing painful bone-on-bone rubbing, stiffness, and loss of side-to-side motion.
Beyond arthritis, chronic instability or significant deformities of the hindfoot can also necessitate subtalar fusion. Surgery may be recommended when conservative treatments, such as medications, orthotics, bracing, physical therapy, or injections, have been exhausted without sufficient pain relief or functional improvement. The goal is to create a stable, fused bone unit to address persistent pain and functional limitations.
The Surgical Procedure
Subtalar fusion is performed as an inpatient or outpatient procedure, with many patients going home the same day. During surgery, an incision is made on the outer side of the foot to access the subtalar joint. The surgeon removes any damaged cartilage from the surfaces of the talus and calcaneus.
After cartilage removal, the bone surfaces are prepared and brought together. To ensure alignment and encourage growth, internal fixation devices, such as screws, are inserted. Bone grafting is also used to promote healing and fusion. This graft material (autograft or allograft) fills gaps and stimulates new bone growth, creating a single, solid bone.
Recovery and Rehabilitation
Following subtalar fusion surgery, the foot is immobilized to protect the fusion site, typically with a cast or specialized boot. Patients are advised to avoid putting weight on the operated foot for an initial period, ranging from 6 to 12 weeks. During this time, assistive devices like crutches or knee scooters are used for mobility.
As bones show signs of healing, a gradual progression to weight-bearing begins, often guided by a physical therapist. Fusion can take several months, with initial bone growth occurring in 8 to 12 weeks. Complete recovery, including return to normal activities, can take up to 6 to 12 months. Physical therapy helps regain strength, manage swelling, and improve mobility in surrounding joints, ensuring long-term function.
Potential Considerations and Expected Outcomes
As with any surgery, subtalar fusion has potential considerations. Non-union, where bones do not fuse, occurs in 10-15% of patients. Factors like smoking and diabetes can increase this risk. Other considerations include infection or nerve irritation, though these are less common.
Expected outcomes of subtalar fusion are pain relief and improved foot stability. By eliminating motion in the affected joint, the surgery provides a stable platform for walking and standing. While side-to-side motion is permanently reduced, most individuals find improved pain and stability greatly enhance function and quality of life. A high success rate, around 85%, is reported for improving patient symptoms.