Subtalar Arthrodesis: Fusion Surgery for Subtalar Joint Arthritis and Flatfoot

Medically reviewed by Dr. Tom Biernacki, DPM — Board-Certified Podiatric Surgeon — Balance Foot & Ankle, Howell & Bloomfield Hills, MI. Last updated April 2026.

When Subtalar Fusion Is Needed

The subtalar (talocalcaneal) joint controls inversion and eversion — the side-to-side tilting that allows the foot to adapt to uneven surfaces. When this joint develops severe arthritis, every step on irregular ground produces sharp hindfoot pain. Post-traumatic arthritis after calcaneal fractures is the most common indication, followed by adult-acquired flatfoot deformity (AAFD) and tarsal coalition.

Calcaneal fractures that extend into the posterior facet of the subtalar joint damage the articular cartilage at the time of injury. Even with anatomic surgical reduction, 30-50% of patients develop symptomatic subtalar arthritis within 5-10 years. In our clinic, subtalar fusion after calcaneal fracture malunion is one of our most frequently performed hindfoot procedures.

Stage III posterior tibial tendon dysfunction (PTTD) with rigid hindfoot valgus deformity is the other major indication. When the flatfoot deformity becomes fixed and cannot be corrected with stretching or manipulation, the subtalar joint must be fused in a corrected position to realign the hindfoot and restore a functional arch.

Pre-Operative Planning and Assessment

Weight-bearing CT (WBCT) is the gold standard for subtalar arthritis evaluation. It reveals the exact pattern of cartilage loss, subchondral cyst formation, and bone quality — all critical for surgical planning. Standard X-rays underestimate subtalar pathology because the joint is oblique to standard radiographic projections.

Adjacent joint assessment is essential. If the ankle joint or talonavicular joint also shows significant arthritis, the surgical plan may need to expand to include those joints (double or triple arthrodesis). Fusing the subtalar joint alone when adjacent joints are arthritic simply transfers stress and accelerates degeneration in those joints.

Hindfoot alignment measurement determines whether the fusion can be performed in situ or requires correction. Varus or valgus deformity must be corrected during the fusion to achieve a plantigrade foot. The goal is 5-7 degrees of hindfoot valgus — the normal physiological alignment that distributes weight optimally.

Surgical Technique

The sinus tarsi approach provides direct visualization of the posterior facet through a lateral incision just below and anterior to the lateral malleolus. The remaining articular cartilage is removed with curettes and osteotomes, the subchondral bone is fenestrated to promote bleeding, and the joint surfaces are apposed in the corrected alignment.

Fixation uses two large-fragment (6.5-7.3mm) partially threaded cannulated screws inserted from the posterior calcaneal tuberosity into the talar body. The screws provide compression across the fusion site, which is critical for bone healing. Some surgeons add a third screw or a lateral plate for additional rotational stability.

Bone grafting — either autograft from the ipsilateral calcaneus or proximal tibia, or allograft cancellous chips — fills any defects and supplements the fusion site biology. For subtalar distraction arthrodesis (when the calcaneus has lost height from a malunited fracture), a structural bone block graft is interposed to restore hindfoot height and alignment.

For flatfoot reconstruction, the subtalar fusion is often combined with additional procedures: medializing calcaneal osteotomy, spring ligament repair, flexor digitorum longus (FDL) tendon transfer, and possibly lateral column lengthening. The combination addresses all components of the deformity simultaneously.

Recovery After Subtalar Fusion

Non-weight-bearing in a short leg cast for 8-10 weeks is standard. The subtalar joint heals more slowly than many other foot fusions due to the large cancellous surface area and variable blood supply. Serial X-rays at 6, 8, and 10 weeks monitor progressive bone bridging across the fusion site.

Protected weight-bearing in a CAM boot begins when X-rays show early union — typically at 8-10 weeks. Full weight-bearing without support transitions at 12-14 weeks. CT scan at 3-4 months definitively confirms solid fusion before releasing the patient to unrestricted activity.

Custom orthotics are fabricated once the patient transitions to regular shoes. Since the fused subtalar joint cannot adapt to terrain, the orthotic must provide the accommodative function that the joint formerly served. Most patients adapt remarkably well to the loss of subtalar motion — walking on flat surfaces is essentially normal, and only aggressive uneven terrain feels different.

In-Office Treatment at Balance Foot & Ankle

Dr. Tom Biernacki performs subtalar arthrodesis as a standalone procedure and as part of comprehensive flatfoot reconstruction. Our approach includes WBCT-guided surgical planning, anatomic fixation, and structured rehabilitation to maximize fusion rates and functional outcomes.

Same-day appointments available. Call (810) 206-1402 or visit michiganfootdoctors.com/new-patient-information/.

The Most Common Mistake We See

The most common mistake we see is delaying subtalar fusion because patients fear losing motion. By the time the joint is arthritic enough to warrant fusion, most patients have already unconsciously eliminated subtalar motion because it hurts. The fusion eliminates pain from a joint that was no longer functional — and the functional loss is minimal for most activities.

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In-Office Treatment at Balance Foot & Ankle

Our team provides sport-specific evaluation and treatment to get you back to your activity safely. We offer same-day X-ray, in-office ultrasound, and custom orthotic fabrication.

Same-day appointments available. Call (810) 206-1402 or book online.

Frequently Asked Questions

How long is recovery from subtalar fusion?

Non-weight-bearing for 8-10 weeks, protected weight-bearing in a boot at 8-10 weeks, full weight-bearing at 12-14 weeks, and return to regular shoes with custom orthotics at 3-4 months. Full recovery takes 6-9 months.

Will I walk normally after subtalar fusion?

Most patients walk with a normal-appearing gait on flat surfaces after subtalar fusion. The loss of inversion/eversion is compensated by ankle, midfoot, and knee motion. Only walking on very uneven terrain feels noticeably different.

What is the fusion rate for subtalar arthrodesis?

Subtalar fusion rates are 85-95% with modern technique and fixation. Risk factors for nonunion include smoking, diabetes, and inadequate fixation. Smoking cessation is strongly recommended before surgery.

Can I run after subtalar fusion?

Light jogging on even surfaces is possible for many patients after solid fusion. High-impact running on trails or uneven terrain is more challenging. Most active patients can cycle, swim, and walk long distances without limitation.

The Bottom Line

Subtalar fusion eliminates the pain of end-stage subtalar arthritis while preserving a functional foot for daily activity. If your hindfoot hurts with every step despite conservative treatment, fusion provides a reliable path to a pain-free, stable platform for walking.

Sources

1. Rammelt S, et al. Subtalar arthrodesis after calcaneal fracture: systematic review. Foot Ankle Int. 2024;45(7):723-735.
2. Hintermann B, et al. Outcomes of subtalar fusion for PTTD stage III. J Bone Joint Surg Am. 2023;105(15):1189-1197.
3. DeCarbo WT, et al. Subtalar joint fusion rates: screw fixation outcomes. Foot Ankle Spec. 2024;17(2):134-140.

Subtalar Fusion Surgery in Michigan

Subtalar arthrodesis (fusion) eliminates pain from severe arthritis or deformity in the subtalar joint while preserving ankle motion. Board-certified podiatric surgeon Dr. Tom Biernacki performs subtalar fusion at Balance Foot & Ankle for patients with post-traumatic arthritis, flatfoot deformity, and coalition.

Learn About Our Joint Fusion Surgery Options | Book Your Appointment | Call (810) 206-1402

Clinical References

1. Easley ME, et al. Isolated subtalar arthrodesis. Journal of Bone and Joint Surgery. 2000;82(5):613-624.
2. Flemister AS, et al. Subtalar arthrodesis for adults and children: a surgical technique. Foot & Ankle International. 2000;21(7):578-583.
3. Mann RA, et al. Isolated subtalar arthrodesis. Foot & Ankle International. 1998;19(8):511-519.