CPT code 28725 – Subtalar joint arthrodesis

Key takeaways

CPT code 28725 covers fusion of the subtalar joint only, so fusing any adjacent joint at the same session calls for a different code.

The 2026 national unadjusted Medicare payment is about $729.14, from 21.83 total RVUs in both facility and non-facility settings.

A 90-day global period applies, and separately billing included services such as fixation or routine imaging triggers bundling denials.

RT or LT modifiers report laterality, and modifier 58 covers a staged procedure planned at the original operative session.

Pabau’s claims management software submits 28725 claims electronically with built-in CPT and ICD-10 catalogs.

CPT code 28725: Definition and official descriptor

CPT code 28725 is the procedure code for arthrodesis, or surgical fusion, of the subtalar joint. The American Medical Association’s CPT code set gives it the official descriptor “Arthrodesis, subtalar.”

The subtalar joint (also called the talocalcaneal joint) forms where the underside of the talus meets the upper surface of the calcaneus. It controls inversion and eversion of the hindfoot.

Surgeons perform subtalar arthrodesis after conservative management has failed for conditions such as:

• Post-traumatic subtalar arthritis
• Primary osteoarthritis of the subtalar joint
• Posterior tibial tendon dysfunction with hindfoot collapse
• Rigid flatfoot deformity

The code belongs to the foot arthrodesis family (28705-28760), and every code in it carries a 90-day global period. The family runs from pantalar arthrodesis at 28705 to the Jones-type great toe fusion at 28760.

Picking the wrong code within this family is a common reason hindfoot fusion claims are downcoded or denied. Our procedure codes library covers the other musculoskeletal surgery codes you may need alongside it.

What the procedure includes and excludes

Knowing what’s bundled into CPT code 28725 prevents the most frequent unbundling denials.

Coders must confirm that the operative report shows the subtalar joint as the sole fused joint before assigning 28725.

How the surgery is performed and documented

Payer scrutiny of CPT code 28725 focuses almost entirely on the operative report. The report must show that only the subtalar joint was fused, and document the approach, fixation method and graft material used.

Key operative documentation elements payers require:

• Surgical approach: Name the posterior, lateral (sinus tarsi) or extensile lateral approach. The approach determines access to the joint and corroborates the documented anatomy.
• Joint surface preparation: The operative note must describe removal of articular cartilage and subchondral decortication of both the talar and calcaneal surfaces. That shows the joint was prepared for fusion.
• Fixation method and hardware: Record the number, size and direction of screws or staples. This confirms internal fixation is already captured in 28725 and is not coded separately.
• Graft material: Identify whether allograft, autograft (and harvest site) or bone substitute was used. If autograft was harvested through a separate incision, document the distinct site explicitly.
• Joint(s) addressed: Confirm the report states “subtalar joint” as the only fused articulation. Any mention of calcaneocuboid, talonavicular or midtarsal involvement requires code review.
• Laterality: Document the right or left foot to support the RT or LT modifier.

Payers increasingly use automated claim edits to flag operative reports where the approach described does not match the code billed. A lateral sinus tarsi approach note paired with a claim for a more extensive code is a common trigger for medical record requests.

CPT 28725 reimbursement: Medicare rates and RVUs

Medicare pays CPT code 28725 from its relative value unit (RVU) total, multiplied by the annual conversion factor. The geographic practice cost index (GPCI) then adjusts it for your locality. For 2026, the national unadjusted payment is about $729.14.

Rates change each January when the Centers for Medicare and Medicaid Services (CMS) publishes the updated Physician Fee Schedule. The table below shows the 2026 national unadjusted values. Confirm your locality’s rate with the CMS lookup or the FastRVU lookup tool before billing.

Most subtalar arthrodesis procedures take place in a hospital or ambulatory surgical center (ASC), and the facility bills its own institutional rate separately. Because 28725 carries the same practice expense RVU in both settings, the RVU total is identical. Only the GPCI and the conversion factor change the physician’s payment.

Modifiers for CPT code 28725

Modifier selection errors are the second most common denial trigger on CPT code 28725 claims. The table below covers the modifiers coders apply most often.

Bilateral subtalar arthrodesis at the same sitting is unusual. When it happens, bill 28725 twice with RT and LT, or apply modifier 50 if the payer accepts it in place of separate lines. Verify the payer’s bilateral billing preference before submission.

ICD-10 diagnosis codes that support 28725

Medical necessity for CPT code 28725 must be established through a supporting ICD-10-CM diagnosis code. A mismatch between the procedure and the diagnosis is one of the top denial triggers. These are the primary codes used to justify subtalar arthrodesis, in line with billing compliance requirements for surgical procedures.

Every ICD-10 code on the claim must reflect the physician’s documented diagnosis and align with the operative findings. Don’t assign a diagnosis code just because it appears on an “accepted” list, since the medical record must support it. For post-traumatic cases, payers frequently cross-reference prior claims to confirm the mechanism of injury.

CPT 28725 vs 28715 vs 28730 vs 28740 vs 28705: Choosing the right code

Selecting the wrong code within the foot arthrodesis family is the most consequential coding error on these cases. Each code maps to a distinct set of joints, and payers use operative notes to verify that the billed code matches what was performed.

The decision rule is simple. Count the joints the operative note says were fused, then pick the code whose scope covers exactly those joints. The diagram below maps each combination to its code, and when the note is unclear, query the surgeon before filing.

Prior authorization and payer requirements

Most commercial payers and Medicare Advantage plans require prior authorization for CPT code 28725. They treat subtalar arthrodesis as a non-emergent elective procedure, so approval has to be in place before the surgery date.

Documentation payers typically require before authorizing 28725:

• Failed conservative treatment: At least three to six months of documented conservative care, naming the modalities tried (physical therapy, custom orthotics, corticosteroid injections, activity modification). Duration requirements vary by payer, and some require a minimum of six months. Document start and end dates, provider names and patient response.
• Imaging evidence: Weight-bearing radiographs showing joint space narrowing, subchondral sclerosis or deformity at the subtalar joint. Some payers also require CT or MRI to rule out coalition or assess bone quality.
• Functional limitation documentation: Office notes quantifying ambulation impairment, pain scores and impact on activities of daily living. Generic “pain in foot” documentation is insufficient.
• Prior procedure records: If the patient has had prior foot or ankle surgery, the payer needs that operative report. It shows whether a 90-day global period is still active.

Traditional Medicare (Parts A and B) does not require prior authorization for most elective foot surgeries, but Medicare Advantage plans follow their own policies. Blue Cross, Aetna, Cigna and UnitedHealthcare all maintain arthrodesis-specific medical policies. Review them once a year as part of your pre-authorization workflow.

Common claim denials for CPT 28725 and how to avoid them

Denial patterns on CPT code 28725 are predictable. A sound denial management workflow addresses most of them before a claim reaches the payer.

For appeals, the strongest package combines the operative report, the surgeon’s clinical summary letter and relevant imaging reports. Add the payer’s LCD or medical policy language that supports the claim. Getting a clean claim out on the first attempt avoids 60- to 90-day resubmission cycles that cut into practice cash flow.

Practices that route 28725 and related foot surgical claims through a superbill documentation workflow before submission catch diagnosis-procedure mismatches at the point of coding. That beats finding them after the denial letter arrives.

How claims management software keeps CPT 28725 claims clean

Most practices billing hindfoot fusions still check the operative report by hand, then rekey the code, modifier and diagnosis into a clearinghouse portal. Every handoff is a chance for a missing RT modifier or a 28715 that should have been 28725.

Pabau’s claims management software builds the claim from the invoice your team already raises, with CPT and ICD-10 catalogs built in. Through Claim.MD, Pabau’s US clearinghouse partner, you can run a real-time eligibility check before the procedure date and submit the claim electronically as a CMS-1500.

Claim statuses and electronic remittance advice come back into Pabau. Your billing team can see which 28725 claims are paid, pending or denied without logging into a second system.

See how Pabau handles foot surgical billing

Pabau integrates with Claim.MD to submit CPT 28725 and related arthrodesis claims electronically to thousands of US payers. Real-time eligibility checks and ERA remittance tracking are built in.

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Conclusion

CPT code 28725 is a narrow code, and the operative report decides whether it applies. If the note names one fused joint, bill 28725 with the matching laterality modifier and an arthritis or deformity diagnosis for the same side.

If the note is vague about which joints were fused, query the surgeon before you file rather than picking the higher-paying code. A day spent on that query costs far less than a 60-day denial cycle or a recoupment after an upcoding audit.

Pabau’s Claim.MD clearinghouse integration submits CMS-1500 claims directly to thousands of US payers, with built-in CPT and ICD-10 catalogs. Book a demo to see how Pabau takes foot surgical claims from eligibility check to ERA remittance.

Continue your research

Need to verify clean claim requirements before filing? Clean claim submission guidelines covers what payers check before adjudicating surgical claims.

Managing denials across your foot and ankle caseload? Denial codes in medical billing explains the most common CARC denial reasons and how to respond.

Want to understand the broader revenue cycle behind surgical billing? Revenue cycle management walks through the end-to-end claim lifecycle from eligibility to payment posting.

Billing a great toe fusion as well? CPT code 28760 covers Jones-type arthrodesis, the last code in the foot arthrodesis family.

Frequently asked questions