CPT code 28110 – Bunionette ostectomy of the fifth metatarsal head

Key takeaways

CPT code 28110 describes partial excision of the fifth metatarsal head to correct a bunionette (tailor bunion), separate from first-ray bunionectomy codes.

Pair it with ICD-10-CM M21.621 (right foot) or M21.622 (left foot), because unspecified M21.629 raises audit risk.

The Medicare global surgery period for 28110 is 90 days, so unrelated post-op visits need modifier 24 or 79.

In 2026, Medicare pays about $467 for 28110 in a non-facility setting and about $282 in a facility.

Pabau’s claims management software keeps a claim from sending until details like authorization codes are in place.

CPT code 28110: Official descriptor and procedure overview

CPT code 28110 is defined by the American Medical Association (AMA) as Ostectomy, partial excision, fifth metatarsal head (bunionette) (separate procedure). The code describes this fifth metatarsal head resection directly, so it applies only to bunionette surgery on the fifth ray.

The “(separate procedure)” label matters at billing time. It means 28110 is reported on its own only when it isn’t an integral part of a larger procedure at the same site. When it is distinct from another procedure on the same foot, modifier 59 or XS tells the payer why.

A bunionette (tailor bunion) is an enlargement of the lateral prominence of the fifth metatarsal head, causing pain, skin irritation, and difficulty fitting footwear. Surgical correction removes the bony prominence through a partial ostectomy or exostectomy. The code sits in the CPT musculoskeletal surgery section, under foot and toes (28001-28899).

Key code facts

• Full descriptor: Ostectomy, partial excision, fifth metatarsal head (bunionette) (separate procedure)
• Code range: Musculoskeletal system surgery, foot and toes (28001-28899)
• Procedure type: Major surgery with a 90-day global period
• Laterality modifiers required: RT (right) / LT (left)
• Bilateral reporting: Modifier 50 or two line items with RT/LT

Procedure description: What happens during a bunionette ostectomy

The operative report is the coder’s main source for justifying CPT code 28110. Most bunionette ostectomy notes follow the same five steps.

1. Incision: A lateral or dorsolateral incision over the fifth metatarsal head exposes the bony prominence.
2. Periosteal dissection: Soft tissue is reflected to expose the fifth metatarsal head fully.
3. Ostectomy: The surgeon resects the lateral prominence using an osteotome or sagittal saw. The extent of resection depends on the deformity severity.
4. Wound irrigation and hemostasis: The surgical site is irrigated and bleeding controlled.
5. Closure: Layered closure of the periosteum, subcutaneous tissue, and skin is documented.

Phrases such as “lateral eminence resection,” “fifth metatarsal head exostectomy,” and “bunionette correction via ostectomy” point to 28110. Language describing a metatarsal shaft osteotomy or bone cuts through the neck of the fifth metatarsal instead signals CPT 28308, not 28110.

CPT 28110 vs adjacent codes: Choosing the right code

Coders often mix up 28110 with 28122, 28308 and 28285. In each case, the deciding factor is what the operative report says the surgeon did to the bone. Use this table when the op note is ambiguous.

Check the AAPC CPT code lookup when you compare adjacent foot surgery codes during a pre-bill audit. If the surgeon cut through the metatarsal shaft or neck (an osteotomy) instead of removing the surface prominence, 28308 is correct, not 28110. The decision path below follows the order a coder reads the op note in.

ICD-10-CM codes that support CPT code 28110 claims

Every CPT code 28110 claim needs laterality. Reporting M21.629 (unspecified foot) when the op note names the foot is a documentation error. It invites audits and can draw a medical necessity denial from payers that require site specificity. Use the CrossCoder CPT-to-diagnosis crosswalk to check ICD-10 pairings against local coverage determinations (LCDs) before billing.

Modifiers for CPT code 28110

Modifier selection for CPT code 28110 affects both reimbursement and audit exposure. The four modifiers coders encounter most often on bunionette claims are listed below.

Billing both feet in one session

Yes, CPT 28110 can be billed bilaterally when the surgeon operates on both fifth metatarsal heads at the same session. Under Medicare, report one line of 28110-50, paid at 150% of the single-procedure allowable. Several commercial payers, however, require two separate line items (28110-RT and 28110-LT) rather than modifier 50. Always verify the payer’s bilateral billing preference in the provider manual or by calling the payer before submitting.

Medicare reimbursement and RVU data for CPT code 28110

Medicare payment for CPT code 28110 comes from the Medicare Physician Fee Schedule (MPFS). The figures below are 2026 national rates at the $33.4009 conversion factor, before geographic adjustment. Check current-year rates in the CMS MPFS Look-Up Tool, because they change with each annual update.

Use the FastRVU 2026 lookup tool to verify current wRVU values and apply geographic practice cost index (GPCI) adjustments for your locality. Work and malpractice RVUs are the same in both settings, so practice expense drives the whole $185 difference. Facility rates apply when the procedure is performed in a hospital or ASC; non-facility rates apply in a physician office setting.

The 90-day global surgery period

CPT code 28110 carries a 90-day global surgery period under the Medicare Physician Fee Schedule, classifying it as major surgery. Confirm the global period in the CMS MPFS database before submitting claims, since assignments can change with annual updates. Flag the surgery date on each superbill so staff can see which follow-up visits fall inside the global window.

During the 90-day global period, the following are bundled and cannot be billed separately:

• Pre-operative visits on the day before or day of surgery
• Intraoperative services integral to the procedure
• Complications managed without a return to the operating room
• Routine post-operative visits related to the bunionette ostectomy

Post-operative visits that CAN be billed separately require modifier 24 (unrelated E/M during global period) or modifier 79 (unrelated procedure during global period). A separate, unrelated diagnosis driving the visit is required to support the modifier.

Prior authorization and medical necessity for CPT 28110

Most payers require prior authorization for CPT code 28110. A documented prior authorization process helps front-desk staff gather the evidence before the patient reaches the OR. Requirements vary by payer and plan year, so verify them with the payer before scheduling surgery.

Common pre-authorization requirements for 28110:

• Conservative treatment documentation: Payers typically want 3-6 months of failed conservative care in the clinical notes before they authorize surgery. That includes accommodative footwear, padding, orthotics, or physical therapy.
• Radiographic evidence: Weight-bearing X-rays of the affected foot confirming the bunionette deformity. Most LCDs require imaging to document the structural abnormality.
• Symptom duration: Persistent pain and functional impairment documented across multiple office visits, not a single acute complaint.
• Functional impairment: Documentation that the deformity limits activities of daily living or causes chronic pain despite conservative management.

Medicare coverage for 28110 follows the LCDs your Medicare administrative contractor (MAC) publishes for podiatric surgery. LCDs differ by jurisdiction (CGS, Noridian, Palmetto, WPS, Novitas), so confirm which MAC administers claims for your practice location before advising patients on expected coverage.

What the operative report must document

Auditors start with the operative report on a CPT code 28110 claim. A clean claim for 28110 depends on the op note establishing three elements: Site, technique, and pre-operative diagnosis. Auditors from Medicare and commercial payers specifically look for these when reviewing 28110 claims.

• Surgical site specificity: The note must state which metatarsal head (fifth) was operated on and which foot (right or left). Ambiguous site language (“bunion correction performed”) is insufficient.
• Technique description: Describe the resection technique (osteotome, sagittal saw), extent of bone removed, and any fixation applied. “Lateral eminence resected” is better than “bunionette corrected.”
• Pre-operative diagnosis: The diagnosis in the op note must map to the ICD-10-CM code on the claim (M21.621 or M21.622). A mismatch between the chart diagnosis and the claim diagnosis is a primary denial trigger.
• Conservative treatment failure: A brief reference to failed conservative care in the pre-operative note strengthens medical necessity. It helps even when prior authorization is already approved.
• Dictation timing: Op notes should be dictated and authenticated within 24 hours of surgery per most hospital bylaws; late dictation raises audit flags.

Notes written to this standard protect the practice against post-payment audits and recoupment demands.

NCCI edits and bundling rules

The National Correct Coding Initiative (NCCI) publishes column 1/column 2 code pairs that Medicare bundles automatically. Check the current CMS NCCI tables before each 28110 claim, because the edit pairs change every quarter.

The pairings below raise most bundling questions, especially 28110 with a hammertoe correction under 28285.

• 28110 and 28285 (hammertoe correction): These procedures are often performed together on the same foot. When they are separate procedures on different sites, modifier 59 or XS may override bundling. An example is a fifth metatarsal head ostectomy plus a separate hammertoe correction on another toe. The operative note must document the distinct sites and procedures.
• 28110 and 28122: Reporting both codes for the same metatarsal head is considered unbundling. 28122 covers infected or necrotic bone excision. Using it alongside 28110 for a routine bunionette case inflates the claim and triggers an edit.
• Surgical approach codes: Standard incision and closure services are included in the global surgical package for 28110 and cannot be billed separately.

Common denial reasons and fixes

Denials on 28110 claims follow predictable patterns. Good denial management sorts each one by root cause, so the same error doesn’t repeat on the next claim. The medical billing denial codes guide shows which claim adjustment reason codes (CARCs) and remark codes (RARCs) signal each failure.

How claims management software prevents CPT 28110 denials

Without a claims system, a podiatry biller checks each 28110 claim by hand. That means confirming the prior authorization, matching ICD-10 laterality to the op note, and logging in to a payer portal for status.

Pabau, the practice management platform we build, keeps that work in one place. Its claims management software stores the patient’s insurer and policy on the patient record, so each invoice routes to the right payer. Before a claim goes out, Pabau checks that membership numbers and authorization codes are present. The Send button stays disabled until they are.

In the US, Pabau connects to Claim.MD for real-time eligibility checks, electronic submission, and electronic remittance advice (ERA) posting. Each claim shows its stage, from pending to paid or error, so staff see a rejected bunionette claim as soon as it comes back.

Catch CPT 28110 claim errors before submission

Pabau checks authorization codes and insurer details before a claim goes out, then tracks it to payment. Your billing team spends less time reworking denied foot surgery claims.

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Conclusion

CPT code 28110 is easy to code once the op note proves three facts. The fifth metatarsal head was resected, on a named foot, after failed conservative care. When one of those is missing, the claim drifts toward 28308, an unspecified diagnosis, or a medical necessity denial.

So the fix starts before the claim exists. Ask surgeons to dictate site, technique, and conservative care history in every bunionette note, and check each payer’s bilateral rule before surgery. Those extra minutes per chart cost far less than appealing a denied surgical claim.

Book a demo to see how Pabau tracks every 28110 claim from prior authorization to payment.

Continue your research

Need to understand how medical billing denials get resolved? Denial management in healthcare walks through denial root-cause analysis and appeal workflows for surgical claims.

Looking for a complete list of denial reason codes? Medical billing denial codes covers CARC and RARC codes that appear on remittance advice for foot surgery claims.

Want to understand how a clearinghouse fits into surgical billing? How Claim.MD clearinghouse works explains how electronic claim submission reduces manual errors on CPT 28110 claims.

Coding a first-ray bunion instead? CPT code 28299 covers double osteotomy bunionectomy and the documentation that separates it from fifth-ray surgery.

Spending hours on surgical authorizations? Prior authorization software compares tools that track payer approvals before foot surgery is scheduled.

Frequently asked questions