Osteotomy of the proximal phalanx of the first toe to correct alignment or structural deformity

Verified May 8, 2026 · 6 sources ↓

Medicare: $565.14
Total RVUs: 16.92
Global, days: 90
Region: Foot & ankle

Drawn from CMSTldsystemsAAOS

Documentation requirements

What must appear in the operative or office note to support the claim.

Source · Editorial brief grounded in 6 cited references ↓

Specify the deformity type being corrected (e.g., interphalangeal hallux valgus, residual valgus deviation) with preoperative imaging findings
Name the osteotomy technique used (e.g., medial closing wedge, transverse) — notes that say 'proximal phalanx osteotomy performed' without technique detail are audit flags
Document which toe and which foot; include laterality and toe-level designation to support LT/RT and HCPCS toe modifiers
If billed same-day with 28297 or any non-bundled code, document the distinct anatomic site or separate clinical purpose for each procedure
If modifier 22 is appended, the operative note must quantify the additional work — prior surgery, adhesions, hardware removal, or abnormal anatomy — not just assert increased difficulty
Record fixation method used (staple, wire, screw) and intraoperative imaging if fluoroscopy was used, noting it as a distinct service if separately billable

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 24 Unrelated E/M during global 51 Multiple procedures 58 Staged or related 59 Distinct service 76 Repeat, same physician 77 Repeat, another physician 78 Unplanned return — related 79 Unrelated during global LT Left side RT Right side

What this code covers

Source · Editorial summary grounded in 6 cited references ↓

CPT 28310 describes a surgical osteotomy of the proximal phalanx of the hallux — a bone cut performed to realign the first toe and correct deformity. This procedure is commonly known as an Akin osteotomy and is used to address interphalangeal hallux valgus or residual toe deviation after bunionectomy. The 90-day global period covers all routine follow-up, dressings, and suture removal through day 90.

A critical NCCI rule governs same-day billing: 28310 cannot be reported alongside bunionectomy codes 28291–28299 for the ipsilateral first toe. CMS's rationale is that several bunionectomy codes already incorporate a proximal phalanx osteotomy; billing both constitutes unbundling. However, when 28310 is paired with 28297 (Lapidus-type arthrodesis), the NCCI modifier indicator is '1 — Allowed,' meaning modifier 59 or a T-digit toe modifier can support separate billing if the osteotomy is genuinely distinct and documented as such.

Lateral vs. medial laterality modifiers (LT/RT) and toe-level HCPCS modifiers (TA, T5, etc.) are standard for foot procedures billed to Medicare and most commercial payers. When substantially increased operative complexity exists — scarring from prior surgery, severe deformity requiring additional fixation — modifier 22 with supporting operative note documentation can be appended to the primary code.

RVU & reimbursement

Component RVUs and Medicare national rate. Actual payment varies by GPCI locality.

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	5.43
Practice expense RVU	10.82
Malpractice RVU	0.67
Total RVU	16.92
Medicare national rate	$565.14
Global period	90 days

Payment by site of service

Medicare pays different rates by setting. HOPD typically pays substantially more than ASC for the same procedure.

Source · CMS OPPS Addendum B·ASC HCPCS payment rates·2026

Setting	Medicare rate (national)
Office (PFS non-facility) Procedure performed in physician's office	$565.14
HOPD (APC 5114) Hospital outpatient department	$7,413.38
ASC (PI A2) Ambulatory surgical center (freestanding)	$3,695.53

Common denial reasons

The recurring reasons claims for CPT 28310 get rejected.

Source · Editorial brief grounded in CMS NCCI edits, AAOS coding appeals, and cited references ↓

Bundled with same-day bunionectomy (28291–28299) on the ipsilateral first toe — NCCI prohibits separate payment regardless of modifier
Missing or ambiguous laterality — claims without LT/RT or HCPCS toe modifier (TA/T5) are rejected or pended by Medicare and many commercial payers
Modifier 59 appended to override a bundling edit with a bunionectomy code where modifier indicator is '0 — Never'; modifier 59 does not override these edits
Lack of supporting diagnosis — payers require an ICD-10 code (e.g., M20.10 hallux valgus, acquired) that clearly justifies the osteotomy as medically necessary
Post-op visit billed separately within the 90-day global period without modifier 24 or 79 establishing it as unrelated

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 6 cited references ↓

01Can I bill 28310 with a bunionectomy code on the same day?

No — not for the ipsilateral first toe. CMS NCCI policy explicitly prohibits reporting 28310 with bunionectomy codes 28291–28299 for the same toe because several bunionectomy codes already include a proximal phalanx osteotomy. The modifier indicator for these pairs is '0,' meaning no modifier overrides the bundle.

02Can 28310 be billed with 28297 on the same day?

Yes, with appropriate modifier. The NCCI modifier indicator for 28297 and 28310 is '1 — Allowed.' Append modifier 59 (or XS if the site distinction is relevant) to 28310, and use toe-level HCPCS modifiers (TA/T5) to distinguish the procedures. Document each procedure's distinct anatomic basis in the operative note.

03What laterality modifiers are required for 28310?

Use LT or RT for facility and most commercial claims. Medicare and many payers additionally require HCPCS toe modifiers: TA (left great toe) or T5 (right great toe). Missing these causes pends or rejections — not clinical denials — but they delay payment the same way.

04Does 28310 have a global period, and what does it cover?

28310 carries a 90-day global period. That covers the day-before visit, the surgery itself, and all routine post-op care — dressing changes, suture removal, and standard follow-up visits — through day 90. Unrelated E/M services during that window need modifier 24. A new unrelated procedure needs modifier 79.

05When is modifier 22 appropriate for 28310?

Use modifier 22 when operative complexity is substantially greater than typical — for example, revision surgery with scarring, severe rigid deformity requiring additional bone work, or prior hardware complicating exposure. The operative note must describe the specific factors that increased time and effort. Simply stating 'increased complexity' without specifics will not survive audit or payer review.

06If the patient returns within the global period for a related complication, what modifier applies?

Use modifier 78 for an unplanned return to the OR for a complication or issue related to the original 28310 procedure. Modifier 79 is for unrelated procedures during the global period. Do not invert these — applying 79 to a related return-to-OR procedure is incorrect and may trigger recoupment.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

Mira AI Scribe

Mira's AI scribe captures the osteotomy technique by name, the specific deformity indication, laterality, and fixation method directly from surgeon dictation. This prevents the two most common audit flags for 28310: operative notes that omit technique detail and claims submitted without toe-level laterality identifiers. When same-day procedures are dictated, the scribe flags the NCCI bundling rule against ipsilateral bunionectomy codes and surfaces the modifier 59 option for permitted pairings like 28297.

See how Mira captures CPT 28310 documentation