Surgical repair of tarsal bone nonunion or malunion, including the calcaneus and other tarsal bones of the foot.

Verified May 8, 2026 · 5 sources ↓

Medicare: $577.84
Total RVUs: 17.3
Global, days: 90
Region: Foot & ankle

Drawn from CMSAAPCMdclarityPrc

Documentation requirements

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

Source · Editorial brief grounded in 5 cited references ↓

Specify which tarsal bone(s) are involved — calcaneus, talus, navicular, cuboid, or cuneiform — by name in the operative report.
Document whether the condition is a nonunion or malunion, with supporting imaging (X-ray, CT) confirming failed or aberrant healing.
Describe the surgical technique: bone graft source and type (autograft vs. allograft), internal fixation hardware used (screws, plates, staples), and approach.
Record preoperative diagnosis with an ICD-10 code distinguishing nonunion (e.g., M84.37x-) from malunion (e.g., M84.27x-) — they are not interchangeable.
Include operative time and any complicating intraoperative findings that would support modifier 22 for increased procedural complexity.
Laterality must be documented — left or right foot — to support LT or RT modifier submission.

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 25 Significant separate E/M 51 Multiple procedures 52 Reduced services 58 Staged or related 59 Distinct service 62 Co-surgeons 78 Unplanned return — related 79 Unrelated during global 80 Assistant surgeon LT Left side RT Right side

What this code covers

Source · Editorial summary grounded in 5 cited references ↓

CPT 28320 covers open surgical repair of a nonunion or malunion involving the tarsal bones — calcaneus, talus, navicular, cuboid, and cuneiforms. The procedure addresses failed or malpositioned fracture healing through bone grafting, hardware fixation, or both, restoring alignment and structural integrity. The calcaneus is the most commonly treated bone under this code, and its inclusion trips up coders who assume a separate calcaneal-specific code exists — it doesn't.

The 90-day global period means all routine postoperative visits, wound checks, and hardware monitoring through day 90 are bundled into the surgical payment. Any E/M service in that window for an unrelated problem requires modifier 24; a separately identified same-day E/M needs modifier 25. If the patient returns to the OR within the global for a related issue — hardware failure, wound dehiscence — append modifier 78. An unrelated OR procedure in the same global window gets modifier 79.

Site of service matters significantly here. The HOPD rate is substantially higher than the ASC rate (see the Site of Service comparison table). If your facility qualifies and the patient is appropriate for outpatient surgery, the ASC setting may be preferred from a payer perspective, but physician RVUs are identical regardless of setting.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	9.14
Practice expense RVU	6.77
Malpractice RVU	1.39
Total RVU	17.3
Medicare national rate	$577.84
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	$577.84
HOPD (APC 5115) Hospital outpatient department	$13,116.76
ASC (PI J8) Ambulatory surgical center (freestanding)	$9,557.85

Common denial reasons

The recurring reasons claims for CPT 28320 get rejected.

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

Missing or vague imaging documentation to establish nonunion or malunion prior to surgery — payers require objective evidence of failed healing.
Laterality modifier absent (LT/RT); many MACs and commercial payers auto-deny bilateral foot codes without side designation.
Upcoding concern when repair of a single small tarsal bone is billed with modifier 22 without a detailed operative note justifying substantially increased work.
Bundling disputes when bone grafting is billed separately without confirming the graft work is not already captured in 28320's base procedure valuation.
Global period violations — E/M services billed within the 90-day window without modifier 24 (unrelated) or 25 (same-day, separate problem).

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 5 cited references ↓

01Does 28320 cover calcaneus nonunion repair, or is there a separate calcaneal code?

28320 covers the calcaneus. The calcaneus is a tarsal bone, so nonunion or malunion repair there bills under 28320. There is no separate CPT for calcaneal nonunion repair.

02Can I bill the bone graft separately when it's performed with 28320?

Only if the graft harvest is from a separate site and represents distinct additional work. Autograft harvest from a remote site (e.g., iliac crest) may support a separate graft code, but local graft or allograft is typically considered part of the repair. Confirm with NCCI edits before billing both.

03What modifier do I use if the surgeon treats a nonunion on the left foot and an unrelated problem on the right foot during the same encounter?

Bill 28320-LT for the left foot procedure. If the right-foot service is a separate distinct procedure, append modifier 59 or RT as applicable and verify NCCI bundling. If it's an E/M for the unrelated right-foot issue, use modifier 25.

04The patient returned to the OR at day 45 for hardware removal after 28320. Which modifier applies?

If the hardware removal is directly related to the original repair (e.g., prominent hardware causing wound problems), use modifier 78 — unplanned return to the OR for a related procedure within the global period. If truly unrelated, use modifier 79.

05When is modifier 22 appropriate with 28320?

When the documented operative complexity substantially exceeds typical — for example, severe scarring from prior surgery, extensive bone loss requiring complex grafting, or prolonged operative time with detailed intraoperative findings. The operative note must explicitly describe what made it harder. A generic 'difficult case' notation won't survive audit.

06Is 28320 ever billed bilaterally in the same session?

Rarely, but it can happen. Bill 28320-50 or separate line items with LT and RT. Expect payer scrutiny — bilateral tarsal nonunion repair in a single session is uncommon, and some payers require documentation that both feet were treated under the same anesthetic.

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 specific tarsal bone repaired, the failure mode (nonunion vs. malunion), fixation hardware used, graft source and type, surgical approach, and operative laterality directly from dictation. That structured capture prevents the two most common denials: a vague operative note that can't confirm medical necessity for surgical repair, and missing laterality that triggers automatic rejection.

See how Mira captures CPT 28320 documentation