Fusion · Hand

Arthrodesis of the thumb metacarpophalangeal joint in the opposition position using an autogenous graft harvested during the same operative session.

Verified May 8, 2026 · 7 sources ↓

Medicare: $813.98
Total RVUs: 24.37
Global, days: 90
Region: Hand

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Documentation requirements

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

Source · Editorial brief grounded in 7 cited references ↓

Specify the joint fused — metacarpophalangeal joint of the thumb in opposition position — not just 'thumb fusion'.
Confirm autogenous graft use and document the harvest site; allograft or synthetic graft does not support 26820.
Describe the fixation method — screw, plate, K-wire — to defend medical necessity and support complexity under modifier 22 if warranted.
Document the pre-operative diagnosis with ICD-10 specificity (e.g., post-traumatic arthritis, traumatic instability) to establish medical necessity.
Record intraoperative fluoroscopy or imaging if used; do not bill separately for guidance that is part of the surgical workflow.
Note laterality (right or left thumb) explicitly in the operative report and on the claim.

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 50 Bilateral procedure 51 Multiple procedures 52 Reduced services 58 Staged or related 59 Distinct service 78 Unplanned return — related 79 Unrelated during global 80 Assistant surgeon LT Left side RT Right side AS PA/NP/CNS assistant

What this code covers

Source · Editorial summary grounded in 7 cited references ↓

CPT 26820 covers surgical fusion of the thumb metacarpophalangeal joint in the opposition position, using an autograft the surgeon harvests intraoperatively. Cartilage is removed from the joint surfaces, the graft is shaped and interposed, and hardware — typically screws or a plate — holds the construct while fusion consolidates. Because graft harvest is bundled into the descriptor, you cannot separately bill a graft procurement code for the same session.

The 90-day global period covers the day-before visit, the operative day, and all routine post-op care through day 90 — splint or cast changes, wound checks, and hardware monitoring visits included. Anything outside the norm (e.g., a separate unrelated procedure, or a complication requiring return to the OR) requires modifier 78 for a related unplanned return or modifier 79 for an unrelated procedure. The MUE for 26820 is 1 unit per date of service, per the PRA adjudication indicator, meaning bilateral thumb fusions billed on the same date require modifier 50 or separate line items with LT/RT.

Code selection within the 26820–26863 range hinges on joint level and graft use. 26820 is specifically the opposition-position MCP fusion with autograft. If the procedure targets the carpometacarpal joint with autograft, 26842 applies. If no graft is used at the MCP joint, there is no direct analog in this family — verify with the operative note before defaulting to an unlisted 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	8.24
Practice expense RVU	14.38
Malpractice RVU	1.75
Total RVU	24.37
Medicare national rate	$813.98
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	$813.98
HOPD (APC 5114) Hospital outpatient department	$7,413.38
ASC (PI G2) Ambulatory surgical center (freestanding)	$3,695.53

Common denial reasons

The recurring reasons claims for CPT 26820 get rejected.

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

Missing or ambiguous laterality on the claim — payers require RT or LT when the thumb is not otherwise specified.
Separate billing of graft harvest (e.g., a bone graft code) when obtaining the autograft is already included in 26820's descriptor, triggering NCCI bundling edits.
Insufficient medical necessity documentation — operative notes that lack a pre-operative diagnosis or fail to show conservative treatment failure.
Billing 26820 when the fused joint is the carpometacarpal (CMC) rather than the MCP joint; that maps to 26841 or 26842.
Global period violations — routine post-op visits billed without modifier 24 or 25 when they fall within the 90-day global window.

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 7 cited references ↓

01Is graft harvest billed separately when performing 26820?

No. Obtaining the autograft is explicitly included in the 26820 descriptor. Billing a separate graft procurement code on the same claim will trigger an NCCI bundling edit and denial.

02Which code applies if the fusion is at the CMC joint of the thumb instead of the MCP joint?

Use 26842 for a CMC thumb arthrodesis with autograft. 26820 is restricted to the metacarpophalangeal joint fused in the opposition position — it does not cover the CMC level.

03Can 26820 and 26850 (MCP arthrodesis without graft) be billed together?

No. Both describe arthrodesis of the MCP joint — one with autograft, one without. Billing both for the same joint on the same date is duplicative. Choose the code that matches what was actually performed.

04How do you handle a bilateral thumb fusion in the same operative session?

Bill 26820 twice — one unit per thumb — with modifier 50 on a single line or on separate lines with LT and RT. The MUE is 1 per side; modifier 50 satisfies that constraint. Confirm your payer's preferred billing format for bilateral procedures.

05What modifier applies if the patient returns to the OR within the 90-day global for a hardware complication?

Use modifier 78 if the return is an unplanned procedure related to the original fusion (e.g., hardware failure, wound dehiscence from the same site). Use modifier 79 only if the return procedure is entirely unrelated to the thumb fusion.

06Does modifier 22 apply if the fusion was technically demanding due to prior trauma or failed prior surgery?

Yes, but document specifically — describe the anatomic distortion, increased operative time, or additional complexity in the operative note. A generic statement that the case was 'difficult' will not support modifier 22 on audit.

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 joint level (MCP in opposition position), graft type and harvest site, fixation hardware used, and laterality directly from the operative dictation. That prevents the most common audit flag for 26820 — operative notes that document 'thumb fusion with graft' without specifying the joint or confirming autograft harvest, which reviewers treat as insufficient to support the code over a lower-complexity arthrodesis.

See how Mira captures CPT 26820 documentation