Structural allograft for spine surgery, reported as an add-on to the primary spinal fusion or reconstruction procedure.

Verified May 8, 2026 · 6 sources ↓

Medicare: $98.20
Total RVUs: 2.94
Global, days
Region: Spine

Drawn from CMSBedrockbillingAAPCAAOS

Documentation requirements

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

Source · Editorial brief grounded in 6 cited references ↓

Identify the primary spinal procedure code being billed alongside 20931
Specify that the allograft used was structural (load-bearing), not morselized or osteopromotive material
Document the source and type of allograft (e.g., cortical strut, femoral ring) in the operative report
Record the spinal levels involved and the surgical indication requiring structural support
Confirm that only one unit of 20931 is reported regardless of the number of levels fused

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

59 Distinct service 62 Co-surgeons 76 Repeat, same physician 79 Unrelated during global 80 Assistant surgeon AS PA/NP/CNS assistant XS Separate structure

What this code covers

Source · Editorial summary grounded in 6 cited references ↓

CPT 20931 covers the use of a structural bone allograft — donor bone shaped to bear load and restore vertebral height or column integrity — during spinal surgery. It is an add-on code, meaning it is never reported alone; it requires a primary spinal procedure code on the same claim. The structural designation distinguishes it from morselized allograft (20930), which is packed into voids and does not provide structural support.

The MUE for 20931 is one unit per operative session, per CMS NCCI policy. That limit holds regardless of how many vertebral levels are fused in a single procedure. Reporting multiple units to reflect multi-level fusion is a known audit trigger — document the graft use clearly, but bill only one unit.

Neurosurgery and orthopedic surgery account for the vast majority of claims. The ZZZ global period means this add-on code carries no independent global package — the global period of the primary procedure governs post-op care. Because 20931 appears as Column 2 in 44 NCCI edit pairs, verify that your primary procedure code is correctly identified before submitting; bundling edits are common and modifier 59 or XS may be required to unbundle legitimate same-session services where policy permits.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	1.76
Practice expense RVU	0.59
Malpractice RVU	0.59
Total RVU	2.94
Medicare national rate	$98.20
Global period	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	$98.20

Common denial reasons

The recurring reasons claims for CPT 20931 get rejected.

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

Billing more than one unit — MUE is 1 per operative session regardless of levels fused
Missing or non-matching primary spinal procedure code — 20931 cannot be billed standalone
Confusing 20931 (structural allograft) with 20930 (morselized allograft or osteopromotive material), resulting in wrong code selection
NCCI bundling conflict with the primary procedure code where a modifier was not appended or was not supported by documentation
Operative report describes graft as 'donor bone' without specifying structural/load-bearing role, leaving the structural vs. morselized distinction ambiguous

Frequently asked questions

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

01Can I bill 20931 for every level fused in a multilevel procedure?

No. CMS NCCI policy sets the MUE at one unit per operative session for 20931 regardless of how many vertebral levels are fused. Bill one unit and document the structural graft use thoroughly in the operative note.

02What is the difference between 20930 and 20931?

20930 covers morselized allograft or osteopromotive material — packed into a void but not load-bearing. 20931 is for structural allograft that provides mechanical support, such as a cortical strut or femoral ring. The operative report must make the structural role explicit.

03What primary procedure codes does 20931 typically accompany?

20931 is reported alongside spinal fusion codes (e.g., 22551, 22554, 22612, 22630) or spinal reconstruction procedures. It cannot be submitted without a qualifying primary spinal procedure code on the same claim.

04Does the ZZZ global period mean I need to track post-op visits differently?

ZZZ means 20931 has no independent global package. Post-op care falls under the global period of the primary spinal procedure code. You do not bill post-op visits against 20931 itself.

05When is modifier 59 or XS appropriate with 20931?

Use modifier 59 or XS if an NCCI edit bundles 20931 into another procedure billed the same day and the graft service is genuinely distinct. Confirm the edit pair and that documentation supports the distinct service before appending — payers scrutinize modifier 59 use on add-on codes.

06Can two surgeons each bill 20931 using modifier 62?

Modifier 62 applies when two surgeons perform distinct portions of a single spinal procedure. If both surgeons contribute to a procedure that includes structural allograft placement, 62 can be appended to 20931, but both operative reports must document each surgeon's distinct role.

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 graft type (structural vs. morselized), vertebral levels involved, and the load-bearing role of the allograft directly from the surgeon's dictation. It flags the primary procedure code so 20931 is always linked at claim creation. This prevents the most common denial trigger: a standalone or mis-typed add-on submission with ambiguous graft characterization.

See how Mira captures CPT 20931 documentation