Sp bone algrft struct add-on

CPT code 20931 covers the additional work of placing structural bone graft material from a donor (allograft) during spinal surgery. This is an add-on code used only when structural bone support is placed in addition to the primary spinal fusion procedure.

Showing rates for

National Average

Base Medicare rate

$107.71

This calculator gives a typical-case estimate using standard Medicare modifier rules. Actual payment depends on payer policies, documentation, code-specific CMS status indicators, and locality. Verify before billing.

RVU breakdown

Work RVU

1.81

PE RVU (NF)

0.92

MP RVU

0.6

Total RVU

3.33

Conversion factor: 32.3465 · Source: CMS MPFS RVU25A · Confidence: High

NCCI bundling edits

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Billing tips

Bill 20931 per additional interspace beyond the first level included in the primary fusion code (e.g., 22558, 22585, 22630)
Impact: Correct unit billing can yield $107.71 per additional level; underbilling loses $107.71 per missed interspace
Document the structural nature of the allograft with specific dimensions, shape, and load-bearing purpose to differentiate from morselized graft
Impact: Prevents denials worth $107.71 per level; structural vs. non-structural differentiation is the most common audit issue
Verify that the primary procedure code does not already include structural allograft placement for the first level before billing 20931
Impact: Prevents automatic denials and audit flags; many primary fusion codes bundle the first structural graft
Use 20931 only with CPT codes that specifically allow it as an add-on; check the code descriptor of primary procedure for compatibility
Impact: Billing with incompatible primary codes results in 100% denial; most compatible with codes 22319, 22532-22534, 22548, 22558, 22585, 22630
Report actual number of additional structural allografts placed; do not combine with autograft codes (20936-20938) for the same level
Impact: Overcoding risk in audits; CMS does not allow billing both autograft and allograft codes for the same interspace
Coordinate with facility billing to ensure they do not separately bill for the allograft device/material under revenue codes
Impact: Prevents duplicate billing denials and compliance issues; physician code covers the placement service only, not the device

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Frequently asked questions

What is CPT code 20931 used for?

CPT code 20931 is used for placing structural spinal bone allograft (donor bone) as an add-on to primary spinal fusion surgery. It represents the additional work of inserting shaped, load-bearing bone blocks between vertebrae at levels beyond the first interspace already included in the primary fusion code.

How much does Medicare pay for CPT 20931 in 2025?

Medicare pays $107.71 for CPT 20931 in 2025 based on the national average for both facility and non-facility settings. This represents 3.33 total RVUs multiplied by the 2025 conversion factor of 32.3465.

Can CPT 20931 be billed alone without another procedure code?

No, CPT 20931 is an add-on code and cannot be billed alone. It must be reported with a primary spinal arthrodesis/fusion procedure code such as 22558, 22585, 22630, or other compatible fusion codes as specified in CPT guidelines.

What is the difference between CPT 20931 and 20930?

CPT 20931 is for structural spinal bone allograft (donor bone) while 20930 is for morselized allograft. Structural grafts are rigid, shaped blocks that provide load-bearing support, whereas morselized grafts are small bone chips or particles used to promote fusion but not provide structural support. Only structural grafts qualify for 20931.

How many times can you bill CPT 20931 for the same patient?

You can bill CPT 20931 once for each additional interspace where structural allograft is placed beyond the first level included in the primary fusion code. For example, in a three-level fusion, if the primary code covers one level, you can bill 20931 twice (two units) for the two additional levels.

What documentation is needed to bill CPT 20931?

Documentation must include the specific type and dimensions of structural allograft used, exact anatomical levels where placed, description of its load-bearing purpose, and clear differentiation from morselized graft. The operative report must show the allograft was used as a structural spacer, not just bone chips for fusion enhancement.

Does CPT 20931 include the cost of the allograft bone material?

No, CPT 20931 covers only the surgeon's work of placing the structural allograft. The actual bone graft material/device is billed separately by the facility using supply codes or revenue codes. Surgeons should not attempt to bill for both the placement service and the material itself.