20933

Add-on code for hemicortical intercalary allograft, partial (hemicylindrical), used between joints after tumor resection — includes templating, cutting, shaping, placement, and fixation of donor bone.

Verified May 8, 2026 · 6 sources ↓

Medicare: $595.54
Total RVUs: 17.83
Global, days
Region: Other

Drawn from AAPCCMSHealthallianceKzanow

Documentation requirements

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

Source · Editorial brief grounded in 6 cited references ↓

Pathology or imaging confirming tumor or lesion requiring resection and structural bone reconstruction
Operative note explicitly identifying the graft as hemicylindrical (partial/hemicortical) — not osteoarticular and not complete cylindrical
Documentation of each included step: templating, cutting/shaping the allograft, placement, and fixation method
Identification of the primary procedure code (e.g., 27645, 24150) to which 20933 is added — payers require clear linkage
Size and location of the intercalary bone defect, confirming the graft is positioned between joints, not spanning the articular surface
Surgeon attestation that 20932 (osteoarticular) and 20934 (complete cylindrical) do not apply to this case

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 52 Reduced services 59 Distinct service 76 Repeat, same physician 77 Repeat, another physician 80 Assistant surgeon

What this code covers

Source · Editorial summary grounded in 6 cited references ↓

CPT 20933 is a ZZZ global add-on code reported alongside a primary tumor resection procedure. It covers the full technical work of the partial intercalary allograft: designing the template, cutting and shaping the donor cortical bone to a hemicylindrical (half-cylinder) profile, placing it in the intercalary defect (between joints, not involving the articular surface), and securing it with internal fixation when performed. The hemicylindrical shape distinguishes 20933 from 20934, which describes a complete cylindrical intercalary allograft. The extent of the allograft — partial vs. complete — must be documented by the operating surgeon; payers will audit operative notes when the two codes could apply.

Valid primary procedures for 20933 include tumor resection codes 23210, 23220, 24150, 25170, 27075, 27076, 27077, 27365, 27645, and 27704. Do not report 20933 with 20932 or 20934 — these are mutually exclusive within the same surgical site. The ZZZ global means 20933 has no independent global period; it inherits the global of the primary procedure it accompanies.

Because this is an add-on code used almost exclusively in oncologic reconstruction, payer scrutiny centers on medical necessity documentation (confirmed tumor diagnosis, resection margins, structural deficit requiring allograft) and the operative note's description of graft geometry. If only the primary resection is documented without explicit detail about the allograft work, the add-on will be denied as unbundled or unsupported.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	11.64
Practice expense RVU	3.71
Malpractice RVU	2.48
Total RVU	17.83
Medicare national rate	$595.54
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	$595.54

Common denial reasons

The recurring reasons claims for CPT 20933 get rejected.

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

Billed without a valid primary tumor resection procedure — 20933 cannot stand alone
Operative note describes a complete cylindrical allograft, making 20934 the correct code instead
Graft type not specified in the operative note — payer downcodes or denies for lack of documentation distinguishing partial from complete intercalary
Reported with 20932 or 20934 on the same claim for the same site — these codes are mutually exclusive
Primary procedure code is not on the approved companion code list (e.g., paired with a non-tumor resection code)

Frequently asked questions

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

01What makes 20933 different from 20934?

Graft geometry. Code 20933 is hemicylindrical — only half the cortical circumference is replaced. Code 20934 is a complete cylindrical intercalary allograft wrapping the full circumference. The operative note must name the geometry; 'intercalary allograft' alone is not sufficient to support either code.

02Can I report 20933 with 20932 on the same claim?

No. Codes 20932, 20933, and 20934 are mutually exclusive. Report only the one that matches the allograft type actually performed. Billing more than one for the same surgical site will result in denial of the add-on.

03Which primary procedure codes can 20933 be added to?

CPT 20933 is approved for use with tumor resection codes 23210, 23220, 24150, 25170, 27075, 27076, 27077, 27365, 27645, and 27704. Pairing it with any other primary code risks denial for an invalid code combination.

04Does 20933 have its own global period?

No. The ZZZ global period means 20933 carries no independent global. It inherits the global period of the primary procedure it accompanies. Post-op E/M services follow the global rules of that primary code.

05Is modifier 59 ever needed on 20933?

If an NCCI PTP edit fires between 20933 and another add-on or primary code on the same claim, modifier 59 can be appended to indicate a distinct procedural service — but only when the clinical circumstances genuinely support it. Don't use 59 to override an edit that reflects a true bundling relationship.

06Do payers require prior authorization for 20933?

Some do. Health Alliance and similar payers have published policies listing 20933 under bone graft substitute coverage criteria. Verify prior authorization requirements with each payer before the case, particularly for commercial and Medicaid plans.

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 geometry (hemicylindrical vs. cylindrical), the intercalary position of the defect (between joints, no articular involvement), and each discrete procedural step — templating, cutting, shaping, placement, and fixation method. That documentation prevents the most common denial: an operative note that doesn't distinguish 20933 from 20934, prompting a payer to reject the add-on as unspecified or duplicate.

See how Mira captures CPT 20933 documentation