Arthroplasty of the temporomandibular joint using allograft (donor) tissue to repair, reposition, or reconstruct joint components.

Verified May 8, 2026 · 7 sources ↓

Medicare: $923.20
Total RVUs: 27.64
Global, days: 90
Region: Other

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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 graft type as allograft with source documentation (tissue bank, lot number) — autograft use would map to 21240 instead
Operative note must name the surgical approach and describe the osseous or soft-tissue components reconstructed
Preoperative imaging (CT, MRI, or Cone Beam CT) establishing structural pathology and supporting surgical necessity
Conservative treatment failure documented in the medical record prior to surgical intervention (most payer policies require it)
Prior authorization approval number recorded in the chart and on the claim
Diagnosis code(s) precisely matching the documented pathology (e.g., internal derangement, degenerative joint disease, ankylosis)

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 62 Co-surgeons 76 Repeat, same physician 77 Repeat, another physician 78 Unplanned return — related 79 Unrelated during global LT Left side RT Right side

What this code covers

Source · Editorial summary grounded in 7 cited references ↓

CPT 21242 covers open surgical reconstruction of the temporomandibular joint (TMJ) in which the surgeon uses allograft material — donor tissue from a tissue bank — to repair or reconstruct osseous or soft-tissue components of the joint. This distinguishes it from 21240, which uses autograft or no graft, and from 21243, which involves a prosthetic joint replacement. The allograft distinction is not cosmetic: payers and auditors will scrutinize operative notes to confirm the graft source matches the code billed.

The procedure carries a 90-day global period under CMS. All routine post-op visits, wound care, and related E/M services within that window are bundled. If you need to bill an unrelated procedure or E/M during the global, append modifier 79 or 24 respectively. A same-day E/M for a separate, unrelated problem requires modifier 24; a staged or planned procedure in the global window needs modifier 58.

Prior authorization is the dominant coverage hurdle for 21242. UnitedHealthcare, Health Alliance, and most commercial payers treat TMJ arthroplasty as a service requiring medical necessity review, and several payers adjudicate it through InterQual criteria. Confirm PA status before scheduling. Some payers also distinguish between dental benefit and medical benefit coverage for TMJ procedures — verifying which bucket applies prevents post-service denials that are difficult to overturn.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	14.23
Practice expense RVU	11.35
Malpractice RVU	2.06
Total RVU	27.64
Medicare national rate	$923.20
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	$923.20
HOPD (APC 5165) Hospital outpatient department	$6,048.05
ASC (PI A2) Ambulatory surgical center (freestanding)	$3,025.62

Common denial reasons

The recurring reasons claims for CPT 21242 get rejected.

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

Missing or expired prior authorization — the single most frequent denial trigger for TMJ arthroplasty across commercial payers
Graft type not documented: claim billed as 21242 (allograft) but operative note describes autograft or no graft, prompting downcoding to 21240
Insufficient documentation of conservative treatment failure before surgical escalation, failing medical necessity criteria
Procedure billed under dental benefit when payer routes TMJ surgery to medical benefit (or vice versa), causing a coverage-mismatch denial
Bundling with diagnostic arthroscopy (29800) or meniscectomy (21060) without an NCCI modifier establishing distinct procedural service

Frequently asked questions

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

01What is the difference between 21240, 21242, and 21243?

21240 uses autograft tissue or no graft. 21242 uses allograft (donor) tissue. 21243 involves a prosthetic joint replacement device. The graft source documented in the operative note determines the correct code — billing the wrong one is a common audit target.

02Does 21242 require prior authorization?

Yes, for virtually all commercial payers. UnitedHealthcare, Health Alliance, and others route TMJ arthroplasty through medical necessity review, often via InterQual criteria. Confirm authorization before the procedure; retro-auth is rarely granted for elective reconstructive surgery.

03Can 21242 be billed bilaterally?

Bilateral TMJ arthroplasty is uncommon but can occur. If both joints are reconstructed in the same session, append modifier 50. Document each side separately in the operative note with independent findings and repair descriptions.

04How is the 90-day global period managed for staged TMJ procedures?

If a second planned surgical procedure falls within the 90-day global window, append modifier 58 to indicate it was staged or planned. Unplanned returns for a related complication use modifier 78. Unrelated procedures in the global period use modifier 79. Always verify payer acceptance of these modifiers before billing.

05Is 21242 covered under the dental benefit or the medical benefit?

It depends on the payer and the member's plan. Many commercial payers route TMJ surgical procedures to the medical benefit, but some plans split coverage or carve TMJ to a dental administrator. Verify benefit assignment before billing to avoid a coverage-mismatch denial that is difficult to appeal retroactively.

06Can 29800 (TMJ diagnostic arthroscopy) be billed on the same day as 21242?

Generally no without a modifier — NCCI bundles diagnostic arthroscopy into the open arthroplasty. If a distinct, separately identifiable diagnostic arthroscopic service was performed at a different anatomic site or encounter, modifier 59 or XS may apply, but confirm with NCCI edit tables before billing.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

Mira AI Scribe

Mira's AI scribe captures graft source (allograft confirmed), surgical approach by name, specific joint components reconstructed, and intraoperative findings from dictation. That detail locks in the 21242 code selection over 21240 or 21243 and prevents the most common audit flag — an operative note that documents autograft or prosthetic implant while the claim reads allograft.

See how Mira captures CPT 21242 documentation