Arthroscopy · Knee

Arthroscopic knee procedure in which osteochondral autograft plugs — harvested from the patient's own joint — are implanted to resurface a focal cartilage defect (e.g., mosaicplasty). Graft harvesting is included in the code.

Verified May 8, 2026 · 7 sources ↓

Medicare: $979.31
Total RVUs: 29.32
Global, days: 90
Region: Knee

Drawn from CMSAAPCAAOSCgsmedicare

Documentation requirements

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

Source · Editorial brief grounded in 7 cited references ↓

Confirm graft source is autologous — document harvest site location within the knee (e.g., superolateral trochlea, intercondylar notch)
Identify the defect site by name and compartment (e.g., medial femoral condyle, lateral femoral condyle, trochlea) with measured defect size in mm
Record number of plugs harvested and implanted, plus plug dimensions
Document the arthroscopic approach, joint compartments visualized, and any additional findings addressed
Specify any concomitant procedures performed and their compartment location to support or rebut bundling with G0289
Include pre-op imaging (MRI) confirming focal chondral or osteochondral defect appropriate for autograft reconstruction

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 24 Unrelated E/M during global 25 Significant separate E/M 51 Multiple procedures 57 Decision for surgery 58 Staged or related 59 Distinct service 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 ↓

29866 covers arthroscopic osteochondral autograft implantation in the knee, the technique commonly called mosaicplasty or OATS. The surgeon harvests cylindrical osteochondral plugs from a lower-demand area of the patient's own knee and press-fits them into a prepared defect site — typically the femoral condyle or trochlea. Because harvesting is bundled into 29866, no separate graft-harvest code is reportable. The autograft origin is what distinguishes this code from 29867, which covers allograft (cadaveric) tissue; using the wrong code is one of the most common submission errors on these cases.

The code carries a 90-day global period. All routine post-op visits, dressing changes, and related E&M services through day 90 are bundled. If the decision for surgery is made at the same encounter as the procedure, append modifier 57 to the associated E&M. An unrelated procedure performed during the global period needs modifier 79; a related, unplanned return to the OR needs modifier 78.

Not all payers treat 29866 as a covered, non-experimental service — some commercial plans and Medicaid programs have coverage restrictions or require prior authorization. Verify coverage before scheduling. Per the NCCI policy manual, 29874 and 29877 cannot be billed with 29866 on the same knee at the same encounter; if debridement is performed in a separate compartment, G0289 may be reportable in limited circumstances.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	14.3
Practice expense RVU	11.98
Malpractice RVU	3.04
Total RVU	29.32
Medicare national rate	$979.31
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	$979.31
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 29866 get rejected.

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

Payer classifies mosaicplasty/OATS as experimental or investigational — requires prior auth and benefit verification before scheduling
29867 (allograft) submitted when operative note indicates autograft, or vice versa — verify graft source before code selection
29874 or 29877 billed same-day same-knee — both are NCCI-bundled into 29866 and will deny without an allowable modifier bypass
Missing or vague documentation of harvest site and defect dimensions — insufficient to support medical necessity on audit or appeal
Global period conflict — post-op E&M billed without modifier 24 when unrelated to the surgical recovery

Frequently asked questions

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

01What is the difference between 29866 and 29867?

29866 is used when the graft is taken from the patient's own knee (autograft). 29867 applies when cadaveric (allograft) tissue is used. The distinction is in the operative note — verify the graft source before submitting either code.

02Can I bill 29877 for chondroplasty performed at the same time as 29866?

No. The NCCI policy manual explicitly prohibits reporting 29877 with any knee arthroscopy code in the 29866–29889 range on the same knee at the same encounter. The edit cannot be bypassed with a modifier for ipsilateral same-encounter work.

03Does 29866 include harvesting of the autograft plugs?

Yes. Graft harvesting is bundled into 29866 by code definition. Do not report a separate harvest code — it will deny as a component service.

04Which modifier do I use if the surgeon performs an unrelated procedure on the same knee during the 90-day global?

Use modifier 79 (unrelated procedure by the same physician during the postoperative period). Modifier 78 is for an unplanned return to the OR for a related procedure. Do not invert them.

05Do I need prior authorization for 29866?

Many commercial payers and some Medicaid programs still classify arthroscopic osteochondral autograft procedures as non-covered or subject to medical necessity review. Verify the patient's specific plan benefits and obtain prior auth before scheduling — a denial on experimental grounds is difficult to overturn after the fact.

06Can 29866 be billed bilaterally?

Bilateral mosaicplasty at one encounter is rare but codeable. Append modifier 50 and bill one line with one unit of service. LT and RT are alternatives when payer policy requires laterality modifiers on separate lines — check payer-specific instructions.

07What ICD-10 diagnoses best support medical necessity for 29866?

Focal osteochondral defects (M93.2x series — osteochondritis dissecans by site), traumatic chondral injuries (S83.xx), and osteochondral loose bodies (M23.4x) are the primary supporting diagnoses. Diffuse degenerative disease (M17.x) without focal defect documentation is a common reason payers downgrade or deny coverage.

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 source (autologous), harvest site with anatomic location, defect site by compartment and compartment, plug count, and plug dimensions from dictation. It also flags when the operative note references allograft tissue — prompting a 29867 review before submission — and notes any same-day debridement by compartment to assess G0289 eligibility. That prevents the two most common 29866 denials: wrong graft-type code and NCCI-bundled debridement.

See how Mira captures CPT 29866 documentation