Fusion · Knee

Surgical arthrodesis of the knee joint, fusing the femur and tibia using any technique to eliminate motion at the joint.

Verified May 8, 2026 · 7 sources ↓

Medicare: $1,354.74
Total RVUs: 40.56
Global, days: 90
Region: Knee

Drawn from CMSAAPCFindacode

Documentation requirements

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

Source · Editorial brief grounded in 7 cited references ↓

Primary indication for arthrodesis — failed TKA, infection, quadriceps loss, or other — stated explicitly in the operative note and supporting clinical records
Technique described in full: fixation method (intramedullary rod, external fixator, plating), bone preparation, and whether bone graft was used
Pre-operative imaging confirming joint pathology that necessitates arthrodesis rather than revision arthroplasty
Informed consent documentation reflecting that fusion is the planned definitive procedure
If concurrent implant removal performed, separate documentation of the explantation as a distinct surgical step with its own medical justification
Post-operative plan addressing weight-bearing status and expected fusion timeline, supporting medical necessity of the procedure

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 51 Multiple procedures 52 Reduced services 58 Staged or related 59 Distinct service 62 Co-surgeons 74 Discontinued post-anesthesia 78 Unplanned return — related 79 Unrelated during global 80 Assistant surgeon LT Left side RT Right side XS Separate structure

What this code covers

Source · Editorial summary grounded in 7 cited references ↓

CPT 27580 covers knee arthrodesis — permanent surgical fusion of the knee joint — performed by any technique. Indications include failed total knee arthroplasty (particularly infected TKA), severe loss of quadriceps function, chronic joint infection, and congenital femoral dysgenesis. Because the technique is not specified, 27580 captures intramedullary rod constructs, external fixation-assisted fusion, plate fixation, and combined approaches under one code.

The 90-day global period means all routine post-operative care from the day before surgery through day 90 is bundled. Bill E/M visits within that window for unrelated problems with modifier 24. Staged or planned additional procedures need modifier 58; unplanned returns to the OR for a related complication use modifier 78; unrelated OR procedures during the global period use modifier 79.

When an infected TKA implant removal (e.g., 27488 or 27091) is performed at the same session as 27580, payer bundling logic is the primary denial risk. Document clearly that the explantation and the fusion are distinct, separately justified surgical steps. Some payers will require modifier 59 or XS; confirm with each MAC before submitting.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	20.57
Practice expense RVU	15.63
Malpractice RVU	4.36
Total RVU	40.56
Medicare national rate	$1,354.74
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	$1,354.74
HOPD (APC 5115) Hospital outpatient department	$13,116.76
ASC (PI J8) Ambulatory surgical center (freestanding)	$8,796.53

Common denial reasons

The recurring reasons claims for CPT 27580 get rejected.

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

Bundling denial when same-day implant removal is billed without a modifier establishing that the two procedures are distinct and separately payable
Medical necessity denial when pre-operative records don't document failure of conservative or less-invasive options prior to proceeding with permanent fusion
Global period violation when post-operative E/M visits are billed without modifier 24 for unrelated conditions or modifier 79 for unrelated procedures
Operative note describes only 'standard approach' or 'knee fusion' without naming fixation method, triggering documentation insufficiency audits
Incorrect laterality — LT or RT modifier omitted, causing claim suspension or rejection under payer edits requiring side designation for lower extremity procedures

Frequently asked questions

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

01Can 27580 be billed the same day as infected TKA implant removal?

Yes, but expect bundling edits. The explantation and the fusion are clinically distinct steps, and most MACs will require modifier 59 or XS on the lower-valued code to override the edit. Document each step separately in the operative note and confirm your MAC's specific modifier preference before submitting.

02Does 27580 require a laterality modifier?

Most payers — including many Medicare MACs — require LT or RT for lower extremity surgical codes. Omitting it is a common suspension trigger. Apply LT or RT on every claim line for 27580.

03What modifiers apply to post-op visits billed during the 90-day global?

Use modifier 24 on E/M visits for problems unrelated to the fusion during the 90-day global. Use modifier 79 if an unrelated procedure is performed in the OR during the global. Modifier 78 covers an unplanned return to the OR for a complication directly related to the fusion.

04Is an external fixator applied at the time of knee fusion separately billable?

Generally no — application of a temporary external fixator used as part of the fusion construct is considered integral to 27580 and not separately reportable. If the fixator serves a distinct, separately documented purpose beyond the fusion itself, consult your MAC policy before adding a separate fixation code.

05What ICD-10 diagnoses support medical necessity for 27580?

Common supporting diagnoses include periprosthetic joint infection after TKA, failed knee replacement, loss of extensor mechanism function, and posttraumatic or septic arthritis with joint destruction. The diagnosis should be specific — nonspecific 'knee pain' codes will not support medical necessity for a permanent fusion procedure.

06Can modifier 22 be used with 27580 for an unusually complex fusion?

Yes, if the procedure required substantially greater work than typical — for example, extensive bone loss requiring structural grafting, severe deformity correction, or prolonged operative time due to prior hardware removal complications. Attach a cover letter quantifying the additional work, and expect the payer to request the operative note before approving the upcharge.

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 fusion technique by name (intramedullary nail, external fixator, plate construct), the operative indication (failed TKA, infection, quadriceps insufficiency), bone graft use, and laterality directly from dictation. That prevents the two most common audit flags for 27580: operative notes that list no fixation method and records that don't explicitly link the indication to the procedure performed.

See how Mira captures CPT 27580 documentation