Surgical reshaping or reconstruction of the acetabulum (hip socket) to correct deformity, relieve impingement, or address dysplasia — performed without prosthetic joint replacement.

Verified May 8, 2026 · 6 sources ↓

Medicare: $1,182.73
Total RVUs: 35.41
Global, days: 90
Region: Hip

Drawn from CMSAcgmeZimmerbiometAapcperfect

Documentation requirements

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

Source · Editorial brief grounded in 6 cited references ↓

Specify the named technique performed (e.g., Whitman, Colonna, Haygroves, cup-type) — 'standard acetabuloplasty' is insufficient for audit defense.
Document the indication with specificity: congenital dysplasia, acquired deformity, osteoarthritis — and why joint preservation was chosen over replacement.
Include preoperative imaging (X-ray, CT, or MRI) findings in the operative note or referenced directly in the record to support medical necessity.
Confirm in the operative note that no prosthetic acetabular component was implanted — absence of implant distinguishes 27120 from 27130/27137.
Document laterality explicitly (left, right, or bilateral) to support modifier application and payer audit review.
Record patient age and skeletal maturity when the indication involves congenital or developmental pathology, as payers may scrutinize medical necessity for adult patients.

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 50 Bilateral procedure 51 Multiple procedures 52 Reduced services 57 Decision for surgery 58 Staged or related 59 Distinct service 62 Co-surgeons 78 Unplanned return — related 79 Unrelated during global 80 Assistant surgeon LT Left side RT Right side

What this code covers

Source · Editorial summary grounded in 6 cited references ↓

CPT 27120 covers acetabuloplasty: open surgical remodeling of the acetabular cup to restore normal hip joint mechanics. Historically associated with procedures such as Whitman, Colonna, Haygroves, and cup-type techniques, this code applies when the surgeon modifies the bony architecture of the socket itself rather than implanting a prosthetic component. Indications include congenital hip dysplasia, acetabular insufficiency, and select cases of hip osteoarthritis where joint preservation — not replacement — is the goal.

This is not a total hip arthroplasty code. If you're billing for a procedure that includes an acetabular prosthetic component, you're in the 27130–27138 range. 27120 sits in the osteotomy/hip reconstruction category alongside 27122 (Girdlestone resection) and is tracked by ACGME fellowship programs under 'Osteotomy Hip.' The 90-day global period applies: all routine post-op care through day 90 is bundled. Unrelated E/M services in that window require modifier 24; a separately identifiable same-day E/M needs modifier 25.

Site-of-service matters here. CMS assigns an OPPS status indicator of 'C' for 27120, meaning it is not separately payable in the hospital outpatient or ASC setting under Medicare — it is packaged or not recognized as independently reimbursable in those environments. Physician billing follows the Physician Fee Schedule regardless of setting, but facility payment strategy must account for this packaging status.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	18.77
Practice expense RVU	12.65
Malpractice RVU	3.99
Total RVU	35.41
Medicare national rate	$1,182.73
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	$1,182.73
HOPD (APC 5115) Hospital outpatient department	$13,116.76
ASC (PI J8) Ambulatory surgical center (freestanding)	$9,493.97

Common denial reasons

The recurring reasons claims for CPT 27120 get rejected.

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

Upcoding to 27130 or 27137 when no prosthetic component was placed — auditors look for implant invoices that don't match the billed code.
Medical necessity not established: operative note lacks imaging correlation or fails to explain why reconstruction rather than replacement was performed.
Facility billing 27120 as separately payable in the HOPD or ASC setting — CMS OPPS status indicator 'C' packages or excludes this code in those environments.
Missing laterality modifier when payer policy requires LT or RT for unilateral hip procedures.
Global period violations: billing routine post-op E/M visits within the 90-day global without modifier 24, triggering automatic denial.

Frequently asked questions

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

01What is the difference between CPT 27120 and CPT 27130?

27120 is acetabuloplasty — the surgeon reshapes the native bone without implanting a prosthetic component. 27130 is total hip arthroplasty, which replaces both the acetabulum and proximal femur with prosthetic components. If a cup implant goes in, you're not in 27120 territory.

02Can 27120 be billed in an ASC or hospital outpatient department under Medicare?

No. CMS assigns 27120 an OPPS status indicator of 'C,' meaning the facility payment is packaged or not separately recognized in the HOPD or ASC setting. Physician fees still follow the Physician Fee Schedule. Confirm non-Medicare payer contracts separately — commercial policies vary.

03What is the global period for 27120?

90 days. The day-before visit, the procedure day, and all routine post-op care through day 90 are bundled. Use modifier 24 for unrelated E/M visits in that window, modifier 79 for an unrelated surgical procedure, and modifier 78 if you return to the OR for a related complication.

04When is modifier 22 appropriate with 27120?

When the acetabuloplasty involves substantially more work than typical — severe deformity, complex prior surgical anatomy, or unusually prolonged operative time. You need a cover letter, the operative note, and documentation of the specific factors that increased complexity. Without that, payers will deny the upcharge.

05Can 27120 and 27130 be billed together on the same operative session?

No. If the procedure progresses to prosthetic replacement, bill 27130 — not 27120 plus 27130. Reporting both implies the surgeon performed two distinct procedures, which is not supported when the session results in a total hip arthroplasty.

06Is 27120 ever billed bilaterally?

Rarely, but yes — bilateral acetabuloplasty in the same session would use modifier 50. Payer authorization requirements for bilateral hip procedures are strict; confirm prior auth covers bilateral before assuming reimbursement.

07What ICD-10 diagnoses support medical necessity for 27120?

Congenital hip dysplasia (Q65.xx), acetabular dysplasia (M16.2, M16.3 for post-traumatic), and hip osteoarthritis codes (M16.xx) are the primary drivers. The diagnosis must justify joint preservation over replacement — payers scrutinize this in adult patients with advanced arthritis.

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 named acetabuloplasty technique from dictation (Whitman, Colonna, Haygroves, cup-type), the specific indication (dysplasia, impingement, osteoarthritis), laterality, and explicit confirmation that no prosthetic component was implanted. That last capture point prevents the most common audit flag on 27120: an operative note that reads ambiguously enough to look like a partial arthroplasty, inviting a 27130 upcoding allegation or a medical necessity denial.

See how Mira captures CPT 27120 documentation