Surgical · Hip

Osteotomy of the iliac, acetabular, or innominate bone without open reduction of the hip joint

Verified May 8, 2026 · 7 sources ↓

Medicare: $1,169.03
Total RVUs: 35
Global, days: 90
Region: Hip

Drawn from CMSAAPCKzanowJposnaGenhealth

Documentation requirements

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

Source · Editorial brief grounded in 7 cited references ↓

Specify which bone was cut: iliac, acetabular, or innominate — generic 'pelvic osteotomy' language invites downcoding
Confirm no open reduction of the hip was performed; if it was, 27147 is the correct code
If billing multiple units for separate bones, the operative note must identify each bone independently with its own osteotomy description
Document the underlying diagnosis driving the osteotomy (e.g., hip dysplasia, congenital deformity, acetabular retroversion) with a matching ICD-10 code
Record laterality (right, left, or bilateral) explicitly in the operative note to support LT, RT, or modifier 50
For staged or revision procedures within the 90-day global, document that the reason for return was distinct from or related to the index procedure to justify modifier 78 or 79

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 76 Repeat, same 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 27146 covers a pelvic osteotomy — a surgical cut through the iliac, acetabular, or innominate bone — performed to correct hip dysplasia, congenital deformity, or structural malalignment of the acetabulum. The procedure repositions the bony anatomy to improve joint coverage, stability, and load distribution without simultaneously performing an open reduction of the hip. If open reduction is added, step up to 27147 instead.

Billing 27146 correctly hinges on understanding its unit rules. Per CPT Assistant guidance, the code is reported once per bone regardless of how many cuts are made in that bone. If the surgeon osteotomizes two separate bones (e.g., the iliac and the innominate), you can report 27146 twice — once per bone. However, a periacetabular osteotomy (PAO/Ganz) involves multiple cuts through the acetabulum itself and does not map cleanly to 27146; most payers require 27299 (unlisted pelvis/hip) for PAO, with 27146 units cited as the comparison code for valuation.

The 90-day global period means all routine follow-up through day 90 is bundled. Separate same-day or post-op services need modifier 24, 25, 57, 58, 78, or 79 as appropriate. Laterality modifiers LT and RT are expected whenever a single hip is addressed; modifier 50 applies for true bilateral cases performed in the same operative session.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	18.45
Practice expense RVU	12.62
Malpractice RVU	3.93
Total RVU	35
Medicare national rate	$1,169.03
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	$1,169.03
HOPD (APC 5114) Hospital outpatient department	$7,413.38
ASC (PI J8) Ambulatory surgical center (freestanding)	$4,682.29

Common denial reasons

The recurring reasons claims for CPT 27146 get rejected.

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

Billing 27146 multiple units for multiple cuts within a single bone — CPT Assistant limits it to one unit per bone, not per osteotomy site
Using 27146 for a periacetabular osteotomy (Ganz/PAO) — payers treating PAO as an unlisted procedure will deny 27146 as mismatched to the operative report
Missing or mismatched laterality modifier when a single-side procedure is billed without LT or RT
Unbundling associated arthroscopic procedures without recognizing that some payers consider them inclusive to 27146 when performed at the same session — check NCCI edits and individual payer policies
Submitting 27146 when 27147 is warranted because the operative report documents concurrent open reduction of the hip

Frequently asked questions

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

01Can I bill 27146 multiple times for a periacetabular osteotomy (Ganz PAO)?

No. PAO involves multiple cuts through the acetabulum — a single bone — and does not meet the criteria for multiple 27146 units. Most payers require 27299 (unlisted pelvis/hip) for PAO, with 27146 units cited as a comparison code for payment valuation purposes.

02When is it correct to bill 27146 more than once on the same date?

Only when separate osteotomies are performed on anatomically distinct bones — for example, the iliac and the innominate. Each bone gets one unit. Multiple cuts within the same bone still equal one unit of 27146.

03What is the difference between 27146 and 27147?

27147 is used when the osteotomy is accompanied by an open reduction of the hip joint. If the surgeon corrects the bony anatomy only — no open reduction — 27146 is correct. The operative note must clearly state whether the hip was openly reduced.

04Does the 90-day global period affect billing for post-op hip dysplasia follow-up?

Yes. Routine post-op visits, dressing changes, and hardware checks within 90 days are bundled. Use modifier 24 for unrelated E/M visits, modifier 58 for planned staged procedures, and modifier 78 for an unplanned return to the OR for a related complication.

05Should I use modifier 50 or separate LT/RT codes for bilateral pelvic osteotomies?

Modifier 50 is appropriate when both hips are addressed in the same operative session. For a single-hip procedure, append LT or RT. Some payers prefer two line items with LT and RT over a single line with modifier 50 — verify payer preference before submitting.

06Can arthroscopic procedures performed at the same session as 27146 be billed separately?

Potentially, but check NCCI edits first. The AAOS global service guidelines for 27146 do not explicitly include labral repair or femoroplasty, so separate arthroscopic billing may be appropriate — but individual payer policies vary and modifier 59 or XS may be required to bypass a bundling edit.

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 specific bone(s) cut (iliac, acetabular, or innominate), confirms the absence of open hip reduction, records laterality, and flags if multiple bones were addressed in a single session. That documentation prevents the two most common 27146 denials: miscoded PAO cases billed as 27146 and multi-unit claims rejected because the note doesn't distinguish bone-by-bone osteotomy sites.

See how Mira captures CPT 27146 documentation