Summary & Overview

CPT 27146: Pelvic Osteotomy — Iliac/Acetabular/Innominate Bone

CPT code 27146 denotes a pelvic osteotomy — a surgical cutting of the iliac, acetabular, or innominate bone to address structural abnormalities of the hip and pelvis. This code captures complex reconstructive work on the pelvic girdle that can affect hip joint mechanics, stability, and long-term function. Nationally, pelvic osteotomies are significant because they represent specialized orthopedic care with implications for surgical resource allocation, reimbursement policy, and post-operative care pathways.

Key payers in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. The publication outlines how these payers typically categorize and reimburse reconstructive pelvic surgery, and it highlights where national payers converge and differ in coverage and claim adjudication practices.

Readers will learn clinical context for CPT code 27146, typical settings where the procedure is performed, and the policy-relevant considerations that affect billing and coverage. The report summarizes benchmark expectations for surgical service lines, common billing modifiers used with complex orthopedic procedures (list provided separately), and areas where payers may require documentation to support medical necessity. Data not available in the input is explicitly noted where applicable.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicare27146CPTpelvic osteotomyorthopedic surgeryhip reconstructionsurgical procedureambulatory surgeryhospital services

Billing Code Overview

CPT code 27146 describes an osteotomy of the pelvis, involving cutting a portion of the iliac, acetabular, or innominate bone. The procedure addresses structural or anatomic problems of the pelvic bones and acetabulum that affect hip stability, alignment, or joint mechanics.

Service type: Surgical procedure — pelvic/hip osteotomy

Typical site of service: Hospital operating room or ambulatory surgical center where orthopedic pelvic or hip reconstructive surgery is performed.

Clinical & Coding Specifications

Clinical Context

A typical patient is a 16–30-year-old with symptomatic acetabular dysplasia or malorientation presenting with lateral hip pain, activity-related groin pain, and progressive hip instability. After conservative management (physical therapy, activity modification, NSAIDs, and intra-articular injection) fails, the orthopedic surgeon evaluates imaging including AP pelvis radiographs, CT scan with 3D reconstruction, and MRI to assess acetabular coverage and labral/chondral pathology. When undercoverage or malalignment is identified, the surgeon schedules an open pelvic osteotomy such as a periacetabular osteotomy (ilium/acetabulum osteotomy) to reorient the acetabular socket.

Preoperative workflow includes history/physical, medical clearance, informed consent documenting indication and laterality, templating, and anesthesia evaluation. In the operating room the patient is positioned supine or lateral, and the provider performs an osteotomy of the iliac, acetabular, or innominate bone to reorient the acetabulum and improve femoral head coverage. Fixation with plates/screws is typically performed and intraoperative fluoroscopy verifies correction. Postoperative care involves inpatient pain control, DVT prophylaxis, limited weight bearing, physical therapy, and follow-up imaging to confirm osteotomy healing.

Coding Specifications

Modifier	Description	When to Use
`50`	Bilateral procedure	Use when both pelvic sides undergo osteotomy and payer requires bilateral reporting.
`RT`	Right side	Use to indicate the procedure was performed on the right pelvic bone when side-specific reporting is required.
`LT`	Left side	Use to indicate the procedure was performed on the left pelvic bone when side-specific reporting is required.
`62`	Concurrent major procedure by two surgeons	Use when two surgeons of different specialties simultaneously perform parts of the operation (co-surgery) on the pelvis.
`66`	Surgical team reporting	Use when a surgical team reports the procedure per payer policy in complex pelvic reconstruction.
`80`	Assistant surgeon - primary	Use when an assistant surgeon provides general assistance and payer requires modifier for reimbursement.
`81`	Minimum assistant surgeon	Use when minimal assistant involvement is documented and payer recognizes reduced assistant fee.
`82`	Assistant surgeon when qualified resident unavailable	Use when a nonphysician or certified assistant provides assistance due to resident unavailability.
`22`	Increased procedural services	Use when work, complexity, time, or technical difficulty substantially exceed usual for the osteotomy.
`52`	Reduced services	Use when the procedure is partially performed or aborted and documentation supports reduced service.
`53`	Discontinued procedure	Use when the procedure is started but terminated due to extenuating circumstances before completion.
`59`	Distinct procedural service	Use to indicate a separate and distinct service when another unrelated procedure is billed same day.
`58`	Staged or related procedure or service by same physician during postoperative period	Use when the osteotomy is staged and a planned subsequent procedure occurs during the global period.
`73`	Discontinued outpatient hospital/ASC procedure prior to anesthesia administration	Use when the osteotomy was cancelled after patient arrival to facility but before anesthesia.
`78`	Return to OR for related procedure during global period	Use when a return to the operating room for a related issue (e.g., fixation revision) occurs during the global period.

Taxonomy Code	Specialty	Notes
207X00000X	Orthopaedic Surgery	Primary specialty that performs pelvic and acetabular osteotomies.
2080P0208X	Pediatric Orthopedic Surgery	Common for developmental dysplasia of the hip and adolescent pelvic osteotomies.
2080S0105X	Adult Reconstructive Orthopedics	Performs complex pelvic realignments and acetabular reorientation in young adults.
207L00000X	Orthopaedic Trauma	Involved when osteotomy is performed in the setting of pelvic fractures or posttraumatic deformity.
207K00000X	Orthopaedic Sports Medicine	May participate when concomitant hip arthroscopy or labral repair is performed.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`M16.0`	Primary osteoarthritis of hip, bilateral	Osteoarthritis with acetabular deformity may be an indication for corrective osteotomy in younger patients to delay arthroplasty.
`Q65.8`	Other congenital deformities of hip	Developmental dysplasia and other congenital hip deformities are common indications for pelvic/acetabular osteotomy.
`M16.1`	Unilateral primary osteoarthritis of hip	Side-specific degenerative changes with focal acetabular malcoverage may prompt osteotomy in select patients.
`M24.85`	Other specific joint derangements of hip	Chronic hip instability or femoroacetabular incongruity potentially treated with reorienting osteotomy.
`M25.851`	Pain in right hip	Symptom code commonly associated with hip pathology leading to surgical correction.
`M25.852`	Pain in left hip	Side-specific symptom code guiding laterality documentation for the osteotomy.
`S73.1XXA`	Dislocation of hip, initial encounter	Posttraumatic acetabular malunion or instability after dislocation can necessitate pelvic osteotomy for reconstruction.
`M17.0`	Primary osteoarthritis of knee, bilateral	Included only when combined lower-extremity alignment issues contribute to hip mechanics and surgical planning involves osteotomy coordination.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`27130`	Arthroplasty, acetabular and proximal femoral prosthetic replacement (total hip arthroplasty)	May be performed if osteotomy is not indicated or as a staged procedure for advanced degenerative disease.
`27299`	Unlisted procedure, pelvis or hip joint	Used for pelvic procedures not described by a specific CPT code when an osteotomy variant lacks a distinct code.
`27216`	Osteotomy, femoral, proximal, with or without internal fixation	Performed when combined femoral and pelvic realignment are required (combined femoral osteotomy and pelvic osteotomy).
`29862`	Hip arthroscopy, surgical; with femoroplasty (e.g., for cam lesion)	May be performed in the same episode to address intra-articular pathology such as labral tears concurrent with acetabular reorientation.
`20690`	Application of external fixation device (unlisted)	May be used if temporary external fixation is required for complex pelvic stabilization during or after osteotomy.
`20936`	Bone allograft, morselized, or placement of osteobiologic graft	Used when structural bone grafting is required to augment acetabular reconstruction or fill defects created by osteotomy.