Glossary · Clinical

ALIF (anterior lumbar interbody fusion)

ALIF (anterior lumbar interbody fusion) is a spinal fusion procedure that accesses the lumbar disc space through an incision in the abdomen, removes the damaged disc, and packs the interspace with bone graft or an interbody device to promote vertebral fusion. It is coded primarily with CPT 22558 and ICD-10-PCS 0SG00A0 for single-level lumbar fusion via open anterior approach.

Verified May 8, 2026 · 7 sources ↓

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Definition

Source · Editorial summary grounded in 7 cited references ↓

In ALIF, the patient lies supine while the surgeon approaches the lumbar spine from the front of the body through a retroperitoneal or transperitoneal corridor. Because the aorta and vena cava overlie the anterior lumbar spine, a vascular or general surgery access surgeon is frequently involved to mobilize those vessels safely before the spine surgeon removes the disc and prepares the endplates. The cleared interspace is then filled with a structural interbody device—typically a cage packed with bone graft material—and may be supplemented with an integrated fixation plate or posterior pedicle screw construct for additional stability.

ALIF is indicated for degenerative disc disease, spondylolisthesis, recurrent disc herniation, pseudarthrosis of a prior fusion, and adjacent-segment disease at lower lumbar levels, particularly L4–L5 and L5–S1. The anterior corridor gives the surgeon unobstructed access to the full disc space, allowing placement of a larger footprint device and better restoration of disc height and lumbar lordosis compared with posterior-only approaches.

From a coding standpoint, ALIF belongs to a family of anterior interbody arthrodesis procedures. The primary level is reported with CPT 22558; each additional interspace adds CPT 22585. Device insertion with integral anterior instrumentation is reported separately with add-on CPT 22853. On the facility side, inpatient encounters use ICD-10-PCS codes anchored by the root operation Fusion, the lumbar vertebral joint body part, an anterior approach, and an interbody fusion device qualifier—yielding codes such as 0SG00A0 (single level) or 0SG10A0 (two or more levels).

Why it matters

Misidentifying the surgical approach—confusing ALIF with PLIF, TLIF, or XLIF—leads to the wrong primary CPT code, which changes the relative value units, the MS-DRG assignment, and ultimately the facility payment by tens of thousands of dollars. For example, ALIF (CPT 22558, APC 5116) reimburses at approximately $27,721 in the outpatient setting under 2026 OPPS rates, while a posterolateral fusion at APC 5117 pays roughly $27,721 but maps to different DRGs on the inpatient side. Failing to append CPT 22853 for a cage with integral anterior fixation leaves a separately billable service on the table, whereas over-reporting it without supporting operative documentation triggers an audit under CMS LCD L37848 for lumbar spinal fusion.

Common mistakes

Where people most often go wrong with this concept.

Source · Editorial brief grounded in cited references ↓

Reporting CPT 22630 (PLIF) or 22633 (TLIF) when the operative report clearly documents an anterior abdominal approach—approach drives code selection, not implant type.
Omitting add-on CPT 22585 when the surgeon fuses more than one lumbar interspace through the same anterior exposure; each additional level requires a separate line.
Failing to report add-on CPT 22853 for a stand-alone interbody cage that includes integral anterior fixation (screws or flanges), which is separately payable and not bundled into 22558.
Using ICD-10-PCS 0SG10A0 (two or more lumbar joints) when only a single level was fused; the operative report must confirm the exact number of interspaces treated.
Appending modifier 62 (co-surgery) when the access surgeon's role is vascular exposure only—modifier 62 is appropriate only when both surgeons perform distinct portions of the same spinal procedure and each documents their distinct work.
Omitting documentation of conservative treatment failure, imaging findings, and functional limitation, all of which are required to satisfy medical necessity under CMS LCD L37848 and most commercial payer clinical policies.
Coding XLIF or DLIF procedures with a lateral interbody CPT rather than 22558—CMS and AAPC guidance confirms that lateral retroperitoneal approaches to the lumbar interbody space are reported with the ALIF code 22558.

Related codes

Codes commonly involved when this concept appears in practice.

CPT

ICD-10

M51.16 M51.17 M43.16 M43.17 M96.1

Modifiers

62 Two surgeons 50 Bilateral procedure 51 Multiple procedures 59 Distinct procedural service 80 Assistant surgeon

Frequently asked questions

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

01What CPT code is used for a single-level ALIF?

CPT 22558 covers anterior interbody arthrodesis at a single lumbar interspace, including the minimal discectomy needed to prepare the space. It does not include the interbody device or any supplemental posterior instrumentation, which are reported separately.

02How do you code a two-level ALIF at L4–L5 and L5–S1?

Report CPT 22558 for the first interspace and add-on CPT 22585 for the second interspace. If an interbody cage with integral anterior fixation is used at each level, also report CPT 22853 for each interspace where that device is placed.

03Can XLIF or DLIF be billed with a different CPT code than ALIF?

No. CMS guidance and AAPC coding resources confirm that XLIF and DLIF—lateral retroperitoneal approaches to the lumbar interbody space—are reported with the same primary code as ALIF, CPT 22558, because they all achieve anterior interbody arthrodesis.

04What ICD-10-PCS code maps to a single-level ALIF performed inpatient?

ICD-10-PCS 0SG00A0 describes fusion of a single lumbar vertebral joint using an interbody fusion device via an anterior approach to the anterior column using an open technique. For two or more lumbar levels, use 0SG10A0.

05Is a vascular access surgeon's work separately billable for an ALIF?

Yes, when a vascular or general surgeon mobilizes vessels to provide access, that surgeon can bill for their work. Modifier 62 applies only when both surgeons contribute distinct components of the spinal procedure itself; pure access work is typically billed under a different mechanism. Verify payer-specific rules before submitting.

06What MS-DRGs apply to inpatient ALIF procedures?

Single-level anterior lumbar fusions typically fall into MS-DRG 518 (spinal fusion without MCC or CC), though the presence of major complications, comorbidities, or a combined anterior-posterior approach can shift the case into MS-DRGs 426–428, with payments ranging from roughly $40,900 to over $80,000 for complex combined cases under 2026 rates.

07What documentation is required to satisfy CMS medical necessity for ALIF?

CMS LCD L37848 for lumbar spinal fusion requires documentation of a specific structural diagnosis (e.g., degenerative disc disease, spondylolisthesis), failure of at least six weeks of conservative non-surgical treatment, relevant imaging confirming pathology, and functional impairment that limits activities of daily living. Missing any of these elements is a common reason for claim denial or post-payment audit recoupment.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

Mira AI Scribe

When Mira captures documentation for an ALIF encounter, the scribe layer should confirm and surface the following elements to support accurate code selection and payer medical necessity review: 1. APPROACH: Operative note must state 'anterior' or 'retroperitoneal/transperitoneal abdominal' approach. If the note says 'posterior' or 'transforaminal,' the primary CPT shifts to 22630 or 22633—flag for surgeon review before claim submission. 2. LEVELS TREATED: Extract the specific interspace(s) (e.g., L4–L5, L5–S1). Single level → CPT 22558. Each additional interspace → add CPT 22585. Populate the level count in the charge capture field. 3. INTERBODY DEVICE WITH INTEGRAL FIXATION: If the operative report describes a cage with built-in screws, flanges, or an anterior plate, CPT 22853 should be added as a separate line per interspace. Mira should alert the coder if device documentation is present but 22853 is missing from the charge. 4. SUPPLEMENTAL POSTERIOR INSTRUMENTATION: If pedicle screws and rods are placed in the same session, a 360-degree or combined fusion scenario exists. CPT 22612 may be separately reportable alongside 22558; NCCI does not bundle these. Flag for coder confirmation. 5. MEDICAL NECESSITY DOCUMENTATION: Surface conservative treatment history (duration, modalities), relevant ICD-10-CM diagnosis codes (degenerative disc disease, spondylolisthesis, pseudarthrosis), and imaging findings from the chart to pre-populate the prior authorization packet and support LCD L37848 criteria. 6. ACCESS SURGEON: If a vascular or general surgeon provided access, their participation should be documented separately. Evaluate whether modifier 62 applies based on distinct documented contributions or whether a different assistant modifier (80, 82) is appropriate.

See Mira's approach

PLIF (posterior lumbar interbody fusion) is a spinal fusion technique in which the surgeon accesses the lumbar disc space from the back of the spine, removes the damaged disc, and inserts an interbody spacer or cage to fuse two adjacent vertebrae into a single solid segment.

TLIF (transforaminal lumbar interbody fusion) Clinical

TLIF (transforaminal lumbar interbody fusion) is a posterior spinal surgery in which the surgeon accesses the disc space through the foramen to remove disc material and pack a cage with bone graft between two lumbar vertebrae, achieving both decompression and fusion from a single posterior approach. It is reported primarily with CPT 22630 for a single interspace, with add-on codes for each additional level.

Spondylolisthesis Clinical

Spondylolisthesis is a spinal condition in which one vertebra slips forward (anterolisthesis) or, less commonly, backward (retrolisthesis) relative to the vertebra below it. It most often occurs at L4–L5 or L5–S1 and ranges in severity from mild instability to frank neurologic compromise.

ICD-10-PCS Coding

ICD-10-PCS (Procedure Coding System) is the U.S. classification system used exclusively in hospital inpatient settings to report surgical and procedural services, assigning a unique 7-character alphanumeric code to each procedure performed. It is distinct from ICD-10-CM, which codes diagnoses.

APC (Ambulatory Payment Classification) Reimbursement

An Ambulatory Payment Classification (APC) is a Medicare prospective payment grouping used under the Outpatient Prospective Payment System (OPPS) that bundles outpatient hospital services with similar clinical intensity and resource cost into a single, fixed reimbursement rate.