ICD-10-CM · Spine

M43.11

Acquired or degenerative anterior displacement of a vertebra in the occipito-atlanto-axial region (the craniocervical junction involving the occiput, C1 atlas, and C2 axis), classified under other deforming dorsopathies.

Verified May 8, 2026 · 4 sources ↓

Status: Billable
Chapter: 13
Related CPT: 10
Region: Spine

Drawn from CDCICD10DataAAPCOutsourcestrategies

Documentation tips

What should appear in the chart to support M43.11.

Source · Editorial brief grounded in 4 cited references ↓

Physician must explicitly name the occipito-atlanto-axial region (occiput, C1, C2) — a generic 'upper cervical' descriptor is insufficient to support M43.11 over M43.12.
Record imaging modality and findings: CT or MRI confirming vertebral displacement at the craniocervical junction, including any dynamic flexion-extension radiograph results showing instability.
Document etiology as acquired or degenerative; if the cause is congenital, route to Q76.2 — M43.11 does not cover congenital spondylolisthesis.
Note whether an acute traumatic mechanism is present; if a fracture caused the slip, code to the appropriate traumatic vertebral fracture code rather than M43.11.
Capture associated neurological findings (myelopathy, radiculopathy, cord compression) as additional diagnosis codes to fully reflect complexity and support medical necessity for surgical intervention.

Related CPT procedures

Procedure codes commonly billed with M43.11. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

22600 $1,282.93

Posterior or posterolateral cervical spinal fusion at a single interspace below C2, performed through a posterior approach to achieve bony arthrodesis.

22595 $1,499.03

Posterior arthrodesis of the atlas and axis (C1-C2), surgically fusing the first and second cervical vertebrae through a posterior approach to stabilize the upper cervical spine.

22830 $791.60

Surgical exploration of a previously performed spinal fusion to assess the integrity of the bone graft, instrumentation, and fusion site.

72125 $130.60

Computed tomography of the cervical spine performed without any contrast agent, used for fracture detection, bony anatomy, and surgical planning.

72127 $196.06

Cervical spine CT acquired first without contrast and then repeated after contrast, with both image sets interpreted together.

72128 $130.26

Computed tomography of the thoracic spine done without contrast, mainly to evaluate fractures, bone detail, and hardware.

72131 $129.93

Computed tomography of the lumbar spine without contrast, used for fractures, bony stenosis, spondylolysis, and checking fusion or screw placement.

72040 $39.75

Radiologic examination of the cervical spine capturing two or three views (e.g., AP, lateral, oblique).

20930 $0.00

Add-on for placing morselized allograft bone or bone-promoting material during spine surgery, reported once per operation.

22840 $668.35

Posterior non-segmental instrumentation placed during spinal surgery, using rods, hooks, or wires that span multiple vertebral levels without anchoring at each intervening segment.

Common coding pitfalls

The recurring mistakes coders make with M43.11 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

Using M43.11 for acute traumatic C1-C2 displacement — acute traumatic cases require a fracture code, not M43.11, per the ICD-10-CM tabular annotation.
Coding M43.11 when documentation only says 'cervical spondylolisthesis' without specifying the occipito-atlanto-axial level — use M43.12 (cervical region) if the level is cervical but not confirmed as C0-C2.
Confusing M43.11 with congenital spondylolisthesis; congenital cases are excluded from M43.1x and belong under Q76.2.
Defaulting to M43.10 (site unspecified) when the imaging report clearly identifies the craniocervical junction — specificity is available and should be used.
Omitting secondary codes for neurological complications such as myelopathy (M47.011, M47.012) or radiculopathy, which are separately billable and critical for medical necessity on surgical claims.

Clinical context

Source · Editorial summary grounded in 4 cited references ↓

M43.11 codes non-congenital, non-acute-traumatic spondylolisthesis specifically localized to the craniocervical junction — the anatomic complex spanning the occiput, atlas (C1), and axis (C2). This is a rare and clinically serious location for vertebral slippage; most spondylolisthesis coding queries involve the lumbar or lumbosacral region, so using M43.11 requires explicit physician documentation placing the pathology at the occipito-atlanto-axial level.

Two important exclusions govern this code. Acute traumatic spondylolisthesis of the upper cervical spine should be coded to the appropriate fracture code (Fracture, vertebra, cervical region) — not M43.11. Congenital spondylolisthesis is excluded entirely and routes to Q76.2. If the physician documents a degenerative or acquired slip at C1-C2 or the occipitoatlantal joint without a qualifying traumatic event, M43.11 is correct.

In practice, M43.11 appears on claims tied to upper cervical decompression, occipitocervical fusion, or diagnostic workup for instability at the craniocervical junction. Always verify that imaging (CT, MRI, or dynamic flexion-extension radiographs) documents the slip and that the operative or clinical note names the occipito-atlanto-axial region specifically, rather than simply 'cervical' or 'upper cervical.' If the physician documents cervical spondylolisthesis without specifying the occipito-atlanto-axial level, use M43.12 (cervical region) instead.

Sibling codes

Other billable codes under M43.1 (laterality / anatomic variants).

M43.19

Spondylolisthesis, multiple sites in spine

M43.14

Spondylolisthesis, thoracic region

M43.12

Spondylolisthesis, cervical region

M43.17

Spondylolisthesis, lumbosacral region

M43.15

Spondylolisthesis, thoracolumbar region

M43.16

Spondylolisthesis, lumbar region

M43.18

Spondylolisthesis, sacral and sacrococcygeal region

M43.10

Spondylolisthesis, site unspecified

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 4 cited references ↓

01What distinguishes M43.11 from M43.12 (cervical region spondylolisthesis)?

M43.11 is restricted to the occipito-atlanto-axial complex (occiput, C1, C2). M43.12 covers the mid-to-lower cervical spine (C3-C7). Use M43.11 only when the physician and imaging specifically identify the craniocervical junction as the site of slippage.

02Can M43.11 be used for a C1-C2 dislocation following a motor vehicle accident?

No. Acute traumatic displacements at any cervical level should be coded to the appropriate traumatic vertebral fracture or dislocation code. The ICD-10-CM tabular instructs coders to route acute traumatic spondylolisthesis at sites other than lumbosacral to the fracture category, not M43.11.

03Does M43.11 cover congenital C1-C2 instability?

No. Congenital spondylolisthesis is explicitly excluded from the M43.1x category and should be reported with Q76.2 (Congenital spondylolisthesis). M43.11 covers only acquired or degenerative pathology at the craniocervical junction.

04Should myelopathy or cord compression be coded separately when present with M43.11?

Yes. Associated myelopathy, radiculopathy, or cord compression carries its own ICD-10-CM code (e.g., M47.011 or M47.012 for spondylotic myelopathy at the occipito-atlanto-axial and cervical levels). Reporting both codes accurately reflects clinical complexity and supports medical necessity.

05What imaging documentation best supports M43.11 on audit?

CT or MRI findings showing anterior vertebral displacement at the craniocervical junction, with or without dynamic flexion-extension radiograph confirmation of instability. Imaging reports should name the involved level (C0-C1 or C1-C2) explicitly.

06Is M43.11 used for os odontoideum-related instability?

Os odontoideum is a separate structural anomaly (often coded as a congenital condition under Q76.x). If the resulting instability is documented as acquired spondylolisthesis at the C1-C2 level, physician documentation and clinical context must guide code selection — this is a genuinely ambiguous scenario that warrants coder-physician query.

Sources & references

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

01CDC ICD-10-CM Tabular List 2026 (FY2026, effective October 1, 2025)
02
icd10data.com
https://www.icd10data.com/ICD10CM/Codes/M00-M99/M40-M43/M43-/M43.11
03
aapc.com
https://www.aapc.com/codes/icd-10-codes/M43.11
04
outsourcestrategies.com
https://www.outsourcestrategies.com/blog/how-to-document-spondylolisthesis-with-accurate-icd-10-codes/

Mira Scribe

Mira captures the physician's explicit identification of the occipito-atlanto-axial region (C0-C2) as the site of vertebral displacement, the documented etiology (degenerative/acquired vs. traumatic vs. congenital), and supporting imaging findings such as CT or MRI evidence of anterior vertebral slip at the craniocervical junction. This prevents downcoding to M43.10 (site unspecified) or misdirection to M43.12 (cervical) and flags cases that should route to a fracture code or Q76.2 instead.

See how Mira captures M43.11 documentation