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
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
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).
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 4 cited references ↓
01What distinguishes M43.11 from M43.12 (cervical region spondylolisthesis)?
02Can M43.11 be used for a C1-C2 dislocation following a motor vehicle accident?
03Does M43.11 cover congenital C1-C2 instability?
04Should myelopathy or cord compression be coded separately when present with M43.11?
05What imaging documentation best supports M43.11 on audit?
06Is M43.11 used for os odontoideum-related instability?
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)
- 02icd10data.comhttps://www.icd10data.com/ICD10CM/Codes/M00-M99/M40-M43/M43-/M43.11
- 03aapc.comhttps://www.aapc.com/codes/icd-10-codes/M43.11
- 04outsourcestrategies.comhttps://www.outsourcestrategies.com/blog/how-to-document-spondylolisthesis-with-accurate-icd-10-codes/
Mira AI 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