Adult osteochondrosis of the spine localized to the occipito-atlanto-axial region — the articulations between the occiput, atlas (C1), and axis (C2) — in a skeletally mature patient.
Verified May 8, 2026 · 4 sources ↓
- Status
- Billable
- Chapter
- 13
- Related CPT
- 7
- Region
- Spine
Documentation tips
What should appear in the chart to support M42.11.
Source · Editorial brief grounded in 4 cited references ↓
- Explicitly name the region as 'occipito-atlanto-axial,' 'C0-C1-C2,' or 'atlantoaxial/atlanto-occipital' — vague 'cervical spine' language maps to M42.12, not M42.11.
- Record imaging findings that support osteochondrosis: endplate irregularity, disc height loss, or subchondral sclerosis on plain films or MRI of the upper cervical spine.
- Note patient age and skeletal maturity to distinguish adult osteochondrosis (M42.11) from juvenile osteochondrosis (M42.01) — the ICD-10-CM structure separates these by category.
- Document whether neurologic or myelopathic symptoms are present; their presence may require an additional code (e.g., M43.3) and affects DRG assignment.
- If conservative care or physical/occupational therapy is being ordered, confirm the record reflects the functional limitation and treatment rationale to satisfy LCD medical necessity requirements.
Related CPT procedures
Procedure codes commonly billed with M42.11. 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 M42.11 and adjacent codes.
Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓
- Assigning M42.12 (cervical region) when the documented pathology is at the occiput-C1-C2 level — the cervical region code applies to C2-C6, not the craniocervical junction.
- Using the unspecified parent code M42.10 when the provider has documented upper cervical or atlantoaxial involvement — that specificity supports M42.11 and should be coded accordingly.
- Confusing juvenile and adult osteochondrosis categories: M42.01 is juvenile (skeletally immature); M42.11 is adult — patient age and growth-plate status determine the correct subcategory.
- Failing to add a secondary neurologic code when the provider documents cord compression or myelopathy alongside the osteochondrosis diagnosis, which can affect DRG weight and medical necessity documentation.
- Applying M42.11 to traumatic or infectious spinal conditions — osteochondrosis is a degenerative, non-infectious process; use appropriate S-codes or infectious disease codes when etiology differs.
Clinical context
Source · Editorial summary grounded in 4 cited references ↓
M42.11 is the billable code for adult spinal osteochondrosis confined to the upper cervical region: the occiput-C1-C2 complex. Use it when the provider documents degenerative or osteochondrotic changes at the atlanto-occipital or atlantoaxial joints in an adult. This region is anatomically distinct from the mid- and lower cervical spine, so M42.12 (cervical) and M42.13 (cervicothoracic) are not interchangeable with M42.11 — laterality does not subdivide this code, but regional specificity does.
Osteochondrosis at this level can present with occipital headache, upper cervical pain, restricted rotation, and, in severe cases, myelopathic symptoms. If atlantoaxial instability with myelopathy is the primary finding, also evaluate M43.3 (recurrent atlantoaxial dislocation with myelopathy) as a potential alternative or additional code. CMS outpatient occupational therapy LCD A53064 explicitly lists M42.11 among ICD-10-CM codes that support medical necessity for rehabilitative services.
If the osteochondrosis spans more than one spinal region, step out to M42.19 (multiple sites). If the clinical documentation lacks regional specificity, M42.10 (site unspecified) is the fallback, but it is a weaker claim for medical necessity and should prompt a clarification query to the treating provider.
Sibling codes
Other billable codes under M42.1 (laterality / anatomic variants).
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 4 cited references ↓
01What distinguishes M42.11 from M42.12?
02Can M42.11 be used for a pediatric patient?
03Should M42.11 and M43.3 ever be coded together?
04Does M42.11 support medical necessity for outpatient occupational therapy under Medicare?
05What imaging documentation best supports M42.11?
06If osteochondrosis involves both the occipito-atlanto-axial region and the cervical region, which code applies?
Sources & references
Editorial content was developed using the following public sources. Last verified May 8, 2026.
- 01CDC ICD-10-CM Tabular List 2026 — https://www.cdc.gov/nchs/icd/icd-10-cm/files.html
- 02icd10data.com M42.11 — https://www.icd10data.com/ICD10CM/Codes/M00-M99/M40-M43/M42-/M42.11
- 03CMS LCD Article A53064 Outpatient Occupational Therapy — https://www.cms.gov/medicare-coverage-database/view/article.aspx?articleid=53064
- 04AAPC Codify M42.1 — https://www.aapc.com/codes/icd-10-codes/M42.1
Mira AI Scribe
The Mira AI Scribe captures the provider's explicit notation of the affected spinal region (occiput, atlas, axis, or C0-C2 complex), any imaging evidence of endplate irregularity or subchondral changes, presence or absence of neurologic symptoms, and patient adult age/skeletal maturity status. This specificity locks in M42.11 over the unspecified M42.10, preventing a downcode and supporting LCD medical necessity criteria for physical or occupational therapy authorization.
See how Mira captures M42.11 documentation