M99.38 identifies bone-related narrowing of the neural canal specifically within the rib cage region, classified as a biomechanical lesion not classifiable elsewhere.
Verified May 8, 2026 · 5 sources ↓
- Status
- Billable
- Chapter
- 13
- Related CPT
- 10
- Region
- Spine
Documentation tips
What should appear in the chart to support M99.38.
Source · Editorial brief grounded in 5 cited references ↓
- Specify that stenosis is osseous (bone-driven) — not disc, ligamentous, or soft-tissue — to justify M99.38 over other thoracic stenosis codes.
- Record imaging findings that confirm bony encroachment: CT or MRI showing cortical thickening, osteophyte formation, or costovertebral joint hypertrophy at the rib cage level.
- Note the clinical rationale for using a biomechanical (M99) code rather than a more specific structural diagnosis — document that no classifiable underlying condition accounts for the stenosis.
- Capture associated neurologic symptoms (intercostal neuralgia, radicular chest-wall pain, dermatomal paresthesia) to support medical necessity for imaging and treatment.
- If chiropractic services are billed to Medicare, document the subluxation complex or biomechanical lesion in terms that satisfy CMS chiropractic coverage criteria alongside M99.38.
Related CPT procedures
Procedure codes commonly billed with M99.38. 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 M99.38 and adjacent codes.
Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓
- Billing M99.3 (parent, non-billable) instead of the fully specified M99.38 — payers will reject the claim for insufficient specificity.
- Using M99.38 when the stenosis has a codeable primary cause (e.g., ankylosing spondylitis, Paget disease, rib fracture malunion) — M99 requires that the condition cannot be classified elsewhere.
- Confusing M99.38 with M99.32 (osseous stenosis of neural canal of thoracic region) — the rib cage is a distinct anatomic zone in this subcategory; choose based on the documented site.
- Applying M99.38 for soft-tissue or disc-mediated canal narrowing — M99.3x is osseous only; ligamentous and connective tissue stenosis fall under M99.4x–M99.6x subcategories.
Clinical context
Source · Editorial summary grounded in 5 cited references ↓
M99.38 applies when bony structural changes cause narrowing of the neural canal at the thoracic rib cage level — distinct from soft-tissue, connective tissue, or intervertebral disc-driven stenosis at the same site. The parent category M99 (Biomechanical lesions, not elsewhere classified) carries a critical note: use it only when the condition cannot be coded under a more specific category. If the osseous stenosis has an identifiable underlying cause — such as a fracture, neoplasm, or spondyloarthropathy — code that condition first and determine whether M99.38 adds necessary specificity.
Within the M99.3x subcategory, the 8th character distinguishes anatomic region: M99.30 (head), M99.31 (cervical), M99.32 (thoracic), M99.33 (lumbar), M99.34 (sacral), M99.35 (pelvic), M99.36 (lower extremity), M99.37 (upper extremity), M99.38 (rib cage), M99.39 (abdomen and other regions). Do not use the parent M99.3 for billing — it is non-specific and will be rejected.
This code surfaces most often in chiropractic, pain management, and thoracic spine practices where intercostal nerve impingement or costotransverse joint ossification produces radicular or referred chest-wall symptoms. It is not laterality-specific; the rib cage is treated as a single anatomic zone at this level of classification.
Sibling codes
Other billable codes under M99.3 (laterality / anatomic variants).
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 5 cited references ↓
01Is M99.38 billable, or do I need a more specific code?
02What is the difference between M99.38 and M99.32?
03Can M99.38 be used as a primary diagnosis for chiropractic claims?
04Does M99.38 require a 7th-character extension?
05When should I use M99.38 versus a thoracic spondylosis code like M47.814?
06What imaging best supports M99.38?
Sources & references
Editorial content was developed using the following public sources. Last verified May 8, 2026.
- 01CDC ICD-10-CM Tabular List 2026 (effective Oct 1, 2025)
- 02icd10data.comhttps://www.icd10data.com/ICD10CM/Codes/M00-M99/M99-M99/M99-/M99.38
- 03icd10data.comhttps://www.icd10data.com/ICD10CM/Codes/M00-M99/M99-M99/M99-/M99.3
- 04aapc.comhttps://www.aapc.com/codes/icd-10-codes/M99.38
- 05cms.govhttps://www.cms.gov/medicare/coding-billing/icd-10-codes
Mira AI Scribe
Mira's AI scribe captures the provider's explicit language about bone-driven neural canal narrowing at the rib cage — including imaging findings (CT/MRI evidence of osteophytes, cortical hypertrophy, or costovertebral bony encroachment), associated intercostal or radicular symptoms, and confirmation that no more-specific classifiable condition underlies the stenosis. This prevents downgrade to the non-billable M99.3 parent and guards against payer denial for unspecified biomechanical lesion coding.
See how Mira captures M99.38 documentation