Narrowing of the neural canal in the rib cage region caused by intervertebral disc pathology, classified under biomechanical lesions (M99) rather than disc displacement or degeneration categories.
Verified May 8, 2026 · 4 sources ↓
- Status
- Billable
- Chapter
- 13
- Related CPT
- 5
- Region
- Spine
Documentation tips
What should appear in the chart to support M99.58.
Source · Editorial brief grounded in 4 cited references ↓
- Specify that neural canal narrowing is attributable to disc tissue at the rib cage / costovertebral level, not to bone or ligament — this distinguishes M99.58 from M99.38 (osseous) and M99.48 (connective tissue).
- Document the clinical findings that support disc-mediated stenosis: restricted motion at the relevant thoracic segment, palpatory findings at costovertebral joints, and any imaging showing disc encroachment on the neural canal.
- If imaging is performed, note the specific thoracic level and disc involved (e.g., T4–T5 costovertebral) to substantiate the rib cage region designation over a standard thoracic spine code.
- Record the reason M99.58 is used instead of a more specific M51 disc code — i.e., the condition meets biomechanical lesion criteria without meeting the threshold for documented disc herniation, displacement, or degeneration.
- For OMT encounters, confirm the M99.58 code aligns with the body region treated and that the somatic dysfunction code (M99.02 for thoracic region) is also captured if separately applicable.
Related CPT procedures
Procedure codes commonly billed with M99.58. 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 M99.58 and adjacent codes.
Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓
- Using M99.58 when a more specific disc diagnosis applies — if the record documents thoracic disc herniation or degeneration, code M51.14 (thoracic disc degeneration) or M51.04 (herniation) instead; M99.58 is a biomechanical lesion code of last resort.
- Confusing the rib cage designation with the thoracic region: M99.52 covers intervertebral disc stenosis of the neural canal at the thoracic vertebral level; M99.58 is reserved for the rib cage articulation zone — verify the anatomy documented.
- Selecting M99.38 (osseous stenosis, rib cage) or M99.48 (connective tissue stenosis, rib cage) when the cause is disc tissue — each subtype in the M99.3–M99.7 range has a distinct etiology that must match the documented mechanism.
- Omitting M99.58 from the claim entirely when it is the only documented diagnosis for a manual therapy encounter, leaving the claim without a billable primary diagnosis code.
Clinical context
Source · Editorial summary grounded in 4 cited references ↓
M99.58 captures intervertebral disc-mediated stenosis of the neural canal specifically at the rib cage (thoracic costovertebral) level. It belongs to the M99.5 subcategory, which distinguishes disc-origin neural canal stenosis from osseous stenosis (M99.3x), connective tissue stenosis (M99.4x), and foraminal stenosis variants (M99.6x–M99.7x). The rib cage designation ('8' as the final digit) is consistent across the M99 series and places this code outside the standard cervical, thoracic, lumbar, or sacral spine designations — use it when the stenotic process is tied to the costovertebral or costotransverse disc articulation zone rather than a classic vertebral segment.
This code sits within Chapter 13 (M00–M99), Biomechanical Lesions Not Elsewhere Classified, meaning it should not be used when a more specific structural diagnosis — such as a herniated thoracic disc (M51.14) or thoracic spinal stenosis of osseous origin — is documented. M99.58 is most defensible when the clinical record attributes neural canal compromise at the rib cage level to disc tissue without specifying degeneration, herniation, or displacement sufficient to warrant a more granular M51 code. It appears frequently in osteopathic and chiropractic billing contexts alongside OMT procedure codes.
When sequencing, list M99.58 as a secondary code if a definitive structural diagnosis drives the encounter. Use it as the primary code when the biomechanical disc stenosis at the rib cage level is itself the documented reason for the visit — for example, a chiropractic encounter targeting thoracic/costal neural canal restriction attributed to disc tissue.
Sibling codes
Other billable codes under M99.5 (laterality / anatomic variants).
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 4 cited references ↓
01What distinguishes M99.58 from M99.52?
02Can M99.58 be used as a primary diagnosis?
03When should I use M51.x instead of M99.58?
04Does M99.58 require a 7th character?
05Is M99.58 appropriate alongside osseous or connective tissue stenosis codes at the same region?
06What CPT codes commonly pair with M99.58?
07Is M99.58 valid for FY2026 ICD-10-CM?
Sources & references
Editorial content was developed using the following public sources. Last verified May 8, 2026.
Mira AI Scribe
The Mira AI Scribe captures the treating clinician's identification of disc-mediated neural canal restriction at the rib cage / costovertebral level — including segmental motion findings, palpatory asymmetry, and any imaging referencing disc encroachment — to support M99.58 over a generic thoracic disc or osseous stenosis code. Precise documentation of the tissue type (disc) and anatomic zone (rib cage) prevents downcoding to an unspecified biomechanical lesion and defends the claim against audit when paired with OMT or manual therapy procedure codes.
See how Mira captures M99.58 documentation