ICD-10-CM · Spine

M99.43

M99.43 identifies connective tissue stenosis of the neural canal specifically in the lumbar region — a biomechanical lesion in which fibrous or connective tissue encroaches on the lumbar spinal canal, reducing neural space.

Verified May 8, 2026 · 5 sources ↓

Status: Billable
Chapter: 13
Related CPT: 16
Region: Spine

Drawn from CDCICD10DataAAPCCMS

Documentation tips

What should appear in the chart to support M99.43.

Source · Editorial brief grounded in 5 cited references ↓

Specify the tissue type causing stenosis: documentation must identify connective tissue (e.g., ligamentum flavum hypertrophy, fibrosis, scar tissue) as the etiologic factor — not disc herniation or bony osteophyte.
Confirm the lumbar region is explicitly named; lumbosacral involvement also maps to M99.43 per the Alphabetic Index, but the provider's note must state the region.
Record imaging findings that support connective tissue stenosis — MRI signal changes in ligamentum flavum, epidural fibrosis, or soft-tissue canal encroachment — rather than just 'lumbar stenosis.'
Rule out a more specific code first: if the stenosis is attributable to degenerative disc disease or spondylosis, M48.06 or M51.16 may be more appropriate; document why M99.43 applies when those are excluded.
When billing for chiropractic or OMT under Medicare, follow your MAC's LCD — M99.4x codes may require a primary subluxation code (M99.0x) with M99.43 listed as a secondary diagnosis.

Related CPT procedures

Procedure codes commonly billed with M99.43. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

72148 $191.72

Non-contrast MRI of the lumbar spine used to evaluate disc pathology, spinal stenosis, nerve root compression, and other structural abnormalities without administration of contrast material.

72158 $318.31

MRI of the lumbar spinal canal and its contents performed first without contrast, then repeated after contrast administration for enhanced visualization.

72100 $40.42

Radiologic examination of the lumbosacral spine capturing two or three views, used to evaluate the lumbar vertebrae and sacrum for injury, degeneration, or structural abnormality.

72110 $53.44

Radiologic examination of the lumbar spine (lumbosacral) with a minimum of four views, including oblique and/or bending views.

97110 $29.06

Therapeutic exercise billed per 15-minute unit, targeting strength, endurance, range of motion, or flexibility with direct one-on-one patient contact.

63030 $898.15

Single-interspace lumbar laminotomy with nerve root decompression, including partial facetectomy, foraminotomy, and/or herniated disc excision performed via open surgical technique.

63047 $1,065.49

Lumbar laminectomy at a single vertebral segment that also includes facetectomy and foraminotomy for decompression of the spinal cord, cauda equina, and/or nerve roots — unilateral or bilateral.

99213 $95.19

Established patient office or outpatient visit requiring 20–29 minutes of total time or low-complexity medical decision-making.

99214 $135.61

Office visit for an established patient requiring moderate-complexity medical decision making (MDM), or 30–39 minutes of total provider time on the date of service.

72131 View procedure details

97530 View procedure details

98940 View procedure details

98941 View procedure details

98942 View procedure details

62323 View procedure details

64483 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M99.43 and adjacent codes.

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

Defaulting to M99.43 for any lumbar canal narrowing without verifying connective tissue is the documented cause — bony or disc-driven stenosis belongs under M48.06 or M51.x, not M99.4x.
Using M99.43 when a more specific condition can be classified elsewhere: the M99 tabular note explicitly excludes conditions codeable to other chapters; failure to check leads to payer denials and audit exposure.
Confusing M99.43 (neural canal stenosis) with M99.03 (segmental and somatic dysfunction of lumbar region) — they are distinct biomechanical lesion codes and are not interchangeable.
Omitting supporting symptom or radiculopathy codes, leaving the clinical picture incomplete and weakening medical necessity justification for advanced imaging or interventional procedures.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

M99.43 sits under parent category M99.4 (Connective tissue stenosis of neural canal) and applies when connective tissue — not disc material, not bony overgrowth — is the primary cause of lumbar neural canal narrowing. The ICD-10-CM tabular note for M99 specifies this category should not be used if the condition can be classified elsewhere; confirm no more specific lumbar stenosis code (e.g., M48.06, spinal stenosis of lumbar region) better captures the documented pathology before assigning M99.43.

This code is frequently used by chiropractors, osteopathic physicians, and spine-focused orthopedic practices when a biomechanical lesion — rather than degenerative disc or facet pathology — drives the neural canal compromise. The Alphabetic Index cross-references lumbosacral stenosis of connective tissue origin to M99.43 as well, so lumbosacral-documented cases land here unless a more specific code applies.

For MS-DRG grouping purposes, M99.43 maps to DRG 551 (Medical back problems with MCC) or DRG 552 (Medical back problems without MCC) under MS-DRG v43.0. Code it as a primary or significant secondary diagnosis depending on the principal reason for the encounter; pair with symptom codes (e.g., lumbar radiculopathy M54.16, low back pain M54.50) when those symptoms are not integral to the documented biomechanical lesion.

Sibling codes

Other billable codes under M99.4 (laterality / anatomic variants).

M99.48

Connective tissue stenosis of neural canal of rib cage

M99.40

Connective tissue stenosis of neural canal of head region

M99.45

Connective tissue stenosis of neural canal of pelvic region

M99.47

Connective tiss stenosis of neural canal of upper extremity

M99.42

Connective tiss stenosis of neural canal of thoracic region

M99.44

Connective tissue stenosis of neural canal of sacral region

M99.46

Connective tiss stenosis of neural canal of lower extremity

M99.49

Conn tiss stenos of neural canal of abdomen and oth regions

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 5 cited references ↓

01When should I use M99.43 instead of M48.06 for lumbar stenosis?

Use M99.43 when the documented cause of lumbar neural canal narrowing is connective tissue — such as ligamentum flavum hypertrophy or epidural fibrosis. Use M48.06 when the stenosis is attributed to spondylosis or degenerative bony changes. The distinction must be supported by provider documentation and imaging.

02Does M99.43 cover lumbosacral stenosis of connective tissue origin?

Yes. The ICD-10-CM Alphabetic Index cross-references lumbosacral connective tissue neural canal stenosis to M99.43. Document the lumbosacral region explicitly in the clinical note.

03Can M99.43 be used as a primary diagnosis on outpatient claims?

Yes, M99.43 is a fully billable code and can be listed as the primary diagnosis when connective tissue stenosis of the lumbar neural canal is the main reason for the encounter. Add symptom codes (e.g., M54.16, M54.50) as secondary if those symptoms are not integral to the biomechanical lesion.

04What MS-DRGs does M99.43 group to?

M99.43 groups to MS-DRG 551 (Medical back problems with MCC) or MS-DRG 552 (Medical back problems without MCC) under MS-DRG v43.0, per the ICD-10-CM data tables.

05Is M99.43 valid for chiropractic and osteopathic billing under Medicare?

M99.43 can appear on chiropractic or OMT claims, but many MACs — including Novitas — require a primary subluxation code (M99.0x) when billing manipulation CPT codes. Check your specific MAC's LCD before listing M99.43 as the primary diagnosis on chiropractic claims.

06Are there any 7th-character extensions required for M99.43?

No. M99.43 is a 5-character code under Chapter 13 (M00–M99) and does not require a 7th-character extension. Seventh-character extensions (A/D/S) apply to injury S-codes, not M-codes.

07What imaging findings support M99.43 in documentation?

MRI findings such as ligamentum flavum hypertrophy, epidural fibrosis, or soft-tissue narrowing of the lumbar spinal canal support M99.43. CT myelogram findings showing neural canal compromise from non-bony, non-disc soft tissue are also relevant. Record the specific structure involved and the degree of canal compromise.

Sources & references

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

Mira AI Scribe

Mira's AI scribe captures the provider's description of connective tissue involvement at the lumbar neural canal — ligamentum flavum thickening, epidural fibrosis, or soft-tissue encroachment confirmed on MRI — along with the lumbar (or lumbosacral) region designation. This prevents the claim from defaulting to an unspecified or incorrect stenosis code, avoiding downcoding to M48.06 when the pathology is biomechanical, or an audit flag for miscategorized lumbar canal narrowing.

See how Mira captures M99.43 documentation