ICD-10-CM · Spine

M46.87

M46.87 classifies inflammatory spondylopathies of the lumbosacral region that are specified but do not fit any named inflammatory spondylopathy category — such as ankylosing spondylitis (M45) or sacroiliitis (M46.1) — when the pathology involves the L5-S1 junction and surrounding structures.

Verified May 8, 2026 · 5 sources ↓

Status: Billable
Chapter: 13
Related CPT: 12
Region: Spine

Drawn from CDCICD10DataAAPCCMSAAOS

Documentation tips

What should appear in the chart to support M46.87.

Source · Editorial brief grounded in 5 cited references ↓

Name the specific inflammatory condition — 'undifferentiated spondyloarthropathy, lumbosacral region' or 'reactive spondylitis at L5-S1' — rather than a generic 'low back pain with inflammation' to justify M46.87 over a symptom code.
Confirm the region explicitly: document 'lumbosacral' or reference L5-S1 involvement by level. 'Lumbar spine' alone maps to M46.86, not M46.87.
Record imaging findings that support an inflammatory etiology — MRI bone marrow edema, erosions at the L5-S1 endplates, or gadolinium enhancement — to substantiate the inflammatory spondylopathy classification.
Document that more specific inflammatory spondylopathy categories (ankylosing spondylitis, sacroiliitis NEC, spinal osteomyelitis) were considered and do not fit the clinical picture, establishing why 'other specified' is the correct level of specificity.
Note relevant lab markers (elevated CRP, ESR, HLA-B27 status) in the assessment — payers use this to validate inflammatory vs. mechanical back conditions when reviewing medical necessity for advanced imaging or biologics.

Related CPT procedures

Procedure codes commonly billed with M46.87. 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.

27096 $175.69

Injection into the sacroiliac joint with fluoroscopic or CT image guidance, including arthrography when performed.

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.

99215 $192.39

Highest-level office or outpatient E/M visit for an established patient, qualifying via high-complexity medical decision making or 40–54 minutes of total provider time on the date of service.

72149 View procedure details

64483 View procedure details

64484 View procedure details

77080 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M46.87 and adjacent codes.

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

Assigning M46.87 when M46.86 (lumbar region) is correct — the lumbosacral code requires documented involvement at the L5-S1 junction, not just general lower lumbar pathology.
Using M46.87 for ankylosing spondylitis at the lumbosacral level — ankylosing spondylitis has its own category (M45.x) and must be coded there, not as 'other specified.'
Defaulting to M46.87 when the spondylopathy type is genuinely unknown — unspecified inflammatory spondylopathy at the lumbosacral region belongs under M46.97, not M46.87, which requires the type to be identified even if not a named ICD category.
Confusing M46.87 with M46.1 (sacroiliitis NEC) when the provider documents sacroiliac joint inflammation — M46.1 is its own billable code and takes priority when SI joint pathology is the primary finding.
Pairing M46.87 with a nonspecific low back pain code (M54.5x) on the same claim without a clear hierarchy — M46.87 should be sequenced as the primary diagnosis when an inflammatory spondylopathy is confirmed, with pain codes as secondary if at all.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

Use M46.87 when the clinical record documents an inflammatory process affecting the lumbosacral spine and the condition is identified as a specific entity that still falls outside the named codes in M45–M46.6. Common examples include undifferentiated spondyloarthropathy localized to the lumbosacral region, psoriatic spondylitis documented at the lumbosacral level, or reactive spondylopathy where the provider has specified the inflammatory nature without a more precise category being available.

M46.87 sits within the M46.8x family, which covers 'other specified inflammatory spondylopathies' across all spinal regions. The 7th character in this subgroup encodes the spinal region: M46.86 covers the lumbar region, M46.87 the lumbosacral region, and M46.88 the sacral and sacrococcygeal region. Do not use M46.87 for pure lumbar involvement — that is M46.86. The lumbosacral region code applies specifically when the inflammatory pathology spans or involves the L5-S1 articulation and adjacent segments.

This code does not apply to ankylosing spondylitis (use M45.x), sacroiliitis not elsewhere classified (use M46.1), or infectious discitis/osteomyelitis at the same level (use M46.2x–M46.5x). If the inflammatory spondylopathy affects multiple spinal regions, consider M46.89 (multiple sites). Unspecified inflammatory spondylopathy at the lumbosacral level falls under M46.97, not M46.87 — specificity in the clinical note is what earns the M46.87 code.

Sibling codes

Other billable codes under M46.8 (laterality / anatomic variants).

M46.82

Oth inflammatory spondylopathies, cervical region

M46.83

Oth inflammatory spondylopathies, cervicothoracic region

M46.81

Oth inflammatory spondylopathies, occipt-atlan-ax region

M46.89

Oth inflammatory spondylopathies, multiple sites in spine

M46.88

Oth inflammatory spondylopathies, sacr/sacrocygl region

M46.84

Oth inflammatory spondylopathies, thoracic region

M46.86

Other specified inflammatory spondylopathies, lumbar region

M46.85

Oth inflammatory spondylopathies, thoracolumbar region

Frequently asked questions

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

01What is the difference between M46.87 and M46.86?

M46.86 covers the lumbar region; M46.87 covers the lumbosacral region, which specifically involves the L5-S1 junction. Use the region your provider documents — 'lumbar' and 'lumbosacral' are not interchangeable in this code family.

02Can M46.87 be used for ankylosing spondylitis at the lumbosacral level?

No. Ankylosing spondylitis is coded under M45.x regardless of the spinal region involved. M46.87 is reserved for other specified inflammatory spondylopathies that do not fit M45 or any more specific M46 subcategory.

03When should I use M46.97 instead of M46.87?

Use M46.97 when the inflammatory spondylopathy is confirmed at the lumbosacral level but the specific type has not been identified. M46.87 requires that the provider has named or described a specific inflammatory condition — even if it falls outside standard named categories.

04Does M46.87 require a 7th character?

No. M46.87 is a 5-character code that is already billable and specific. The trailing '7' encodes the lumbosacral region within the M46.8 subgroup — it is not a 7th-character extension in the ICD-10 injury-code sense.

05Is M46.87 appropriate for a patient with psoriatic arthritis affecting the lumbosacral spine?

Psoriatic arthritis has its own ICD-10 category (L40.5x / M07.x), so sequence those codes first. M46.87 may apply as a secondary code if the provider documents lumbosacral inflammatory spondylopathy as a distinct clinical finding beyond the joint disease, but review your payer's coding guidelines before stacking.

06What CPT procedures are commonly billed with M46.87?

Lumbar MRI (72148, 72158), lumbar spine X-rays (72100, 72110), sacroiliac joint injection (27096), and E/M office visits (99213–99215) are the most frequent pairings. Confirm that imaging CPTs reflect the lumbosacral level documented in the order.

07Will payers accept M46.87 without supporting imaging?

Some payers, particularly for advanced imaging authorization or injectable biologic coverage, require objective evidence of inflammation. MRI findings (bone marrow edema, endplate erosions) or elevated inflammatory markers in the record reduce denial risk when M46.87 is the primary diagnosis.

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)
02
icd10data.com
https://www.icd10data.com/ICD10CM/Codes/M00-M99/M45-M49/M46-/M46.87
03
aapc.com
https://www.aapc.com/codes/icd-10-codes/M46.87
04
cms.gov
https://www.cms.gov/medicare/coding/icd10/downloads/icd10clinicalconceptsorthopedics1.pdf
05
aaos.org
https://www.aaos.org/globalassets/quality-and-practice-resources/coding-and-reimbursement/resident-guide/resident-guide_icd10.pdf

Mira AI Scribe

Mira captures the spinal region (lumbosacral / L5-S1), the inflammatory qualifier, the specific condition name as documented by the provider, and any supporting imaging or lab findings from the encounter. This prevents the claim from dropping to M46.97 (unspecified) or M46.80 (site unspecified) — both of which carry higher audit risk and may fail medical necessity review for advanced imaging or injection procedures.

See how Mira captures M46.87 documentation