M11.80

Crystal-induced joint inflammation caused by a deposit type other than urate or calcium pyrophosphate dihydrate, with the affected joint not documented or not specified in the record.

Verified May 8, 2026 · 5 sources ↓

Status: Billable
Chapter: 13
Related CPT: 8
Region: General

Drawn from CDCICD10DataAAPCNIH

Documentation tips

What should appear in the chart to support M11.80.

Source · Editorial brief grounded in 5 cited references ↓

Record the specific joint by name — knee, wrist, shoulder, etc. — so the site-specific M11.8x subcodes can be used instead of this unspecified-site fallback.
Document crystal type explicitly: CPPD, hydroxyapatite, or other — so the correct parent code within M11 is applied rather than defaulting to M11.8x.
Include synovial fluid analysis results (CPP crystal identification) or imaging findings (chondrocalcinosis on X-ray) to clinically validate the crystal arthropathy diagnosis.
If multiple joints are involved, document each joint separately; ICD-10-CM does not have a polyarticular code for M11.8, so each affected site requires its own code.
Note whether the condition is acute (flare) or chronic, as this affects medical necessity documentation for joint aspiration and corticosteroid injection claims.

Related CPT procedures

Procedure codes commonly billed with M11.80. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

20610 $68.81

Aspiration and/or injection of a major joint or bursa (shoulder, hip, knee, or subacromial bursa) performed without ultrasound guidance.

20611 $104.21

Aspiration or injection of a major joint or bursa performed under real-time ultrasound guidance, with permanent image documentation.

73060 $32.06

Radiologic examination of the humerus (upper arm bone), requiring a minimum of 2 views.

73100 $34.40

Radiologic examination of the wrist with a minimum of two views.

73562 $42.42

Three-view radiographic examination of the knee joint, capturing anteroposterior, lateral, and a third angle such as a sunrise or oblique view.

73564 $49.43

Radiologic examination of the knee consisting of four or more views, including oblique and tunnel projections, for a complete diagnostic workup.

73630 $34.07

Radiologic examination of the foot requiring a minimum of three views, used to evaluate fractures, arthritis, tumors, or structural abnormalities.

77072 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M11.80 and adjacent codes.

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

Using M11.80 when the joint is documented elsewhere in the note — always check imaging reports, physical exam findings, and prior visit records before accepting 'unspecified site.'
Confusing M11.80 (other specified crystal arthropathy, unspecified site) with M11.90 (crystal arthropathy, unspecified type and site) — M11.80 implies the crystal type is specified (e.g., CPPD) but the site is not; M11.90 is unspecified on both dimensions.
Coding chondrocalcinosis to M11.80 when the joint is documented — chondrocalcinosis with a known joint maps to M11.2x site-specific subcodes, not M11.8x.
Failing to code gout separately: gout (M10.-) is excluded from M11 and requires its own code if that is the documented diagnosis.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

M11.80 covers crystal arthropathies that fall outside the named subtypes in category M11 — specifically not hydroxyapatite deposition disease (M11.0), familial chondrocalcinosis (M11.1), or idiopathic chondrocalcinosis (M11.2) — and where no anatomic site is documented. The approximate synonym listed in the ICD-10-CM index is calcium pyrophosphate deposition disease (CPPD), making this a common landing code when a provider documents CPPD or pseudogout without specifying the joint involved.

This is a site-unspecified code and should be a last resort. If imaging, synovial fluid analysis, or the clinical note identifies the joint, use the site-specific M11.8x codes instead (e.g., M11.861 for right knee, M11.862 for left knee). The unspecified-site code is appropriate only when the joint genuinely cannot be identified from the documentation — not as a shortcut when site information exists elsewhere in the chart.

M11.80 maps to MS-DRG 553 (Bone diseases and arthropathies with MCC) and 554 (without MCC). Because DRG assignment can shift based on comorbidities, ensure all concurrent conditions are coded to maximize appropriate reimbursement and avoid a DRG mismatch on audit.

Sibling codes

Other billable codes under M11.8 (laterality / anatomic variants).

M11.88

Other specified crystal arthropathies, vertebrae

M11.89

Other specified crystal arthropathies, multiple sites

Frequently asked questions

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

01When is M11.80 the correct code versus a site-specific M11.8x code?

Use M11.80 only when no joint site is documented anywhere in the encounter record. If the provider specifies the joint — even in the imaging report — assign the corresponding site-specific code such as M11.861 (right knee) or M11.831 (right wrist).

02Can M11.80 be used for pseudogout?

Yes. Pseudogout caused by CPPD is the primary approximate synonym listed in the ICD-10-CM index for M11.80. Use it when the provider documents pseudogout or CPPD but does not specify the affected joint. If the joint is documented, move to the appropriate M11.8x site-specific code.

03How does M11.80 differ from M11.90?

M11.80 means the crystal type is identified (e.g., CPPD or another specified crystal) but the site is not documented. M11.90 is unspecified on both dimensions — neither the crystal type nor the joint is identified. Use M11.90 only when the provider documents crystal arthropathy without further detail.

04Is M11.80 appropriate for chondrocalcinosis?

Only if the joint is not documented. Chondrocalcinosis with a known joint maps to M11.2x (idiopathic chondrocalcinosis) or M11.1x (familial chondrocalcinosis), not to M11.8x. Confirm the crystal type and family history before selecting the subcategory.

05What CPT codes are commonly billed alongside M11.80?

Joint aspiration or injection without ultrasound guidance (20610) and with ultrasound guidance (20611) are the most common procedural codes paired with crystal arthropathy diagnoses. Imaging codes such as 73562 or 73564 (knee X-ray) support the diagnosis when chondrocalcinosis is identified radiographically.

06Does M11.80 require a 7th character extension?

No. M11.80 is a 5-character code in category M11, which does not use 7th-character extensions. The 7th-character A/D/S convention applies to injury S-codes, not to musculoskeletal disease M-codes.

07Which MS-DRGs does M11.80 map to?

M11.80 groups to MS-DRG 553 (Bone diseases and arthropathies with MCC) or 554 (without MCC) under MS-DRG v43.0. Accurate comorbidity coding determines which DRG applies and affects facility reimbursement.

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)
02
icd10data.com
https://www.icd10data.com/ICD10CM/Codes/M00-M99/M05-M14/M11-/M11.80
03
aapc.com
https://www.aapc.com/codes/icd-10-codes/M11.80
04
aapc.com
https://www.aapc.com/codes/icd-10-codes/M11.8
05
pmc.ncbi.nlm.nih.gov
https://pmc.ncbi.nlm.nih.gov/articles/PMC6918617/

Mira AI Scribe

The Mira AI Scribe captures crystal type (CPPD, hydroxyapatite, or other), the specific joint(s) involved, synovial fluid crystal findings, and any imaging evidence of chondrocalcinosis or soft-tissue calcification. Locking in the affected site at the point of care prevents a drop to M11.80 and lets the coder assign the more specific M11.8x site code — avoiding an unspecified-site flag on payer audit and supporting medical necessity for joint aspiration or corticosteroid injection claims.

See how Mira captures M11.80 documentation