M11.29

Calcium pyrophosphate dihydrate (CPPD) crystal deposition affecting cartilaginous structures across two or more distinct joint sites, classified under other chondrocalcinosis when not attributable to a single anatomic location.

Verified May 8, 2026 · 6 sources ↓

Status: Billable
Chapter: 13
Related CPT: 10
Region: Multi-region

Drawn from CDCICD10DataAAPCIcdlistUnboundmedicine

Documentation tips

What should appear in the chart to support M11.29.

Source · Editorial brief grounded in 6 cited references ↓

Enumerate each affected joint by name in the clinical note — 'chondrocalcinosis of bilateral knees and right wrist' rather than 'polyarticular chondrocalcinosis' — to justify the multiple-sites code over a single-site code.
Reference the imaging modality and findings: plain radiograph showing cartilage calcification, ultrasound, or CT, with the specific joints identified as positive.
If synovial fluid analysis was performed, document the joint aspirated and the result (CPP crystals under compensated polarized light microscopy).
When a metabolic disorder is the underlying cause, the provider must explicitly link the CPPD deposition to that condition so E83.59 or another etiology code can be appended.
Document whether the presentation is acute (pseudogout flare) vs. chronic/incidental radiographic finding — this affects management documentation even though it does not change the M11.29 code itself.

Related CPT procedures

Procedure codes commonly billed with M11.29. 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.

73560 $34.40

Radiologic examination of the knee joint, one or two views, unilateral.

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.

73590 $31.40

Two-view radiographic examination of the tibia and fibula (lower leg), between the knee and ankle.

73600 $32.40

Radiologic examination of the ankle joint, two views — typically AP and lateral — used to evaluate for fracture, dislocation, or other bony pathology.

73610 $37.07

Radiologic examination of the ankle joint requiring a minimum of three views, used to evaluate bone structure, alignment, and soft-tissue abnormalities.

27447 $1,159.35

Knee replacement surgery addressing both the medial and lateral tibiofemoral compartments, with or without resurfacing of the patella.

27130 $1,162.02

Primary total hip arthroplasty replacing both the acetabular socket and proximal femoral components with prosthetic implants, with or without bone graft.

Common coding pitfalls

The recurring mistakes coders make with M11.29 and adjacent codes.

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

Assigning M11.29 when only one joint is affected: if imaging and documentation identify a single site, use the site-specific code (e.g., M11.261 right knee) rather than the multiple-sites code.
Confusing M11.2x (other chondrocalcinosis) with M11.0x (hydroxyapatite deposition) or M11.1x (familial chondrocalcinosis) — the underlying crystal type and etiology differ; use the parent category that matches documented clinical and lab findings.
Defaulting to M11.20 (unspecified site) when the provider has named multiple joints — M11.29 is the correct specificity level when multiple sites are documented.
Omitting a secondary metabolic etiology code when the provider explicitly attributes the CPPD to a calcium metabolism disorder; E83.59 should accompany M11.29 in those cases.
Treating chondrocalcinosis as a bone diagnosis rather than a joint (arthropathy) diagnosis, which can cause incorrect department routing or DRG grouping.

Clinical context

Source · Editorial summary grounded in 6 cited references ↓

Use M11.29 when the provider documents chondrocalcinosis (also known as CPPD disease or pseudogout) involving multiple joints simultaneously and no single site accounts for the entire clinical picture. This is the appropriate code when imaging or synovial fluid analysis confirms calcification in two or more anatomically distinct joints — for example, bilateral knees plus a wrist, or a knee plus vertebral involvement. Do not use M11.29 if the disease is confined to one joint or one bilateral pair that maps cleanly to a single-site code; instead, drop to the specific site code (e.g., M11.261 for right knee, M11.262 for left knee).

Chondrocalcinosis is a joint disease, not a bone disease. When a provider documents involvement "related to the femur" without specifying hip vs. knee, query for clarification before coding — AAPC forum guidance confirms this ambiguity is a known coding challenge. If metabolic disease (e.g., hyperparathyroidism, hemochromatosis) drives the CPPD deposition, add E83.59 (other disorders of calcium metabolism) as an additional code to capture the underlying etiology.

MS-DRG assignment for M11.29 falls under DRG 553 (bone diseases and arthropathies with MCC) or DRG 554 (without MCC), per MS-DRG v43.0. The code has been stable and billable since the first ICD-10-CM implementation year (FY2016) with no changes through FY2026.

Sibling codes

Other billable codes under M11.2 (laterality / anatomic variants).

M11.20

Other chondrocalcinosis, unspecified site

M11.28

Other chondrocalcinosis, vertebrae

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 6 cited references ↓

01When should I use M11.29 instead of individual single-site M11.2x codes?

Use M11.29 when the provider documents chondrocalcinosis at two or more anatomically distinct joints within the same encounter and no single-site code captures all the affected locations. If you can map each affected joint to its own specific code, coding each individually is also acceptable and may provide greater claim-level detail, but M11.29 is valid and preferred when the multi-site involvement is the primary documented picture.

02Is pseudogout coded the same as chondrocalcinosis?

Yes. Pseudogout refers to acute CPP crystal-induced arthritis; chondrocalcinosis is the broader term for calcium pyrophosphate deposition in cartilage. Both index to the M11.2x range in ICD-10-CM. If the presentation is an acute pseudogout flare at multiple sites, M11.29 still applies — ICD-10-CM does not have a separate acute-flare code for CPPD the way it does for gout.

03Should I add an etiology code when chondrocalcinosis is linked to a metabolic disorder?

Yes. When the provider documents a causal metabolic condition (e.g., hyperparathyroidism, hemochromatosis, hypomagnesemia), add the appropriate metabolic code as an additional diagnosis. E83.59 (other disorders of calcium metabolism) is the most commonly paired code; select the specific metabolic code that matches the documented condition.

04What imaging documentation supports M11.29?

Plain radiographs showing calcification within articular or fibrocartilage at multiple joints are the classic support. Ultrasound or CT findings can also substantiate the diagnosis. Document the joints imaged, the findings at each site (e.g., linear calcification in menisci bilaterally, calcification in triangular fibrocartilage of wrist), and the interpreting provider's conclusion.

05Does M11.29 require a 7th character extension?

No. M11.29 is a complete billable code as a 5-character code. Seventh-character extensions in ICD-10-CM apply to injury codes (S- and T-categories) for encounter type. M-codes in Chapter 13 do not use 7th-character extensions.

06Which MS-DRGs does M11.29 map to?

M11.29 groups to MS-DRG 553 (bone diseases and arthropathies with MCC) or MS-DRG 554 (bone diseases and arthropathies without MCC) under MS-DRG v43.0. The presence or absence of a major complication or comorbidity on the claim determines which of the two DRGs is assigned.

07Can M11.29 be the primary diagnosis for a joint aspiration or injection claim?

Yes, M11.29 can serve as the primary diagnosis supporting CPT codes for aspiration or injection (e.g., 20610, 20611) when the procedure is performed to diagnose or treat multi-site CPPD. Ensure the operative or procedure note names the specific joint(s) treated so the CPT-to-diagnosis linkage is unambiguous on the claim.

Sources & references

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

Mira AI Scribe

The Mira AI Scribe captures joint-level specificity from the encounter — the names of each involved joint, imaging modality and calcification findings at each site, any synovial fluid crystal analysis results, and any documented underlying metabolic condition. This prevents the encounter from being coded down to the unspecified-site default (M11.20) or miscoded as a single-site entry, both of which can trigger medical necessity gaps or DRG downgrouping.

See how Mira captures M11.29 documentation