Secondary osteoarthritis at a joint site that is not captured by any other specific M19 subcategory — a catch-all for secondary OA affecting joints outside the shoulder, elbow, wrist, hand, hip, knee, ankle, and foot.

Verified May 8, 2026 · 4 sources ↓

Status: Billable
Chapter: 13
Related CPT: 5
Region: Other

Drawn from CDCICD10DataAAPCCMS

Documentation tips

What should appear in the chart to support M19.29.

Source · Editorial brief grounded in 4 cited references ↓

Name the exact joint involved (e.g., 'left sternoclavicular joint,' 'right sacroiliac joint') — M19.29 has no laterality character, so the chart must carry that specificity.
Identify and document the underlying cause of the secondary OA (e.g., prior septic arthritis, hemochromatosis, rheumatoid arthritis sequela) so reviewers can confirm secondary vs. primary etiology.
Explain why a more specific M19.2x code does not apply — a brief note confirming the joint is not shoulder, elbow, wrist, hand, hip, knee, ankle, or foot protects against downcoding queries.
Record imaging findings that support degenerative changes: joint space narrowing, subchondral sclerosis, osteophyte formation, or articular erosion relevant to the affected joint.
If a second diagnosis drives the secondary OA (e.g., M10.x for gout), code that condition as well and sequence appropriately per provider documentation of the principal reason for the encounter.

Related CPT procedures

Procedure codes commonly billed with M19.29. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

20600 $56.11

Needle aspiration and/or injection of a small joint or bursa — such as a finger or toe joint — performed without ultrasound guidance.

20605 $57.12

Aspiration and/or injection of an intermediate joint or bursa — such as the wrist, elbow, ankle, acromioclavicular joint, or olecranon bursa — performed without ultrasound guidance.

20610 $68.81

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

27096 $175.69

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

29999 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M19.29 and adjacent codes.

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

Using M19.29 for spinal OA — osteoarthritis of the spine is explicitly excluded from M15-M19 and belongs in M47.-; assigning M19.29 for facet joint OA will trigger a payer edit.
Assigning M19.29 when a more specific lateral code exists — if the joint is shoulder, elbow, wrist, hand, hip, knee, ankle, or foot, a dedicated M19.2x code with laterality is required; M19.29 is not a valid shortcut.
Confusing secondary OA (M19.29) with post-traumatic OA (M19.1x) — if the cause is a prior fracture, dislocation, or joint injury, the M19.1 family applies, not M19.29.
Omitting the secondary cause code — because M19.29 signals an underlying etiology, payers expect an additional diagnosis code explaining the cause; missing it raises a medical-necessity audit flag.
Selecting M19.93 (Secondary osteoarthritis, unspecified site) instead of M19.29 when the site is documented — if the provider names the joint, M19.29 is the correct, more specific code.

Clinical context

Source · Editorial summary grounded in 4 cited references ↓

M19.29 applies when secondary osteoarthritis is confirmed at a joint that lacks its own dedicated ICD-10-CM code — for example, the sternoclavicular joint, acromioclavicular joint, sacroiliac joint (non-spinal context), or temporomandibular joint when managed orthopedically. Secondary OA means the cartilage breakdown is attributable to an identifiable underlying cause: prior septic arthritis, metabolic disease (gout, hemochromatosis), inflammatory arthropathy, or a prior surgical insult that does not qualify as post-traumatic OA (M19.1x). If the cause is post-traumatic, use the M19.1x family instead.

Before defaulting to M19.29, verify the site is not already covered by a more specific billable code. The M19.2 family has dedicated subcodes through M19.279 covering shoulder, elbow, wrist, hand, hip, knee, ankle, and foot with laterality. M19.29 is the correct landing point only after those are exhausted. Spinal osteoarthritis is explicitly excluded — route those to M47.-.

M19.29 was added as a new code effective FY2021 (10/1/2020). It groups into MS-DRG v43.0 553 (Bone diseases and arthropathies with MCC) and 554 (without MCC). Because the code carries no laterality character and no etiology subtype beyond 'secondary,' payer scrutiny is higher; documentation must make the secondary cause and the specific joint unambiguous.

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 4 cited references ↓

01What makes M19.29 'secondary' versus primary osteoarthritis?

Secondary OA has an identifiable underlying cause — metabolic disease, prior inflammatory arthropathy, prior septic arthritis, or similar. Primary (idiopathic) OA lacks that attributable cause. If documentation is unclear, query the provider before assigning M19.29.

02Can I use M19.29 for sacroiliac joint osteoarthritis?

Yes, if the OA is secondary and the provider documents the SI joint as the affected site, M19.29 is appropriate — the SI joint has no dedicated M19 subcode and is not a spinal structure for M47 purposes when coded in an orthopedic context. Confirm with the provider that this is joint OA, not sacroiliitis (M46.1).

03Is M19.29 valid for post-traumatic OA at an unlisted site?

No. Post-traumatic OA maps to the M19.1x subcategory. M19.29 is specifically for secondary OA where the etiology is something other than direct trauma to that joint. Use M19.179 (post-traumatic OA, unspecified ankle and foot) or M19.19x equivalents for trauma-driven cases.

04Does M19.29 require a laterality modifier?

The code itself has no laterality character — it is a 5-character code with no further expansion in the FY2026 tabular. Laterality must be captured in the clinical documentation and the operative or procedure report; it will not appear in the code string.

05When should I use M19.93 instead of M19.29?

Use M19.93 (Secondary osteoarthritis, unspecified site) only when the provider genuinely cannot or does not specify which joint is involved. If the joint is named in the record, M19.29 is required — unspecified-site codes when the site is documented is a payer audit trigger.

06What DRG does M19.29 map to for inpatient claims?

M19.29 groups to MS-DRG v43.0 553 (Bone diseases and arthropathies with MCC) or 554 (without MCC), per the FY2026 ICD-10-CM tabular grouping data.

07Should I code the underlying condition causing the secondary OA alongside M19.29?

Yes. Sequence according to the reason for the encounter, but include the underlying condition (e.g., M10.x for gout, M05-M06 for rheumatoid arthritis) as an additional diagnosis. Submitting M19.29 without a supporting etiology code invites medical-necessity denials.

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/M15-M19/M19-/M19.29
03
aapc.com
https://www.aapc.com/codes/icd-10-codes/M19.29
04
cms.gov
https://www.cms.gov/medicare/coding/icd10/downloads/icd10clinicalconceptsorthopedics1.pdf

Mira AI Scribe

Mira AI Scribe captures the named joint (e.g., 'left sternoclavicular'), the confirmed secondary etiology (prior infection, metabolic disease, or inflammatory arthropathy), imaging findings showing degenerative change, and any conservative treatment history — ensuring M19.29 is supported rather than flagged for unspecified-site downgrade or secondary-cause audit.

See how Mira captures M19.29 documentation