M19.90

Degenerative joint disease documented without specification of the affected joint, body region, or OA subtype (primary, post-traumatic, or secondary).

Verified May 8, 2026 · 6 sources ↓

Status: Billable
Chapter: 13
Related CPT: 11
Region: General

Drawn from CDCICD10DataAAPCCMSUnboundmedicine

Documentation tips

What should appear in the chart to support M19.90.

Source · Editorial brief grounded in 6 cited references ↓

Name the specific joint or body region in the assessment — even 'right knee' without laterality confirmation allows a more specific code than M19.90.
Document OA etiology when known: primary (idiopathic), post-traumatic (prior injury), or secondary (inflammatory disease, metabolic cause) to support M19.91, M19.92, or M19.93 respectively.
Summarize imaging findings (joint space narrowing, osteophytes, subchondral sclerosis) and tie them to the documented joint — this anchors specificity and supports medical necessity for associated procedures.
If multiple joints are involved, list each one by name so the coder can evaluate M15-series (polyosteoarthritis) versus multiple individual site-specific codes.
For transitional encounters where site is genuinely unknown, note that imaging is pending and plan to update the diagnosis at follow-up — this creates an audit trail for the unspecified code use.

Related CPT procedures

Procedure codes commonly billed with M19.90. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

99203 $117.57

New patient office or outpatient visit requiring a medically appropriate history and/or examination with low-complexity medical decision-making, or 30–44 minutes of total provider time on the date of the encounter.

99204 $177.36

New patient office or outpatient visit requiring moderate medical decision making, or 45–59 minutes of total provider time on the date of the encounter.

99205 $236.81

New patient office or outpatient visit requiring high-complexity medical decision making, or 60–74 minutes of total time on the date of encounter.

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.

20610 $68.81

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

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.

97140 $27.72

Skilled, hands-on manual therapy techniques — including joint mobilization/manipulation, manual lymphatic drainage, and manual traction — applied to one or more body regions, billed per 15-minute unit.

99202 View procedure details

99212 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M19.90 and adjacent codes.

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

Using M19.90 when the joint is documented elsewhere in the note — the site is in the exam findings or radiology report but was omitted from the assessment; coders must query or the site-specific code is missed.
Defaulting to M19.90 for 'generalized arthritis' when M15.9 (polyosteoarthritis, unspecified) may be more accurate if multiple distinct joint groups are involved — these are not interchangeable.
Failing to check M19 category exclusions: spinal OA (M47), hallux rigidus (M20.2), and polyarthritis (M15) are explicitly excluded and will not code correctly to M19.90.
Leaving M19.90 on the claim at a follow-up visit after imaging has confirmed the site and type — the code should be updated once specificity is available.
Pairing M19.90 with a site-specific procedure (e.g., knee arthrocentesis 20610) without a diagnosis-to-procedure linkage note — payers flag the mismatch between an unspecified diagnosis and a procedure that implies a specific joint.

Clinical context

Source · Editorial summary grounded in 6 cited references ↓

M19.90 is the last-resort code for osteoarthritis when the clinical note fails to identify both the anatomic site and the OA type. It sits at the bottom of the M19 specificity ladder: M19.91 (primary, unspecified site), M19.92 (post-traumatic, unspecified site), and M19.93 (secondary, unspecified site) all outrank it when the etiology is known. If the joint is documented — even without laterality — a site-specific code from M15–M17, M18, or M19.0x–M19.27x must be used instead.

Note the category-level exclusions at M19: osteoarthritis of the spine routes to M47 (spondylosis), hallux rigidus routes to M20.2, and polyarthritis involving five or more joints routes to M15. M19.90 does not substitute for those conditions. Generalized arthritis documented without further detail is a common gray area — some coders default to M19.90, but if the note supports involvement of multiple distinct joint groups, M15.9 (polyosteoarthritis, unspecified) may be more accurate; this is a genuinely ambiguous scenario that warrants provider query.

In orthopedic practice, M19.90 should appear rarely. Its primary legitimate use is a transitional encounter — the patient presents with a new complaint, imaging is pending, and the provider documents 'osteoarthritis' without further qualification. Update the code at the follow-up visit once the site and type are confirmed.

Inclusion & exclusion notes

Per the official ICD-10-CM Tabular List.

Source · CDC ICD-10-CM Official Tabular List · 2026

Includes

Arthrosis NOS
Arthritis NOS
Osteoarthritis NOS

Sibling codes

Other billable codes under M19.9 (laterality / anatomic variants).

M19.93

Secondary osteoarthritis, unspecified site

M19.92

Post-traumatic osteoarthritis, unspecified site

M19.91

Primary osteoarthritis, unspecified site

Frequently asked questions

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

01When is M19.90 actually appropriate to bill?

Use it only when the provider documents osteoarthritis without specifying the joint or OA type and a query or chart review cannot resolve the ambiguity — typically a first visit with imaging pending. It should be rare in an orthopedic setting.

02Can M19.90 be used for generalized arthritis involving multiple joints?

Not automatically. If the note supports involvement of multiple joint groups, M15.9 (polyosteoarthritis, unspecified) is the more accurate code. M19.90 is appropriate only when site is truly undocumented, not when multiple sites are documented.

03Does spinal osteoarthritis code to M19.90?

No. Osteoarthritis of the spine is explicitly excluded from M19 and codes to M47 (spondylosis). Using M19.90 for spinal OA is a coding error.

04What is the difference between M19.90, M19.91, M19.92, and M19.93?

All four are site-unspecified, but M19.91 specifies primary (idiopathic) OA, M19.92 specifies post-traumatic OA, and M19.93 specifies secondary OA. M19.90 is used only when the etiology is also undocumented. If the provider documents 'primary OA' without naming the joint, use M19.91, not M19.90.

05Will payers deny M19.90 paired with a joint-specific procedure like a knee injection?

Likely yes. An unspecified-site diagnosis paired with a procedure that implies a specific joint (e.g., CPT 20610 for knee arthrocentesis) creates a diagnosis-procedure mismatch. Document the specific joint in the assessment to support both the procedure and a site-specific ICD-10 code.

06Should I query the provider before submitting M19.90?

Yes, if the joint is identifiable elsewhere in the note (exam, imaging report, prior visits). Only use M19.90 without a query when the site is genuinely absent from the entire encounter documentation.

07Is hallux rigidus coded under M19.90?

No. Hallux rigidus is excluded from the M19 category and codes to M20.2. Applying M19.90 to hallux rigidus is a coding error that will not survive audit.

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/M15-M19/M19-/M19.90
03
aapc.com
https://www.aapc.com/codes/icd-10-codes/M19.90
04
aapc.com
https://www.aapc.com/codes/icd-10-codes/M19.9
05
cms.gov
https://www.cms.gov/medicare/coding/icd10/downloads/icd10clinicalconceptsorthopedics1.pdf
06
unboundmedicine.com
https://www.unboundmedicine.com/icd/view/ICD-10-CM/867788/all/M19_90___Unspecified_osteoarthritis__unspecified_site

Mira AI Scribe

Mira's AI scribe flags when a provider documents 'osteoarthritis' in the assessment without specifying the joint, laterality, or OA subtype — the three data points that lift M19.90 to a site-specific, billable code. Capturing these details at the point of documentation prevents downcoding, payer mismatch denials between the diagnosis and any associated joint procedure, and audit exposure from habitual use of an unspecified code.

See how Mira captures M19.90 documentation