M67.99

Unspecified disorder affecting the synovium and/or tendon tissue at multiple anatomical sites, where the exact pathology cannot be further specified.

Verified May 8, 2026 · 3 sources ↓

Status: Billable
Chapter: 13
Related CPT: 5
Region: Multi-region

Drawn from CDCicd10data.com 2026CMS

Documentation tips

What should appear in the chart to support M67.99.

Source · Editorial brief grounded in 3 cited references ↓

Explicitly name every affected anatomical site in the clinical note — 'multiple sites' is not sufficient alone; list each tendon or synovial structure involved.
Record whether imaging (ultrasound, MRI) was performed and what it showed, even if findings are non-specific; this supports medical necessity for an unspecified code.
Document why a more specific diagnosis could not be assigned — e.g., 'workup pending,' 'diffuse involvement without definitive pathology identified.'
Note the clinical course: acute versus chronic onset, prior treatment attempts, functional limitations — these details support medical necessity when specificity is limited.
If conservative care has been tried, record modality, duration, and response; this is especially important when M67.99 appears on claims for injections or imaging.

Related CPT procedures

Procedure codes commonly billed with M67.99. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

20550 $60.46

Injection into a single tendon sheath, ligament, or aponeurosis (such as the plantar fascia) — one anatomical site per unit.

20551 $60.46

Injection of a therapeutic substance into the origin or insertion point of a single tendon, used to treat tendinitis, enthesopathy, or localized inflammation at the bone-tendon junction.

73564 $49.43

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

73221 $205.08

MRI of any upper extremity joint — shoulder, elbow, or wrist — performed without contrast material.

27370 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M67.99 and adjacent codes.

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

Using M67.99 when only one body site is documented — if a single region is involved, assign the appropriate site-specific M67.9x code instead.
Defaulting to M67.99 when a named condition (tenosynovitis, synovial hypertrophy, ganglion cyst) is present and a more specific code exists — check M65–M67 subcategories before settling here.
Failing to move off M67.99 at subsequent encounters once a definitive diagnosis is established; continuing to use the unspecified code after diagnosis confirmation is an audit risk.
Confusing 'multiple sites' with bilateral involvement of the same joint — bilateral same-joint involvement typically maps to the bilateral or unspecified laterality code for that specific site, not M67.99.
Omitting external cause codes when the synovium/tendon disorder is attributable to an identifiable cause such as overuse or occupational activity; the tabular note for M00–M99 instructs coders to add an external cause code when applicable.

Clinical context

Source · Editorial summary grounded in 3 cited references ↓

M67.99 is the catch-all code for synovial and tendon disorders spanning multiple body sites when the clinical documentation does not support a more specific diagnosis. It sits at the bottom of the M67 hierarchy — use it only after confirming that no definitive named condition (e.g., synovial hypertrophy, tendon contracture, tendon rupture) and no single-site code more accurately captures the encounter.

In orthopedic practice, this code appears most often during early workup visits where imaging or pathology is pending, or in follow-up encounters for diffuse tendinopathy affecting more than one region simultaneously. The 'multiple sites' designation is key: if the disorder is confined to a single anatomical region, step laterally to the site-specific M67.9x codes (e.g., M67.91 right shoulder, M67.92 left shoulder) rather than defaulting to M67.99.

Because M67.99 carries no laterality component and signals diagnostic uncertainty, payers scrutinize it for medical necessity. Reserve it for situations where multiple sites are genuinely involved and documented in the clinical note. If a definitive diagnosis becomes available — tenosynovitis, synovitis, ganglion — recode at the next encounter with the appropriate specific code from M65–M67.

Sibling codes

Other billable codes under M67.9 (laterality / anatomic variants).

M67.90

Unsp disorder of synovium and tendon, unspecified site

M67.98

Unspecified disorder of synovium and tendon, other site

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 3 cited references ↓

01When should I use M67.99 instead of a site-specific M67.9x code?

Use M67.99 only when the disorder genuinely involves multiple distinct anatomical sites and the documentation names more than one affected tendon or synovial structure. If a single site is involved, assign the appropriate site-specific code (e.g., M67.91 for right shoulder).

02Can M67.99 be a primary diagnosis on a claim for an injection procedure?

Yes, it can serve as the primary diagnosis, but expect heightened payer scrutiny. The clinical note must clearly document multiple sites of involvement and medical necessity for the procedure. An unspecified code without supporting documentation is a common denial trigger.

03Is M67.99 valid for FY2026 dates of service?

Yes. M67.99 is a billable, specific code in the FY2026 ICD-10-CM code set (effective October 1, 2025), confirmed in the CDC ICD-10-CM Tabular List 2026.

04What excludes1 conditions should I check before assigning M67.99?

The M67 parent code excludes palmar fascial fibromatosis/Dupuytren (M72.0), tendinitis NOS (M77.9-), and xanthomatosis localized to tendons (E78.2). Verify none of these more specific conditions apply before assigning M67.99.

05Should I continue using M67.99 at every follow-up visit if the diagnosis remains unclear?

Only if the diagnosis genuinely remains unspecified. Once a definitive diagnosis is established — such as tenosynovitis or a specific tendon disorder — recode with the appropriate specific code. Continued use of an unspecified code when a specific diagnosis is documented is an audit risk.

06Does M67.99 require a 7th character extension?

No. M67.99 is an M-code (disease code), not an injury S-code. The 7th-character encounter extension (A/D/S) applies to injury codes, not to M-category disease codes like M67.99.

07Can I report M67.99 alongside a more specific synovium or tendon code for the same encounter?

Generally no — if you can assign a specific code for the condition, that code should be used instead of or in addition to M67.99 only if a truly separate unspecified disorder at additional sites is present. Avoid stacking M67.99 as a redundant secondary code when the specific code already captures the pathology.

Sources & references

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

01CDC ICD-10-CM Tabular List 2026 — https://www.cdc.gov/nchs/icd/icd-10-cm/index.html
02icd10data.com 2026 entry for M67.99 — https://www.icd10data.com/ICD10CM/Codes/M00-M99/M65-M67/M67-/M67.99
03CMS ICD-10 codes page — https://www.cms.gov/medicare/coding-billing/icd-10-codes

Mira AI Scribe

Mira's AI scribe captures every anatomical site mentioned in the encounter note where synovial or tendon pathology is described, flags whether imaging results are documented, and notes any explicit statement of diagnostic uncertainty — preventing downcoding to an unspecified single-site code or an audit flag for unsupported 'multiple sites' designation.

See how Mira captures M67.99 documentation