M61.09

Traumatic myositis ossificans affecting two or more distinct muscle sites simultaneously, classified under calcification and ossification of muscle disorders.

Verified May 8, 2026 · 5 sources ↓

Status: Billable
Chapter: 13
Related CPT: 8
Region: Multi-region

Drawn from CDCICD10DataAAPCIcd

Documentation tips

What should appear in the chart to support M61.09.

Source · Editorial brief grounded in 5 cited references ↓

Specify each anatomical site affected by traumatic myositis ossificans — 'right thigh and left forearm' is required to justify the multi-site code over a single-site code.
Document the inciting trauma explicitly (e.g., motor vehicle accident, crush injury, repeated blunt-force impact) to distinguish M61.09 from progressive or neurogenic ossification.
Record imaging confirmation (plain X-ray, CT, or MRI) identifying heterotopic bone formation at each named site, including the approximate stage of maturity if available.
Note the timeline from injury to onset of ossification findings — this supports medical necessity and differentiates traumatic from progressive etiology.
If conservative management (NSAIDs, radiation therapy, physical therapy) has been trialed prior to surgical excision, document that history to support higher-acuity E/M coding and prior-authorization requirements.

Related CPT procedures

Procedure codes commonly billed with M61.09. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

20150 $920.86

Surgical removal of an epiphyseal bar (physeal bar) from a long bone, with or without autogenous soft tissue graft harvested through the same fascial incision.

27035 $1,035.43

Surgical denervation of the hip joint by cutting or ablating the intra-articular nerve branches of the sciatic, femoral, or obturator nerves, performed via an intrapelvic or extrapelvic approach to reduce arthritic hip pain.

27036 $942.91

Open hip capsulectomy or capsulotomy, with or without heterotopic bone excision and release of hip flexor muscles including gluteus medius, gluteus minimus, and iliopsoas.

27070 $826.00

Superficial partial excision of the wing of the ilium, symphysis pubis, or greater trochanter of the femur using craterization or saucerization technique, typically performed for osteomyelitis or bone abscess.

27071 $916.19

Deep partial excision of the iliac wing, symphysis pubis, or greater trochanter of the femur, including techniques such as craterization or saucerization.

73700 $130.26

CT scan of the lower extremity performed without contrast material, producing cross-sectional images of bones, soft tissue, and other structures without injected dye.

73721 $204.41

MRI of a lower extremity joint (hip, knee, or ankle) performed without contrast material.

77080 View procedure details

Common coding pitfalls

The recurring mistakes coders make with M61.09 and adjacent codes.

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

Assigning M61.09 when only one site is involved — if imaging and notes identify a single location, use the site-specific M61.01–M61.08 code instead.
Confusing M61.09 with M61.9 (unspecified calcification/ossification of muscle) — M61.9 lacks etiologic specificity and will not accurately reflect traumatic pathology, potentially triggering medical necessity queries.
Using M61.09 for postoperative heterotopic ossification without documented traumatic etiology — surgical trauma alone may not satisfy the specificity requirement; verify the provider's documented rationale.
Failing to distinguish M61.09 (traumatic) from M61.1x (myositis ossificans progressiva) — the latter is a progressive genetic disorder and a completely separate subcategory with different clinical management and coding pathway.

Clinical context

Source · Editorial summary grounded in 5 cited references ↓

M61.09 applies when heterotopic bone formation within muscle tissue — triggered by trauma — is documented at multiple anatomical sites in the same patient. This is the correct code when the provider has identified traumatic myositis ossificans in, for example, both the thigh and the upper arm following a polytrauma event, a crush injury, or repeated blunt-force trauma across body regions. The trauma etiology must be explicitly documented; if the etiology is progressive (fibrodysplasia ossificans progressiva) or neurogenic, the M61.0x subcategory does not apply.

Within the M61.0 subcategory, site-specific codes (M61.01–M61.08) take precedence when involvement is limited to one named region. Use M61.09 only when the ossification spans two or more distinct sites and the clinical note or imaging reports confirm multi-site involvement. If documentation names only one site, assign the appropriate site-specific code instead. M61.09 maps to MS-DRG 557 (Tendonitis, myositis and bursitis with MCC) or 558 (without MCC) under DRG v43.0.

Do not confuse M61.09 with M61.9 (calcification and ossification of muscle, unspecified), which carries no etiologic specificity, or with M61.1x (myositis ossificans progressiva), a genetically driven disorder. For postoperative heterotopic ossification — a common concern after total hip arthroplasty — the coding community has debated appropriate ICD-10-CM assignment; M61.09 is defensible only when documented traumatic etiology underlies the ossification at multiple sites.

Sibling codes

Other billable codes under M61.0 (laterality / anatomic variants).

M61.08

Myositis ossificans traumatica, other site

M61.00

Myositis ossificans traumatica, unspecified site

Frequently asked questions

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

01When should I use M61.09 instead of a site-specific M61.0x code?

Use M61.09 only when traumatic myositis ossificans is documented at two or more distinct anatomical sites. If the provider identifies involvement at a single named region (e.g., right thigh only), assign the corresponding site-specific code such as M61.05x instead.

02Does M61.09 require a 7th character?

No. M61.09 is a 5-character code under the M-code section of ICD-10-CM. The 7th-character extension convention (A/D/S) applies to injury S-codes, not to musculoskeletal disorder M-codes.

03How does M61.09 differ from M61.9?

M61.09 specifies traumatic etiology affecting multiple sites, while M61.9 represents calcification or ossification of muscle with no etiology or site specified. Use M61.9 only when documentation provides no further detail — which should be rare in an orthopedic setting.

04Can M61.09 be used for heterotopic ossification following total hip arthroplasty?

Only if the provider explicitly attributes the ossification to traumatic etiology at multiple sites. Post-surgical heterotopic ossification coding is debated; when etiology is surgical rather than traumatic, verify with the provider before defaulting to M61.09. M61.9 or another M61 subcategory may be more defensible depending on documentation.

05Which DRGs does M61.09 map to?

M61.09 groups to MS-DRG 557 (Tendonitis, myositis and bursitis with MCC) or MS-DRG 558 (without MCC) under DRG v43.0, per CMS grouper logic.

06How do I differentiate traumatic myositis ossificans (M61.09) from myositis ossificans progressiva (M61.1x)?

Traumatic myositis ossificans (M61.0x) follows a discrete injury or repeated trauma and is typically localized. Myositis ossificans progressiva (M61.1x) is a rare autosomal dominant genetic disorder with progressive, widespread ossification unrelated to trauma. The provider's clinical documentation must clearly state the etiology.

07Is M61.09 valid for FY2026 (dates of service on or after October 1, 2025)?

Yes. M61.09 has been unchanged since its introduction in the 2016 ICD-10-CM edition and remains valid in the FY2026 code set effective October 1, 2025, per CDC ICD-10-CM Tabular List 2026.

Sources & references

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

01CDC ICD-10-CM Tabular List 2026 (effective October 1, 2025)
02
icd10data.com
https://www.icd10data.com/ICD10CM/Codes/M00-M99/M60-M63/M61-/M61.09
03
aapc.com
https://www.aapc.com/codes/icd-10-codes/M61.09
04
icd.who.int
https://icd.who.int/browse10/2019/en#/M61.1
05
icd10data.com
https://www.icd10data.com/ICD10CM/Codes/M00-M99/M60-M63/M61-/M61.9

Mira AI Scribe

Mira captures the specific muscle sites involved, the documented trauma mechanism, imaging findings confirming heterotopic bone at each location, and any conservative or surgical treatment history. This prevents a drop to nonspecific M61.9 or misassignment to the progressive ossification subcategory (M61.1x), both of which can trigger medical necessity audits or payer denials.

See how Mira captures M61.09 documentation