Pain in the metatarsal region of an unspecified foot, encompassing discomfort in the metatarsal bones, metatarsophalangeal joints, and/or intermetatarsal joints without documented laterality.
Verified May 8, 2026 · 6 sources ↓
- Status
- Billable
- Chapter
- 13
- Related CPT
- 5
- Region
- Foot & ankle
Documentation tips
What should appear in the chart to support M77.40.
Source · Editorial brief grounded in 6 cited references ↓
- Document laterality by name ('right foot' or 'left foot') in every encounter note — this single step moves the code from M77.40 to M77.41 or M77.42 and eliminates the unspecified flag.
- Record the specific anatomical location of pain: metatarsal head(s) involved (e.g., 2nd/3rd), metatarsophalangeal joint, or intermetatarsal space, to support clinical specificity.
- Note aggravating and relieving factors (prolonged standing, high-impact activity, footwear) and any physical exam findings such as point tenderness under the metatarsal heads or a positive Mulder's click test.
- Document imaging results that support the diagnosis — weight-bearing X-ray findings such as dropped metatarsal, stress reaction, or joint space changes; or MRI/ultrasound if Morton's neuroma is ruled out.
- Record prior conservative management (orthotics, NSAIDs, activity modification, physical therapy) when billing for injections or advanced procedures, as payers may require documented failed conservative care.
Related CPT procedures
Procedure codes commonly billed with M77.40. Linking the right diagnosis to the right procedure is what establishes medical necessity.
Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis
Common coding pitfalls
The recurring mistakes coders make with M77.40 and adjacent codes.
Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓
- Defaulting to M77.40 when laterality is present in the note but overlooked during coding — review the full HPI and physical exam before assigning the unspecified code.
- Using M77.40 on injection claims: CMS articles A57079 and A52863 recognize only M77.41 and M77.42 as medical necessity codes for metatarsal injections; M77.40 is not listed and may trigger a denial.
- Confusing metatarsalgia with Morton's metatarsalgia — if the provider documents Morton's neuroma or interdigital neuroma, the correct code is G57.6- (laterality-specific), not any M77.4x code. The Excludes1 note at M77.4 makes these mutually exclusive.
- Coding M77.40 when bilateral metatarsalgia is the actual finding — bilateral involvement should be coded with M77.41 and M77.42 together, not collapsed into the unspecified code.
Clinical context
Source · Editorial summary grounded in 6 cited references ↓
M77.40 is the fallback code for metatarsalgia when the treating provider has not documented which foot is affected. It sits under the M77.4 parent category within Other Enthesopathies (M77), Chapter 13. The two laterality-specific codes — M77.41 (right foot) and M77.42 (left foot) — are always preferred. Use M77.40 only when the clinical note genuinely omits laterality; do not default to it as a shortcut.
An important Excludes1 note at the M77.4 level bars Morton's metatarsalgia (G57.6-) from this code family. If the provider documents Morton's neuroma as the cause of forefoot pain, G57.6- is the correct code, not M77.40. Similarly, M77 excludes bursitis NOS (M71.9-), use-related bursitis (M70.-), osteophytes (M25.7-), and spinal enthesopathy (M46.0-).
CMS coverage articles for injection procedures (A57079, A52863) list M77.41 and M77.42 — not M77.40 — among the ICD-10-CM codes that support medical necessity for metatarsal injections. Submitting M77.40 for injection claims may generate a medical necessity denial. Always resolve laterality before billing procedure codes tied to a specific foot.
Sibling codes
Other billable codes under M77.4 (laterality / anatomic variants).
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 6 cited references ↓
01When is it acceptable to use M77.40 instead of M77.41 or M77.42?
02Can M77.40 support medical necessity for a metatarsal injection?
03Is Morton's metatarsalgia coded under M77.40?
04How should bilateral metatarsalgia be coded?
05What MS-DRG does M77.40 group into?
06Does M77.40 require a 7th-character extension?
07What is the difference between M77.40 and M77.50?
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)
- 02icd10data.comhttps://www.icd10data.com/ICD10CM/Codes/M00-M99/M70-M79/M77-/M77.40
- 03aapc.comhttps://www.aapc.com/codes/icd-10-codes/M77.40
- 04cms.govhttps://www.cms.gov/medicare-coverage-database/view/article.aspx?articleid=57079&ver=3
- 05cms.govhttps://www.cms.gov/medicare-coverage-database/view/article.aspx?articleId=52863&ver=58
- 06cdek.pharmacy.purdue.eduhttps://cdek.pharmacy.purdue.edu/icd10/M77.4/
Mira AI Scribe
Mira captures the affected foot (right or left), the location of tenderness within the forefoot (metatarsal head(s), MTP joint, intermetatarsal space), aggravating factors, relevant physical exam findings (e.g., Mulder's click, plantar tenderness), and any imaging results. Capturing laterality at dictation converts M77.40 to M77.41 or M77.42, preventing a medical necessity denial on injection claims and eliminating unspecified-code audit flags.
See how Mira captures M77.40 documentation