M20.41

M20.41 identifies an acquired hammertoe deformity affecting one or more lesser toes of the right foot, distinguished from congenital deformities and from deformities of the great toe.

Verified May 8, 2026 · 6 sources ↓

Status: Billable
Chapter: 13
Related CPT: 5
Region: Foot & ankle

Drawn from CDCICD10DataAAPCIcdcodesOrthoInfo

Documentation tips

What should appear in the chart to support M20.41.

Source · Editorial brief grounded in 6 cited references ↓

Specify laterality explicitly — 'right foot' must appear in the clinical note to support M20.41 over M20.40.
Identify whether the deformity is flexible (passively correctable) or rigid; rigid deformity strengthens medical necessity for surgical intervention.
Name the specific toe(s) affected (e.g., 2nd, 3rd) — particularly important when multiple toes are treated under separate CPT codes.
Document failed conservative treatment (padding, orthotics, shoe modifications, physical therapy) when supporting surgical authorization.
Include weight-bearing X-ray findings — PIP joint flexion angle, joint space changes, or osteophytes — to support clinical validation requirements.
Note 'acquired' etiology explicitly; if the deformity is congenital, the correct code is Q66.8, not M20.41.

Related CPT procedures

Procedure codes commonly billed with M20.41. Linking the right diagnosis to the right procedure is what establishes medical necessity.

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

28285 $548.44

Surgical correction of hammertoe deformity, which may involve interphalangeal joint fusion, partial or total phalangectomy, arthroplasty, or other procedures that restore normal toe alignment.

28286 $430.20

Surgical correction of a hammertoe deformity at the proximal interphalangeal joint, which may involve soft-tissue release, partial or complete bone resection, and stabilization of the affected toe.

28313 $545.77

Surgical reconstruction of an angular toe deformity using soft tissue techniques only — such as tendon transfers, tendon releases, and capsulotomies — without bony procedures. Typical indications include overlapping second toe, fifth toe, and curly toe deformities.

73630 $34.07

Radiologic examination of the foot requiring a minimum of three views, used to evaluate fractures, arthritis, tumors, or structural abnormalities.

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.

Common coding pitfalls

The recurring mistakes coders make with M20.41 and adjacent codes.

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

Assigning M20.40 (unspecified foot) when the note clearly documents the right foot — always code to the highest specificity supported.
Using M20.41 for congenital hammertoe; congenital deformities belong in Q66.8 and are excluded from M20 by an Excludes1 note.
Failing to add M20.42 when bilateral hammertoe is documented — bilateral involvement requires both M20.41 and M20.42, not just M20.41.
Conflating hammertoe with mallet toe or claw toe; if the deformity is not a classic PIP flexion contracture, evaluate M20.5X1 instead.
Omitting laterality in the surgical report, then coding M20.40 — query the surgeon before defaulting to unspecified.

Clinical context

Source · Editorial summary grounded in 6 cited references ↓

Use M20.41 when the provider documents an acquired hammertoe deformity — flexion contracture at the proximal interphalangeal (PIP) joint — specifically on the right foot. The 'acquired' qualifier is critical: congenital hammertoe routes to Q66.8, not M20.41. The M20 category excludes congenital deformities (Q66.-, Q68–Q70, Q74.-) and acquired absence of toes (Z89.-) by Excludes1 note, so do not assign M20.41 alongside those codes for the same toe.

If both feet are affected, assign M20.41 for the right foot and M20.42 for the left foot simultaneously — do not fall back to M20.40 (unspecified) when laterality is documented. M20.40 is a last resort when the operative or clinical note genuinely omits side.

When the deformity doesn't fit the classic hammertoe pattern — for example, a mallet toe or claw toe not otherwise specified — consider M20.5X1 (other acquired deformities of toe(s), right foot) as a differential. Hammertoe documentation should note whether the deformity is flexible or rigid, the specific toe(s) involved, and any imaging confirming PIP joint flexion or structural change, particularly when surgical correction is planned.

Sibling codes

Other billable codes under M20.4 (laterality / anatomic variants).

M20.40

Other hammer toe(s) (acquired), unspecified foot

M20.42

Other hammer toe(s) (acquired), left foot

Frequently asked questions

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

01Can I use M20.41 for a congenital hammertoe on the right foot?

No. M20.41 is strictly for acquired deformities. Congenital hammertoe maps to Q66.8, and the M20 category carries an Excludes1 note blocking simultaneous use of M20.41 with congenital toe deformity codes.

02What code do I use if both feet have hammertoe?

Assign both M20.41 (right foot) and M20.42 (left foot). Do not use M20.40 (unspecified) when laterality is documented — bilateral involvement requires two separate codes.

03Is M20.41 appropriate for a mallet toe or claw toe of the right foot?

Not necessarily. Hammertoe is a PIP flexion contracture. Mallet toe involves DIP flexion. If the deformity doesn't fit the hammertoe pattern, evaluate M20.5X1 (other acquired deformities of toe(s), right foot) before assigning M20.41.

04Does M20.41 require a 7th character extension?

No. M20.41 is an M-code (musculoskeletal disease), not an injury S-code. The 7th-character A/D/S convention does not apply here.

05What CPT codes pair most commonly with M20.41 in the surgical setting?

28285 (correction of hammertoe, PIP fusion or arthroplasty) is the primary procedure code. 28286 covers correction with implant. 73630 (X-ray, foot, minimum 3 views) supports pre-operative imaging. Always verify the operative report matches the specific technique billed.

06When would I use M20.40 instead of M20.41?

M20.40 (unspecified foot) is only appropriate when the clinical documentation genuinely does not specify which foot is affected. Query the provider before defaulting to unspecified; payers may deny or downcode claims lacking laterality.

07Does M20.41 cover all lesser toes on the right foot, or just one?

M20.41 covers any combination of lesser toes on the right foot under one code. You do not need a separate code per affected toe; however, the operative report should identify each toe individually for CPT-level specificity.

Sources & references

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

Mira AI Scribe

Mira's AI scribe captures the affected foot (right), the specific toe(s) involved, deformity type (flexible vs. rigid), PIP joint flexion on exam or imaging, and prior conservative care history. Capturing these elements upfront prevents downcoding to M20.40 (unspecified foot), blocks an Excludes1 conflict if congenital etiology is mentioned, and provides the clinical validation trail needed for surgical pre-authorization and audit defense.

See how Mira captures M20.41 documentation