ICD-10 code S99.239A: Salter-Harris Type III physeal fracture of phalanx of toe

Key takeaways

ICD-10 code S99.239A describes a Salter-Harris Type III physeal fracture of the phalanx of an unspecified toe, at the initial encounter.

S99.239A is a billable ICD-10-CM code effective October 1, 2025, so it can be submitted for reimbursement on its own.

Seventh character A covers a closed fracture during active treatment, and B covers an open fracture at the same stage.

Once active treatment ends, the seventh character moves to D, G, K or P, and S marks a sequela.

Practice management software like Pabau validates ICD-10-CM codes through the Claim.MD clearinghouse before the claim reaches the payer.

ICD-10 code S99.239A is a billable diagnosis code for a Salter-Harris Type III physeal fracture of the phalanx of an unspecified toe, initial encounter. It sits in the S99.23- subcategory, which covers growth plate fractures of the toe that run into the joint.

The seventh character carries most of the coding risk on this code. It tracks the stage of the care episode rather than the severity of the injury, so it changes across the visits that treat one fracture.

The table below summarizes what a coder or clinician needs at a glance for S99.239A.

What does ICD-10 code S99.239A mean?

S99.239A means a Salter-Harris Type III physeal fracture of the phalanx of an unspecified toe, treated at an initial encounter. Each segment of the code adds a layer of specificity.

• S99: Other and unspecified injuries of ankle and foot
• S99.2: Physeal fracture of phalanx of toe
• S99.23: Salter-Harris Type III physeal fracture of phalanx of toe
• S99.239: Salter-Harris Type III physeal fracture of phalanx of unspecified toe
• S99.239A: Salter-Harris Type III physeal fracture of phalanx of unspecified toe, initial encounter

The “unspecified toe” designation means the clinical record does not identify which toe is affected. Coders should assign a laterality-specific code whenever the record supports one. The seventh character A confirms an initial encounter, so the patient is under active treatment for a closed fracture.

Is S99.239A a billable ICD-10-CM code?

Yes. S99.239A is a billable and specific ICD-10-CM code that can go on a claim by itself to indicate a diagnosis for reimbursement. It took effect on October 1, 2025 as part of the 2026 ICD-10-CM edition maintained by CMS.

A clean claim for S99.239A carries three things. It needs the correct seventh character and the imaging report that names the fracture type. It also needs an external cause code where the mechanism of injury is documented.

Salter-Harris classification and how ICD-10-CM uses it

The Salter-Harris classification grades physeal (growth plate) fractures by how far the fracture line runs through the physis, metaphysis, and epiphysis. Robert B. Salter and W. Robert Harris published it in 1963. ICD-10-CM uses the system directly, and picking the wrong type is one of the most common coding errors on pediatric fracture claims.

Type III fractures are intra-articular, so the fracture line enters the joint space. The operative or radiology report must specify “Type III” or “Salter-Harris III” for the code to hold up. An imaging description such as “epiphyseal fracture” or “growth plate injury” carries no type, so it does not support S99.239A.

Seventh-character guide for S99.239A

ICD-10-CM requires a seventh character on every fracture code in chapter S00-T88. The S99.239- code group takes seven valid extensions. Choosing the wrong one is the single most common reason for payer rejection on physeal fracture claims.

Per the ICD-10-CM Official Guidelines for Coding and Reporting, Section I.C.19, seventh character “A” applies while the patient is receiving active treatment for the fracture. That holds whether it is the first visit for that purpose or a later one. Once active treatment has ended, use “D” through “S” as appropriate.

The choice comes down to two questions, asked in this order.

S99.239 code hierarchy: Parent and sibling codes

S99.239A sits at the bottom of a layered classification path. Knowing the levels above it helps coders find a more specific code when the documentation supports one.

• S00-T88: Injury, poisoning and certain other consequences of external causes
• S90-S99: Injuries to the ankle and foot
• S99: Other and unspecified injuries of ankle and foot
• S99.2: Physeal fracture of phalanx of toe
• S99.23: Salter-Harris Type III physeal fracture of phalanx of toe
• S99.231-: Right toe
• S99.232-: Left toe
• S99.239-: Unspecified toe (parent of S99.239A)

When the record names a particular toe, assign the more precise sibling code instead. The ICD-10-CM code index covers the rest of the S99 family. The AAPC Codify ICD-10-CM lookup tool and the CDC/NCHS ICD-10-CM web tool both display the complete sibling set.

What the clinical record must document

Accurate coding of S99.239A depends on what the clinical record contains. The provider must document each element the code asserts, and a missing element leaves the claim open to audit or denial.

• Fracture classification: The record must state “Salter-Harris Type III” or its equivalent. A radiology report describing an intra-articular epiphyseal fracture through the growth plate qualifies. Generic terms like “toe fracture” do not support this code.
• Anatomical location: Documentation must confirm the phalanx of the toe, not the metatarsal or calcaneus. The operative note, imaging report, or exam note should name the specific bone.
• Laterality: The record should identify which toe, and ideally which foot. Where it does not, “unspecified toe” is correct, but clinicians should name the toe in every fracture note because more specific codes exist.
• Encounter context: The chart must show that active treatment is being rendered. That is what supports seventh character A. A visit for follow-up, a healing complication, or sequela management moves the character to D through S.
• Imaging evidence: A radiograph, CT scan, or MRI report confirming the fracture type and location is the standard supporting document for any physeal fracture code.

Running the record through software that validates claims against payer edits before submission catches a missing element while the claim can still be corrected.

ICD-10 coding guidelines for toe fractures

Several ICD-10-CM official coding rules apply directly to S99.239A and to toe fractures generally. Review them alongside the tabular list before assigning the code.

• Open versus closed: Where documentation does not say whether a fracture is open or closed, ICD-10-CM instructs coders to default to closed. An open Salter-Harris Type III fracture of a toe phalanx takes seventh character B at the initial encounter.
• Traumatic versus pathological: S99.239A covers traumatic fractures only. A fracture through diseased or weakened bone is pathological and uses a code from the M84- series instead. Review the clinical context before assigning.
• External cause codes: A secondary code from the external cause chapter (V00-Y99) should accompany S99.239A. It identifies the mechanism of injury, such as a fall or a sporting injury. These codes are not required for reimbursement, but they support medical necessity.
• Active treatment versus aftercare: ICD-10-CM does not use aftercare codes (Z47-) for fractures. The fracture code with the appropriate seventh character drives all billing throughout the care episode.

Common coding errors on S99.239A

Four errors generate most of the denials and audit flags on this code.

• Wrong seventh character on follow-up visits: Coders sometimes keep “A” across the whole treatment episode. Once active treatment ends and the visit is for monitoring a healing fracture, the character becomes “D” for routine healing or the matching complication suffix.
• Confusing Salter-Harris types: A Type II fracture runs through the physis and metaphysis. On a first look at the film, that can read like a Type III. Assigning S99.239A when the radiology report describes a Type II produces an inaccurate code, so never assume the type.
• Defaulting to unspecified toe when laterality is documented: If the chart says “right second toe,” reach for the most specific available code. Using S99.239A when a more specific code exists is a documentation compliance issue.
• Missing external cause code: Submitting S99.239A with no mechanism-of-injury code weakens medical necessity support, particularly for workers’ compensation and liability payers.

Tracking denial reason codes against S99.239A submissions shows which of the four errors a practice repeats. Correcting the pattern at source beats reworking rejected claims one at a time.

Approximate synonyms and related clinical terms

Several clinical terms map to S99.239A in the ICD-10-CM alphabetic index. Coders searching under any of them should confirm the entry reaches S99.239A before assigning it.

• Closed Salter-Harris type III physeal fracture of phalanx of lesser toe
• Closed Salter-Harris type III physeal fracture of phalanx of unspecified toe
• Growth plate fracture of toe phalanx, type III, initial encounter
• Epiphyseal fracture of toe, Salter-Harris type III, initial encounter
• Physeal injury of toe phalanx, type III

“Lesser toe” is not a separate laterality designation in this subcategory. It refers to toes 2 through 5 rather than the great toe, and both map into the same S99.23- codes.

ICD-9-CM crosswalk for S99.239A

Practices running historical billing audits, legacy system reconciliations, or reviews of pre-2015 records need the ICD-9-CM equivalent for S99.239A. The conversion is approximate, because ICD-9-CM did not classify toe fractures by Salter-Harris type.

Because ICD-9-CM carried no Salter-Harris detail for toe phalanges, treat any crosswalk to 826.0 as approximate. Verify it against the CMS ICD-10 code reference files when the result will be used for audit work.

How Pabau keeps physeal fracture claims clean

A seventh-character error usually surfaces once the remittance advice arrives. The claim goes out with “A” on a follow-up visit, the payer rejects it, and a biller reworks it weeks later.

Pabau is practice management software that keeps the diagnosis code, the clinical note, and the claim in one patient record. A coder can see the imaging report that names the Salter-Harris type on the same screen as the code they are about to submit.

Claims then reach the payer through the Claim.MD clearinghouse, which validates every ICD-10-CM code against payer edits first. Errors surface while the claim is still editable, so a mistyped seventh character costs a minute rather than a full rework cycle.

Submit physeal fracture claims with confidence

Pabau connects directly to the Claim.MD clearinghouse, validating ICD-10-CM codes before they reach the payer. Seventh-character errors and missing documentation surface immediately, not after a denial.

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Conclusion

S99.239A is simple to look up and easy to get wrong at the seventh character. Three pieces of documentation settle it. The imaging report must name the Salter-Harris type, and the note must name the phalanx. The chart must also show which stage of treatment the visit belongs to.

Fix the documentation and the code follows. Practices that record the fracture type and the encounter stage at the point of care spend far less time reworking these claims. Book a demo to see how Pabau validates ICD-10-CM codes before a fracture claim reaches the payer.

Continue your research

Need to understand how claims reach payers? How a medical claims clearinghouse works explains the validation steps between a submitted claim and a payer decision.

Seeing repeated denials on fracture codes? Denial codes in medical billing maps common remittance advice codes to the documentation problems behind them.

Managing billing compliance across a growing practice? Medical billing compliance covers the regulatory framework practices must follow when coding and submitting claims.

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