ICD code S59.231S – Salter-Harris Type III right radius fracture sequela

Key takeaways

S59.231S is a billable, HIPAA-valid ICD-10-CM code effective October 1, 2025, unlike the non-billable parent S59.231.

Suffix S means sequela only, so the fracture has resolved and the visit addresses a late effect rather than continued care.

Confusing S with K (nonunion) or D (routine follow-up) is the top denial trigger for this code family.

Documentation must state that the fracture is healed and name the late effect it caused.

Pabau’s claims management software supports clean-claim submission for orthopedic diagnosis codes, reducing S59.231S denials before they reach the payer.

ICD-10 Code S59.231S: Definition and billable status

ICD-10 Code S59.231S is the complete, billable form of the parent code S59.231.

It is valid for HIPAA-covered transactions and accepted for claim submission as of October 1, 2025. The S appended as the 7th character turns the non-billable parent into a specific, reimbursement-ready code. Without that character, S59.231 cannot go on a claim at all.

Before the claim goes out, confirm the encounter matches the sequela definition rather than the suffix that was used last time. That check takes a moment. Reworking a denied orthopedic claim takes considerably longer.

Understanding the 7th character: Sequela (S) explained

S59.231 requires a 7th character for every claim submission. The character signals the encounter type to the payer and determines medical necessity alignment. Selecting the wrong suffix is the fastest route to a denial on this code family.

Sequela coding for ICD-10 Code S59.231S turns on one condition. The original fracture must be resolved, and the current visit must treat something that fracture left behind. Laid out along the injury’s own timeline, the six suffixes stop competing with each other.

What is a Salter-Harris Type III fracture?

A Salter-Harris Type III fracture is a physeal (growth plate) injury whose fracture line runs through the epiphysis and exits at the articular surface. The physis itself stays partially intact on one side. It is an intra-articular fracture involving epiphyseal bone and physis, without crossing the metaphysis.

Accurate type assignment is essential for coding because each Salter-Harris type maps to a distinct ICD-10-CM code family. Conflating Type II (which exits through the metaphysis) with Type III in documentation leads to a miscoded claim that payers can identify on audit.

• Type I: Fracture through the physis only; epiphysis separates from metaphysis
• Type II: Through physis and metaphysis; most common physeal fracture
• Type III: Through physis and epiphysis, exiting at the joint surface (intra-articular)
• Type IV: Through metaphysis, physis, and epiphysis
• Type V: Crush injury to the physis; often missed acutely

Anatomy: Lower end of radius and the physis

The distal radial physis is the most commonly fractured growth plate in children. It sits at the wrist end of the radius and stays active until skeletal maturity, usually between ages 14 and 17.

Laterality is a mandatory coding element here. Right arm and left arm map to different ICD-10-CM codes, and the unspecified-arm code belongs only in notes that genuinely omit the side.

Code hierarchy and parent codes for S59.231S

S59.231S sits inside a clear hierarchical chain. Knowing where it sits helps when a payer queries the code’s validity, or when you are crosswalking from an older edition. The same chapter-to-code path runs through the rest of the ICD-10-CM code library, so the method transfers to any injury code you verify.

The CDC/NCHS ICD-10-CM web tool carries the official tabular list and index for FY2026, so you can check the chain above against the source. Check the effective date while you are there. S59.231S has been valid since October 1, 2025, and a FY2025 lookup will miss any structural change made at that update.

Sibling codes: All S59.231 variants by encounter

Each 7th character produces a distinct, separately billable code. Every injury code that carries this suffix structure follows the same encounter-type rules. The full sibling set for S59.231 is:

The left-arm equivalents (S59.232x) follow the same suffix structure. S59.239x covers unspecified laterality, though a documented side is always preferable. Submitting S59.231K for a united fracture with residual deformity is a coding error. That encounter belongs under S59.231S, and the distinction affects coverage determination and audit exposure.

When to use S59.231S: Sequela vs subsequent encounter

Sequela (suffix S) and subsequent encounter (suffixes D, G, K, P) describe different clinical situations. ICD-10 Code S59.231S applies once the fracture is healed. The patient’s current problem must be a late consequence of that healed fracture, not the fracture itself.

Getting that through orthopedic claims management depends on the clinician’s note stating the distinction in words a reviewer can find.

• Use S59.231S when: The fracture has fully healed, confirmed radiographically or clinically. The patient presents with a condition the prior fracture caused, such as growth arrest, premature physeal closure, or radial shortening. Treatment targets the late effect.
• Do not use S59.231S when: The fracture is still healing, even slowly. The patient returns for cast removal, X-ray confirmation, or physical therapy during the active healing phase. The fracture has failed to unite (use K) or has united in poor alignment (use P).
• Sequencing note: Code the sequela condition first, then S59.231S as the injury responsible for it. That order follows ICD-10-CM Official Guidelines, Section I.C.19.a.

A practical scenario: a 10-year-old treated for a distal radial physeal fracture two years ago returns with a measurably shorter right radius. The wrist is visibly asymmetric. The fracture is healed, and the presenting problem is growth disturbance from physeal damage. S59.231S is the correct injury code for this encounter.

Clinical scenarios and documentation requirements

Sequela coding requires documentation that connects the current condition to the prior injury. Without that link, payers treat the sequela as a new, unrelated diagnosis. The scenarios below illustrate correct and incorrect applications, based on guidance from the CMS ICD-10-CM coding page.

Scenario 1: Correct sequela use

A 13-year-old presents to orthopedic clinic with progressive wrist deformity 18 months after a Salter-Harris Type III fracture of the right distal radius. Imaging confirms physeal arrest of the right distal radius with radial shortening of 8 mm. The prior fracture is healed.

Correct coding: the physeal arrest or radial shortening first, then S59.231S as the injury responsible for it.

Scenario 2: Incorrect sequela use (common error)

A 9-year-old returns 6 weeks post-injury for cast removal and repeat X-ray. Radiograph shows early callus but incomplete bridging. The fracture is not yet healed.

Incorrect: S59.231S. Correct: S59.231D for routine healing, or S59.231G if the healing timeline is abnormal. Using S59.231S here misrepresents the fracture status and carries audit risk.

Documentation checklist for S59.231S

• Confirm and document that the original fracture is healed (radiology report or clinical determination)
• Identify the specific late effect (growth disturbance, deformity, restricted range of motion, pain)
• Link the late effect explicitly to the prior Salter-Harris Type III right distal radius fracture
• Record laterality (right arm) in the clinical note to support the specificity of S59.231S over S59.239S
• Include the sequela condition ahead of S59.231S in the diagnosis sequence

Pulling the original fracture note forward into the sequela visit is what makes the causal link visible to a reviewer. Where the patient’s history sits in one longitudinal record, that takes two minutes instead of a records request.

Coding guidelines and ICD-10-CM official instructions for sequela

The ICD-10-CM Official Guidelines for Coding and Reporting, Section I.C.19.a, govern sequela coding for injuries. The residual condition is sequenced first, and the injury code carrying the S suffix follows it. Reversing that order is a common finding in an injury-coding audit.

• Section I.C.19.a rule: When coding sequelae of injuries, first code the condition resulting from the injury, then the injury code with the S suffix. For S59.231S, the physeal arrest or deformity leads, and S59.231S identifies the injury that caused it.
• No time limit: There is no defined time threshold before a sequela code can be used. The fracture must be healed, and that call is clinical rather than calendar-based.
• Not for active treatment: The S suffix is never used during active fracture management, cast changes, or surgical fixation. Those encounters use suffix A.
• AHA Coding Clinic guidance: The American Hospital Association’s Coding Clinic for ICD-10-CM/PCS addresses fracture sequela coding. It asks documentation to state both the healed status and the causal link to the late effect.

Denied sequela claims almost always cite a medical necessity mismatch. It usually traces back to what the original note failed to say. Sorting those denials by encounter type is ordinary denial management, and it shows quickly whether the team’s suffix selection holds up.

How claims management software keeps S59.231S claims clean

A wrong 7th character usually surfaces on the remittance advice, weeks after the encounter. The claim then gets worked a second time, and whoever picks it up is reconstructing a note they did not write. On a pediatric orthopedic caseload, that rework lands on the same handful of codes every month.

Practice management software like Pabau keeps the fracture history and the sequela visit in the same patient record. The prior note is one click away when the coder needs it. Pabau’s claims tools then validate diagnosis codes through the Claim.MD clearinghouse before submission. That is where a suffix mismatch gets caught, rather than on the remittance.

The outcome for an orthopedic or pediatric practice is fewer reworked claims on a code family that is easy to get wrong. Coders spend the time on documentation instead of on resubmission.

Reduce claim denials on orthopedic diagnosis codes

Pabau integrates with Claim.MD to validate ICD-10-CM codes before submission, 7th character accuracy included. That cuts orthopedic claim denials at the source.

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Conclusion

S59.231S is a specific, billable code, but its conditions are narrow. The fracture must be healed and the encounter must address a late effect. The note also has to make that causal chain explicit. Miss one of the three and the claim is exposed.

If you code pediatric orthopedics at any volume, a standing documentation phrase is cheaper than a quarterly audit. Write healing status into the note at the visit, and the 7th character stops being a judgment call months later.

Pabau’s integration with Claim.MD catches 7th character errors before submission, so this code family stops generating rework. Book a demo to see how sequela coding validation works end to end.

Continue your research

Need a guide to clean-claim submission for injury codes? Clean claim best practices covers documentation requirements that reduce denials across ICD-10-CM injury code submissions.

Looking for 837 file guidance for orthopedic claims? 837 EDI file essentials explains how diagnosis codes like S59.231S are transmitted in electronic claim submissions.

Want to understand how payer eligibility affects sequela claims? Insurance eligibility verification walks through how to confirm coverage before submitting late-effect encounters.

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