ICD-10 code S52.389A: Bent bone of unspecified radius

Key takeaways

ICD-10 code S52.389A describes a bent bone fracture of the unspecified radius at the initial encounter for a closed fracture.

The code is billable and valid for the 2026 ICD-10-CM year, effective October 1, 2025.

Use S52.381A for the right radius or S52.382A for the left whenever the record documents the side.

Reserve S52.389A for encounters where laterality is genuinely absent from every available note and imaging report.

Practice management software like Pabau ties the code you assign to the clinical note behind it, so fewer fracture claims come back.

ICD-10 code S52.389A is the billable diagnosis code for a bent bone of the unspecified radius, initial encounter for closed fracture. A bent bone fracture, also called plastic bowing, is a permanent bend with no break through the cortex. The word unspecified refers to laterality, not to the fracture type.

Bowing fractures of the forearm are most common in pediatric patients, whose radius bends before it breaks. Coding the encounter correctly matters for reimbursement and for tracking the injury through subsequent and sequela visits.

ICD-10 code S52.389A: quick reference and code details

The table below summarizes the properties of S52.389A as published in the 2026 ICD-10-CM Official Tabular List, effective October 1, 2025.

What is a bent bone fracture of the radius?

A bent bone fracture is a permanent bend in the bone with the cortex still intact all the way around. It is also called a plastic bowing fracture. The radius keeps its structural continuity while it deforms.

That intact cortex is what separates bowing from two lookalikes. A greenstick fracture breaks one cortex. A complete transverse fracture breaks both.

The mechanism is predominantly pediatric. Children’s bones hold more collagen and less mineral density, so the radius has enough elasticity to bow without snapping. Falls onto an outstretched hand, direct forearm impact, and loading during contact sports are the usual causes.

Orthopedic and sports medicine practices see these injuries in waves through the youth sports calendar. That volume is where an unspecified code quietly becomes the default.

The unspecified designation in S52.389A points at laterality alone. When the record does not say whether the injured radius is right or left, S52.389A is the correct assignment. Code to the highest specificity the documentation supports.

• Plastic bowing fracture: permanent bending with no cortical breach.
• Greenstick fracture (S52.31x): one cortex breaks, so a different code family applies.
• Torus (buckle) fracture: cortical buckling at the metaphysis, a different mechanism and a different code.
• Complete fracture: both cortices disrupted, coded from a separate family.

Where S52.389A sits in the code hierarchy

ICD-10-CM organizes codes as a breadcrumb, from the broad chapter down to the billable code. Walking that chain confirms S52.389A is the most precise option available for the documented encounter. Neighboring radius codes such as S52.514G sit under the same category and follow the same structure.

7th character extensions for S52.389

The 7th character is mandatory on every S52 fracture code. It identifies the encounter type and, for subsequent encounters, the healing status. A code submitted without it is not billable. The complete extension set for S52.389 appears below, per the CMS ICD-10 codes page and the ICD-10-CM Official Tabular List.

Ten of those 16 characters describe open fractures. Plastic bowing is almost always closed, so A, D, G, K, P, and S cover nearly every claim you will code. The open-fracture characters still matter when a bowing injury carries a wound down to bone.

In that situation the Gustilo classification decides the choice. Type I or II wounds take the B, E, H, M, or Q characters. Type IIIA to IIIC wounds take C, F, J, N, or R.

Initial encounter, character A, covers every visit in the active treatment phase, not only the first appointment. A casting review two weeks after diagnosis is still an initial encounter while treatment is active.

Once active management ends and the visit is for healing evaluation, move to the matching subsequent-encounter character. Every other forearm code works the same way, including S52.629D.

For practices seeing fracture patients across several visits, structured clinical documentation in each note is what justifies the character on that claim.

S52.389A vs related laterality codes

ICD-10-CM requires coders to capture laterality whenever the record documents it. S52.389A belongs only to encounters where the injured side is genuinely undocumented. Using it when the chart clearly says right or left is a coding error and an audit flag.

The CDC ICD-10-CM web tool lists the laterality family for the S52.38 group, which runs to three codes rather than two.

Synonyms and alternate diagnostic terms

Clinicians document bowing injuries under several interchangeable terms. Recognize all of them, and confirm each one maps to S52.389A or a laterality-specific variant before you assign the code. The AAPC code lookup cross-references these synonyms against the official tabular list.

• Bent bone of radius (NOS)
• Plastic bowing fracture of radius
• Plastic deformation of radius
• Bowing fracture of forearm
• Greenstick-type bowing, which sits in a separate code family and needs imaging to confirm
• Radius NOS, bowing injury
• Traumatic bowing deformity of forearm

If a clinician writes greenstick fracture but imaging shows no cortical break, send a query. Greenstick fractures sit in the S52.31x family, so assigning S52.389A to a true greenstick is an error.

Coders supporting physical therapy practices that handle fracture rehabilitation should watch this distinction across the whole episode of care.

ICD-10-CM fracture coding guidelines

Section I.C.19.c.2 of the ICD-10-CM Official Guidelines for Coding and Reporting covers the coding of traumatic fractures. Coders assigning S52.389A apply those rules across the whole treatment episode. The same rules decide when a later visit becomes a subsequent-encounter code such as S52.692R.

• Initial encounter (characters A, B, C): use through the entire active treatment phase, including fracture management visits, manipulation, casting, and reduction.
• Subsequent encounter (characters D through R): use once active treatment ends. Pick the character matching the healing status, whether routine, delayed, nonunion, or malunion.
• Sequela (character S): use for late effects that arise after healing, such as residual deformity or pain attributed to the old injury.
• Laterality specificity: always code to the highest documented specificity. S52.389A is acceptable only when the side is absent from all available documentation.
• Open versus closed: S52.389A covers closed fractures only. For an open fracture, assign character B or C according to the Gustilo classification.
• Combination coding: when the same encounter involves both the radius and the ulna, a combination code may apply. Review the instructional notes under S52.

What the clinical record must document

Billing S52.389A takes more than picking the right code number. The record has to support every element of the code description. Practices using digital intake forms can build encounter templates that capture each required data point automatically.

Those templates still sit inside the rules set out in HIPAA documentation practices. Retention and access controls apply to a fracture note like any other clinical record.

• Fracture type: the note or radiology report must describe a bent bone, bowing, or plastic deformation. A greenstick, torus, or complete fracture points elsewhere.
• Laterality attempt: the record should show that the clinician assessed the injured limb. If imaging labels establish the side, that side must be captured.
• Encounter type: the note must reflect active fracture management to justify character A. A fracture check after healing has begun needs a subsequent-encounter character.
• Open versus closed: document whether the skin is intact. Wording such as closed fracture or skin intact supports character A, and an absent notation invites a payer query.
• Mechanism and site: the mechanism of injury and the specific bone both strengthen medical necessity on a fracture management claim.

Practices handling fracture care across several visits benefit from a claim review step that flags incomplete documentation before submission. Incomplete records, rather than the code itself, are the usual reason an S52.389A claim is challenged on audit.

Common coding errors to avoid

Bent bone radius claims are denied or queried for a handful of repeating reasons. Spotting the pattern before submission costs far less than correcting it after a denial. Keeping a medical coding cheat sheet at the desk helps a newer coder run the first checks without a lookup.

• Omitting the 7th character: S52.389 submitted without an extension is not billable, and most payers reject it outright.
• Using S52.389A when laterality is documented: if any part of the record says left radius, S52.382A is the correct code.
• Holding character A past active treatment: switch to the subsequent-encounter characters once treatment ends. Prolonged use of A triggers medical-necessity queries.
• Confusing bent bone with greenstick: a greenstick has one broken cortex, a bent bone has none. The distinction needs imaging review and, where it stays unclear, a clinician query.
• Applying S52.389A to an open fracture: if skin integrity is compromised, character B or C applies. Character A on an open fracture is a compliance risk.
• Defaulting to unspecified: unspecified codes are for records that truly cannot support more detail. Routine use of S52.389A invites audit scrutiny.

How Pabau supports fracture coding and clean claims

A missing 7th character usually surfaces when the payer sends the claim back. Laterality sits in the radiology report while the claim still reads unspecified. Someone reopens the chart, amends the code, and resubmits weeks later.

Practice management software like Pabau keeps the coding decision next to the clinical record. Encounter templates prompt for fracture type, skin integrity, and side at the point of care. The diagnosis code is entered against that note, rather than reconstructed from memory a month on.

Pabau’s claims management tools then check the claim against the note before it leaves the practice. Automated workflows chase the missing detail instead of leaving it for the biller to catch.

The result is fewer amended claims and less rework for orthopedic, urgent care, and sports medicine teams. Your coders spend their time on the genuinely ambiguous cases, not on hunting laterality through old imaging.

Submit fracture claims that hold up first time

Pabau captures fracture type, laterality, and encounter status in the clinical note, then checks the claim against it before submission. Coders assign the right 7th character once, so denials and rework drop across the treatment episode.

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Conclusion

Bent bone coding turns on three facts: laterality, fracture class, and where the patient sits in the treatment episode. S52.389A is right when the side is genuinely undocumented, the skin is intact, and treatment is still active. Change any one of those and a different code in the S52.38 family applies.

Treat unspecified laterality as a temporary state rather than a coding destination. The side is usually recoverable from an imaging label or the cast application note. Recovering it costs less than defending the unspecified code on audit.

Set the four-check habit now and the S52 family stops generating rework. To see how Pabau handles fracture documentation and billing end to end, book a demo.

Continue your research

Tracking a forearm injury into its late effects? S56.428S walks through the sequela character on a forearm claim.

Coding a follow-up visit at the elbow? S53.442D shows how the subsequent-encounter character works one joint up from the radius.

Documenting a flexor tendon injury after healing? S56.125S covers the record a sequela claim needs behind it.

Billing a vascular forearm injury at review? S55.899D sets out the documentation a subsequent-encounter claim relies on.

Want laterality captured before the clinician walks in? Our new patient questionnaire gives you a structured intake form to build the encounter note on.

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