ICD code S52.326K – Nondisplaced transverse fracture of shaft of unspecified radius

Key takeaways

S52.326K is a billable ICD-10-CM code for a nondisplaced transverse fracture of the radial shaft, reported at a subsequent encounter with nonunion.

The 7th character K carries three facts: closed fracture, subsequent encounter, and nonunion.

K is not the open-fracture or delayed-healing character. In contrast, H reports an open type I or II fracture with delayed healing.

Use S52.324K for the right radius and S52.325K for the left, and keep S52.326K for records that never name the side.

The parent code S52.326 is not billable alone, so every S52 fracture claim needs all seven characters.

Practice management software like Pabau carries ICD-10-CM and CPT lookup libraries, and checks required claim fields before submission.

S52.326K is billable, but only with all seven characters

S52.326K can go on a claim exactly as it stands. In fact, the seventh character is what makes it billable, and the parent code S52.326 will not pass without one.

Code validity is refreshed each October, so check the fiscal year against the CMS ICD-10 codes page before you submit. Once the code is confirmed, the work moves to the last character.

The 7th character K says the fracture never united

K marks a subsequent encounter for a closed, ununited fracture: active treatment has ended, but the bone has not joined.

In short, twelve of the 16 characters describe a subsequent encounter, split by healing status and fracture type. The set skips I, L and O, so letters jump from H to J and K to M.

Use the CDC/NCHS ICD-10-CM web tool to confirm the current character set — the letters only help once the note states healing status.

Nonunion, delayed healing and malunion are three different codes

In short, nonunion means the fracture has not joined. Specifically, imaging shows a persistent fracture line with no bridging callus, past the point at which union should have happened. In contrast, delayed healing means union is still moving, only slower than expected. Malunion means the bone joined in the wrong position.

In short, all three are subsequent encounters for the same injury, and each takes its own character:

• Nonunion (K): Closed fracture, no union. In fact, no bridging callus on imaging after the expected healing window.
• Delayed healing (G): Closed fracture, union progressing slowly. In fact, healing is still expected.
• Malunion (P): Closed fracture united in malposition. Indeed, deformity confirmed on imaging.
• Routine healing (D): Closed fracture healing as expected. In short, no complication documented.
• Sequela (S): Late effect of the original injury. In short, active fracture care is finished.

The wound at the time of injury moves the letter as well. In short, the K character covers closed fractures only. In contrast, nonunion of an open type I or II wound takes M, and a type IIIA, IIIB or IIIC wound takes N.

Notably, H sits next to K in the alphabet, and the two get swapped on claims. H reports an open type I or II fracture with delayed healing, so it differs from K on two counts, not one. If the note describes a closed fracture that has stopped healing, H is the wrong character.

Nondisplaced, transverse, shaft: what the descriptor requires

Specifically, three anatomical facts sit in front of the seventh character, and each one has to appear in the record.

• Nondisplaced: Specifically, the fragments stayed in anatomical alignment. The cortex broke, but the bone ends remained in contact or close to it. A displaced transverse shaft fracture takes S52.321, S52.322 or S52.323 instead, by side.
• Transverse: The fracture line runs perpendicular, or close to it, to the long axis of the shaft. As a result, direct impact and bending forces produce this pattern. Oblique, spiral and comminuted shaft fractures have their own subcategories under S52.3.
• Shaft of the radius: The diaphysis, or middle segment. That site differs from the lower end of the radius, coded in S52.5x, which covers Colles, Smith and Barton fractures. It also differs from the radial head and neck, coded in S52.1x.

The six base codes in S52.32

S52.32 splits by displacement first and side second. Therefore, reading the group in order is the quickest way to catch a displacement error before it reaches the claim.

• S52.321: Displaced transverse fracture of shaft of right radius
• S52.322: Displaced transverse fracture of shaft of left radius
• S52.323: Displaced transverse fracture of shaft of unspecified radius
• S52.324: Nondisplaced transverse fracture of shaft of right radius
• S52.325: Nondisplaced transverse fracture of shaft of left radius
• S52.326: Nondisplaced transverse fracture of shaft of unspecified radius

In short, every one of those six takes the same 16 seventh characters. So the nondisplaced, closed, nonunion follow-up reads as S52.324K on the right, S52.325K on the left, and S52.326K when the record does not say.

Use S52.326K when four conditions hold

In short, a subsequent encounter is any visit after active treatment has ended. Once the patient has had definitive treatment, such as a cast, a reduction or fixation, every follow-up is a subsequent encounter. Visit number does not matter, because the ICD-10-CM Official Guidelines tie the character to the phase of care.

Reach for ICD-10 code S52.326K when all four of these hold at the time of the visit:

1. The fracture is a transverse fracture of the shaft of the radius.
2. The fracture was nondisplaced at the time of injury.
3. The fracture was closed, not open.
4. The physician documents nonunion, and the record does not identify the side.

Here is how that plays out. For example, a patient breaks the radial shaft in January and comes out of a cast in March. Then, at the October visit the film shows an unchanged fracture line and no callus, and the physician writes nonunion. If that note never names an arm, the encounter codes to S52.326K.

In contrast, change one of those four elements and a sibling code takes over:

• Right radius documented: S52.324K
• Left radius documented: S52.325K
• Displaced at the time of injury: S52.323K, or S52.321K and S52.322K by side
• Open fracture, type I or II: S52.326M
• Healing slowly but still progressing: S52.326G

Check the AAPC ICD-10-CM code lookup for the full sibling set when displacement or laterality is in doubt.

Laterality: S52.326K should be your last choice

Specifically, the sixth character 6 means the record does not say which radius. As a result, payers screen unspecified codes in pre-payment edits, and Medicare Advantage plans screen them hardest.

The Official Guidelines do not ban unspecified laterality. They do require the most specific code the documentation supports, so the side belongs in the note whenever anyone knows it.

• S52.324K: Nondisplaced transverse fracture of shaft of right radius, subsequent encounter for closed fracture with nonunion
• S52.325K: Nondisplaced transverse fracture of shaft of left radius, subsequent encounter for closed fracture with nonunion
• S52.326K: Use only when the record genuinely does not identify the side, or when laterality cannot be recovered from it

There is a second reason to query the provider. In addition, a nonunion repair billed on the same claim needs an RT or LT modifier on the procedure line. That side has to come from the same record. As a result, a claim that pairs an unspecified-laterality diagnosis with a sided procedure contradicts itself, and payer edits catch that pattern.

In short, laterality and displacement are two of the most common triggers for orthopedic claim edits. Both are worth catching before submission rather than after the payer returns the claim.

Where the code sits in the S52 fracture tree

In fact, reading the hierarchy is a quick way to confirm you are at the right level of specificity. It also prevents the most common error on these claims, which is billing the parent code.

• S00-T88: Injury, poisoning and certain other consequences of external causes
• S50-S59: Injuries to the elbow and forearm
• S52: Fracture of forearm
• S52.3: Fracture of shaft of radius
• S52.32: Transverse fracture of shaft of radius
• S52.326: Nondisplaced transverse fracture of shaft of unspecified radius (not billable)
• S52.326K: …subsequent encounter for closed fracture with nonunion (billable)

As a result, S52.326 submitted bare fails claim validation before it reaches the payer. In fact, that rule runs across every S52 fracture code, not just the transverse shaft group.

Coding guidelines that apply to this code

Section I.C.19 of the ICD-10-CM Official Guidelines for Coding and Reporting governs injury codes, fractures included. Specifically, four of its rules bear directly on this code.

• Active treatment sets the encounter, not the visit count. Specifically, Character A covers every visit where the provider is delivering active treatment for the injury. In contrast, the subsequent characters take over once treatment is complete and the patient is healing.
• Nonunion surgery is still a subsequent encounter. In fact, care for a nonunion is reported with K, M or N even when that care is an operation. The claim does not go back to A because a procedure was performed.
• Nonunion has to be documented. Indeed, a coder cannot infer it from the calendar. Instead, the physician must state the diagnosis, usually backed by a film or CT showing a persistent fracture gap without bridging callus.
• External cause codes are additional. Where the mechanism is known, such as a fall or a collision, add a code from Chapter 20 (V00-Y99). In short, S52.326K reports the diagnosis and the external cause code reports how it happened.
• Traumatic and pathological fractures are separate families. Specifically, S52.326K is a traumatic fracture code. In contrast, a fracture caused by neoplasm, osteoporosis or other disease belongs in M84.3x through M84.6x.

Excludes notes and neighboring code families

Specifically, two exclusion notes sit on the S52 category. They decide whether a second injury can be reported on the same claim.

• Excludes1, traumatic amputation of forearm (S58.-): An Excludes1 note means the two codes cannot be reported together for the same condition. Where the forearm has been amputated, the S58 codes apply instead of S52.326K.
• Excludes2, fracture at wrist and hand level (S62.-): The excluded condition is a different one that may occur at the same time. In fact, a patient can carry both S52.326K and a wrist-level fracture from S62, and both may be reported when documented.
• Neighboring families to keep apart: Lower end of radius fractures code to S52.5x, and radial head and neck fractures to S52.1x. In addition, ulnar shaft fractures code to S52.2x. The shaft assignment holds only where the note places the fracture in the diaphysis.

The note has to carry seven details, or the code will not hold

Each element of S52.326K has to be written down somewhere in the chart, because coders may not assume any of them. Notably, two elements slip more often than the rest: displacement and the closed status. Both were settled months earlier at the initial encounter, and the follow-up note rarely repeats them.

Instead, query the physician whenever an element is missing. A coder cannot assign nonunion from an imaging report alone, however clear the film looks. Instead, the physician has to acknowledge the finding in the clinical note first.

Practices that rehabilitate these patients after repair can hold displacement, wound status and healing status in structured note fields. Those details then carry forward to each follow-up visit instead of being retyped.

CPT codes commonly paired with S52.326K

Specifically, nonunion of the radial shaft has its own CPT family, separate from the 256xx group used for the lower end of the radius. In fact, site matters here as much as it does on the diagnosis side. The codes below are the ones that turn up on these claims, and AMA CPT codebook descriptors govern the precise indication for each.

The two graft rows follow a bundling rule that supply codes do not share. Codes 25405 and 25420 include obtaining the autograft, so 20900 is not reported alongside them. A skin substitute product such as HCPCS code Q4107 bills per square centimeter and requires a qualifying wound care procedure on the same claim.

Indeed, CPT codes are maintained by the American Medical Association (AMA). Treat the pairings above as context, then verify them against the current codebook and the payer’s own policy. Some plans also require prior authorization for nonunion repair, which is worth reading before the visit rather than after the denial.

Five checks before the claim goes out

In short, denials on these claims usually trace back to one of five details. Run this list while the note is still open:

• Specifically, the note names the shaft or diaphysis of the radius, not just the radius or the forearm.
• The pattern reads transverse, and the displacement status reads nondisplaced.
• The closed status appears at this visit, or is carried forward from the initial encounter record.
• In fact, the physician has written nonunion, and an imaging finding supports it.
• In short, the code carries all seven characters, ends in K, and uses S52.324K or S52.325K if the chart names the side.

If a claim does come back denied, start with the seventh character and then the note behind it. The remittance advice narrows the search, because denial codes name the field the payer rejected. The procedure line is worth a second look too. As a result, a sided modifier next to an unspecified diagnosis is an easy edit for a payer to catch.

Crosswalking S52.326K back to ICD-9-CM

ICD-10-CM replaced ICD-9-CM for HIPAA-covered transactions on October 1, 2015. The General Equivalence Mappings are approximate, and no single ICD-9-CM code matches S52.326K, because ICD-9-CM carried neither laterality nor a seventh character.

Specifically, the GEMs are published by CMS and NCHS, and they serve research and data migration rather than current-year claims. In addition, ResDAC publishes separate guidance on using ICD codes in Medicare research files. Code from the current fiscal year tabular list instead.

How Pabau keeps the seventh character intact from note to claim

Where the clinical record and the billing system sit apart, the diagnosis gets typed twice. A coder reads the follow-up note, picks S52.326K, then re-enters it in a separate system along with the payer, provider and authorization details. As a result, every re-entry is a chance to drop the last character.

Pabau, our practice management platform, removes that second pass. The claim form pre-fills from the patient record, so the codes attached to the visit land on the charge lines as they were coded.

Search icons open the ICD-10-CM and CPT lookup libraries whenever a coder wants to confirm a character, and both libraries refresh with each official release. In addition, the Send button stays locked until the claim’s required fields are complete, membership and authorization numbers included.

In the US, claims route through the Claim.MD clearinghouse, with real-time eligibility checks, ERA posting and claim-status tracking on one screen. Remittances land against the visit they belong to, so a short payment is visible the same week.

Pabau’s claims management software does not read the note or decide whether K is the right character, so that judgment stays with the coder. In short, what it removes is the retyping, the half-filled claim, and the wait on a paper remittance.

Send fracture claims without retyping the code

Pabau pre-fills the claim from the patient record, then checks that every required field is complete before submission. In the US, Claim.MD handles eligibility checks, ERA remittances and claim-status tracking.

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Conclusion

S52.326K is a narrow code, and that is the point of it. One fracture pattern, one displacement status, one closed wound, one healing outcome, one phase of care.

Indeed, the pair worth watching is K against H, two letters that sit next to each other in the character set. In contrast, H describes an open fracture that is still healing, which is a different injury altogether. A closed radial shaft fracture that has stopped healing is always K, on the side the chart supports.

In short, Pabau keeps the coding, the invoice and the claim on one patient record. Book a demo to see how a fracture claim leaves your practice with its codes, charges and required fields already complete.

Continue your research

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Want to know how a fracture claim gets denied, and how to appeal it? Denial codes in medical billing covers the common remittance reason codes and the appeal route for each.

Need the rules behind a compliant submission? Medical billing compliance sets out the documentation and submission standards for HIPAA-covered claims.

Following the money from note to payment? What is revenue cycle management walks the chain from documentation through to remittance.

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