ICD-10 code S52.131Q: Displaced fracture of neck of right radius

Key Takeaways

ICD-10 code S52.131Q describes a displaced fracture of neck of right radius, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with malunion.

S52.131Q is a billable, specific ICD-10-CM code valid for submission; the parent code S52.131 (without a 7th character) is non-billable.

The 7th character Q applies only when the open fracture is type IIIA, IIIB, or IIIC (Gustilo classification) AND malunion is confirmed by imaging and physician documentation.

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Open radius fractures with malunion generate some of the most complex coding decisions in orthopedic billing. The difference between a clean reimbursement and a denial often comes down to a single 7th character. ICD-10 Code S52.131Q captures a very specific clinical situation: a displaced fracture of the neck of the right radius, encountered at a follow-up visit, where the fracture was open and classified as Gustilo type IIIA, IIIB, or IIIC, and where the bone has healed in an abnormal position. This reference covers code anatomy, 7th character selection, Gustilo classification, documentation requirements, and related codes in the S52.131 series.

According to the Centers for Medicare and Medicaid Services (CMS), all HIPAA-covered entities must use ICD-10-CM diagnosis codes for covered transactions. Getting the 7th character wrong on a code like S52.131Q is one of the fastest routes to a claim denial or audit flag.

ICD-10 code S52.131Q: Quick reference

Claims management software needs to capture the right code the first time. Here is the essential reference data for S52.131Q.

Breaking down S52.131Q: What each segment means

Every character in S52.131Q carries clinical meaning. Misreading one segment is enough to submit the wrong code entirely.

Note that laterality is embedded in the 6th character: “1” = right radius, “2” = left radius, “9” = unspecified. The displaced vs. non-displaced distinction is also encoded here; S52.136 covers non-displaced fractures of the neck of the right radius.

The 7th character Q: Subsequent encounter with malunion explained

The 7th character is where most coders run into trouble with the S52.131 family. There are 19 valid 7th character options for this code, spanning initial encounters, subsequent encounters with various healing outcomes, and sequela. The full table below covers the most clinically relevant ones.

Q is one of only two 7th characters that encode malunion for open type III fractures. The other (for closed fractures) is M. P and Q are easy to confuse: P = nonunion (fracture failed to heal), Q = malunion (fracture healed in a poor position). Those are different clinical outcomes requiring different documentation.

Gustilo open fracture classification and ICD-10 code S52.131Q

The Gustilo-Anderson classification system is the basis for 7th character selection in open fracture coding. Without a documented Gustilo type in the physician notes, a coder cannot legitimately assign B, F, P, or Q. The CDC/NCHS ICD-10-CM tool confirms that these 7th characters require explicit fracture-type documentation.

A critical and often overlooked point: ICD-10-CM groups types IIIA, IIIB, and IIIC under the same 7th characters (B, F, J, P, Q). The classification system does not distinguish between the three subtypes at the code level. The specific subtype (IIIA vs. IIIB vs. IIIC) must still appear in the physician documentation for medical necessity and audit purposes, but it does not change the code.

When to use S52.131Q: Subsequent encounter vs. initial encounter

Encounter type selection is one of the most compliance-sensitive decisions in fracture coding. Using an initial encounter code (A or B) for a follow-up visit is a frequent audit trigger. Encounter type selection in ICD-10 follows the same core logic across diagnostic categories: the encounter type reflects what the provider is doing, not how long ago the injury occurred.

Use S52.131Q when ALL of the following apply:

• Active treatment of the fracture is complete
• The patient is receiving routine aftercare or follow-up care
• The fracture was open, documented as Gustilo type IIIA, IIIB, or IIIC
• Radiographic evidence and physician documentation confirm malunion
• The visit is not the one where the diagnosis was first established or acute treatment was initiated

Do NOT use S52.131Q when:

• The patient is presenting for the first time with this fracture (use S52.131B instead)
• The fracture is still in active treatment (use the appropriate initial encounter character)
• Malunion has not been radiographically confirmed and documented by the physician
• The fracture was closed (malunion of a closed type III fracture uses different characters)

What is malunion? Clinical and coding implications

Malunion means the fracture has healed, but in an abnormal position. The bone segments united, unlike nonunion (where they did not heal at all) or delayed union (where healing is slower than expected but still progressing). For coders, the distinction matters enormously: P = nonunion, Q = malunion. Confusing the two is a common and auditable error.

For S52.131Q to be correctly assigned, the physician documentation must include:

• Explicit statement of malunion (not just “poor alignment” or “angulation”)
• Radiographic evidence supporting the diagnosis (X-ray or CT findings)
• Confirmation that healing has occurred (i.e., the fracture is no longer active)

Malunion of the radial neck commonly produces functional consequences including restricted forearm rotation and reduced grip strength. These downstream effects may generate additional codes, but malunion itself is captured by the Q character on S52.131Q.

Related ICD-10 codes in the S52.131 series

S52.131Q belongs to a family of codes covering displaced fractures of the neck of radius by laterality and healing status. Other ICD-10-CM diagnosis codes within the same chapter follow the same 7th character logic, so understanding the S52.131 family builds transferable coding skills across the S52 category.

Verify each code against the AAPC ICD-10-CM code lookup to confirm current-year billability before submitting.

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Documentation requirements for S52.131Q

Every element of S52.131Q must be supported by clinical documentation. Medical documentation workflows that capture each axis at the point of care prevent denials before they happen. Use digital clinical forms to build structured intake and follow-up templates that prompt for each required data point.

• Laterality: Documentation must confirm “right radius” explicitly. “Radius fracture” alone is insufficient.
• Displacement: Physician note must state “displaced.” Non-displaced fractures map to different codes (S52.136x series).
• Anatomical site: “Neck of radius” must be specified. Radial head fractures (S52.12x) and radial shaft fractures (S52.3x) are different codes.
• Open fracture: Operative or emergency documentation must confirm the wound was open (compound fracture).
• Gustilo type: Must be explicitly documented as IIIA, IIIB, or IIIC by the treating physician. Coder cannot infer this from wound description alone.
• Malunion: Radiographic evidence (X-ray or CT) plus physician statement of malunion required. “Angulation” or “malalignment” without the word malunion is not sufficient.
• Encounter type: The visit must be a follow-up after active treatment is complete. Documentation should reflect routine care or evaluation of the malunion complication.

Practices using patient record management tools that prompt for structured clinical fields are better positioned to capture all seven axes at the time of the encounter rather than chasing addenda post-visit.

Common coding errors and how to avoid them

S52.131Q is involved in several recurring coding errors that generate denials and compliance risk. Complex ICD-10 coding scenarios across multiple specialties share a common thread: the 7th character is where coders get tripped up.

• Submitting S52.131 without a 7th character: The parent code S52.131 is non-billable. Claims submitted with S52.131 (six characters) will reject. The 7th character is mandatory for all fracture codes in the S52 category.
• Confusing malunion (Q) with nonunion (P): P = the fracture never healed. Q = the fracture healed but in a wrong position. The clinical outcome is different, the documentation requirement is different, and the code is different.
• Using an initial encounter character for a follow-up visit: S52.131B is for the first encounter with a type III open fracture. Using B for a six-week post-op check is an incorrect encounter type assignment and a common audit flag.
• Assuming Gustilo type III without documentation: A large wound does not automatically equal Gustilo type III. Only the treating physician can assign the Gustilo classification; coders must see it explicitly stated.
• Using the unspecified laterality code (S52.139Q): When laterality is documented, the laterality-specific code (S52.131Q for right, S52.132Q for left) is required. Unspecified codes are only acceptable when laterality is genuinely not documented.

Clinical coding scenarios: ICD-10 code S52.131Q in practice

These scenarios illustrate how S52.131Q applies across real-world clinical situations. They reflect the documentation and encounter-type decision process that sports medicine software and physical therapy EMR software workflows need to support.

Scenario 1: Eight-week post-op malunion evaluation. A 34-year-old presents for follow-up after surgical fixation of a Gustilo IIIB open fracture of the neck of the right radius sustained in an industrial injury. Operative report documented: open wound, type IIIB, right radius neck, displaced. At the eight-week follow-up, X-ray shows the fracture has united but with 20 degrees of angulation. Physician documents: “malunion confirmed radiographically.” Correct code: S52.131Q. Active treatment is complete, follow-up encounter, open type III confirmed, malunion confirmed by imaging and physician statement.

Scenario 2: Follow-up with nonunion, not malunion. Same patient presentation but X-ray shows a persistent fracture gap with no callus formation at 12 weeks. Physician documents: “nonunion.” Correct code: S52.131P, not S52.131Q. The fracture has not healed, so malunion cannot apply.

Scenario 3: Incorrect encounter type assignment. A patient presents to the emergency department with a fresh open right radial neck fracture. The treating physician documents Gustilo IIIA. Correct code for this visit: S52.131C (initial encounter, open fracture type IIIA/IIIB/IIIC). S52.131Q would be incorrect here because this is not a subsequent encounter and malunion has not yet occurred.

Check all codes against the ICD List code lookup to confirm billability and valid-for-submission status before each claim submission. Practices with HIPAA-compliant clinical documentation systems are better positioned to support the audit trail these complex codes require.

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Conclusion

Correctly assigning S52.131Q requires five things to be true simultaneously: displaced fracture, neck of right radius, subsequent encounter, open type III (Gustilo), and confirmed malunion. Miss any one of those axes and the code is wrong. The most preventable errors are submitting the non-billable parent S52.131, confusing P (nonunion) with Q (malunion), and applying initial encounter characters to follow-up visits.

Practices that build structured documentation templates for fracture follow-up visits, prompt for Gustilo type on every open fracture note, and use medical practice scheduling software to track encounter type across the care episode will catch these errors before claims go out. To see how Pabau supports orthopedic billing documentation workflows, book a demo.

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