ICD code S52.001C – Open fracture of upper end of right ulna, type IIIA-IIIC

Key takeaways

S52.001C is billable and specific for FY2027. It covers an unspecified fracture of the upper end of the right ulna, at the back of the elbow.

The 7th character C means an initial encounter for an open Gustilo-Anderson Type IIIA, IIIB, or IIIC fracture. Open Type I and II fractures take B instead.

When the record names the olecranon or coronoid process, a more specific S52.02-, S52.03- or S52.04- code replaces S52.001C.

Two avoidable denial triggers are a missing external cause code and a radial head CPT code paired with this ulna diagnosis.

Pabau’s claims management supports ICD-10 code assignment and electronic claim submission for orthopedic and fracture-care practices.

ICD-10 code S52.001C: Code descriptor and at-a-glance reference

ICD-10 code S52.001C is the billable diagnosis code for an unspecified fracture of the upper end of the right ulna. Its 7th character C marks the initial encounter for an open fracture, Gustilo-Anderson Type IIIA, IIIB, or IIIC. The code sits in category S52 (fracture of forearm), which covers both forearm bones. The “upper end” qualifier places the injury at the proximal ulna, the olecranon and coronoid region of the elbow, not the wrist.

According to the Centers for Medicare and Medicaid Services (CMS), the ICD-10-CM code set is updated every October. S52.001C and its descriptor carry over unchanged in the FY2027 release, effective October 1, 2026. Check the tabular list again at each new fiscal year, because descriptor wording and extension characters can change.

Understanding the 7th character C in proximal ulna fracture codes

The 7th character C designates an initial encounter for an open fracture classified as Gustilo-Anderson Type IIIA, IIIB, or IIIC. “Initial encounter” means the patient is still in active treatment for the fracture, whether or not the provider has seen them before. A repeat debridement or a staged flap during the same active treatment course still uses character C.

In category S52, the initial-encounter characters split three ways. A is a closed fracture, B is an open Type I or II fracture, and C is an open Type III fracture. A frequent error on this code is reading C as the Type I or II character.

Gustilo-Anderson classification and code selection

The Gustilo-Anderson classification grades open fractures by wound size, energy of injury, and soft-tissue damage. The treating surgeon must document the Gustilo grade in the operative report. Coders cannot assign the grade on their own from imaging or wound photographs.

Under the S52 tabular 7th-character definitions, an open fracture with no documented Gustilo type takes character B (type I or II). So character C needs an explicit Type IIIA, IIIB, or IIIC grade in the record. Assigning C to a Type I or II wound, or to an ungraded open fracture, is a coding error that affects reimbursement and audit exposure.

Inclusions, exclusions, and coding notes for S52.001C

Category S52 and subcategory S52.0 carry notes that decide whether S52.001C applies or a different code is required. Misreading them, or skipping the more specific codes in S52.0, is a common source of coding errors.

What S52.001C includes

• Open (compound) fracture of the proximal right ulna, documented as Gustilo Type IIIA, IIIB, or IIIC
• Fractures where the record confirms the upper end of the ulna but names no olecranon, coronoid or other specific pattern
• Every visit during initial active treatment, including staged debridement and soft-tissue coverage procedures

What S52.001C excludes

• Olecranon process fractures: Code to S52.02- (without intraarticular extension) or S52.03- (with intraarticular extension)
• Coronoid process fractures: Code to S52.04-
• Left or unspecified side: Code to S52.002C (left ulna) or S52.009C (side not documented)
• Fractures of the ulna shaft: Code to S52.2- (Excludes2 note at S52.0)
• Fracture of the elbow NOS: Code to S42.40- (Excludes2 note at S52.0)
• Pathological fractures of the ulna: Code to M84.4- or the matching M80-M84 code for the underlying bone disease
• Periprosthetic fractures around an elbow prosthesis: Code to M97.4-

Report the external cause codes (see the section below) alongside S52.001C at the initial encounter. Type IIIC wounds also involve an arterial injury, so code the vascular injury separately when the surgeon documents it.

Codes commonly confused with ICD-10 code S52.001C

Five codes are routinely confused with S52.001C, because their descriptors differ by one character or one word. The table sets each one against S52.001C.

The proximal radius is the other common confusion point. The radial head and neck sit in S52.1-, one subcategory away, and both bones meet at the elbow. Confirm the bone in the imaging report before coding, because a radius diagnosis also needs radius CPT codes. The CDC ICD-10-CM browser tool lists the full S52 family with descriptors for a quick side-by-side check.

The decision path below runs the four checks in the order a coder meets them, with the neighboring code at each exit.

Required documentation to support ICD-10 code S52.001C

S52.001C requires a specific documentation set. Missing any element leaves the coder without the clinical basis to assign the code, and leaves the practice exposed to a post-payment audit reversal.

• Imaging report: X-ray or CT confirming a fracture of the upper end (proximal) of the right ulna
• Open wound documentation: Clinical or operative note confirming the fracture is open, with the skin broken and bone exposed or communicating with the outside
• Gustilo grade in the operative report: The surgeon must state “Type IIIA,” “Type IIIB,” or “Type IIIC,” or describe the matching criteria. The coder cannot infer the grade from wound measurements alone
• Soft-tissue and vascular findings: Periosteal stripping and flap coverage plans support Type IIIB, and an arterial repair supports Type IIIC. These details also justify the procedure codes
• Encounter phase: The visit must fall within the active treatment course for this fracture, not a follow-up after active treatment has ended
• Laterality and fracture pattern: S52.001C is the right side only. Use S52.002C for the left side, S52.009C when the side is not documented, and S52.02- to S52.04- when the surgeon names the pattern

Many orthopedic practices build their operative note templates to prompt for the Gustilo grade, side and fracture pattern at the time of documentation. That shortens the coding review cycle, because a structured field prompts the surgeon and a free-text field does not.

External cause and additional codes to report with S52.001C

The ICD-10-CM Official Guidelines, Section I.C.20, call for external cause codes alongside fracture codes whenever the cause of injury is known. These codes are secondary diagnoses and do not affect principal diagnosis selection, but many payers use them in medical necessity review.

Report the external cause codes at the same specificity level as the fracture code. A documented fall from a ladder at home maps to a specific W-code, Y92 place, Y93 activity, and Y99 status, not to W19 alone. Type III wounds usually follow high-energy injuries, so the mechanism code often carries weight in medical necessity review.

CPT codes commonly billed with S52.001C

The CPT codes billed with ICD-10 code S52.001C depend on how the proximal ulna fracture is treated. Type III open fractures almost always need surgical debridement, and most go on to open treatment with fixation. Because the injury is in the ulna, radial head and neck codes (24650-24666) do not pair with it.

Wound debridement bills as 11011 when it reaches muscle, or 11012 when contaminated bone is removed. Check current CMS National Correct Coding Initiative (NCCI) edits before pairing any CPT code with S52.001C, because bundling rules are updated quarterly.

Claims software for billers, such as Pabau’s, carries the coded encounter through to electronic submission. The diagnosis and CPT pairing you confirmed against the operative note is then the pairing the payer receives.

Common claim denial reasons and how to avoid them

Claims submitted with S52.001C are denied for a predictable set of reasons. Most trace back to a detail missing from the operative report, or to a wrong 7th character. Each denial returns with a reason code, so it helps to know the common medical billing denial codes.

A structured clean claim process removes most of these denial triggers. It checks the diagnosis code, external cause code, CPT pairing and modifier logic before transmission. For denials that still come back, the denial management workflow guide covers appeal and resubmission.

Payer coverage and pre-authorization considerations

Open fracture repair of the proximal ulna is generally covered under Medicare and most commercial plans as medically necessary surgical treatment. Prior authorization requirements, however, vary significantly by payer and plan year.

• Medicare: Open fracture repair is covered under the Medicare Physician Fee Schedule. Document medical necessity using the operative report and imaging, with S52.001C as the primary diagnosis on the CMS-1500 form
• Medicaid: Coverage and prior authorization thresholds vary by state. Check the state Medicaid fee schedule and any prior authorization requirement before scheduling planned procedures
• Commercial payers: Most commercial plans require prior authorization for planned open reduction with internal fixation (ORIF). Submit the Gustilo grade, imaging and clinical rationale with the request. Emergent debridement of an open fracture generally needs no authorization, but a staged flap for a Type IIIB wound may

Sound billing compliance requirements for fracture claims include keeping the operative report, imaging, and Gustilo documentation for the payer’s audit look-back period. Medical billing documentation standards require every diagnosis code on the claim to be supported by the record at the time of service. Adding a Gustilo grade to an operative report after the claim is submitted creates a compliance risk.

Subsequent encounter and sequela coding for proximal ulna fractures

Once active treatment for the S52.001C fracture ends, the 7th character changes for every later visit. Because this is an open Type III fracture, the subsequent characters come from the Type IIIA-IIIC set. Using character C beyond the active treatment phase is a coding error that payers flag during claims review.

E, H, M and Q are the subsequent characters for open Type I or II fractures, so they never follow S52.001C. The closed-fracture characters D, G, K and P do not apply either. Nonunion (N) and malunion (R) need imaging or clinical findings that confirm the healing failure, not a delayed healing assumption. The distinction matters because revision surgery for nonunion or malunion may trigger a separate authorization review.

How Pabau supports accurate coding for open proximal ulna fractures

Coding S52.001C correctly depends on three details that often sit in different documents: The bone, the side and the Gustilo grade. Many orthopedic practices still pull them by hand from imaging reports and operative notes before building the claim.

Pabau keeps the encounter note, the diagnosis code and the claim in one patient record. Structured note templates can prompt the surgeon for the Gustilo grade and fracture pattern at the point of care. Claims management then carries the coded encounter through to electronic submission.

With the grade captured in a structured field, fewer claims go out with a wrong 7th character or a radius code on an ulna injury. That leaves billing teams less rework once the payer responds.

Code fracture claims from a complete operative note

Pabau keeps the operative note, the ICD-10 code and the claim in one patient record. Its claims management supports electronic submission, so the code built from the surgeon’s note is the code the payer receives.

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Conclusion

S52.001C is a narrow code, and most errors come from treating it as a broader one. It fits only a right proximal ulna fracture with an open Type IIIA, IIIB, or IIIC wound and no named olecranon or coronoid pattern. If any of those details is missing, one of its neighbors in S52.0 is the correct code.

The fix sits upstream of the coder. When surgeons document the Gustilo grade, the side and the fracture pattern in the operative report, the code follows from the note.

Pabau’s claims management supports electronic claim submission, so billing teams can see which claims the payer returned. Book a demo to see how Pabau supports ICD-10 coding for orthopedic and fracture-care practices.

Continue your research

Need a framework for reducing claim denials across your practice? Denial codes in medical billing covers the most common CARC denial codes and how to address them in your billing workflow.

Submitting claims electronically for the first time? 837 file format guide explains how electronic claim files are structured for payer submission and what coders need to verify before sending.

Verifying patient coverage before fracture treatment? Insurance eligibility verification outlines the steps to confirm active coverage and authorization status before surgical encounters.

Tracking which claims the payer paid or denied? Electronic remittance advice explains how payers report paid, adjusted and denied claims back to the practice.

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