ICD code S52.281Q – Bent right ulna, open type I or II fracture with malunion

Key takeaways

S52.281Q covers follow-up visits for a bent (plastically deformed) right ulna after an open type I or II fracture that has healed in malunion.

Right laterality is built into the sixth character, so the left ulna takes S52.282Q and an undocumented side takes S52.283Q.

Q means malunion, not routine healing. Routine healing is E, delayed healing is H, and nonunion is M for the same open type I or II fracture.

Most denials trace back to a missing malunion statement, a wrong 7th character, or a CPT code that doesn’t match a malunion visit.

ICD-10 code S52.281Q: Definition and clinical description

ICD-10 code S52.281Q is a billable ICD-10-CM code for a malunited bent bone of the right ulna. It applies at follow-up visits after an open type I or II fracture. Its full official descriptor is: Bent bone of right ulna, subsequent encounter for open fracture type I or II with malunion.

The code sits in Chapter 19 (S00-T88) under category S52, Fracture of forearm, as listed in the CMS ICD-10-CM code files. Within S52 it belongs to subcategory S52.28, Bent bone of ulna.

A bent bone is a plastic deformation, also called a bowing fracture. The ulna bends under load without a clean break line, which happens mostly in children. Malunion means the bone has healed in a bowed or angled position, which can limit forearm rotation.

The code carries four specifications at once. They are the injury (a bent ulna shaft), the side (right), the fracture type (open, Gustilo I or II), and the care phase. The record must support all four before the code is assigned.

Breaking down the code structure

Each character in S52.281Q narrows the diagnosis. The table maps every position to its value and what it tells the coder and the payer.

The bent-bone subcategory is easy to confuse with its neighbors. A greenstick fracture of the ulna shaft is coded to S52.21-, and a Monteggia fracture of the ulna to S52.27-. A bent radius goes to S52.38-, so the bone named in the imaging report decides the subcategory.

What “subsequent encounter with malunion” means

A subsequent encounter is any visit after the patient has completed active treatment of the fracture. The ICD-10-CM Official Guidelines (Section I.C.19.c.1) say that malunion and nonunion are reported with the subsequent-care 7th characters. Malunion care therefore takes P, Q or R, with one exception. A patient who delayed seeking treatment for the fracture gets the initial-encounter character instead.

For an open type I or II fracture of the right ulna, the 7th character follows the phase and the healing status:

• B (S52.281B): Initial encounter for open fracture type I or II. Use it while the patient receives active treatment, such as wound debridement or the first reduction.
• E (S52.281E): Subsequent encounter with routine healing. The fracture is healing as expected and no complication is documented.
• H (S52.281H): Subsequent encounter with delayed healing. Union is slower than expected but still progressing.
• M (S52.281M): Subsequent encounter with nonunion. The physician documents that the fracture has failed to heal.
• Q (S52.281Q): Subsequent encounter with malunion. The fracture has healed, but in a deformed position the physician documents as malunion.
• S (S52.281S): Sequela. Use it for a late effect of the healed injury, coded alongside the condition it caused.

The most common error here is billing E (routine healing) at a visit where the physician has diagnosed malunion. Once malunion is documented, every follow-up for that deformity takes Q, including a corrective osteotomy.

Gustilo classification and 7th character selection

The open-fracture 7th characters in category S52 are based on the Gustilo-Anderson classification. The surgeon grades the wound by size, soft tissue damage, contamination, and vascular injury. The coder does not assign the grade, but translates the documented grade into the matching 7th character.

Q applies to open fractures graded type I or II. Q is also assigned for an open fracture with no documented grade. If the operative note records type IIIA, IIIB, or IIIC, a malunion visit takes S52.281R instead.

A closed bent ulna that healed in malunion takes S52.281P. The chart below runs those choices as three questions, in the order a coder answers them.

S52.281Q vs commonly confused codes

Codes in the S52.281 family differ only by the 7th character, and S52.282 differs only by side. The wrong choice is simple to audit after the fact, but it causes repeated claim rework when it slips through.

The E versus Q confusion matters most. Suppose the note describes healing with residual bowing and lost supination. That is malunion, so the claim needs Q. Billing E at that visit understates the condition and weakens medical necessity for any corrective procedure.

Includes, excludes, and coding notes

Category S52 carries instructional notes that affect how ICD-10 code S52.281Q is reported with other codes. Confirm them against the current tabular in the CDC/NCHS ICD-10-CM web tool for the applicable fiscal year, since notes can change in annual updates.

• Excludes1: Traumatic amputation of forearm (S58.-). The two are never reported together for the same injury.
• Excludes2: Fracture at wrist and hand level (S62.-). A separate wrist or hand fracture may be coded in addition.
• Open or closed default: A fracture not documented as open or closed is coded as closed. S52.281Q needs an explicit statement that the fracture was open.
• Gustilo basis: The open-fracture 7th characters follow the Gustilo classification, so the record should state the grade where known. Q is also assigned for an open fracture with no documented grade.
• External cause code: An external cause code from Chapter 20 may be added to show how the injury happened. It takes its own 7th character (A, D or S) for each encounter, not Q.

Documentation requirements to support S52.281Q

The medical record must support each element encoded in S52.281Q, or the payer has grounds to deny or downcode the claim. Medical billing compliance reviews often flag open-fracture malunion codes. Their elements are spread across the original injury note and the current follow-up note.

• Injury type: The note or imaging report describes plastic deformation, bowing, or a bent bone of the ulna. A greenstick or complete shaft fracture belongs to a different subcategory.
• Side: The record names the right forearm. A left-sided injury takes S52.282Q.
• Open fracture grade: The original note states the fracture was open and should record the Gustilo grade where known. Q is also assigned for an open fracture with no documented grade, while a type III grade moves the code to S52.281R.
• Malunion: The current note states malunion in words, ideally with the angulation on imaging and any loss of pronation or supination.
• Care phase: The note confirms that active treatment of the original injury has ended and this visit addresses the malunion.

Payer requirements and prior authorization for S52.281Q

Follow-up office visits for a malunion rarely need prior authorization. A planned corrective osteotomy or malunion repair often does, so check the payer policy before scheduling surgery. Running insurance eligibility verification before each visit also prevents coverage-lapse denials unrelated to the code.

Medicare and commercial payers expect each visit to show a clinical reason, a functional assessment, and a plan for the deformity. Medicare Administrative Contractor (MAC) policies vary by jurisdiction. Practices billing across regions should check the local coverage rules for forearm malunion surgery.

A clean claim for S52.281Q pairs the diagnosis with a matching CPT code and a date of service after the initial treatment. It also carries any modifier the visit needs, such as -25 for a separately identifiable E/M on the day of a minor procedure. A missing or mismatched element stalls the claim or triggers a denial.

Common claim denial reasons for S52.281Q

ICD-10 code S52.281Q draws a predictable set of denials, and most are preventable with a check before submission. Each reason below carries its CO adjustment code, and the full set is explained in our denial codes for billers reference. Effective denial management workflows start by spotting the pattern, and these five come up most often:

• Malunion not documented (CO-16): The claim uses Q, but the note never states malunion. Resolution: Ask the physician to document the malunion and the imaging findings before resubmitting.
• Wrong healing character (CO-11): The claim uses Q while the note describes routine healing, or uses E while the note describes malunion. Resolution: Match the 7th character to the healing status in the note.
• Gustilo grade mismatch (CO-16): The original note records type III, yet the claim uses the type I or II character. Resolution: Recode to S52.281R if the record supports type III.
• Procedure inconsistent with diagnosis (CO-11): A malunion repair is billed with the E character. The payer sees surgery on a fracture coded as healing normally and denies it.
• Global period conflict (CO-97): Malunion repair carries a 90-day global period. Follow-up visits inside it are usually bundled, and an unrelated visit needs modifier -24.

CPT codes commonly paired with S52.281Q

The CPT code for an S52.281Q visit depends on what the physician does at that visit. S52.281Q is the diagnosis, and the CPT code describes the service. Payers compare the two to check medical necessity, so the pairing has to make clinical sense. The AAPC ICD-10-CM code lookup lists current crosswalk references.

Forearm radiographs billed under CPT 73090 often come from the imaging department or facility rather than the treating practice. The medical billing workflow for the orthopedic visit should still note the order, so documentation is complete on both sides.

How Pabau reduces S52.281Q coding errors

Malunion codes depend on details spread across two or more notes, which makes them a steady source of preventable rework. Catching the mismatch while the visit is being coded costs far less than fixing a denied claim weeks later.

Pabau, the practice software we build for clinical teams, links the clinical note to the claim through its claims software for coders. The coder can open the signed note and confirm the malunion statement before choosing the 7th character.

For orthopedic and physical therapy practices with a steady flow of fracture follow-ups, that cuts the manual audit before submission. Claims then go out through the Claim.MD clearinghouse integration.

Catch fracture coding errors before claims go out

Pabau links each clinical note to its insurance claim, so coders can check the record before a fracture claim goes out. See how orthopedic practices use Pabau to cut denials on follow-up claims.

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Conclusion

S52.281Q is a narrow code, and each of its seven characters can be wrong on its own. Bone, injury pattern, side, open grade, and healing status all have to agree across the original note and the current one.

Practices that read the healing status before choosing the 7th character avoid most S52.281Q denials. Treat malunion as its own diagnosis, written in words, and bill E, H, M, or Q to match. To see how Pabau keeps those checks inside the coding workflow, book a demo.

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