ICD code S52.125Q – Radial head fracture malunion

Key takeaways

S52.125Q covers malunion of a nondisplaced open type I or II fracture of the left radial head at a subsequent encounter. Nonunion takes M and sequela takes S.

The Q 7th character is valid only when imaging or a clinical note confirms malunion at a subsequent encounter, never at an initial one.

A common denial trigger is billing initial encounter character B instead of Q, or leaving malunion out of the operative note.

Claims management software such as Pabau helps orthopedic practices submit clean S52.125Q claims and rework rejected ones quickly.

ICD-10 code S52.125Q: Full descriptor and official definition

ICD-10-CM defines S52.125Q as: Nondisplaced fracture of head of left radius, subsequent encounter for open fracture type I or II with malunion. ICD-10 code S52.125Q is billable and valid for FY2025 and FY2026 under the CMS ICD-10-CM tabular list. All six descriptor elements in the table below must be present in the clinical record before the code is assigned.

Code hierarchy: Where S52.125Q sits in ICD-10-CM

S52.125Q belongs to a five-level hierarchy within ICD-10-CM Chapter 19. Each level narrows the diagnosis, from the forearm category down to the encounter and healing outcome. Knowing the levels helps you avoid picking a code from a neighboring subcategory.

Use the CDC/NCHS ICD-10-CM web tool to verify the hierarchy and confirm code validity for each fiscal year before submitting claims. The S52.125 base code is not billable on its own, so a valid 7th character is always required. Neighboring forearm fracture codes sit in the same ICD-10-CM code library.

What S52.125Q covers: Clinical meaning explained

Each word in the S52.125Q descriptor carries coding weight. A mismatch between any descriptor element and the clinical documentation is grounds for claim denial or audit.

• Nondisplaced: The fracture fragments have not shifted from their anatomical position. The clinical or operative note must confirm this, either in words (“fracture remains in anatomical alignment”) or through the imaging interpretation. A displaced fracture of the left radial head uses a different 6th character, giving S52.122.
• Head of radius: The radial head is the proximal, disc-shaped end of the radius at the elbow joint. Fractures here are common in fall-on-outstretched-hand injuries. The neck of the radius (S52.13x codes) is a distinct anatomical site and a frequent miscoding target.
• Left: Laterality is locked to the left upper extremity. The right equivalent is S52.124Q. Unspecified laterality maps to S52.126Q.
• Open fracture type I or II: An open fracture has a skin breach communicating with the fracture site. Gustilo type I has a wound under 1 cm with minimal contamination, and type II a wound over 1 cm with moderate contamination. Both types share the same 7th characters. Gustilo types IIIA, IIIB and IIIC use C (initial), F (routine healing), J (delayed healing), N (nonunion) and R (malunion).
• Subsequent encounter: The patient is past the active treatment phase. The fracture has received definitive treatment, and this visit assesses or manages the healing complication.
• Malunion: The fracture healed, but in an abnormal position or alignment. Malunion is confirmed radiographically or by clinical assessment. It is distinct from nonunion (fracture fails to heal) and from sequela (a fixed residual condition after healing is complete).

For orthopedic and sports medicine practices, a note template with one field per descriptor element lets coders confirm all six before a claim goes out.

Understanding the 7th character Q: Subsequent encounter with malunion

The 7th character for S52.125 codes sets the episode of care and the healing outcome. ICD-10-CM provides 16 valid 7th characters for this base code, from A to S with I, L and O left out.

Q is one of nine characters (G, H, J, K, M, N, P, Q and R) for a subsequent encounter with a healing complication. The grid below shows how the wound type and the healing outcome combine to pick each one.

Section I.C.19.c of the ICD-10-CM Official Guidelines for Coding and Reporting governs how fracture 7th characters are applied.

The key distinction: Q requires both an open type I or II fracture history and confirmed malunion at the time of the encounter. Confusing P, Q and R, which differ by open or closed injury and Gustilo grade, is a frequent 7th character error.

S52.125Q vs adjacent codes: Avoiding common coding errors

Five codes are commonly confused with S52.125Q. A side-by-side comparison shows which clinical or documentation factor decides the correct assignment.

S52.125M and S52.125Q share the same open type I or II wound, so the healing outcome alone separates them. Nonunion (M) means the fracture did not heal, while malunion (Q) means it healed in an incorrect position.

The operative note or radiographic report must state which outcome is present. A note that says only “fracture complication” supports neither code, so query the physician before submission.

Documentation requirements for accurate S52.125Q assignment

Every element of the S52.125Q descriptor must be traceable to the clinical record. This applies at charge capture in the medical billing workflow, not only at claim submission.

A compliant note must include all of the following:

1. Laterality stated as left. Documentation must name “left” explicitly. Phrases such as “dominant arm” or “same side as prior injury” do not satisfy the laterality requirement.
2. Fracture site documented as head of radius. Notes that say “proximal radius” or “elbow fracture” without specifying the radial head require a query. Radial neck fractures are coded differently.
3. Displacement status confirmed as nondisplaced. The imaging report or clinical assessment must state the fracture is nondisplaced, undisplaced, or in anatomical alignment. A note that is silent on displacement needs a query before the code is assigned.
4. Open fracture type I or II confirmed. The original treatment record (ED note, operative note) must document the wound classification. Record the Gustilo type. If only wound size is noted, it must meet type I or II criteria.
5. Encounter documented as subsequent. The visit note must show that active treatment has concluded and the patient is being seen for follow-up assessment of healing. Initial encounter documentation (active casting, acute surgical intervention) does not support the Q character.
6. Malunion confirmed by imaging or clinical assessment. A radiograph interpretation or clinical note must state “malunion,” “healed in malposition,” or “abnormal healing alignment.” The radiographic or clinical evidence behind the code must appear in the record itself.

CPT codes commonly paired with S52.125Q

S52.125Q most often supports claims for corrective procedures on a malunited radial head. Verify each CPT code against the AMA CPT manual and the current CMS fee schedule before submission. Post-surgical rehabilitation visits also list S52.125Q as a secondary diagnosis for therapy codes.

Note: CPT 25600 covers distal radius fractures, which are anatomically distinct from radial head fractures. Confirm with the operative note that the procedure site matches the ICD-10 diagnosis site before pairing these codes. The AAPC Codify ICD-10-CM lookup tool includes crosswalk data to check CPT-to-ICD-10 medical necessity alignment.

Payer requirements and prior authorization

Prior authorization requirements for procedures billed with ICD-10 code S52.125Q vary by payer and policy year. The guidance below reflects common published payer practices, so always check the payer’s current LCD and benefits manual before submitting.

• Medicare and Medicare Advantage: Medicare Advantage plans may require prior authorization for corrective surgery on radial head malunion, such as osteotomy or radial head arthroplasty. Traditional Medicare fee-for-service does not require prior authorization for most orthopedic procedures. Medical necessity documentation linked to S52.125Q must still be in the record. Review the LCDs for the MAC jurisdiction that covers the practice.
• Commercial payers: Many commercial payers require prior authorization for elective corrective surgery billed with malunion codes. The record should include radiographic confirmation of malunion and documented functional limitation. It should also show that conservative management was tried or is not appropriate.
• Medical necessity evidence: Payers commonly ask for three items before approving procedures billed with S52.125Q. The first is an imaging report confirming malunion, with angles or measurements where applicable. The others are a documented functional deficit, such as limited range of motion, and the ordering physician’s proposed corrective approach.
• Supporting documentation package: Before submitting for authorization, include the original injury record confirming an open type I or II fracture. Add the imaging series showing healing status, the current operative plan and any conservative treatment history.

Submitting S52.125Q claims through a clearinghouse that scrubs each claim before transmission reduces the risk of technical denials.

Common claim denials and how to prevent them

Denials on ICD-10 code S52.125Q cluster around three root causes: Wrong 7th character, missing malunion documentation, and missing prior authorization. Each one is preventable and has a clear resubmission path.

Tracking denials by ICD-10-CM code shows where documentation breaks down across the practice. Denial management workflows that flag S52.125Q claims for pre-submission review cut the number of corrective resubmissions. Clean claim submission protocols should also check the 7th character against the encounter type in the schedule.

Excludes notes and coding instructions

Several Excludes notes at the S52 level affect S52.125Q claim validity. Review them before assigning the code alongside other diagnoses.

• Excludes1 at S52: Traumatic amputation of forearm (S58.-). A code from S58 and a code from S52 cannot be reported together for the same limb at the same encounter.
• Excludes2 at S52: Fracture at wrist and hand level (S62.-). The S52 category covers the forearm shaft and the proximal and distal ends of the radius and ulna. Wrist fractures are coded separately.
• Periprosthetic fractures: If the fracture occurs around a radial head prosthesis, code M97.41x- (right elbow) or M97.42x- (left elbow) instead of S52.125Q. Check for this whenever the patient has had a prior radial head arthroplasty.
• Open fracture Gustilo classification and 7th character alignment: For S52.125Q, the original fracture must have been Gustilo type I or II. If the original wound was Gustilo IIIA, IIIB or IIIC, a subsequent encounter for malunion takes R, so Q no longer applies. Verify the Gustilo classification in the original operative or emergency department record before assigning Q.
• Code-also instructions: When the visit is for corrective surgery on a malunion, code any documented, clinically relevant nerve or vascular injury separately.

The Check ICD-10 database, which mirrors official CMS and NCHS data, lists the full Excludes note hierarchy for S52 and adjacent codes. Verify the excludes notes for your fiscal year, because they can change in annual revisions.

Billing S52.125Q with Pabau’s claims management tools

Orthopedic and hand surgery practices billing ICD-10 code S52.125Q need to catch 7th character errors and missing malunion notes before a claim reaches the payer. Pabau, the practice management platform we build, includes claims management software that scrubs every claim for missing or invalid details before it leaves the system.

Pabau sends CMS-1500 claims through Claim.MD to thousands of US payers. Eligibility checks run before the visit, and electronic remittance advice (ERA) comes back into Pabau matched to each claim.

When a payer rejects an S52.125Q claim, Pabau flags it as Needs action and shows the reason. Your billing team can correct the 7th character or attach the missing malunion note, then resubmit. Each correction stays on the claim record, which supports your medical billing compliance audits.

Stop S52.125Q denials before they start

Pabau scrubs every claim for missing or invalid details before it leaves the system. Rejected claims come back flagged with the reason, so your team can fix the 7th character and resubmit.

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Conclusion

Before you assign S52.125Q, confirm two facts in the record. The original wound was Gustilo type I or II, and imaging shows the fracture healed in malposition.

If either fact is missing, query the physician rather than guessing among the M, P, Q and R codes. A one-line query costs far less than a denied corrective surgery claim and its resubmission.

Pabau scrubs each claim before it goes to thousands of US payers through Claim.MD, and it flags rejected claims with the reason. Book a demo to see how Pabau keeps S52.125Q claims clean from charge entry to payment.

Continue your research

Need a structured approach to managing claim denials? Denial management in healthcare covers the end-to-end workflow for tracking, appealing, and preventing common denial patterns in orthopedic billing.

Want to understand how clearinghouses work? Medical claims clearinghouse guide explains how ICD-10-CM code validation happens between the practice and the payer before claim adjudication.

Looking to tighten your billing compliance process? Superbill documentation guide outlines how to structure encounter documentation to support accurate ICD-10-CM code assignment from the point of care.

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