ICD-10 Code S52.532N: Colles’ fracture left radius nonunion

Key Takeaways

S52.532N describes Colles’ fracture of the left radius, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with nonunion, and is a billable ICD-10-CM code valid from FY2016 through FY2026.

The 7th character N is critical: it signals nonunion in an open fracture graded Gustilo Type IIIA, IIIB, or IIIC, distinguishing this code from S52.532K (closed nonunion) and S52.532M (open Type I or II nonunion).

Nonunion must be explicitly documented by the treating physician; coders cannot assume it from imaging findings or treatment notes alone.

Pabau’s claims management software supports accurate fracture code capture and billing workflow, reducing denial risk for complex subsequent-encounter codes like S52.532N.

ICD-10 Code S52.532N: definition and clinical description

Open fractures of the distal radius that fail to heal are among the hardest cases in orthopedic billing. As a result, coders routinely misfile nonunion claims under routine healing codes, triggering denials that delay payment by weeks. ICD-10 code reference guides for injury codes require precise 7th-character selection, and S52.532N is therefore one of the most detail-dependent codes in the fracture chapter.

ICD-10 Code S52.532N is the billable, specific diagnosis code for Colles’ fracture of the left radius, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with nonunion. It is valid for all claims with a date of service on or after October 1, 2015, and remains current through FY2026 per the CMS ICD-10-CM annual update files. Additionally, the code carries POA (Present on Admission) exempt status for inpatient claims, meaning it is left out of POA indicator reporting requirements.

Clinically, a Colles’ fracture is a fracture of the distal radius where the broken end shifts toward the back of the wrist. When the fracture is open and classed as Gustilo Type IIIA, IIIB, or IIIC, and the fracture site fails to heal within the expected window, S52.532N therefore becomes the correct code for every follow-up visit until union is recorded or surgery is carried out.

Code hierarchy and parent codes

S52.532N sits within a tightly structured hierarchy. Consequently, knowing the parent codes helps coders confirm they are at the right level of detail before billing.

S52.532 is a non-billable parent code. As a result, claims sent with only six characters will be rejected. The 7th character is required for this code family. For reference, the CDC/NCHS ICD-10-CM web tool provides the full code list and any relevant notes for the S52 chapter.

7th character extensions for S52.532

The 7th character for S52.532 carries three layers of information at once: visit type (initial vs. follow-up), fracture type (open or closed), and healing status. For this reason, picking the wrong character is one of the leading causes of fracture claim denials. The ICD-10 diagnostic code lookup process requires matching all three factors before settling on the final code.

The jump from J (delayed healing, Type IIIA/IIIB/IIIC) to N (nonunion, Type IIIA/IIIB/IIIC) reflects a clinically important distinction. Specifically, delayed healing means the fracture is still moving toward union but more slowly than expected. Nonunion, in contrast, means the fracture site has stopped healing and will not mend without treatment. Only the treating physician can make this call, and coders must therefore see it clearly written in the notes before assigning ICD-10 Code S52.532N.

Gustilo classification: understanding types IIIA, IIIB, and IIIC

The Gustilo-Anderson classification is the standard system used by orthopedic surgeons to grade open fracture severity based on wound size, soft tissue damage, and blood vessel or nerve injury. Accordingly, all three Type III subtypes are more severe than Type I or II, which is why they carry a distinct set of 7th characters (C, F, J, N, R) separate from the Type I/II characters (B, E, H, M, Q). For physical therapy EMR workflows, knowing this system helps rehab teams match their notes to the billing codes used during the surgical and acute phases.

• Type IIIA: Large wound with adequate soft tissue coverage of the bone despite extensive laceration or flap injury. Periosteal stripping is present but bone can be covered.
• Type IIIB: Extensive soft tissue injury with periosteal stripping and bone exposure. Requires local or free flap coverage. Significant contamination is common.
• Type IIIC: Open fracture associated with arterial injury requiring repair, regardless of wound size or soft tissue damage.

The subtype (IIIA, IIIB, or IIIC) must be recorded by the operating surgeon in the operative report. For billing purposes, however, S52.532N covers all three subtypes under the same 7th character, so the coder does not need to tell them apart at the code level. What matters is that the physician has noted one of the three Gustilo Type III subtypes and has also noted nonunion.

Nonunion vs. malunion vs. delayed healing: coding distinctions

These three outcomes are often mixed up in both clinical notes and billing. As a result, each maps to a different 7th character, and using the wrong one is a common audit finding. For ICD-10-CM diagnostic coding accuracy, therefore, telling these healing statuses apart is essential.

ICD-10 Code S52.532N applies only when the treating physician has clearly stated that the fracture site has reached nonunion. Without that note, coders working with a patient who has slow healing should stay on J (S52.532J) until the provider updates the diagnosis. Switching too early to N is, therefore, a compliance risk, especially under payer audits.

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Documentation requirements for ICD-10 Code S52.532N

Strong record-keeping is the foundation for a defensible S52.532N claim. In particular, payers look closely at nonunion claims because they often come before costly surgical procedures such as bone grafting or repeat fixation. For this reason, using digital intake forms at each follow-up visit helps ensure the required details are captured every time.

The treating physician’s note must include all of the following elements for S52.532N to be supportable:

• Laterality confirmation: The fracture involves the left radius specifically. This distinguishes S52.532N from S52.531N (right radius) and S52.539N (unspecified).
• Colles’ fracture morphology: The original injury involved dorsal displacement of the distal radial fragment, confirming the Colles’ classification.
• Open fracture type: The surgeon’s operative report from the initial encounter must document Gustilo Type IIIA, IIIB, or IIIC classification.
• Subsequent encounter status: The visit is not the initial treatment encounter; the patient is in active management of a known fracture.
• Nonunion diagnosis: An explicit physician statement that the fracture has failed to heal and meets criteria for nonunion, supported by clinical and/or imaging evidence.

Orthopedic practices using claims management software can build checklists into their post-visit workflow, flagging visits where one or more of these details is missing before the claim goes out. As a result, this cuts down the rework cycle common in complex fracture billing.

Related ICD-10 codes and crosswalk reference

S52.532N sits within a family of closely related codes. Consequently, picking the right code requires knowing the related codes for the right radius and for other healing statuses, as well as the nearby codes for fractures of the lower radius outside the Colles’ pattern. For example, the AAPC Codify ICD-10-CM lookup provides full crosswalk data for the S52 chapter. For sports medicine documentation teams handling distal radius injuries, knowing the crosswalk therefore helps prevent upcoding or downcoding errors on nonunion claims.

Additionally, practices treating wrist fracture nonunion through surgery may want to confirm CPT codes linked to nonunion repair, such as bone grafting and repeat ORIF procedures. In that case, the ICD List free ICD-10-CM lookup tool provides DRG grouper data useful for inpatient claim checks alongside S52.532N.

Billing workflow: from initial fracture encounter to S52.532N

The journey from the first emergency or acute orthopedic visit to a nonunion follow-up code involves several code changes, each tied to a recorded clinical milestone. As a result, practices with strong patient record management can track these milestones reliably and reduce the risk of using outdated 7th characters on follow-up claims.

1. Initial encounter (acute injury): Code S52.532C when the open fracture type IIIA, IIIB, or IIIC is first treated, typically in the emergency department or operating room.
2. Subsequent encounters (active treatment): Transition to subsequent encounter characters (D through R) for all follow-up visits. The appropriate character depends on the current healing status at each encounter.
3. Delayed healing identified: When the physician determines healing is slower than expected but still progressing, use S52.532J.
4. Nonunion diagnosed: Once the physician explicitly documents nonunion, transition to ICD-10 Code S52.532N. Continue using this code for every subsequent encounter until union is achieved or the diagnostic picture changes.
5. Surgical intervention for nonunion: If bone grafting, revision fixation, or other surgical procedures are performed, the appropriate CPT procedure codes are added. S52.532N remains the diagnosis code for the surgical encounter.
6. Healed or sequela: After documented healing, transition to the appropriate code or S52.532S for sequela encounters addressing late effects of the original injury.

Furthermore, using compliance management tools within your practice platform helps flag when a patient’s code needs a status review, stopping claims from going out with outdated 7th characters that no longer match the patient’s current condition.

Conclusion

Nonunion in a Gustilo Type III open Colles’ fracture is a serious clinical outcome and a high-stakes billing scenario. ICD-10 Code S52.532N covers this precisely; however, it requires accurate physician notes, the correct Gustilo grade from the operative record, and a clear nonunion diagnosis before the code is used.

In summary, practices managing complex fracture cases benefit from clear workflows that link clinical milestones to code changes. Pabau’s automated billing workflows and joined-up patient records help orthopedic and rehab teams stay on top of follow-up coding accuracy from first injury through final resolution. See how Pabau supports your billing workflow with a personalized demo.

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