ICD-10 code S52.242J: Nondisplaced radius shaft fracture with nonunion
Most fracture billing errors happen not at the code level but at the encounter l...
Last Updated: August 6, 2026
Key takeaways
ICD-10 code S52.355R covers a nondisplaced comminuted fracture of the left radial shaft. The 7th character R marks a subsequent encounter for an open type IIIA, IIIB, or IIIC fracture with malunion.
The letter R is easy to confuse with J. R means malunion, and J on the same base code means delayed healing.
Laterality is built into the base code. S52.355 is the left arm, S52.354 the right arm, and S52.356 the unspecified arm.
Only 16 letters are valid 7th characters for this code family, and I, L, and O are never used.
Practice management software like Pabau helps orthopedic and musculoskeletal practices document displacement status, Gustilo subtype, and encounter type at every visit.
ICD-10 code S52.355R is a billable diagnosis code for a nondisplaced comminuted fracture of the shaft of the left radius. Coders apply it at a subsequent encounter, after an open Gustilo type IIIA, IIIB, or IIIC injury has healed in malposition.
The code is valid for fiscal year 2026 under CMS ICD-10-CM guidance. It took effect on October 1, 2025, and is accepted for HIPAA-covered transaction submission.
One letter separates this code from a denied claim. S52.355J describes the same fracture with delayed healing, while S52.355R describes malunion. This guide walks through the full description, the 16 valid 7th characters, and the documentation each one needs.
ICD-10 code S52.355R: Quick reference
S52.355R is a specific, billable ICD-10-CM code. The table below captures every detail a coder needs at a glance before reviewing the supporting sections.
Full code description and clinical meaning
Each word in the ICD-10 code S52.355R description carries a billing consequence. Misreading any component leads to the wrong code selection.
- Nondisplaced: The fracture fragments remain in anatomic alignment. No separation of bone ends has occurred. This is the opposite of a displaced fracture, where fragments shift out of position.
- Comminuted: The bone has shattered into three or more fragments at the fracture site. Comminuted fractures are associated with higher-energy mechanisms, such as motor vehicle accidents and falls from height.
- Shaft of radius: The fracture sits in the diaphysis, or mid-section, of the radius. It is not at the distal end (Colles or Smith-type) or the radial head. Anatomical specificity is required.
- Left arm: Laterality is part of the base code itself. S52.355 always means the left arm. The right arm uses S52.354, and S52.356 covers a record that never states a side.
- Subsequent encounter: The patient is receiving care after the initial treatment phase has concluded. Routine follow-up visits, wound checks, and physical therapy consultations after definitive treatment all fall under subsequent encounter.
- Open fracture type IIIA, IIIB, or IIIC: The fracture was open, with the skin breached and bone exposed, and graded Gustilo-Anderson type III. ICD-10-CM does not distinguish IIIA, IIIB, and IIIC within this 7th character, so the code applies to all three subtypes.
- With malunion: The fracture has healed, but in a non-anatomic position. This healing complication is the reason the encounter is taking place.
For practices documenting complex musculoskeletal cases, digital intake forms capture displacement status and encounter type at the point of care. That removes most of the post-visit chart chasing.
Understanding the 7th character R in fracture coding
The 7th character is the most consequential element of any S52-range fracture code. Without it, the code is invalid and unpayable. For S52.355, there are 16 valid 7th character options covering initial encounters, subsequent encounters, and sequela across closed and open fracture types.
Character R sits at the far end of that list. It encodes three facts at once: a subsequent encounter, a Gustilo type IIIA, IIIB, or IIIC open fracture, and malunion as the healing outcome.
Characters I, L, and O are not used in this range, because ICD-10-CM avoids letters that resemble the numerals 1 and 0. The same 16-character table runs across the whole S52 forearm category, including S52.033J.
Gustilo classification for open fractures: Types IIIA, IIIB, and IIIC
The Gustilo-Anderson classification is the standard system for grading open fracture severity. It grades on wound size, degree of soft tissue injury, and vascular involvement.
For ICD-10 code S52.355R, the medical record must document that the original fracture was a Gustilo type III injury. The subtype determines surgical management, but character R covers IIIA, IIIB, and IIIC alike. For practices managing these patients, a physical therapy EMR helps structure follow-up documentation across the rehabilitation episode.
When the operative note or discharge summary specifies the Gustilo subtype, coders should record it in the documentation. ICD-10-CM groups IIIA, IIIB, and IIIC under one 7th character, but the detail supports medical necessity and protects against audit queries. Type IIIB cases often need staged wound bed preparation before soft tissue coverage, billed as an add-on under CPT code 15005.
Malunion vs. nonunion vs. delayed union: What each means for coding
These three healing complications are frequently confused, and coding them incorrectly changes the 7th character entirely. The table below shows how each one maps to a different character in the S52.355 family. The same malunion logic runs elsewhere in the upper limb, as in S42.409P.
The critical distinction is simple. Malunion means the bone has healed, just incorrectly. Nonunion means the bone has not healed at all. Submitting S52.355R when the patient actually has a nonunion is a material coding error with fraud and abuse implications.
ICD-10-CM hierarchy and parent codes for S52.355R
Understanding the classification tree helps coders verify that S52.355R is the most specific code available, and it supports chart audits. Each level narrows the clinical picture, and the 7th character attaches only once the base code is settled.
Related codes: Laterality siblings and the S52.355 family
Two different decisions sit behind every code in this range. First, pick the base code that matches the documented side. Second, pick the 7th character that matches the encounter and healing status.
S52.351, S52.352, and S52.353 look like near neighbors, but they belong to the displaced comminuted family. Swapping one of them in changes the clinical picture on the claim. Concurrent injuries at other sites keep their own codes, so a shoulder laceration with a retained foreign body is coded S41.021A.
Once the side is settled, the 7th character does the rest of the work. The table below lists the siblings most often confused with S52.355R. Practices treating sports-related forearm injuries can cut selection errors with a sports medicine platform that builds coding into the follow-up workflow.
Use the AAPC Codify ICD-10-CM lookup to verify the full S52.355 sibling list. Confirm which 7th characters are valid for the fiscal year you are billing before submission.
Documentation requirements for S52.355R
Every element of the 7th character R must appear explicitly in the medical record. Coders cannot infer these details from context, and payer audits look for documented support for each qualifier. Gustilo subtype is the element most often missing. Purpose-built clinical documentation software keeps each qualifier in the note rather than in a coder’s follow-up query.
- Displacement status: The operative report or clinical note must state “nondisplaced.” If displacement status is not documented, do not assume it. Query the provider instead.
- Fracture type: The record must confirm the fracture was open. It should also carry the wound description or surgical findings that support that classification.
- Gustilo subtype: The orthopedic note or operative report must specify type IIIA, IIIB, or IIIC. “Open fracture type III” alone is insufficient, even though ICD-10-CM groups the three subtypes together.
- Encounter type: The visit must be a follow-up, not the initial treatment episode. A patient presenting for the first time after this fracture takes S52.355C, not S52.355R.
- Laterality: S52.355R is the left arm. If the record documents the right radius, use S52.354R. Reserve S52.356R for records that genuinely never state a side.
- Healing complication: The treating clinician must document malunion specifically, through radiographic findings, examination findings, or both. That documentation belongs in the note for the visit being coded.
Practices using customizable clinical forms can build encounter-type and healing-status checkboxes into follow-up templates. Providers then capture every required ICD-10 qualifier at the point of care, rather than during a retrospective chart review.
Pro Tip
Before submitting any S52.355R claim, run a short documentation checklist. Confirm that nondisplaced status is stated, and that the operative note names the open fracture and its Gustilo subtype. Check that the visit is a follow-up rather than an initial encounter, and that the record names the left radius. Malunion must be documented explicitly, not inferred from an X-ray report alone.
Common coding errors and how to avoid them
With S52.355R, most errors happen at the 7th character, not the base code. The clinical descriptions are granular, and coders working quickly through high-volume orthopedic encounters often apply the wrong qualifier. Tools that streamline medical records management reduce the retrospective coding burden behind those error rates.
- Confusing malunion (R) with delayed healing (J): These two characters cover the same fracture and the same open fracture grade. R means the bone healed in the wrong position. J means it is still healing, only slower than expected.
- Confusing malunion (R) with nonunion (N): Malunion means healed incorrectly. Nonunion means not healed at all. The clinical note must state which complication is present.
- Coding the wrong arm: S52.355R is the left arm. The right-arm equivalent is S52.354R, and S52.356R covers an undocumented side. Auditors flag unspecified laterality whenever the chart clearly names a side.
- Using the initial encounter code on a follow-up visit: S52.355C is the initial encounter equivalent of S52.355R. A patient attending a six-week post-op review should never carry S52.355C on the claim.
- Missing Gustilo subtype in the source document: If the subtype is absent, query the provider rather than defaulting to a lower-grade code. Incorrect downgrading affects case mix reporting and DRG assignment on inpatient claims.
- Applying S52.355R to a closed fracture with malunion: R encodes an open type IIIA, IIIB, or IIIC fracture. A closed fracture with malunion takes S52.355P, and an open type I or II fracture takes S52.355Q.
The CDC/NCHS ICD-10-CM web tool lets coders look up codes by description. It also shows the 7th character table straight from the official tabular list, which is the fastest way to confirm R before submission.
Approximate synonyms and clinical terms
Operative notes, discharge summaries, and referral letters use varied clinical language. Coders who meet any of these terms should treat S52.355R as a candidate code, then verify every qualifying condition.
- Nondisplaced comminuted left radial shaft fracture, open type III, with malunion
- Malunited open comminuted fracture of the left radius shaft
- Left radius shaft comminuted fracture, Gustilo III, healed in malposition
- Subsequent care: Nondisplaced open comminuted fracture of the left radius with malunion
- Comminuted left radial diaphysis fracture with malunion, open wound, type IIIA/IIIB/IIIC
None of these synonyms replaces a direct code lookup. They work as pattern-recognition triggers. When a coder meets this language, it signals that the S52.355 family is the right starting point. The 7th character then follows a full documentation review.
How Pabau supports accurate fracture coding workflows
Orthopedic and musculoskeletal practices treating open fractures face the same documentation problem at every follow-up. The note has to carry laterality, Gustilo subtype, and healing status, or the coder cannot defend the 7th character. Miss one element and the claim either changes code or becomes unpayable.
Practice management software like Pabau closes that loop inside the clinical record. Pabau’s claims management software links diagnosis codes to each encounter, checks documentation completeness before submission, and tracks claim status afterward.
Paired with the platform’s appointment management tools, it separates initial from subsequent encounter visits at the scheduling stage. Your team therefore settles the 7th character before the claim is ever generated, instead of correcting it after a denial.
Code fracture follow-ups right the first time
Pabau's claims management tools link every diagnosis code to the encounter that supports it. Your team catches a missing Gustilo subtype or laterality before the claim goes out.
Conclusion
S52.355R is narrow by design, and that narrowness is what makes it defensible. Five facts have to line up in the record before the code holds. If any one of them is missing, the answer is a provider query rather than a best guess.
The letter is where the money sits. R, J, N, and P all describe the same broken bone at the same stage of care. Only the documented healing status separates them. A follow-up template that forces the clinician to name that status turns a recurring denial into a routine claim.
Book a demo to see how Pabau keeps laterality, Gustilo subtype, and healing status on every fracture follow-up note.
Continue your research
Need a closed-fracture parallel to this malunion code? S42.409P applies the same malunion qualifier to the lower end of the humerus.
Coding a fracture that never healed? S42.131K shows how the nonunion 7th character works on a displaced coracoid fracture.
Documenting a late effect rather than active care? S43.491S covers the sequela 7th character for a shoulder sprain.
Coding an open fracture at the initial encounter? S42.009B walks through open fracture documentation before any healing status applies.
Handling an upper-limb injury with no fracture? S40.019A covers contusion coding when imaging rules a fracture out.
Frequently asked questions
What is ICD-10 code S52.355R?
ICD-10 code S52.355R is a billable ICD-10-CM diagnosis code for a nondisplaced comminuted fracture of the shaft of the left radius. It applies at a subsequent encounter, after an open fracture graded Gustilo type IIIA, IIIB, or IIIC has healed with malunion. The code is valid for FY2026, effective October 1, 2025, and is accepted for HIPAA-covered transaction submission.
What is the difference between S52.355R and S52.355J?
Both codes describe the same fracture at a subsequent encounter for an open type IIIA, IIIB, or IIIC injury. R means the fracture has healed in a non-anatomic position, which is malunion. J means the fracture is still healing, but more slowly than expected. Choose the character that matches the healing status documented at the visit you are coding.
What is the difference between malunion and nonunion in ICD-10 fracture coding?
Malunion means the fracture has healed, but in a non-anatomic position. Nonunion means the fracture has failed to heal at all. For the left-arm base code S52.355, 7th character R covers malunion after an open type IIIA, IIIB, or IIIC fracture. The same site with nonunion takes 7th character N, giving S52.355N. Swapping the two is one of the most common errors in this code family.
When is a subsequent encounter coded instead of an initial encounter for fractures?
Subsequent encounter applies once the patient has received active treatment and has moved into the healing or rehabilitation phase. Follow-up visits, wound checks, pin removal appointments, and physical therapy evaluations all qualify. The initial encounter code for this fracture is S52.355C, and it covers only the episode of care that delivered the first treatment.
Which code do I use if the fracture is on the right arm?
Use S52.354R for the right arm. S52.355R is the left arm, and S52.356R covers an arm the record never identifies. All three share the same base description, a nondisplaced comminuted fracture of the shaft of the radius. Do not reach for S52.351 through S52.353, because those codes describe displaced fractures.
When should unspecified arm laterality be used for this fracture?
Use it only when the medical record genuinely never identifies left or right. In that case the code is S52.356R, not S52.355R, because S52.355 already means the left arm. Auditors routinely flag unspecified laterality when the chart clearly names a side. Query the provider rather than defaulting to the unspecified code.
What does the Gustilo classification system mean for ICD-10 coding?
The Gustilo-Anderson classification grades open fracture severity by wound size, soft tissue damage, and vascular involvement. Types I and II map to 7th characters B, E, H, M, and Q in this code family. Types IIIA, IIIB, and IIIC map to C, F, J, N, and R instead. ICD-10-CM does not separate IIIA from IIIB or IIIC, so the operative report must still name the subtype.
Is S52.355R billable, and which payers accept it?
Yes, S52.355R is a specific, billable ICD-10-CM code valid for FY2026 and accepted for HIPAA-covered transactions. Medicare, Medicaid, and commercial payers that use the current ICD-10-CM tabular list all recognize it. Verify payer-specific medical necessity and prior authorization rules separately, because individual policies vary.
