ICD code S49.091P – Physeal fracture of upper humerus with malunion

Key takeaways

S49.091P is a billable ICD-10-CM code specific to the right arm and a subsequent encounter with confirmed malunion, not routine healing or nonunion.

The 7th character P means the fracture healed in a malunited position, distinct from K (nonunion) and D (routine healing). Payer systems enforce that distinction.

Physeal fractures of the proximal humerus mostly occur in children and adolescents whose growth plates are still open. Laterality and age context both belong in the note.

Practice management software like Pabau links the diagnosis code to the procedure at billing, so 7th-character errors surface before the claim goes out.

What is ICD-10 Code S49.091P?

ICD-10 Code S49.091P is the billable, specific ICD-10-CM code for other physeal fracture of the upper end of the humerus, right arm.

The 7th character P marks a subsequent encounter for a fracture that has healed with malunion.

The code is valid under the FY2026 edition of ICD-10-CM, maintained by CMS and the National Center for Health Statistics (NCHS). That edition took effect on October 1, 2025, which is the start of the current annual cycle. S49.091P itself has been in ICD-10-CM for years, so the date reflects the edition rather than the creation of the code.

The code sits in the S40-S49 block, which covers injuries to the shoulder and upper arm. It is specific enough to be used directly on claims, with no further child code required.

The descriptor breaks down into four components, and each one has to be supported by documentation:

• The injury type: a physeal fracture
• The anatomical site: the upper end of the humerus
• The laterality: the right arm
• The encounter qualifier: a subsequent encounter for fracture with malunion

Missing laterality and an unconfirmed malunion finding are the two fastest routes to a coding query or a denial on this code.

Code at a glance

Clinical description: Physeal fracture of the upper humerus

A physeal fracture is a fracture involving the growth plate (physis) of a bone. The physis is a cartilaginous zone near the end of long bones where longitudinal growth occurs. Because the physis closes in late adolescence, these fractures mostly occur in children and adolescents whose growth plates are still open.

The proximal humerus is one of the most common sites for physeal injury in young patients. It is usually caused by a fall on an outstretched arm, a contact sports injury, or direct trauma to the shoulder.

Orthopedic clinicians often use the Salter-Harris classification to characterize the fracture pattern. ICD-10-CM does not follow that convention here. The S49.091x codes describe the injury as an “other physeal fracture” rather than mapping to a numbered Salter-Harris type.

The “upper end of humerus” descriptor refers to the proximal end of the bone, covering the proximal physis and the epiphyseal region. Laterality is encoded in the 5th digit (1 = right, 2 = left, 9 = unspecified), which is why S49.091P applies exclusively to right-arm injuries. The encounter that produces the code is the follow-up visit where malunion is diagnosed, not the original injury visit.

Understanding the 7th character ‘P’: Subsequent encounter for fracture with malunion

The 7th character in ICD-10-CM fracture codes specifies the encounter type and the healing status of the fracture. For the S49.091 base code, six 7th characters are valid. The character P means the patient is presenting for a subsequent encounter rather than the initial acute treatment visit. It also means the fracture has united in an abnormal alignment.

Malunion is clinically distinct from nonunion. Malunion means the bone has healed, but not in the correct anatomical alignment. Nonunion means the fracture has failed to heal at all. Confusing P (malunion) with K (nonunion) is the most common 7th-character error on this code group. Payer edits flag any mismatch between the stated healing status and the imaging documentation.

The ICD-10-CM Official Guidelines for Coding and Reporting define a subsequent encounter as any visit after the patient has received active treatment. At that point the provider is managing the healing process or its complications. Two questions then settle the character on an S49.091 claim: whether active treatment has ended, and what the imaging shows at that visit.

All S49.091 code variants by 7th character

The S49.091 base code (right arm) has six valid 7th-character extensions. Select the character that reflects the encounter type and healing status documented in the clinical record. Each variant is a separate billable code.

ICD-10-CM code hierarchy for S49.091P

S49.091P sits at the most specific level of the ICD-10-CM hierarchy for shoulder and upper arm injuries. Knowing the parent codes helps coders confirm code placement and navigate the tabular list accurately.

The injury chapters follow this pattern consistently. The block defines the body region, the category and subcategory narrow the injury type, and the 7th character captures encounter and healing status. Reading the hierarchy in that order keeps a claim from landing on a non-billable parent code instead of the specific billable one.

Approximate synonyms and alternate descriptions

The following alternate descriptions and clinical synonyms map to ICD-10 Code S49.091P. Coders meet these terms in operative reports, discharge summaries, and referring provider notes, and each one supports this code.

• Right proximal humerus physeal fracture with malunion, subsequent encounter
• Right proximal humerus growth plate fracture, malunited, follow-up visit
• Malunion of other physeal fracture, upper end of humerus, right side
• Right shoulder growth plate fracture with abnormal healing (follow-up)
• Salter-Harris fracture, proximal humerus right arm, malunion (subsequent encounter)
• Right humerus proximal physis fracture, subsequent care, malunion confirmed

These synonyms are clinically equivalent for coding purposes. Where documentation uses Salter-Harris terminology alongside a confirmed malunion finding, check whether a numbered Salter-Harris code applies instead. S49.091P stays correct only while the record describes an “other physeal fracture”. The AAPC’s ICD-10-CM code lookup is a useful cross-reference for that comparison.

ICD-10-CM coding guidelines for fracture subsequent encounters

The ICD-10-CM Official Guidelines for Coding and Reporting set out specific rules for fracture encounter types. These are the rules to apply consistently to S49.091P and its sibling codes. CMS and NCHS publish the full guidelines annually, and they are available through the CDC ICD-10-CM web tool.

• Active treatment vs aftercare: The 7th character A applies to every visit where active treatment is being provided. That holds even when it is not the first visit. A patient seen in urgent care and then by an orthopedist may carry A on both visits.
• Subsequent encounter definition: The subsequent encounter characters (D, G, K, P, S) apply once active treatment has concluded. The character selected must match the healing status documented at that visit.
• Malunion vs nonunion distinction: Use P when imaging confirms the fracture has healed in an abnormal alignment. Use K when imaging shows no healing, no callus formation, and a fracture line that persists without bridging.
• Sequela coding: S applies to late effects that remain after healing is complete, such as residual stiffness or deformity from the malunion. The sequela code S49.091S is sequenced after the code describing the specific late effect.
• Laterality is required: Use the unspecified laterality codes (S49.099x) only when the record genuinely does not say which arm was injured. Where the record specifies right, ICD-10 Code S49.091P is always the better assignment.

The same encounter-type logic runs across every trauma chapter. A coder fluent in it on one fracture family can apply it to the next. At the subsequent-encounter stage, accurate billing depends on the diagnosis code reflecting exactly what the provider documented at that visit.

Related and sibling ICD-10 codes

These codes are the most relevant lateral variants, hierarchical siblings, and related fracture codes a coder handling S49.091P should know.

Coders who handle several of these variants can work through the full ICD-10 diagnostic codes library and confirm each sibling descriptor before assigning one. Cross-reference the WHO ICD-10 browser when you need the international equivalent of a code.

Documentation requirements for S49.091P

ICD-10 Code S49.091P needs four documentation elements to be defensible on audit. Each element maps to a component of the code descriptor. Missing one of them moves the encounter to a less specific code, which may reduce reimbursement or prompt a medical necessity query.

• Confirmed physeal involvement: The record or imaging report must show fracture involvement of the physis at the upper end of the humerus. A general proximal humerus fracture is not enough. Radiology reports citing the “proximal physis” or “growth plate” give the most direct support.
• Right-side laterality: The record must state right arm, right shoulder, or right upper extremity. “Right” in the examination findings, the imaging report, or the surgical note all qualify. An unclear or bilateral finding calls for the unspecified code until it is clarified.
• Subsequent encounter status: The provider’s note must reflect a follow-up or post-acute visit rather than initial active treatment. Language such as “follow-up”, “re-evaluation”, “post-operative check”, or “monitoring healing” supports the subsequent encounter qualifier.
• Malunion confirmed: Imaging must document mal-alignment or an abnormal healing position. Radiology language such as “healed in varus/valgus”, “malunited fracture”, or “angular deformity at fracture site” supports the P qualifier. Clinical assessment without imaging rarely defends a malunion code on audit.

Structuring the encounter note around all four elements is the most reliable way to avoid post-payment audits. Pabau’s denial-reducing claims management links the assigned ICD-10-CM code to the encounter documentation. That cross-check prompts the provider to confirm each required element before the claim is submitted.

Common coding errors and how to avoid them

Four errors account for the majority of claim issues on S49.091P and its sibling codes. Each one is preventable with the right documentation discipline and coding workflow.

• Confusing malunion (P) with nonunion (K): Malunion means healed in an abnormal position, and nonunion means not healed. The two outcomes take different ICD-10 codes. Payer edits cross-check the treatment provided against the healing status, so a nonunion code paired with a corrective osteotomy claim is usually flagged. Read the imaging report language before choosing between K and P.
• Using an initial encounter code (A) for follow-up visits: The A character applies only while active treatment is being provided. Once the patient enters the monitoring phase, the encounter type shifts to D, G, K, or P as appropriate. Using S49.091A on a scheduled follow-up misrepresents the encounter and may trigger an audit.
• Omitting laterality and defaulting to the unspecified code: S49.099P (unspecified arm) is valid only when the record does not say which arm was injured. Defaulting to it when the right arm is clearly documented is a specificity error, and it may reduce reimbursement under some payer contracts.
• Using the base code S49.091 without a 7th character: S49.091 on its own is not a valid billable code. Claims submitted with it will reject. Every S49.091 claim must carry one of the six valid extensions (A, D, G, K, P, or S).

Practices with high denial rates on these codes benefit from a review of their denial management workflows. That review shows which 7th-character errors recur in their own claim population. Pre-submission validation catches the structural problems first, including a missing or invalid 7th character, before the claim reaches the payer.

How Pabau keeps the 7th character tied to the imaging report

In most orthopedic practices the coding decision and the evidence for it live in separate places. The radiology report sits in one system, the encounter note in another, and the claim is built from whichever one the biller happens to open. A malunion coded as routine healing is then discovered weeks later, in a remittance advice.

Practice management software like Pabau keeps the three in one record. The imaging report is attached to the encounter it belongs to, and the diagnosis code is assigned against that same encounter. Billing then pulls the code from the note rather than from a separate worksheet. A coder reviewing an S49.091P claim can see the report that justifies the P in the same screen.

The outcome is fewer claims going out with a 7th character the documentation does not support. Denials on this code family tend to come from that single mismatch. Catching it before submission removes most of the rework a billing team would otherwise carry.

Reduce claim denials on fracture subsequent encounter codes

Pabau’s claims management software links ICD-10 diagnosis codes to procedures at the point of billing. That catches 7th-character errors before a claim reaches the payer. See how it works for orthopedic and sports medicine practices.

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Conclusion

ICD-10 Code S49.091P demands precision on all four of its descriptor components: physeal injury at the proximal humerus, right arm, subsequent encounter, and confirmed malunion. Denials on this code almost always trace back to one of two issues. Either the 7th character is wrong, or the malunion is not confirmed in the documentation.

The practical move is to treat the imaging report as the source of the 7th character, not the coder’s memory of the last visit. A practice that builds that habit into its billing review will see this code family settle down. Book a demo to see how Pabau ties the code to the documentation before an orthopedic claim leaves the practice.

Continue your research

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