ICD-10 Code S02.642A: Fracture of ramus of left mandible

Key Takeaways

ICD-10 Code S02.642A describes a fracture of the ramus of the left mandible, initial encounter for a closed fracture.

S02.642A is a billable, specific ICD-10-CM code valid for FY2026 claims (effective October 1, 2025).

The 7th character sets the encounter type: ‘A’ for initial encounter with a closed fracture, ‘B’ for open fracture, and ‘S’ for sequela. Selecting the wrong one is a common audit trigger.

Pabau’s claims management software supports accurate ICD-10 diagnosis coding workflows, helping practices catch missing documentation before claims go out.

ICD-10 Code S02.642A is a billable, specific code for a closed fracture of the ramus of the left mandible, initial encounter. It covers one anatomical location, one laterality, and one encounter type, and each of those is a separate coding decision that must be confirmed before claim submission.

Oral and maxillofacial surgical practices and emergency departments use this code to document mandibular ramus fractures, recording the laterality, encounter type, and fracture classification directly from the clinical note.

ICD-10 Code S02.642A: Full description and billable status

ICD-10 Code S02.642A is a billable, specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.

The complete clinical description is: Fracture of ramus of left mandible, initial encounter for closed fracture. Every element of that description carries a coding implication:

• Ramus specifies the anatomical sub-site.
• Left establishes laterality.
• Initial encounter determines the 7th character.
• Closed defines the fracture type.

The 2026 edition of ICD-10-CM S02.642A became effective on October 1, 2025, under the standard CMS annual update cycle. According to the CMS ICD-10 codes page, this code remains in the S02 category covering fractures of skull and facial bones.

What is the ramus of the mandible?

The mandible has two main structural regions. The body is the horizontal portion that bears the lower teeth. The ramus is the vertical portion that rises from each end of the body, connecting the lower jaw to the skull via the temporomandibular joint (TMJ).

A ramus fracture disrupts this vertical strut. Clinically, that means restricted jaw opening, malocclusion, and in more severe cases, instability of the TMJ articulation.

Ramus fractures are less common than condylar or symphyseal mandibular fractures, which is one reason accurate sub-site coding matters: billing a generic mandible fracture code rather than S02.642A misses the laterality and anatomical specificity that payers and clinical records require.

• Mandibular body: horizontal portion, houses lower teeth
• Mandibular ramus (left): vertical portion on the left side, coded by S02.642A for initial closed fractures
• Condylar process: the uppermost projection of the ramus, articulating with the skull (separate code family: S02.61-S02.63)
• Coronoid process: anterior projection of the ramus (separate sub-site)

Understanding the 7th character: Initial encounter, subsequent encounter, and sequela

The 7th character is what separates S02.642A from its sibling codes within the same anatomical sub-site. Per ICD-10-CM Official Guidelines Section I.C.19, fracture codes require a 7th character to specify the encounter type. For S02.642, the valid 7th characters are A, B, D, G, K, and S.

Applying the wrong character is one of the most common audit findings in trauma coding.

A key clarification: “initial encounter” does not mean the patient’s first-ever medical visit. It refers to the period during which the patient is receiving active treatment for the injury. A patient who had emergency surgery and is returning three weeks later for a wound check is still in the initial encounter phase if active fracture management is ongoing.

S02.642A code hierarchy and parent codes

Understanding where ICD-10 Code S02.642A sits in the classification tree helps coders navigate related codes and apply parent-level coding guidelines correctly. The full hierarchy is:

You can verify the current code hierarchy and any FY2026 updates using the CDC/NCHS ICD-10-CM web tool, the official U.S. government lookup for the tabular list and alphabetic index. This is also where coders can confirm applicable-to notes and excludes-1 or excludes-2 annotations at each level.

Related and sibling codes for fracture of ramus of left mandible

S02.642A sits within a family of codes covering the mandibular ramus by laterality and encounter type. Knowing the sibling codes helps coders select the right one when documentation specifies a different side, encounter stage, or fracture type.

A thorough head and neck assessment at intake helps confirm which of these related codes actually applies before the claim goes out.

Approximate clinical synonyms

ICD-10-CM coding indexes map a range of clinical phrases to S02.642A. Knowing these synonyms helps coders match the diagnosis correctly when the operative report or ED note uses different phrasing than the tabular descriptor.

Where the note describes surgical excision of the mandible rather than a simple fracture, the diagnosis code sits alongside a separate procedure code. CCSD code V1422 covers that excision procedure, since diagnosis and procedure codes serve different purposes on the same claim.

• Closed fracture of left mandibular ramus
• Fracture, ramus, left mandible (closed)
• Left ramus fracture, lower jaw
• Mandibular ramus fracture, left, closed (initial)
• Non-open fracture of ramus of left mandible
• Left jaw ramus fracture, initial treatment encounter

Clinical notes may also use “mandibular ramus fracture, left” or simply document “closed left ramus fracture.” All of these map to S02.642A when the encounter is initial and no open wound is present.

The AAPC’s ICD-10-CM code lookup includes an alphabetic index search that is useful for finding the tabular listing from narrative documentation phrases.

Coding guidelines and documentation requirements for S02.642A

Clean claim submission for ICD-10 Code S02.642A depends on five documentation elements being clearly recorded. Missing any one of them creates grounds for a coding query or payer denial. Good claims management software flags incomplete diagnosis linkages before submission, but the clinical record itself must supply the source data.

• Laterality confirmed: Documentation must state “left” explicitly. “Mandibular ramus fracture” without a side forces use of S02.649A (unspecified), which some payers flag for additional documentation.
• Open vs closed fracture: The physician or surgeon must document whether the fracture is open (bone through mucosa or skin) or closed. Closed = S02.642A; open = S02.642B. Absence of documentation defaults to closed per ICD-10-CM guidelines, but the source note should make this explicit.
• Encounter type: Active treatment = 7th character A. Follow-up after active treatment = D (routine), G (delayed), or K (nonunion). Late effects = S. The stage of care must be clear in the note.
• Injury mechanism (for external cause coding): An external cause code (W-code for falls, V-code for motor vehicle, Y-code for assault) should accompany S02.642A per ICD-10-CM guidelines. Payers, particularly workers’ compensation and auto insurers, often require this.
• Associated injuries: Document any dental injuries, soft tissue lacerations, or concussion alongside the ramus fracture. These code separately and affect clinical management and claim complexity.

Maintaining HIPAA-compliant clinical documentation practices ensures that the diagnosis detail needed for coding is captured consistently at the point of care, not reconstructed after the fact.

Common comorbidities and additional codes to consider

Ramus fractures rarely present in isolation. Most arise from high-energy trauma such as motor vehicle collisions, assaults, or sporting injuries, which affects multiple structures at once.

Coding only S02.642A when the patient also has dental injuries, a concussion, or soft tissue involvement leaves clinical complexity unreported and can affect DRG assignment and case mix index. Accurate patient data security practices also require that every documented diagnosis is captured correctly in the permanent record.

A concurrent neck laceration, for example, would be coded separately as S11.82XS rather than folded into the mandible fracture code. Use the ICD List code lookup tool to cross-reference associated diagnosis codes and verify they remain valid and billable for FY2026.

For surgical cases, the digital intake forms completed at the initial encounter should capture mechanism, laterality, and associated injury details to support complete coding downstream.

Practices managing maxillofacial trauma cases benefit from structured clinical documentation workflows that prompt clinicians for each required field at the point of care. A standardized dental treatment consent form at intake is one place to capture mechanism of injury alongside consent.

Pabau’s practice management platform supports customizable clinical encounter templates that can be configured to capture laterality, fracture type, and associated injury fields as structured data rather than free text, reducing the coding queries that follow incomplete documentation at billing time.

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Pabau helps maxillofacial and surgical practices capture structured clinical data at the point of care, reducing coding queries and claim denials. See how structured encounter templates can support clean ICD-10 documentation.

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Conclusion

Ramus fractures are anatomically specific injuries that require equally specific coding. ICD-10 Code S02.642A covers exactly one clinical scenario: a closed fracture of the left mandibular ramus at the initial treatment encounter. Get the laterality wrong, misassign the 7th character, or omit associated injury codes, and the claim faces denial or audit exposure.

Practices that capture laterality, fracture type, and encounter stage as structured fields at the point of care dramatically reduce downstream coding queries. Pabau’s AI-assisted clinical documentation helps clinicians structure notes that contain the precise detail coders need, without adding time to the encounter.

To see how structured documentation workflows can support cleaner ICD-10 coding across your practice, book a demo.

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