ICD-10 code S02.641B: Mandibular ramus open fracture

Key Takeaways

S02.641B is a billable ICD-10-CM code for fracture of the ramus of the right mandible, initial encounter for open fracture

The 7th character ‘B’ specifically designates an open fracture at the initial (active treatment) encounter – distinct from ‘A’ (closed fracture) and ‘D’ (subsequent encounter)

Physician documentation must explicitly state the fracture is open, identify the ramus as the site, and confirm laterality (right side) to support this code

Pabau’s claims management software and digital forms help oral surgery and maxillofacial practices capture the documentation required to bill S02.641B accurately

ICD-10 code S02.641B: Definition and billable status

ICD-10 code S02.641B is a billable ICD-10-CM diagnosis code that describes a fracture of the ramus of the right mandible, initial encounter for open fracture. It is valid for use on claims submitted under the current ICD-10-CM fiscal year and requires all seven characters to be billable.

The difference between a closed and an open ramus fracture, or between an initial and a subsequent encounter, determines which of several closely related codes applies to a given claim.

This reference covers the code’s official description, its place in the ICD-10-CM hierarchy, 7th character guidance, related codes, associated CPT procedures, and the documentation a provider must have on file to use it correctly.

Code details at a glance: S02.641B ICD-10-CM

The table below summarises the key properties of ICD-10 code S02.641B for quick reference.

Clinical description: ICD-10 mandibular ramus fracture (open, initial encounter)

The mandibular ramus is the flat, roughly quadrilateral portion of the lower jaw that rises vertically from the body of the mandible up to the condylar process and coronoid process. It sits behind the molars and below the temporomandibular joint (TMJ) – but the ramus itself is part of the jawbone, not the joint, so it is not a TMJ injury.

Ramus fractures typically result from a direct blow to the side of the jaw and are one of the less common mandibular fracture sites compared with the angle, body, or condyle, but they still occur regularly after high-velocity trauma – motor vehicle accidents, falls, and assaults account for most cases.

Plastic surgery EMR software used by maxillofacial teams needs to capture ramus fracture details accurately at the point of care so coding reflects the clinical picture.

S02.641B applies when three clinical facts are simultaneously true:

• Right side: The ‘1’ in S02.641 designates the right ramus per ICD-10-CM laterality convention. The left ramus would be S02.642x.
• Open fracture: The skin or mucosa overlying the fracture site is breached, communicating the fracture with the external environment. This is a physician determination, not a coder inference. Documentation must state “open.”
• Initial encounter: The patient is presenting for active treatment of the fracture. This covers the emergency visit, surgical intervention, and any follow-up appointments still within the active treatment phase for that injury episode.

Don’t confuse the ramus with the condylar process, which sits at the top of the ramus and forms part of the temporomandibular joint. Condylar process fractures are coded separately, under the S02.61x subcategory (S02.611 for the right side, S02.612 for the left) – not under S02.64x.

When the documentation clearly identifies the fracture site as the ramus – the flat, vertical portion of the bone below the condylar process and coronoid process – S02.641B is the correct code for an open, right-sided fracture at initial encounter.

Understanding the 7th character ‘B’ for ICD-10 code mandibular fracture initial encounter

Fracture codes under ICD-10-CM require a 7th character to specify both the type of fracture and the phase of treatment. For mandibular fracture codes in the S02.64x family, the valid 7th character options are:

A critical point: “initial encounter” refers to the phase of treatment, not necessarily the patient’s first visit to your facility.

Per CMS ICD-10-CM guidelines, a patient may see multiple providers during the active treatment phase, and each of those providers correctly uses the ‘A’ or ‘B’ character. Once active treatment ends and the patient enters routine monitoring, switch to ‘D’ for subsequent encounter.

Many ramus-fracture patients continue care with jaw-mobility rehab during this subsequent phase, and practices offering that follow-up need physical therapy EMR software to keep the surgical and rehab record connected.

Code hierarchy and parent codes for S02.641 ICD-10 code

S02.641B sits at the most specific level of a well-defined code hierarchy. Understanding where it sits helps coders confirm they are using the right code and identify related codes quickly. The same S00-S09 block structure governs S06.6X0A, showing how the classification system organizes codes consistently across different head-injury sites.

• Chapter 19: Injury, poisoning and certain other consequences of external causes (S00-T88)
• Block S00-S09: Injuries to the head
• Category S02: Fracture of skull and facial bones
• Subcategory S02.6: Fracture of mandible
• Subcategory S02.64: Fracture of ramus of mandible
• Subcategory S02.641: Fracture of ramus of right mandible
• Specific code S02.641B: Initial encounter for open fracture

The parent code S02.641 is not billable on its own. A valid claim requires the full 7-character code. Submitting S02.641 without the 7th character will result in a claim rejection.

S02.641B vs related mandibular fracture ICD-10 codes

Mandibular ramus fractures have a broad set of related codes covering laterality, fracture type, and encounter phase. The table below compares the most frequently used codes alongside ICD-10 code S02.641B. S02.642A mirrors this same logic for the left side.

When to use S02.641B vs S02.641A

The open vs closed distinction is the most consequential coding decision for this fracture site. Using S02.641A when the fracture is open – or S02.641B when it is closed – misrepresents the clinical picture and may trigger payer audits. The choice must be grounded in physician documentation, not assumed from the mechanism of injury.

• Use S02.641B when the operative or ED note explicitly documents “open fracture,” “intraoral laceration communicating with the fracture,” or equivalent language confirming a breach in overlying tissue.
• Use S02.641A when documentation confirms the fracture is closed – no communication between the fracture site and the external environment, even if the injury involved significant soft-tissue swelling or bruising.
• Query the provider when the documentation is ambiguous about open vs closed status. Coders should not infer fracture type from imaging alone.

Coding guidelines for ICD-10 code S02.641B

The ICD-10-CM Official Guidelines for Coding and Reporting, maintained jointly by CMS and the NCHS, govern how S02.641B is sequenced and used on claims. Practices that invest in solid claims management software can automate the checks that catch common sequencing errors before submission. The key guidelines relevant to this code are:

• Sequencing as principal diagnosis: When the mandibular ramus fracture is the reason for the encounter, S02.641B sequences as the principal (first-listed) diagnosis.
• External cause codes: ICD-10-CM guidelines strongly encourage – and some payers require – an additional external cause code to explain how the fracture occurred. Common codes include W00-W19 (falls) and V00-V99 (transport accidents). These sequence after S02.641B, never before it.
• Multiple fractures: If the patient has fractures in multiple sites, code each fracture separately. S02.641B is limited to the right ramus; a simultaneous left ramus fracture would require S02.642B as a separate code.
• 7th character must match encounter phase: Switch from ‘B’ to ‘D’, ‘G’, ‘K’, or ‘S’ at the appropriate clinical transition. Using ‘B’ at a routine 6-week post-operative visit is incorrect and may trigger an audit flag.
• Placeholder ‘X’: Some S02 codes require a placeholder ‘X’ to maintain the 7th character position. Confirm the correct structure for each code in the Tabular List.

The same phase-of-care logic governs S02.69XK, where the nonunion character carries equivalent documentation weight.

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Associated CPT codes for treating a mandibular ramus open fracture

S02.641B is a diagnosis code, not a procedure code. On a claim, it pairs with CPT procedure codes that describe the surgical or non-surgical treatment performed. The appropriate CPT depends on the treatment approach documented by the surgeon. Having organised medical forms that capture operative technique detail makes accurate CPT selection more straightforward during coding review.

CPT-to-ICD-10 medical necessity crosswalks are available through the AAPC crosswalk tool, which confirms covered CPT/ICD pairings for specific payers. CPT pairings listed above are commonly associated; payer-specific requirements vary and should always be verified against the applicable LCD or coverage policy before billing.

Documentation requirements for accurate ICD-10 code S02.641B billing

Every element of the S02.641B code description must be supported by a corresponding entry in the medical record. Missing documentation for any of the five required elements below is the most common reason this code triggers a denial or audit.

Clinical documentation compliance frameworks apply equally to oral surgery – the principle that what is not documented cannot be coded holds across specialties.

• Fracture type – open: The note must explicitly state “open fracture” or describe a wound communicating with the fracture site (e.g., intraoral laceration overlying the ramus). Imaging reports alone are not sufficient.
• Anatomical site – ramus: Documentation must identify the ramus as the fracture location. “Mandibular fracture” without site specificity does not support the ramus-level subcategory.
• Laterality – right: The record must state “right” side. Bilateral fractures require S02.641B and S02.642B coded separately.
• Encounter type – initial (active treatment): The note must reflect that the patient is receiving active treatment. Progress notes for follow-up visits should clearly indicate whether treatment is ongoing or the patient has transitioned to monitoring.
• Mechanism of injury: Documentation of how the fracture occurred supports the accompanying external cause code and is increasingly reviewed during payer audits.

Practices using digital intake forms can build structured trauma documentation templates that prompt clinicians to capture each of these data points at the point of care, rather than relying on retrospective addenda. Consistent patient data security practices also ensure that detailed fracture notes are stored and accessible in a compliant, auditable format.

Maintaining accurate, up-to-date patient records protects the practice if a payer requests documentation months after the original encounter.

Pabau’s structured patient records give maxillofacial and oral surgery practices a single place to store clinical notes, operative reports, and coding-relevant documentation, reducing the risk of missing information at audit. The platform’s claims management tools can then surface this documentation directly in the billing workflow.

Conclusion

Open mandibular ramus fractures present coders with a tight set of documentation requirements, and a single missing element – fracture type, site, laterality, encounter phase, or mechanism – can flip a clean claim into a denial.

S02.641B is valid for billing when the clinical record explicitly supports all five elements. The 7th character ‘B’ is not interchangeable with ‘A’ – the open-vs-closed distinction carries real reimbursement consequences.

For practices managing oral surgery and maxillofacial billing, Pabau’s integrated claims management platform helps teams build documentation workflows that capture what payers need at the point of care. To see how Pabau supports accurate fracture coding from intake to claim submission, book a demo with the team.

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