Crystal's Coder Hub🧬 ICD-10 CM S02.631A — Fracture of Coronoid Process of Right Mandible, Initial Encounter for Closed Fracture
Billable Code Confirmed
es; character 4 (6) narrows to mandible fractures; character 5 (3) specifies the coronoid ICD-10 CM S02.631A is a valid, billable 7-character ICD-10-CM code for FY2026. Characters 1-3 (S02) identify the category as fracture of skull and facial bonprocess; character 6 (1) designates right-side laterality; and character 7 (A) is the encounter qualifier for initial encounter, closed fracture. No additional characters are required or permitted.
Non-Billable Parent Codes — Never Submit These
- ❌
S02— 3-character header — missing fracture site, laterality, and encounter type- ❌
S02.6— 4-character header — missing specific process, laterality, and encounter type- ❌
S02.63— 5-character header — missing laterality and encounter type- ❌
S02.631— 6-character header — missing 7th-character encounter qualifier (A/D/G/K/S)Always submit S02.631A (all 7 characters) when a closed fracture of the coronoid process of the right mandible is documented at initial encounter.
Clinical Context: 7th Character Encounter Qualifier Is Required
ICD-10-CM S02.631A requires the 7th character to specify the episode of care. Character A = initial encounter applies when the patient is receiving active treatment for the fracture regardless of whether this is the first time the provider sees the patient — it means the fracture is still in the active treatment phase. Do not default to D (subsequent encounter) simply because the patient has been seen before; use D only when the fracture is healing and routine follow-up care is being provided.
Code Classification
ICD-10-CM Diagnosis Code — wRVU, assistant payable status, and global period fields are not applicable to ICD-10-CM diagnosis codes. For procedural billing associated with this diagnosis, refer to the CPT Procedural Crosswalk and ICD-10-PCS Crosswalk sections below.
🔍 Code Description
ICD-10 CM S02.631A classifies a closed fracture of the coronoid process of the right mandible presenting for initial encounter. The coronoid process is the thin, triangular anterior projection of the mandibular ramus, serving as the primary attachment site for the temporalis muscle; fractures here are among the rarest of all mandibular fractures, typically caused by direct blunt trauma to the face, motor vehicle accidents, or forceful muscular avulsion.²
Because the temporalis muscle inserts at the coronoid process, fracture fragments may be displaced superiorly and posteriorly by muscle pull, potentially limiting trismus (restricted jaw opening) and causing significant pain with mastication. Imaging typically includes CT of the facial bones with 3D reconstruction to assess displacement, comminution, and involvement of adjacent structures including the temporomandibular joint.²⁻³
🌳 Code Tree / Hierarchy
S02 — Fracture of skull and facial bones ❌ Non-billable
│
├── S02.0XX_ — Fracture of vault of skull ✅ Billable (with 7th char)
├── S02.1__ — Fracture of base of skull ❌ Non-billable header
├── S02.2XX_ — Fracture of nasal bones ✅ Billable (with 7th char)
├── S02.3XX_ — Fracture of orbital floor ✅ Billable (with 7th char)
├── S02.4__ — Fracture of malar, maxillary, zygoma ❌ Non-billable header
├── S02.5__ — Fracture of tooth ❌ Non-billable header
│
├── S02.6 — Fracture of mandible ❌ Non-billable header
│ │
│ ├── S02.60__ — Fracture of mandible, unspecified ❌ Non-billable
│ ├── S02.61__ — Fracture of condylar process of mandible ❌ Non-billable
│ ├── S02.62__ — Fracture of subcondylar process of mandible ❌ Non-billable
│ │
│ ├── S02.63 — Fracture of coronoid process of mandible ❌ Non-billable header
│ │ │
│ │ ├── S02.631A — Fx coronoid process RIGHT mandible, initial, closed ◀ THIS CODE ✅ Billable
│ │ ├── S02.632A — Fx coronoid process LEFT mandible, initial, closed ✅ Billable
│ │ └── S02.639A — Fx coronoid process UNSPECIFIED mandible, initial, closed ✅ Billable
│ │
│ ├── S02.64__ — Fracture of ramus of mandible ❌ Non-billable
│ ├── S02.65__ — Fracture of angle of mandible ❌ Non-billable
│ ├── S02.66__ — Fracture of symphysis of mandible ❌ Non-billable
│ ├── S02.67__ — Fracture of alveolar border of mandible ❌ Non-billable
│ └── S02.69__ — Fracture of mandible of other specified site ❌ Non-billable
│
└── S02.9__ — Fracture of other specified skull/facial bones ❌ Non-billable
Laterality and Specificity Drive Code Selection
Never assign
S02.639A(unspecified side) when operative reports, CT imaging, or clinical notes clearly identify the right mandible. Payers, particularly Medicare, may deny or down-code claims for failure to code to the highest level of specificity available in the documentation.¹
✅ Includes
The following clinical terms and scenarios map to S02.631A when documented:
- Closed fracture of the coronoid process of the right mandible, initial encounter
- Right mandibular coronoid process fracture, active treatment phase
- Traumatic right coronoid process fracture (closed), presenting for surgical evaluation or non-operative management
- Avulsion fracture of the right coronoid process secondary to temporalis muscle pull (closed, initial)
❌ Excludes
Excludes 1 — Cannot Be Coded Simultaneously with S02.631A
| Code | Description | Note |
|---|---|---|
| S02.401A | Malar fracture unspecified side, initial encounter | Malar fractures are anatomically distinct; if both are present from same trauma, code each separately only if clinically distinct — but verify Excludes 1 logic in the tabular |
| S09.90XA | Unspecified injury of head, initial encounter | Do not use the unspecified head injury code when a specific fracture site has been identified and documented |
Excludes 1 Violation Risk
The most common error is coding S09.90XA (unspecified head injury) alongside a specific facial bone fracture. Once imaging confirms and the provider documents a coronoid process fracture, S09.90XA must be dropped — submit only the specific fracture code S02.631A with appropriate external cause codes.¹
Excludes 2 — May Be Coded in Addition if Separately Present
| Code | Description | Note |
|---|---|---|
| S09.0X_A | Injury of blood vessels of head | Code additionally if vascular injury is separately documented in same trauma encounter |
| S09.8XX_ | Other specified injuries of head | May be coded additionally for other distinct head injuries present in the same encounter |
📋 Clinical Overview
Coronoid Process vs. Other Mandibular Fracture Sites
Coronoid process fractures are the least common mandibular fracture type, making up fewer than 1% of all mandibular fractures. Distinguishing the coronoid process from the condylar and subcondylar processes is essential for accurate code selection.²
| Feature | S02.631A — Coronoid Process (Right) | S02.611A — Condylar Process (Right) | S02.621A — Subcondylar Process (Right) |
|---|---|---|---|
| Anatomic Location | Anterior ramus projection, temporalis attachment | Superior condylar head, TMJ articulation | Below condylar neck, above angle |
| Common Mechanism | Direct blow, MVC, temporalis avulsion | Indirect force (chin impact), MVC | Indirect force; parasymphyseal impact |
| Prevalence | < 1% of mandibular fractures | ~30-35% of mandibular fractures | ~20% of mandibular fractures |
| Primary Symptom | Trismus, pain with mastication | TMJ pain, malocclusion | Malocclusion, preauricular pain |
| Treatment | Observation vs. coronoidectomy | Often conservative; ORIF if displaced | Conservative vs. ORIF |
| Key Imaging | CT facial bones with 3D recon | Panoramic X-ray, CT | Panoramic X-ray, CT |
CDI Query Trigger — Coronoid vs. Condylar Process
Operative and radiology reports may use the terms “coronoid” and “condylar” interchangeably or imprecisely. If the documentation is ambiguous, a CDI query to the operating surgeon or radiologist is warranted before assigning S02.631A vs. S02.611A. These are anatomically distinct structures, and the difference drives laterality character selection as well as surgical CPT code assignment.
Manifestations & Symptom Burden
Common clinical presentations documented with coronoid process fractures include:
- Trismus: Restricted mouth opening secondary to temporalis muscle spasm or mechanical obstruction of the coronoid fragment against the zygomatic arch
- malocclusion: Altered bite alignment if fracture is displaced or associated with other mandibular injuries
- Facial asymmetry / swelling: Right-sided periorbital or premasseteric edema on presentation
- Pain with mastication: Exacerbated by any temporalis muscle activation (chewing, clenching)
- Paresthesia: Rare; may involve inferior alveolar nerve if fracture extends inferiorly
Coding Manifestations
Always code documented manifestations to fully capture patient complexity. Examples include:
- M26.60 — Temporomandibular joint disorder, unspecified (if TMJ involvement documented)
- R68.84 — Jaw pain
- M26.50 — Dentofacial functional abnormalities, unspecified (if malocclusion documented)
💰 HCC Risk Adjustment (CMS-HCC v28)
| Field | Detail |
|---|---|
| CMS-HCC Model Version | v28 (2024-2025 Implementation) |
| HCC Assignment | ❌ Not HCC-Mapped |
| HCC Category | N/A |
| RAF Coefficient | N/A |
S02.631A does not map to an HCC under CMS-HCC model v28.⁴
Not Applicable for Risk Adjustment
Traumatic fracture codes are acute/episodic in nature and are excluded from the chronic condition HCC framework. This code does not contribute to a patient’s RAF score and annual recapture is not required. Focus documentation efforts on any underlying chronic comorbidities (e.g., osteoporosis, coagulopathy) that may have contributed to fracture risk, as those may carry their own HCC mappings.
🏥 MS-DRG Assignment
MDC 03 — Diseases and Disorders of the Ear, Nose, Mouth, and Throat
| DRG | Title | Est. Relative Weight* |
|---|---|---|
| DRG 133 | Other Ear, Nose, Mouth and Throat Diagnoses with MCC | ~0.9-1.1 |
| DRG 134 | Other Ear, Nose, Mouth and Throat Diagnoses with CC | ~0.7-0.9 |
| DRG 135 | Other Ear, Nose, Mouth and Throat Diagnoses without CC/MCC | ~0.5-0.7 |
Approximate. Verify against IPPS FY2026 Final Rule tables.
Sequencing and Surgical Re-Grouping
When S02.631A is the principal diagnosis and the patient is managed non-operatively, the case groups to DRGs 133-135. However, if ORIF or another operative procedure is performed (e.g., PCS code 0NST04Z — Reposition Right Mandible, Open Approach, Internal Fixation), the DRG grouper will re-assign the case to an operative partition DRG (DRGs 130-132 — Other Ear, Nose, Mouth and Throat OR Procedures). Always confirm that the ICD-10-PCS procedure codes are coded before finalizing the DRG. Secondary diagnoses such as traumatic brain injury or aspiration pneumonia may elevate the case to MCC status and significantly impact DRG weight and reimbursement.⁵
🔗 Related ICD-10-CM Codes
Laterality Variants — Coronoid Process Fractures
| Code | Description |
|---|---|
| S02.631A | Fracture of coronoid process of right mandible, initial encounter, closed ← This Code |
| S02.632A | Fracture of coronoid process of left mandible, initial encounter, closed |
| S02.639A | Fracture of coronoid process of unspecified mandible, initial encounter, closed |
Encounter Type Variants — Right Coronoid Process
| Code | Description |
|---|---|
| S02.631A | Initial encounter, closed fracture ← This Code |
| S02.631B | Initial encounter, open fracture type I or II (Non-billable without open documentation) |
| S02.631D | Subsequent encounter, routine healing |
| S02.631G | Subsequent encounter, delayed healing |
| S02.631K | Subsequent encounter, nonunion |
| S02.631S | Sequela |
Anatomic Site Variants — Mandible Fractures
| Code | Description |
|---|---|
| S02.611A | Fracture of condylar process of right mandible, initial encounter, closed |
| S02.621A | Fracture of subcondylar process of right mandible, initial encounter, closed |
| S02.641A | Fracture of ramus of right mandible, initial encounter, closed |
| S02.651A | Fracture of angle of right mandible, initial encounter, closed |
| S02.661A | Fracture of symphysis of mandible, initial encounter, closed |
🛠️ Commonly Associated CPT Codes (Oral and Maxillofacial Surgery / Trauma)
Inpatient and Outpatient Surgical Setting Context
The CPT codes below are associated with surgical and procedural management of coronoid process mandible fractures. In the profee setting, professional component billing applies. Modifier -RT may be appended to laterality-sensitive codes to designate right side. If an E/M is performed the same day as fracture treatment, append Modifier -25 to the E/M.
| CPT Code | Description | Profee Coding Notes |
|---|---|---|
| 21325 | Open treatment of mandibular fracture, without interdental fixation | Use for ORIF of uncomplicated coronoid process fracture; confirm approach documentation |
| 21470 | Open treatment of complicated mandibular fracture, multiple surgical approaches | Use when multiple fracture sites or approaches are involved; requires detailed op note |
| 21310 | Closed treatment of nasal bone fracture without manipulation | Do not confuse — listed here as common co-injury CPT; verify anatomic site |
| 21085 | Impression and custom preparation; oral surgical splint | May be billed if intermaxillary fixation device fabricated for fracture stabilization |
| 70486 | CT maxillofacial area without contrast | Commonly ordered for fracture characterization; bill with Modifier -26 for professional read |
| 70487 | CT maxillofacial area with contrast | Used when vascular injury or abscess is a concern; bill with Modifier -26 for professional component |
NCCI Bundling Considerations
- CT Maxillofacial (70486 or 70487) billed on the same day as ORIF (21325 or 21470) may be bundled under NCCI edits — append Modifier -59 to the imaging code if it represents a distinct, separately documented service performed at a different time or for a different clinical purpose.
- E/M codes billed on the same DOS as fracture treatment require Modifier -25 on the E/M to confirm a separately identifiable service was performed.
🔬 ICD-10-PCS Crosswalk (Inpatient Procedures)
When S02.631A is an inpatient diagnosis, these PCS codes are relevant for associated inpatient procedures.
| PCS Section | Body System | Root Operation | Clinical Application |
|---|---|---|---|
| 0 (Medical & Surgical) | N (Head and Facial Bones) | S (Reposition) | ORIF right coronoid process with plate/screws: 0NST04Z — Reposition Right Mandible, Open Approach, Internal Fixation Device |
| 0 (Medical & Surgical) | N (Head and Facial Bones) | S (Reposition) | Closed reduction right mandible, no fixation: 0NST3ZZ — Reposition Right Mandible, Percutaneous Approach, No Device |
| 0 (Medical & Surgical) | N (Head and Facial Bones) | T (Resection) | Coronoidectomy (resection of coronoid process for trismus): 0NT_0ZZ — consult full PCS table for body part character |
| 0 (Medical & Surgical) | N (Head and Facial Bones) | Q (Repair) | Repair of associated facial bone injury without reposition: 0NQT0ZZ — Repair Right Mandible, Open Approach |
💊 Coding Scenarios and Examples
Scenario 1 — Inpatient: Traumatic Right Coronoid Process Fracture After MVC
Clinical Vignette: A 34-year-old male presents to the ED following a high-speed motor vehicle collision. CT of the facial bones with 3D reconstruction confirms a non-displaced closed fracture of the coronoid process of the right mandible with significant trismus. The patient is admitted for pain management, airway monitoring, and surgical evaluation. No intracranial injury is identified. He is managed non-operatively with a liquid diet, analgesia, and physical therapy referral.
Principal Diagnosis:
- S02.631A — Fracture of coronoid process of right mandible, initial encounter for closed fracture (reason for admission)
Secondary Diagnoses:
- R68.84 — Jaw pain (documented manifestation)
- V49.50XA — Car driver injured in collision, initial encounter (external cause of injury)
- Y93.89 — Activity, other specified (if applicable per documentation)
MS-DRG Assignment: Without a CC or MCC, this case groups to DRG 135. If the trismus is documented as severe with functional impairment requiring additional intervention, query the provider for more specific documentation that may support a CC and upgrade to DRG 134.
Scenario 2 — Inpatient Operative: ORIF Right Coronoid Process Fracture with Trismus
Clinical Vignette: A 28-year-old female is admitted following assault with blunt facial trauma. Imaging reveals a displaced closed fracture of the coronoid process of the right mandible with the coronoid fragment displaced superiorly beneath the zygomatic arch, causing complete trismus (0 mm interincisal opening). The oral maxillofacial surgery team performs open reduction and internal fixation via a preauricular/intraoral approach with titanium plate fixation.
Principal Diagnosis:
- S02.631A — Fracture of coronoid process of right mandible, initial encounter for closed fracture
Secondary Diagnoses:
- R68.84 — Jaw pain
- W50.0XXA — Accidental hit/strike by another person, initial encounter (external cause)
ICD-10-PCS Procedure Code:
- 0NST04Z — Reposition Right Mandible, Open Approach, Internal Fixation Device
MS-DRG Assignment: The presence of an operative PCS procedure code re-groups this case from the medical partition to the operative partition — DRGs 130-132 (Other Ear, Nose, Mouth and Throat OR Procedures), with the final DRG determined by CC/MCC status. ORIF significantly increases the relative weight compared to medical management alone.⁵
Scenario 3 — CDI Query: Coronoid vs. Condylar Process Documentation Ambiguity
Clinical Vignette: The emergency department note documents “right mandibular condylar fracture” but the radiology CT report reads “fracture of the right coronoid process of the mandible.” The operative note references “coronoid process ORIF via preauricular approach with coronoidectomy for trismus release.” There is a direct conflict between the ED note and the imaging/operative documentation.
Action / Outcome: The coder cannot default to either code without clarification. The conflict between “condylar” (ED note) and “coronoid” (radiology and op note) requires a CDI query to the attending OMFS surgeon to clarify the final operative/clinical diagnosis.
Query Response: Provider updates the final diagnosis to confirm: “The fracture involved the coronoid process of the right mandible, not the condylar process. The operative note and CT report are accurate.”
Corrected ICD-10-CM Coding:
- S02.631A — Fracture of coronoid process of right mandible, initial encounter for closed fracture
- 0NST04Z (PCS) — Reposition Right Mandible, Open Approach, Internal Fixation Device
⚠️ Coding Pitfalls and Tips
| Pitfall or Tip | |
|---|---|
| ❌ | Confusing Coronoid with Condylar Process. These are anatomically distinct structures. Using S02.611A (condylar) when the fracture is at the coronoid process (S02.631A) is a specificity error that can affect surgical CPT code selection and DRG grouping. Always verify with imaging reports and operative notes. |
| ❌ | Omitting the 7th Character. Submitting S02.631 (6 characters) without the encounter qualifier will result in a claim rejection. The 7th character (A = initial, D = subsequent, S = sequela) is mandatory for all fracture codes in Chapter 19.¹ |
| ❌ | Using “Unspecified” Laterality. Assigning S02.639A when the documentation clearly identifies the right mandible is a specificity failure. Medicare and most commercial payers expect the highest level of specificity supported by documentation. |
| ✅ | Match 7th Character to Episode of Care, Not Visit Number. Character A (initial encounter) is appropriate for any visit during active treatment — including follow-up surgical visits. Transition to D (subsequent) only when the fracture is healing and the care is routine/maintenance. |
| ✅ | Code the Mechanism of Injury. Always append an external cause code (V/W/X/Y codes) to trauma fracture codes. These are required by many payers and support accurate trauma registry data, public health reporting, and legal documentation. |
| ✅ | Query for Open vs. Closed Designation. If the operative note or imaging report mentions soft tissue laceration overlying the fracture site, the fracture may qualify as open (7th character B or C). This changes the code entirely and may affect DRG assignment and infection risk documentation. |
📚 Sources
¹ CMS/NCHS. ICD-10-CM Official Guidelines for Coding and Reporting, FY2026. Section I.C.19 — Injury, Poisoning and Certain Other Consequences of External Causes.
² Chrcanovic, B.R., et al. (2012). Fractures of the Mandible: A Review of Current Literature. Journal of Cranio-Maxillo-Facial Surgery, 40(5), 388-395. (Source for coronoid process fracture epidemiology, clinical presentation, and anatomical context.)
³ Kühnel, T.S., & Reichert, T.E. (2015). Trauma of the midface. GMS Current Topics in Otorhinolaryngology, Head and Neck Surgery, 14, Doc06. (Source for imaging and clinical management context of facial bone fractures.)
⁴ CMS. 2025-2026 Medicare Advantage Risk Adjustment — CMS-HCC Model v28 ICD-10-CM Mappings. (Source confirming S02.631A is not mapped to an HCC category under v28.)
⁵ CMS. IPPS Final Rule FY2026 — MS-DRG Definitions Manual v43. MDC 03 and MDC 21 logic tables. (Source for DRG 133-135 and operative partition DRG 130-132 assignments.)
⁶ AMA. CPT Professional Edition 2026. Surgery — Musculoskeletal System, Skull, Facial Bones, and Temporomandibular Joint (CPT 21XXX series). (Source for CPT code descriptions and billing guidance.)