ICD code S12.390D – Other displaced C4 fracture, subsequent encounter

Key takeaways

S12.390D codes an “other” displaced fracture of the fourth cervical vertebra (C4) at a follow-up visit with routine healing.

It is the displaced code, and S12.391D is its nondisplaced twin. A note that never states alignment defaults to displaced, so it lands here.

The subcategory digit sits one behind the vertebra: S12.3 is C4, while C7 fractures live under S12.6.

Use D only while the fracture heals as expected; switch to G for delayed healing, K for nonunion, and S once it has healed.

Any associated cervical spinal cord injury is coded first, from S14.0 or S14.1-, with S12.390D listed after it.

ICD-10 code S12.390D: Quick reference table

ICD-10 code S12.390D is the billable code for an “other” displaced fracture of the fourth cervical vertebra (C4). It is reported at follow-up visits while the fracture heals as expected. Each attribute below matches the current ICD-10-CM tabular list on the CMS ICD-10 codes page.

What S12.390D covers: Full code description

S12.390D covers a traumatic fracture of the fourth cervical vertebra (C4) in which the fragments have moved out of normal alignment. It applies at follow-up visits after the patient has already received active treatment, while the fracture heals as expected.

The word “other” is the key qualifier. It separates S12.390 from the unspecified C4 fracture codes, S12.300 and S12.301. It also separates it from the C4 traumatic spondylolisthesis codes in S12.33, S12.34, and S12.35. So S12.390D fits a displaced C4 fracture that the record describes, but that none of those subcategories match.

C4 sits in the subaxial cervical spine, the C3 to C7 segment below the atlas and axis. It is injured less often than the lower levels, where C5 to C7 take the peak flexion and extension loads. Motor vehicle collisions, falls in older adults, and diving injuries account for most C4 fractures.

• Traumatic origin required: S12.390D is for fractures caused by external trauma, not pathological fractures from osteoporosis or a tumor.
• Displaced, or alignment never stated: The S12 tabular note codes a fracture not documented as displaced or nondisplaced to displaced. Silence in the note lands on S12.390D, not S12.391D.
• Closed by default: A fracture not documented as open or closed is coded as closed. That choice matters at the initial encounter, where A and B differ, but D covers both.
• Subsequent encounter only: The D extension marks visits after active treatment has been delivered. The provider is managing routine healing, not performing the first definitive intervention.

Understanding the 7th character D (subsequent encounter)

The 7th character defines the phase of care, and payers check it against the visit history on the claim. The S12.390 root code takes six 7th characters, one for each stage of the fracture.

Per ICD-10-CM Official Guidelines Section I.C.19.a, the D extension applies to encounters after active treatment, while the patient receives routine care during healing. That holds even when a different provider sees the patient.

A patient treated in the ED on Monday who sees a spine surgeon on Friday for a brace check gets S12.390D on that Friday claim.

The same section says aftercare Z codes are not used for injuries. A displaced C4 fracture in routine follow-up is reported with S12.390D, not with a general aftercare code.

S12.390D vs. similar codes: How to choose the right code

The S12 category holds dozens of codes that differ from S12.390D by a single character. One wrong digit changes the vertebral level, the displacement status, or the phase of care.

Cross-check the final code against the CDC/NCHS ICD-10-CM web tool before submission. The decision path below settles the four choices in the order a coder makes them.

Two mix-ups are easy to make in this family. The first is mixing up displacement: S12.390D is displaced, and S12.391D is nondisplaced. If the imaging report confirms alignment, the code is S12.391D.

The second is reading the subcategory digit as the vertebra. S12.0 starts at C1, so the digit always sits one behind: S12.3 is C4, and S12.6 is C7. Check the digit against the level named in the imaging report before the claim goes out.

S12 tabular notes and coding restrictions

The S12 category carries instructional notes that shape every S12.390D claim. None of them is an Excludes1 note, but each one changes what goes on the claim or in which order.

• Code first: Any associated cervical spinal cord injury, using S14.0 or S14.1-. The cord injury is sequenced first, and S12.390D follows it on the same claim.
• Displaced by default: A fracture not indicated as displaced or nondisplaced is coded to displaced. This is why a vague note still points to S12.390D.
• Closed by default: A fracture not indicated as open or closed is coded to closed.
• Includes: Fractures of the cervical neural arch, spine, spinous process, transverse process, and vertebral arch, as well as fracture of the neck.
• External cause codes: The Chapter 19 note calls for secondary codes from Chapter 20 to describe the cause of injury. Carry them on follow-up claims where your payer asks for them.
• Pathological fractures sit elsewhere: A vertebral fracture caused by osteoporosis or a tumor is coded in Chapter 13, M80 or M84, not in S12.

The code-first note is the one that reorders the claim. A follow-up for an incomplete cord lesion at the same level lists S14.154D first, with S12.390D after it.

Documentation requirements for S12.390D

Accurate documentation separates a clean S12.390D claim from a denial. The record must support each part of the code: the vertebral level, the displacement status, and the encounter type. A note template that asks for each field before the provider signs keeps those details on the record.

• Vertebral level: The note or radiology report must name C4, the fourth cervical vertebra. “Mid cervical fracture” or “cervical fracture, NOS” is not enough and calls for a provider query.
• Displacement status: X-ray, CT, or MRI showing the fragments out of alignment supports S12.390D. If imaging confirms alignment, the code is S12.391D instead.
• Fracture type: The record should describe a C4 fracture that is not a traumatic spondylolisthesis. Anterolisthesis of C4 on C5 points to S12.33-, S12.34X, or S12.35-.
• Healing status: Each follow-up note should state how healing is progressing, with imaging findings and any change to the brace or collar. “Healing as expected” supports D, while “delayed union” moves the code to G.
• Prior treatment: The record should show that active treatment already happened, such as surgical fixation or halo placement. That history is what makes the visit subsequent.
• Injury date and mechanism: Keep the original injury date and mechanism, such as a fall or a car crash, on the record. Auditors and claim forms both ask for them.

Attach the superbill to the encounter note before the claim is built. A missing element then surfaces in-house, before the payer’s edits catch it.

Payer requirements and prior authorization for subsequent encounter billing

Most payers do not require prior authorization for routine cervical fracture follow-up billed with S12.390D. Several scenarios still trigger closer review. Checking eligibility before the visit flags a coverage problem while there is still time to sort it out.

• Medicare: Follow-up E/M services billed with S12.390D are covered under Part B when medical necessity is documented. Medicare sets no fixed limit on fracture follow-up visits, but unusual frequency can trigger medical review.
• Global surgery periods: Displaced C4 fractures are often fixed surgically. Routine follow-up by the operating surgeon inside the 90-day global period is reported with 99024 and is not paid separately.
• Medicaid: Coverage and prior authorization rules vary by state. Some managed care plans cap specialist follow-up visits, so check the plan policy before the encounter.
• Commercial payers: Most follow Medicare-style criteria for fracture follow-up. Narrow-network plans may require an in-network provider for subsequent encounters, even when the initial care was out of network.
• Workers’ compensation: These payers track the exact level and displacement status when they set case reserves. Coding a displaced C4 fracture as nondisplaced, or at the wrong level, can affect the claim’s value.

When submitting clean claims for S12.390D, include the date of the original injury in the claim field your payer specifies. Payers use it to check that the follow-up timeline is clinically plausible.

Common claim denial reasons and how to avoid them

S12.390D denials follow predictable patterns, and most can be stopped at documentation or charge entry. Effective denial management workflows for cervical fracture claims target these five root causes.

CPT codes commonly billed with S12.390D

S12.390D is a diagnosis code, so it does not map to one procedure. The CPT code must match the service documented at that visit. Billing teams can check the full descriptor of each pairing below in our CPT reference for coders.

Practices using claims management software can pre-map these CPT and ICD-10 pairings. That cuts charge-entry time on busy follow-up days.

ICD-10-CM code history and annual updates

S12.390D has been a valid billable code since the US moved from ICD-9-CM to ICD-10-CM on October 1, 2015. Its descriptor has not changed in any annual update since, including the FY2027 release effective October 1, 2026.

ICD-10-CM codes update every year on October 1. Coders should confirm S12.390D against the current release, because changes to nearby S12 entries can affect code choice. The AAPC Codify ICD-10-CM lookup reflects the current US code set. An automated validity check before each October update catches a revised or deleted code before it reaches a claim.

Related ICD-10 codes

• S12.391S: Other nondisplaced C4 fracture, sequela
• S12.690B: Other displaced C7 fracture, initial encounter for open fracture
• S13.4: Sprain of ligaments of cervical spine

How Pabau keeps C4 fracture follow-up claims ready to submit

A displaced C4 fracture produces a long trail of evidence. The surgeon’s note, the imaging reports, and the brace changes often sit in different systems. When a payer asks why S12.390D was billed, someone has to rebuild that history by hand.

Pabau, the practice management and billing platform we build, keeps the injury date, the vertebral level, and every imaging report on one patient record. You record the level and displacement once, and each follow-up note reads from it.

On the billing side, Pabau builds the claim from the coded encounter and sends it electronically through its Claim.MD integration. Your coder confirms the 7th character once, before submission. The result is fewer returned claims, faster audit responses, and less unpaid admin time.

Manage cervical fracture follow-up claims without the rework

Pabau keeps the fracture level, alignment findings, and encounter type on one patient record. Your coders send C4 follow-up claims with the evidence already attached.

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Conclusion

S12.390D holds three coding decisions. The level is C4, the fracture is displaced or its alignment was never documented, and the visit is a follow-up while healing goes to plan. Get any one wrong and the claim comes back for rework, a query, or an appeal.

Those decisions are settled in the record before a coder opens the code book. A note that names C4, states alignment, and tracks healing will hold up at review. Book a demo to see how Pabau keeps cervical fracture follow-up claims ready to submit.

Continue your research

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Seeing denials you can’t trace back to a coding error? Reading electronic remittance advice (ERA) walks through how to interpret 835 remittance files and match CARC denial codes to specific S12.390D claim edits.

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