ICD code S92.321K – Displaced second metatarsal fracture, right foot, nonunion

Key takeaways

S92.321K codes a displaced fracture of the right second metatarsal at a follow-up visit where the provider has diagnosed nonunion.

The sixth character carries both side and displacement, so 1 means displaced on the right foot and 4 means nondisplaced on the right.

Choose K only when the note states nonunion. Healing that is slow but still progressing takes G, and normal healing takes D.

Nonunion care keeps the K even when it includes surgery, such as a metatarsal nonunion repair billed with CPT code 28322.

A stress fracture of the second metatarsal codes to M84.374- instead, even when it later fails to heal.

S92.321K means a broken right second metatarsal has stopped healing

ICD-10 code S92.321K reports a displaced fracture of the second metatarsal bone in the right foot, at a subsequent encounter for nonunion.

Put simply, the bone broke out of alignment, was treated, and has since failed to unite. It is a valid, billable code in the current ICD-10-CM code set, according to the CDC/NCHS ICD-10-CM browser tool.

The second metatarsal is the long bone behind the second toe, so toe fracture codes never apply here. Use the reference table below to confirm where the code sits before you assign it.

Each character of S92.321K pins down the bone, the side and the stage

Read S92.321K from left to right and it tells the whole clinical story. A wrong digit at any position points the claim at a different bone, foot or stage of care.

The sixth character does double duty. Values 1 to 3 mean displaced, for the right, left and unspecified foot. Values 4 to 6 mean nondisplaced, in the same order.

Laterality is therefore built into the code, and the foot named in the note must match it. When the record never says displaced or nondisplaced, the official guidelines default to displaced. An unstated open or closed status defaults to closed.

What displaced, second metatarsal and nonunion mean in the chart

Each part of the descriptor maps to a finding the provider must have recorded.

• Displaced fracture: the bone ends have shifted out of alignment. A break whose pieces stay lined up is nondisplaced and moves to S92.324K on the right foot.
• Second metatarsal: the long bone between the midfoot and the base of the second toe. It is also a common site for stress fractures, which are coded elsewhere.
• Right foot: the sixth character 1 fixes the side. A left-sided break codes to S92.322K instead.
• Nonunion: the fracture has failed to heal, and bone union has stopped. ICD-10-CM sets no time limit, so the code follows the provider’s diagnosis rather than the calendar.
• Subsequent encounter: active treatment of the fracture is complete. The patient is back for care of the complication.

The K suffix is one of seven 7th-character options for this fracture

Category S92 offers seven 7th characters, and each one describes a different encounter. Unlike some arm and leg fracture categories, S92 has no C option. Every open metatarsal fracture therefore takes B at the initial encounter.

G and K turn on one word in the note. G means the bone is still knitting, just more slowly than expected. K means union has stopped, and the provider has said so. When healing stays on track, the visit codes to S92.321D instead. Moving from G to K needs a new provider statement, not another month on the calendar.

Ask the questions in the order below, and the first yes sets the 7th character for the visit.

One rule surprises many coders. AHA Coding Clinic guidance keeps the K character for nonunion care, even when the visit includes surgery. A nonunion repair is therefore coded S92.321K, never S92.321A.

Sibling codes swap the side, the displacement or the bone

Most S92.321K errors involve a close neighbor. Check the codes below before you finalize the claim, and browse the full family in the AAPC ICD-10-CM lookup if you need more.

When imaging confirms a metatarsal nonunion but the note never names the bone, S92.301K is the fallback, though a provider query is the better fix.

A worked example shows how the chart earns the K

A 52-year-old patient fell from a stepladder 14 weeks ago. The first visit was coded S92.321A for a displaced right second metatarsal fracture. The foot was then managed in a walking boot.

Today, the patient still has pain when bearing weight. A three-view foot series shows a persistent fracture line with no bridging bone. The podiatrist writes “displaced right second metatarsal fracture, nonunion” and plans a bone stimulator.

• Diagnosis: S92.321K, because the note states nonunion, displacement and the right side.
• External cause, if your payer wants it: W11.XXXD, fall on and from ladder, subsequent encounter.
• Services: an established-patient office visit, plus 73630 for the three-view foot X-ray.

Had the note said only that healing was slow, the same visit would code S92.321G. That single word changes the 7th character and the claim’s story.

Documentation that holds up when a payer asks for records

A nonunion claim is easy to audit, because the record either supports K or it doesn’t. Use this checklist on every S92.321K visit, and keep your wider medical billing compliance process in step with it.

• A nonunion diagnosis in the provider’s own words.
• The bone and side, named as the right second metatarsal.
• Displacement status, taken from the exam or the imaging report.
• Dated imaging that shows no bridging across the fracture line.
• The injury date and prior care, such as a boot, cast or fixation.
• The plan for the nonunion, such as a stimulator or surgical repair.

A bone growth stimulator raises the bar for Medicare patients. LCD L33796 counts the metatarsals as long bones. It also needs two sets of radiographs, taken at least 90 days apart, that show no clinically significant healing. That record supports the stimulator line, whether it is 20974 or 20979.

CPT codes that usually travel with S92.321K

The procedure lines on a nonunion claim should describe nonunion care. Codes for fresh fracture treatment belong to the original injury instead.

Watch the dates, too. Metatarsal fracture care carries a 90-day global period. If the nonunion visit falls inside it, Medicare generally bundles follow-up care unless the patient returns to the operating room.

How an S92.321K claim moves from visit to payment

A US claim for S92.321K passes through six handoffs. Each one can catch an error before it costs money.

1. The provider documents the visit. The note records nonunion, the side and the imaging result.
2. The coder assigns S92.321K. An external cause code follows if the payer wants one.
3. CPT lines are linked to the diagnosis. Each line on the CMS-1500 points to S92.321K.
4. The clearinghouse checks the file. Format and payer-field errors bounce back before the payer sees them.
5. The payer adjudicates. Medical review may ask for the notes and X-rays.
6. The remittance posts. The ERA shows the payment or a denial reason code.

What trips up S92.321K claims most often

Each of these errors is cheap to prevent and slow to fix after a denial.

• The wrong foot. Character 1 means right. A left-foot note needs S92.322K.
• Treating the bone as a toe. Toe fractures sit in S92.4- and S92.5-, so they never describe a metatarsal.
• K from the calendar. Time alone never makes a nonunion. The provider has to diagnose it.
• A for nonunion surgery. AHA Coding Clinic guidance keeps the K for complication care, even in the operating room.
• Reaching for M84.1-. That nonunion code exists in the WHO’s ICD-10, but not in ICD-10-CM.
• Adding an aftercare Z code. The guidelines rule these out for injuries, because the 7th character already carries the stage of care.

When a mismatch does slip through, the remittance often shows CO-11, which means the diagnosis is inconsistent with the procedure. Our guide to denial codes in medical billing explains how to read and work these.

External cause codes on a nonunion visit follow their own rules

ICD-10-CM has no national rule that makes external cause codes mandatory. Some states and payers require them, though, so check your contracts. The official CMS guidelines set out how to report them.

When you do report one on a K visit, it takes D as its 7th character. Place of occurrence (Y92), activity (Y93) and status (Y99) codes are reported only at the initial encounter. Common causes for a second metatarsal fracture include:

• W10.-: a fall on or from stairs and steps.
• W11.XXXD: a fall on and from a ladder.
• W18.3-: other and unspecified falls on the same level.
• W20.8XXD: a strike by a thrown, projected or falling object.

Before you submit, run this five-point S92.321K check

A last look takes under a minute and saves weeks of back-and-forth. Confirm each point before the claim leaves the practice.

• The side in the note matches the sixth character.
• The note says nonunion, not just slow healing.
• CPT lines describe nonunion care, not fresh fracture treatment.
• Any external cause code ends in D, with no repeated Y92 or Y93 code.
• Prior authorization is on file for a stimulator or surgery, where the payer requires it.

How Pabau keeps nonunion claims tidy from chart to payer

Fracture follow-ups often stretch over months and several providers. Over that time, sides, dates and 7th characters can drift apart.

Pabau, the practice management and billing platform we build, pre-fills the CMS-1500 from the invoice. Its built-in ICD-10-CM and CPT libraries make S92.321K and its siblings quick to find. Its claims management software then validates the claim before it goes to the clearinghouse.

US claims go out through Pabau’s Claim.MD integration. Eligibility checks, claim-status tracking and ERA posting sit in the same place, so a nonunion follow-up never needs a second system.

Send cleaner fracture follow-up claims

Pabau pre-fills claims from the invoice, checks required fields and sends them through Claim.MD, so nonunion follow-ups reach the payer complete.

Book a demo

Conclusion

S92.321K rewards precision more than speed. The code is only as strong as the visit note behind it, so the provider’s words decide the claim.

Make three facts a habit on every follow-up: the foot, the displacement and the healing status. If one is missing, query before you code. That short pause costs far less than a records request later.

Book a demo to see how Pabau turns each fracture follow-up into a complete, validated claim.

Continue your research

Coding the same fracture while it heals normally? ICD-10 code S92.321D covers routine-healing follow-ups for the right second metatarsal.

Need guidance on managing claim denials across your practice? Denial management in healthcare covers the workflows that prevent write-offs on complication codes.

Want to understand how clearinghouse edits catch errors before submission? How the Claim.MD clearinghouse works explains what happens between your system and the payer.

Looking for a practical overview of medical billing? What is medical billing covers the claim lifecycle from code assignment through payment posting.

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