ICD-10 code S89.121S: Right distal tibia fracture sequela

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Key takeaways

ICD-10 code S89.121S covers the sequela of a Salter-Harris type II fracture at the lower end of the right tibia.

The left-side equivalent is S89.122S, and S89.129S covers a tibia whose side was never documented.

The 7th character S applies only once the fracture has healed, never during active fracture care.

Sequence the residual condition first and S89.121S second, because the S sits on the injury code alone.

As a sequela code, S89.121S groups to the aftercare MS-DRGs 559, 560 and 561 rather than the acute fracture DRGs.

ICD-10 code S89.121S is the billable code for a Salter-Harris type II physeal fracture of the lower end of the right tibia, sequela. That site is the distal tibial growth plate above the ankle, not the knee and not the fibula. The 7th character S tells the payer the fracture healed and the visit treats what it left behind.

Sequencing is where these claims go wrong. A sequela code rarely leads the diagnosis list, and it never travels alone on a claim. Get the pairing and the order right, and the claim clears. Miss either and the payer sees a healed fracture with no stated reason for the visit.

S89.121S at a glance: Billable, specific and FY 2026 valid

S89.121S is a complete seven-character code, so no placeholder X is needed. The CMS ICD-10-CM tabular list places it in the S89 category, with the reference data below.

Every character in S89.121S narrows the diagnosis

The last two characters do most of the work. The sixth fixes the side, and the seventh fixes the encounter.

The base code S89.121 is not billable on its own. A claim carrying six characters will be rejected as invalid before a coder ever sees it.

Six 7th characters fit S89.121, and only one is a sequela

Only the S marks a sequela. The other five describe the fracture episode itself, and the CDC ICD-10-CM coding tool lists them in full. There is no B value here, because the S89 category notes that a fracture not documented as open or closed is coded to closed.

Nonunion and malunion are healing states rather than sequelae. Both belong to the fracture episode itself, which is why they get their own characters. Reach for K or P while the fracture is still the problem, and for S once it no longer is.

What a Salter-Harris type II distal tibia fracture leaves behind

A Salter-Harris type II fracture runs along the growth plate and then exits through the metaphysis, leaving the epiphysis intact. It is the most common pattern by a wide margin. StatPearls puts type II at roughly 75% of all physeal injuries.

At the lower end of the tibia, this is an ankle injury in a skeletally immature patient. The distal tibial physis closes at around 15 in girls and 17 in boys, and it closes unevenly.

Ossification starts at an anteromedial ridge known as Kump’s bump, then spreads over roughly 18 months. That uneven closure is why adolescent ankles produce such distinctive fracture patterns.

Growth disturbance is the complication that matters here, and it is common enough to keep this code busy. A 143-patient series reported growth disturbance in 15.4% of distal tibial physeal fractures, over a mean 29-month follow-up.

StatPearls reports premature growth plate closure in 27.2% of distal tibial injuries. Younger age, higher Salter-Harris types and an associated fibula fracture all raise the risk.

That is what S89.121S usually stands behind. The residual condition is most often premature physeal closure, angular deformity at the ankle, or a leg-length discrepancy. Persistent pain and stiffness in a joint that healed out of line also qualifies.

Sequence the residual condition first, S89.121S second

Two codes are required, and the order is fixed. The FY 2026 ICD-10-CM Official Guidelines set it out in Section I.B.10 and Section I.C.19.a.

• The residual condition is sequenced first, because that is what the patient is being seen for today.
• S89.121S is sequenced second, naming the injury responsible for that residual condition.
• The S is added only to the injury code, never to the code for the sequela itself.
• The acute-phase code is never reported alongside the late effect, so S89.121A and S89.121S do not appear on the same claim.
• There is no time limit on sequela coding. A growth arrest picked up three years later still codes this way.

For the documentation to hold up, the note needs the side, the end of the tibia, and the Salter-Harris type. It also needs a clear statement that the fracture has healed, the named residual condition, and the link between them. Missing any one of those turns the claim into a coder query.

When the sequela character replaces A, D, G, K or P

S89.121S applies only after the fracture has finished healing. Assignment turns on whether active treatment is still under way, not on whether the provider has seen the patient before.

A child still in a boot or under orthopedic management takes D, G, K or P instead. The same child returning two years later with a leg-length discrepancy takes the discrepancy code first, then S89.121S.

An ankle injury that still codes to the lower leg block

S89.121S sits in the knee and lower leg block, even though the injury is clinically at the ankle. Reading the code from the top down is the quickest way to catch a wrong-bone or wrong-end error.

The Type 2 Excludes note under S80-S89 is what catches people out, because it sends injuries of the ankle and foot elsewhere. Distal tibial physeal fractures stay in S89 all the same.

The reason is simple enough. The physeal fracture codes in S99 reach only the calcaneus, the metatarsals and the toe phalanges. No code in the ankle and foot block covers a distal tibial physis.

The sibling codes coders reach for when the chart differs

These are the codes to check when the chart does not match S89.121S exactly. All of them carry the sequela 7th character, so they compare like for like.

The AAPC code lookup and the CDC tool both confirm the full sibling set if the chart describes something none of these covers.

The sequela character moves the case into the aftercare DRGs

On an inpatient claim, the 7th character moves the case into a different DRG family altogether. Under MS-DRG v43.0, S89.121S groups to the aftercare DRGs:

• 559, aftercare of the musculoskeletal system and connective tissue with MCC
• 560, aftercare of the musculoskeletal system and connective tissue with CC
• 561, aftercare of the musculoskeletal system and connective tissue without CC or MCC

The acute code lands somewhere else. S89.121A groups to DRG 562 or 563, fracture, sprain, strain and dislocation except femur, hip, pelvis and thigh. On a polytrauma admission it can also pull into the multiple significant trauma DRGs, 963 to 965.

S89.121S is also exempt from present on admission reporting, which follows from the same reasoning. The residual condition was there before the admission by definition.

For legacy record mapping, the general equivalence mapping sends S89.121S to ICD-9-CM 905.4, late effect of fracture of lower extremities. Final DRG assignment still depends on the whole claim, so confirm it against a current grouper.

Four coding errors that get S89.121S denied

These four show up again and again on pediatric orthopedic claims carrying this code. The first two account for most of the volume.

• Submitting S89.121S on its own. The code names the injury behind the problem, not the problem. Without a code for the residual condition sequenced ahead of it, the payer sees no reason for the visit and denies for medical necessity. Review your denial codes for the CO-50 and CO-16 patterns this produces.
• Using S while the fracture is still healing. An S on a claim that also carries active fracture management contradicts itself. The suffix should be D, G, K or P until the orthopedic team documents union.
• Confusing the tibia and fibula families. S89.1 is the lower end of the tibia. The upper end of the fibula is S89.2 and the lower end of the fibula is S89.3, so S89.121S and S89.221S describe different bones. Check the descriptor, not the digit pattern.
• Defaulting laterality. S89.129S exists for a reason, but it is a last resort. Query the provider before an unspecified code goes out, because payers increasingly reject them on limb injuries.

A standing check against your denial management reporting will surface all four, since each one leaves a recognizable footprint in the remittance data.

How the claim moves, and where it still fails

Each rule above attaches to a different moment in the claim’s life. Laid out end to end, they show where a sequela claim usually breaks, and which stage to check first.

Billing staff rarely read the chart, so the checks below have to work off the claim itself. Run them before the batch goes out.

• Read the diagnosis line above S89.121S and confirm it names the residual condition, not the fracture.
• Look for a clear healing statement in the note, rather than a date of injury on its own.
• Match laterality across the claim, so a right-side diagnosis sits with a right-side procedure line.
• Scan the same claim for active fracture management, and hold it if any appears.

How Pabau keeps S89.121S claims clean

Most of the rework on a code like this starts with re-keying. A coder picks S89.121S in one system, then someone types it into a claim form in another. Somewhere in between, the side or the 7th character drifts.

Practice management software like Pabau closes that hand-off. The CMS-1500 is built from the record itself, so the diagnosis codes on the claim come from the problem list a clinician already recorded.

Built-in ICD-10-CM and CPT lookup libraries are refreshed with each official release, which matters on a fiscal year boundary. Required fields also get checked before the send button unlocks, so a claim missing an authorization or membership number never leaves the practice.

For US practices, claims go out through the Claim.MD clearinghouse integration. That adds real-time eligibility checks, claim status tracking and electronic remittance posting.

Sequencing and the 7th character stay a coding judgment, because no software reads the clinical note for you. The software removes the retype that turns a correct code into a denied claim.

Send ICD-10-CM claims straight from the record

Pabau builds the claim from the chart and checks the required fields before it goes. Claim status and remittances come back into the same system, so your team stops re-keying codes.

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Conclusion

S89.121S is a narrow code doing a specific job. It marks a healed Salter-Harris type II fracture of the right distal tibia as the cause of what is being treated now. Read it as an explanation rather than a diagnosis, and the sequencing rule stops feeling arbitrary.

Two habits keep these claims clean. Confirm from the note that the fracture has healed, and never let the code travel alone. The side, the end of the bone and the Salter-Harris type all come off a descriptor you can check in seconds.

Pabau handles medical claims management from the chart through to the clearinghouse, with no retype in between. Book a demo to see how it fits the way your practice already bills.

Continue your research

Need to resolve denials on fracture and injury codes? Denial management in healthcare covers how to build a tracking and appeal workflow for your practice.

Want to know what makes a claim clean before it goes out? Clean claim requirements explains the elements payers check before they accept a claim for processing.

Curious how a clearinghouse handles your diagnosis codes? Medical claims clearinghouse explains how claims get scrubbed on the way to the payer.

Coding another lower-limb sequela? ICD-10 code S82.036S applies the same 7th character rules to a healed patella fracture.

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