ICD code S99.122A – Salter-Harris Type II physeal fracture of left metatarsal

Key takeaways

S99.122A is the billable FY2026 code for a Salter-Harris Type II physeal fracture of the left metatarsal, initial encounter for closed fracture.

Seven 7th characters are valid for S99.122: A, B, D, G, K, P and S.

Character B reports the same fracture when the wound is open, so every note must state whether the fracture is closed or open.

D, G, K and P separate the subsequent encounters by healing status: routine, delayed, nonunion and malunion.

ICD-10-CM gives Salter-Harris Types I through IV their own metatarsal subcategories, so a Type V crush injury routes to S99.19 instead.

Definition and code details

S99.122A is a specific, billable ICD-10-CM code for a Salter-Harris Type II physeal fracture of the left metatarsal. The 7th character A reports the initial encounter for a closed fracture.

When the same fracture breaks the skin, the initial encounter is S99.122B instead. Both took effect on October 1, 2025, under the FY2026 edition of ICD-10-CM. ICD-10-CM is the US Clinical Modification and differs from the international WHO ICD-10 classification.

The code sits within the S99 block, which covers other and unspecified injuries of the ankle and foot. S99.122A pins down four facts at once: the fracture type, the laterality, the wound status, and the encounter phase. That is the maximum diagnostic specificity ICD-10-CM offers for this injury pattern.

How the Salter-Harris classification works

The Salter-Harris classification describes physeal fractures, meaning injuries that involve the growth plate or physis, in skeletally immature patients. Robert Salter and W. Robert Harris built the system around where the fracture line passes relative to the physis, epiphysis, and metaphysis.

For metatarsal physeal fractures, ICD-10-CM gives Types I through IV their own subcategories under S99.1. Type V and any pattern the classification does not cover route to S99.19, other physeal fracture of metatarsal.

What is a Salter-Harris Type II physeal fracture?

A Salter-Harris Type II fracture is the most commonly encountered growth plate fracture in clinical practice, accounting for roughly 75% of all physeal injuries.

The fracture line runs along the physis, the cartilaginous growth plate, then exits through the metaphysis. That leaves a triangular metaphyseal fragment, sometimes called a Thurston-Holland fragment. The blood supply to the epiphysis is typically preserved, which explains the relatively low risk of permanent growth disturbance.

In the left metatarsal, the injury usually follows a twisting or axial load mechanism. It affects children and adolescents whose growth plates have not yet fused. Plain radiographs confirm the fracture pattern and establish laterality.

The physician note must state Salter-Harris Type II and left metatarsal to support ICD-10 Code S99.122A. It must also record whether the fracture is closed or open, since that choice decides between the A and B characters. A note reading metatarsal fracture, left foot, with no Salter-Harris classification, will not support this code.

Decoding the 7th character: All seven options for S99.122

S99.122 takes seven valid 7th characters, and choosing the wrong one causes most billing errors on this code. The CMS ICD-10-CM Official Guidelines set the fracture rules under Section I.C.19.

Two characters cover the initial encounter, A for a closed fracture and B for an open one. Four more cover subsequent encounters, and each names how the fracture is healing. The last, S, is reserved for a sequela. The chart below maps all seven against the phase of care.

Choosing between the seven characters

A common misconception is that initial encounter means only the first visit. Under CMS guidelines, character A applies throughout the active treatment phase. A patient who has surgery on day 14 and returns for a wound check on day 21 still carries S99.122A. Active orthopedic management, not the visit count, keeps A in place.

Wound status is what separates A from B, not the severity of the fracture. Use B when the fracture site communicates with an open wound at the initial encounter. A closed Salter-Harris II fracture keeps A even when it needs internal fixation.

Once active treatment ends, the healing status picks the character. D covers routine healing. G covers healing that lags but is still progressing. K applies after imaging confirms the fragments have not united. P applies when the bone healed in the wrong position.

One detail catches coders out on open fractures. B has no subsequent-encounter counterpart, so a follow-up visit for an open Salter-Harris II fracture takes D, G, K, or P like any other. The open-wound distinction only exists at the initial encounter.

Reserve S for an encounter aimed at a late effect of the fracture. Premature growth plate closure and the limb-length discrepancy that follows it are the usual examples. Sequence the residual condition first, then S99.122S.

Code hierarchy and parent codes

Understanding the full hierarchy helps coders confirm they are using the most specific code available. It also makes it easier to trace the code block against payer edits.

S99.122 itself is not billable. Coders must add one of the seven 7th characters, A, B, D, G, K, P or S, to reach a reportable code. Submitting S99.122 with no 7th character produces a claim rejection for an invalid code.

Related ICD-10-CM codes for metatarsal fracture coding

Several sibling and adjacent codes are commonly referenced alongside S99.122A. Selecting the wrong laterality or Salter-Harris type is a frequent audit trigger.

Use the AAPC ICD-10-CM code lookup or the CDC/NCHS tabular list to verify current status before submitting. Our diagnostic codes library carries the same field-by-field breakdown for each of the codes below.

Approximate synonyms and index references

Coders searching the ICD-10-CM alphabetical index will meet several clinical terms that route to S99.122A. Recognizing these terms in physician documentation is essential for accurate code assignment. None of them settle the wound status, so check the note for closed or open before you pick the 7th character.

• Salter-Harris Type II fracture, left metatarsal
• Growth plate fracture, Type II, left foot metatarsal
• Physeal fracture, left metatarsal, Salter-Harris classification Type II
• Epiphyseal plate fracture, left metatarsal, Type II
• Closed left metatarsal growth plate fracture, initial treatment
• Pediatric left metatarsal fracture, Salter-Harris Type II
• Left foot Thurston-Holland fracture (metaphyseal fragment with physis involvement)

In the ICD-10-CM alphabetical index, start at Fracture, traumatic, then move to metatarsal and physeal. From there, find Salter-Harris Type II and trace to S99.12. Add the laterality character, then the 7th character.

The WHO ICD-10 browser provides the international base classification, while the US-specific modifications live in the CDC/NCHS ICD-10-CM tool.

Clinical documentation requirements for S99.122A

Clean claim submission for ICD-10 Code S99.122A depends on the physician note carrying every specificity element below. If one is missing, the coder cannot supply it and the claim stalls. Practices that build a clean claim checklist into the workflow see fewer denials on pediatric fracture codes.

• Salter-Harris type: The note must state “Salter-Harris Type II” explicitly. “Growth plate fracture” or “physeal fracture” alone is insufficient for this level of specificity.
• Laterality: The note must state “left” metatarsal or “left foot.” If laterality is absent, query the provider rather than dropping to S99.129A, which loses clinical specificity.
• Wound status: The note must say whether the fracture is closed or open. Closed supports S99.122A and open supports S99.122B. Wording such as no overlying skin breach settles it in one phrase.
• Anatomical site: Metatarsal must be specified as distinct from phalanges, calcaneus, talus, or other foot bones. The specific metatarsal number aids clinical completeness, though S99.122A does not sub-specify by number.
• Encounter phase: The note should show whether the visit is active treatment, which supports A or B, or a subsequent encounter. A follow-up note must also state the healing status, so the coder can choose the right character.
• Imaging confirmation: Radiographic confirmation of the fracture type is standard of care. The note should reference the imaging modality and findings, including a metaphyseal fragment (Thurston-Holland sign) where applicable.

CDI professionals should flag notes where the physician writes metatarsal fracture with no Salter-Harris classification. That is a query opportunity, not a coding assumption. The classification also shapes the rehabilitation plan, so the phrase serves the care team as well as the claim.

CPT codes commonly paired with S99.122A

The diagnosis code is only half of the claim. The procedure codes below are the ones most often reported alongside S99.122A in a pediatric foot fracture encounter. Confirm each against the current CPT code set and your payer policy before billing.

• 28470: Closed treatment of metatarsal fracture, without manipulation, each
• 28475: Closed treatment of metatarsal fracture, with manipulation, each
• 28485: Open treatment of metatarsal fracture, includes internal fixation when performed, each
• 29405: Application of a short leg cast, below knee to toes
• 73620 and 73630: Radiologic examination of the foot, two views and complete minimum three views
• Office or ED evaluation and management code: Reported when the visit is not covered by a fracture care code

Watch the wording on 28485. Open treatment describes the surgical approach, not an open fracture. A closed Salter-Harris II fracture that gets internal fixation still carries the A character, not B.

Common coding errors and how to avoid them

Denial patterns for S99.122A cluster around a handful of recurring mistakes. Practices that address them inside the coding workflow see fewer post-submission queries. On pediatric fracture codes, most of the fix is documentation discipline rather than coding knowledge.

• Switching to D too early: Assigning S99.122D to visits that are still inside the active treatment window. Coders often switch right after cast application. The test is the clinical phase, not the visit number.
• Coding an open fracture as closed: Defaulting to S99.122A when the note describes an open wound at the fracture site. The initial encounter for an open fracture is S99.122B.
• Ignoring G, K and P: Reporting D for every follow-up, even when the note documents delayed healing, nonunion or malunion. Each of those three findings has its own 7th character.
• Laterality defaults: Using S99.129A when the physician note clearly states “left foot.” Payers increasingly flag unspecified codes when specificity sits in the record. Query the provider instead.
• Salter-Harris type confusion: Assigning S99.112A or S99.132A based on general knowledge of common fracture patterns rather than the documented type. Never infer the Salter-Harris type from the code alone.
• Using non-physeal metatarsal codes: Applying S92.302A for a pediatric patient whose note specifies a physeal injury. When Salter-Harris classification is documented, the S99.12x codes must be used.
• Missing the 7th character entirely: S99.122 with no 7th character is an invalid code. It gets rejected at claim adjudication.

How Pabau supports accurate ICD-10-CM coding for pediatric fractures

A code reference stops at the code. The claim still has to carry that code from the note to the payer, with the laterality, the wound status and the 7th character intact. That handoff is where pediatric fracture claims usually come apart.

Practices handling pediatric orthopedic cases want the note, the diagnosis code, and the claim in one workflow. Practice management software like Pabau is built that way. Pabau’s claims management software links the ICD-10-CM code captured at documentation straight to claim submission. That removes the manual re-entry behind most laterality mismatches and 7th character mistakes.

For practices submitting claims electronically, Pabau integrates with Claim.MD, our US clearinghouse partner. Claim.MD connects to thousands of US payers and validates ICD-10-CM codes against built-in catalogs before transmission.

It returns electronic remittance advice, so coders can see denial reasons tied to a specific code. An S99.122 submitted with no 7th character is caught before it reaches the payer, which is one less rejection to rework.

Pabau’s structured clinical records also support the specificity S99.122A demands. A clinician records the Salter-Harris type, the laterality, the wound status and the encounter context in a structured SOAP note. That detail stays searchable and auditable without a manual chart pull.

Reduce coding errors on pediatric fracture claims

Pabau connects ICD-10-CM diagnosis codes to clean claim submission through Claim.MD. Codes are validated before they reach thousands of US payers. See how it works for your practice.

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Conclusion

Four documented facts are the whole job on this code: type, side, wound status, and phase of care. Get them into the note and S99.122A is unambiguous. Leave one out and the coder is guessing, which is how a pediatric fracture claim gets downcoded.

The trade-off worth remembering is a small one. Specificity costs the clinician a phrase at the point of care and saves the practice a rework cycle later. A note template that prompts for Salter-Harris type and laterality is cheaper than a quarterly denial review.

Pabau’s claims management software and Claim.MD integration keep that documentation-to-claim connection intact, validating codes before transmission. Book a demo to see how Pabau handles ICD-10-CM workflows for orthopedic and pediatric practices.

Continue your research

Need to understand claim denial patterns for fracture codes? Denial management in healthcare covers the most common reasons fracture claims are rejected and how to address them systematically.

Looking for a guide to electronic claim submission? 837 file submission explains the EDI transaction format used to submit ICD-10-CM coded claims to payers and clearinghouses.

Want to understand how clearinghouses validate ICD-10 codes before transmission? Medical claims clearinghouse explains how code validation works in the submission pipeline.

New to the revenue cycle behind a coded claim? What is medical billing walks through each step from the encounter note to the payer remittance.

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