ICD code S99.201B – Physeal fracture of right toe phalanx

Key takeaways

S99.201B describes an open, initial-encounter fracture through the growth plate of a right toe phalanx where the Salter-Harris type is not documented.

The 7th character B means the patient is receiving active treatment for an open fracture at this visit. Character A covers the same scenario for a closed fracture.

If the physician documents a Salter-Harris type (I through IV), use the matching code from S99.211B to S99.241B instead of S99.201B.

Pabau’s claim validation checks each claim for missing or invalid details before it leaves Pabau, which helps cut avoidable S99.201B denials.

ICD-10 code S99.201B: Definition and clinical description

ICD-10 code S99.201B is a seven-character ICD-10-CM diagnosis code for an unspecified physeal (growth plate) fracture of a right toe phalanx.

Its 7th character B marks the initial encounter for an open fracture. It sits in chapter S00-T88 (Injury, poisoning and certain other consequences of external causes) and block S90-S99 (Injuries to the ankle and foot). Within category S99, it falls under subcategory S99.2 (Physeal fracture of phalanx of toe).

The code is valid and billable under ICD-10-CM. Per CMS ICD-10 coding guidance, coders must use the most specific code available. S99.201B therefore applies only when the documentation states no Salter-Harris fracture type. When the type is specified, a more precise code in the S99.21x through S99.24x subcategories is required.

Code details at a glance

Understanding the 7th character: Initial encounter for open fracture

The 7th character in S99.201B tells the payer which phase of treatment the visit belongs to, and payers adjudicate the claim on it. Per ICD-10-CM Official Guidelines Section I.C.19.c, the encounter type reflects the phase of treatment at the visit being billed. It doesn’t depend on when the injury occurred.

A patient presenting to the ED with a freshly identified open toe fracture gets 7th character B on that claim. The same patient returning three weeks later for a wound check gets 7th character D (or G, K or P if healing is complicated). Applying B to a follow-up visit is a frequent denial trigger on S99.201B claims. It usually reflects a documentation mismatch rather than a fraud flag.

What is a physeal fracture of the right toe?

A physeal fracture is a break through the growth plate (physis) of a bone. Growth plates are present only in skeletally immature patients, which is why this code appears almost exclusively on pediatric and adolescent claims. The physis is the weakest structural zone in a developing bone. It gives way before the surrounding ligaments and tendons, which would bear the load in an adult.

The WHO ICD-10 classification framework groups physeal injuries under broader injury codes. The US-specific ICD-10-CM system adds the S99.2 subcategory to capture Salter-Harris detail. When the radiologist or treating physician doesn’t describe the fracture in Salter-Harris terms, the coder uses the “unspecified” codes. That is where S99.201B sits.

Salter-Harris classification and how it affects code selection

The Salter-Harris classification system grades physeal fractures by how much of the growth plate and surrounding bone is involved. Each type maps to a specific ICD-10-CM subcategory within S99.2. Coders can’t assign the Salter-Harris type themselves. It comes from physician documentation and radiologic interpretation.

If the documentation reads “Salter-Harris Type II fracture, right great toe,” the correct code is S99.221B, not S99.201B. Using S99.201B when the type is documented is a specificity violation that may trigger a medical record audit. Query the physician before defaulting to “unspecified.” Per guidance from the American Academy of Professional Coders (AAPC), coders should always use the highest level of specificity supported by the documentation.

Codes to include, exclude, and differentiate

Several neighboring codes in the S99.20x family are easy to confuse. The table below sets out how each one differs from S99.201B.

The 7th character B already marks the fracture as open. Category S91 (open wound of ankle, foot and toes) excludes open toe fractures, so the same site normally needs no separate open-wound code. If the record shows an associated wound infection or another injury, follow the tabular instructions for category S99 when coding it.

Documentation requirements for accurate S99.201B coding

The medical record must support every element of ICD-10 code S99.201B before submission. Missing a single element shifts the code to a sibling code or triggers a payer denial. Integrate these requirements into your medical billing compliance checklist.

• Right-side laterality: The clinical notes, operative report, or radiology report must confirm the right foot. “Toe fracture” without laterality forces S99.209B.
• Open wound confirmation: The physician must document skin disruption, exposed bone, or wound communication. An open fracture cannot be inferred from the mechanism of injury alone.
• Initial encounter (active treatment): The visit must be the active-treatment episode. This includes the ED visit, urgent care, or surgical day, not a post-operative wound check.
• Fracture site: Phalanx: Documentation must identify the phalanx specifically, not just “toe fracture.” The metatarsal is coded separately under S92.
• Salter-Harris type: Not specified: The record should either omit the classification or include language like “growth plate fracture, type not specified.” If a type is mentioned, move to the appropriate S99.21x through S99.24x code.
• Growth plate involvement confirmed: The radiologist or treating physician must confirm physeal involvement. Coders cannot determine this independently.

Confirm all six elements are in the chart before coding to support clean claim submission. A physician query takes less time than a denial and resubmission cycle.

Paired CPT codes and procedure billing

S99.201B pairs with CPT procedure codes based on the treatment provided. Payer bundling rules and National Correct Coding Initiative (NCCI) edits may affect which CPT codes can be billed together. Verify current NCCI tables before submitting.

Pabau, the practice management and billing platform we build, connects to the Claim.MD clearinghouse. Practices that connect Claim.MD to Pabau can turn invoices into electronic claims and run real-time eligibility checks. They can also track claim status and bring electronic remittance advice (ERA) files back into Pabau.

Consult AMA CPT code set guidance for the current edition definitions before selecting a procedure code. CPT 28496 (percutaneous fixation, great toe) and 28515 (closed manipulation, lesser toe) can pair with S99.201B when the fracture needs reduction. Open treatment is reported with 28505 (great toe) or 28525 (other toes).

Payer and prior authorization requirements

Medicare and commercial payer requirements for S99.201B vary by jurisdiction and plan. Complete insurance eligibility verification before treatment whenever possible, since open fracture repairs often cross prior authorization thresholds.

• Medicare: Surgical treatment of an open physeal fracture typically requires a Medicare Administrative Contractor (MAC) LCD review. LCDs are jurisdiction-specific, so confirm which MAC covers the provider’s state before billing.
• Commercial insurers: Most require prior authorization for operative treatment. An open fracture seen in the ED under emergent circumstances is usually exempt, but planned surgical correction generally needs authorization. That includes delayed open reduction and internal fixation (ORIF).
• Medicaid: Programs are state-administered, so coverage criteria and prior authorization rules vary. Some states carve out pediatric orthopedic procedures into managed care plans with separate PA processes.
• Operative report: For any surgical pairing (CPT 28496, or open treatment codes 28505 and 28525), payers expect an operative report. It should document open wound involvement, surgical approach, fixation method, and intraoperative findings consistent with an open physeal fracture.

Common claim denial reasons and how to avoid them

S99.201B denials follow a predictable pattern. The table below covers the most common denial patterns and how to resolve each one. Pair these checks with a structured denial management workflow to catch errors before they reach the clearinghouse.

Review denial codes in medical billing to match the claim adjustment reason code (CARC) on the remittance to a denial reason above. CARC 29 (time limit for filing has expired) and CARC 16 (missing or invalid claim information) can both appear on S99.201B rejections. Pabau’s claims management software shows why a claim was rejected and flags it as Needs action, so billers can find and fix the cause.

When to use S99.201B vs. related codes

Work through these six questions in order before assigning any code in the S99.2 family. The flow below shows where each “no” sends you.

1. Is the fracture site the phalanx of a toe? If it involves the metatarsal, use S92.3x instead (S99.1x if the metatarsal physis is involved).
2. Is the physis (growth plate) confirmed as involved? The radiologist or physician must document growth plate involvement. Without that confirmation, code a toe phalanx fracture to S92.4x (great toe) or S92.5x (lesser toe), and request clarification.
3. Is the toe on the right foot? Right = S99.201x. Left = S99.202x. Unspecified = S99.209x.
4. Is this the initial active-treatment encounter? Yes = characters A or B. No = characters D, G, K or P. Late effects = S.
5. Is there an open wound? Yes = character B (S99.201B). No = character A (S99.201A).
6. Is the Salter-Harris type documented? If yes: Type I = S99.211B; Type II = S99.221B; Type III = S99.231B; Type IV = S99.241B. Only reach S99.201B when the type is genuinely not specified.

Use the CDC/NCHS ICD-10-CM web tool to verify current code validity and tabular hierarchy for S99.201B and its siblings before your next submission cycle.

How Pabau helps prevent S99.201B claim denials

An S99.201B denial usually starts with a chart detail, such as a missing side or an undocumented wound. It surfaces weeks later as a remittance code that a biller has to trace back to the visit, fix and resubmit by hand.

Pabau’s claim validation checks each claim for missing or invalid details before submission. When a payer rejects a claim, Pabau shows why and flags it as Needs action, so it doesn’t sit unnoticed in a queue.

For US practices, Pabau also settles payments from ERA files, so billers spend less time posting remittances by hand. The result is fewer avoidable resubmissions on fracture codes like this one.

Reduce coding errors before they become denials

Pabau’s claim validation checks claims before submission, flags rejections for rework and, for US practices, settles payments from ERA files.

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Conclusion

S99.201B only fits when the chart confirms five facts. The fracture is in a right toe phalanx and runs through the growth plate. The wound is open, the visit is active treatment, and no Salter-Harris type is recorded.

When one of those facts is missing or unclear, query the physician before you code. A two-line addendum costs far less than a denial, an appeal and a resubmission.

Pabau’s medical billing workflows connect invoices to electronic claims, so claim details are checked before submission. Book a demo to see how Pabau checks fracture-code claims before they reach the payer.

Continue your research

Need a structured denial recovery workflow? Denial management in healthcare covers root-cause analysis, appeal strategies, and prevention frameworks for common ICD-10 rejection patterns.

Submitting claims electronically? Claim.MD clearinghouse overview explains how electronic claim routing, real-time eligibility checks, and 835 remittances connect to ICD-10 coding accuracy.

Want to understand ERA processing? Electronic remittance advice (ERA) explains how CARC and RARC denial codes map to your posted payments and resubmission queue.

Capturing codes at the visit? Encounter form template records the ICD-10 and CPT codes for each visit, so the encounter type is clear before billing.

Filing a paper claim? Medical insurance claim form sets out the fields payers expect on a submitted claim.

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