ICD-10 Code S82.422B: Left Fibula Fracture Guide

Key takeaways

ICD-10 Code S82.422B identifies a displaced transverse fracture of the shaft of the left fibula, initial encounter for open fracture type I or II.

S82.422B is a billable ICD-10-CM code valid for HIPAA-covered transactions effective October 1, 2025 (FY2026).

The 7th character ‘B’ is critical: confusing it with ‘A’ (closed fracture) or ‘C’ (open type IIIA/IIIB/IIIC) is a top claim denial trigger.

Practice management software like Pabau helps orthopedic and sports medicine practices pair diagnosis and procedure codes accurately and keep documentation organized.

ICD-10 Code S82.422B identifies a displaced transverse fracture of the shaft of the left fibula. Specifically, it applies to the initial encounter for an open fracture, Gustilo-Anderson type I or II. CMS requires every fracture code in the S82 category to carry a 7th character. For S82.422B, that character confirms the encounter is initial, the fracture is open, and the wound is type I or II rather than type III.

This reference covers the full code breakdown, all valid 7th character extensions, and the Gustilo-Anderson classification mapped to ICD-10-CM 7th characters. In addition, it covers related sibling codes, documentation requirements, and associated CPT codes. Three coding errors are most likely to trigger a denial or audit flag on S82.422B claims.

ICD-10 Code S82.422B: Quick reference

S82.422B is a billable ICD-10-CM diagnosis code effective for dates of service on or after October 1, 2025. It is valid for submission on HIPAA-covered transactions and appears in the CDC/NCHS ICD-10-CM web tool for FY2026. The table below provides the key reference data coders need before submitting a claim.

What does S82.422B mean? Code breakdown

Every character in S82.422B carries a specific clinical meaning. As a result, understanding the code alphanumerically helps coders verify accuracy before submission and identify which part of the documentation to check when a claim is queried. Codes like S37.502S follow the same positional logic, with laterality and encounter type built into the same character positions across every injury chapter.

The 5th character is where the fracture pattern is encoded. A “2” in this position means transverse, where the fracture line runs perpendicular to the long axis of the fibula. This distinguishes it from oblique (3), spiral (4), comminuted (5), and segmental (6) fracture patterns, each of which maps to different subcategory codes. The 6th character “2” specifies left laterality. The parallel code for the right fibula is S82.421B.

7th character extensions for S82.422 codes

The 7th character is required for all S82.422x codes and cannot be omitted. It captures the encounter type and, for initial encounters, whether the fracture was open or closed and which Gustilo-Anderson type applies. This is where most coding errors occur. For a comparison of how another injury-chapter code documents its own encounter and severity details, see T31.42.

The “initial encounter” designation (7th characters A, B, C) applies to every visit during the active treatment phase, not just the first physical visit. In other words, a patient seen three times for wound management and cast adjustments after an initial open fibula fracture should carry 7th character B at each visit. This holds as long as active treatment continues. By contrast, the switch to a “subsequent encounter” (D through R) occurs when the patient is receiving routine care during the healing phase, not active treatment.

Understanding open fracture types I and II (Gustilo-Anderson)

The Gustilo-Anderson classification system is the clinical framework that determines whether a coder uses 7th character B or C for an open fracture. Therefore, coders cannot assign the Gustilo type independently. It must be explicitly documented by the treating physician in the operative or emergency department note. Per the CMS ICD-10 coding guidance, coders are bound by the clinical documentation. They may not infer Gustilo type from imaging or mechanism of injury alone.

For S82.422B, the clinical context is Gustilo Type I or II. Both types share the same 7th character (B) because ICD-10-CM groups them together at the initial encounter level. For example, a physician who documents “open fracture, Gustilo type II” supports the code’s 7th character B designation. However, if the physician documents “Gustilo type IIIA” instead, the code requires 7th character C, making it S82.422C rather than S82.422B.

Related ICD-10 codes: S82.422 siblings and nearby fibula fracture codes

S82.422B sits within a family of closely related codes. Understanding the full sibling set helps coders verify laterality, displacement status, and fracture pattern before finalizing a claim. The AAPC ICD-10-CM code lookup provides a searchable sibling view for the S82.42 subcategory. For those managing coding conventions across multiple specialties, such as M35.9, the S82 category offers a useful example. It shows how laterality and displacement are encoded at the 5th and 6th character positions.

ICD-10 code hierarchy: where S82.422B fits

Knowing the hierarchy helps coders navigate the tabular list when verifying code selection and supports appeals documentation when a claim is questioned. The WHO ICD-10 browser provides the international classification framework. The Ottawa ankle rules calculator complements this hierarchy by guiding clinical decision-making at the point of assessment.

• ICD-10-CM Chapter S00-T88: Injury, poisoning and certain other consequences of external causes
• Block S80-S89: Injuries to the knee and lower leg
• Category S82: Fracture of lower leg, including ankle
• Subcategory S82.4: Fracture of shaft of fibula
• Subcategory S82.42: Transverse fracture of shaft of fibula
• Code S82.422: Displaced transverse fracture of shaft of left fibula (requires 7th character)
• Full code S82.422B: Initial encounter, open fracture type I or II

The parent code S82.422 is not billable on its own. A 7th character is required to submit a valid claim. As a result, submitting S82.422 without the 7th character will result in a rejection from most payers and from Medicare/Medicaid processing systems.

Clinical documentation requirements for S82.422B

Six documentation elements must appear in the clinical record to support ICD-10 Code S82.422B. Missing even one can shift the code to an unspecified variant (S82.402B or S82.423B) or trigger a medical necessity query. Practices using a patient records system that enforces structured clinical note fields can reduce the risk of these omissions at the point of care. Similarly, the same documentation discipline carries into recovery, where a follow-up range of motion assessment confirms healing progress against the original injury record.

Per ICD-10-CM Official Guidelines, fractures not indicated as open or displaced default to closed and displaced, respectively. However, relying on defaults increases audit risk considerably. Therefore, practices should build documentation templates that prompt physicians to record all six elements explicitly.

Associated CPT codes for left fibula shaft fractures

ICD-10 Code S82.422B pairs with CPT procedure codes based on the treatment method chosen by the surgeon. Specifically, the correct CPT code depends on whether the fracture was treated with closed or open methods and whether internal or external fixation was applied. Pabau’s claims management software supports structured pairing of diagnosis and procedure codes, helping orthopedic and sports medicine practices keep fracture documentation accurate and audit-ready. The codes below reflect commonly used CPT codes for fibula shaft fractures. Verify applicability against the AMA CPT 2026 manual and individual payer policies, since CPT applicability varies by treatment method and clinical context.

CPT 27784 is the most likely match for an open fibula shaft fracture requiring surgical treatment. For instance, for open fractures with significant soft tissue injury at the initial encounter, external fixation codes (20690 series) may be reported alongside the fracture treatment code. However, this is subject to payer bundling rules and NCCI edits. Always verify pairing against the sports medicine payer contract and current CMS National Correct Coding Initiative policies.

Coding tips: avoiding common errors with S82.422B

Three error patterns account for most claim denials and audit flags on S82.422B claims. In particular, each has a specific root cause and a straightforward prevention step. Practices using physical therapy EMR or orthopedic practice management systems should review these against their current documentation templates and coding workflows. Accurate encounter-type coding matters across the full care episode, including companion diagnoses such as M16.4, where the same documentation discipline applies.

• Wrong laterality. Using S82.421B (right fibula) when the documented injury is the left. This is the most mechanical error and the easiest to catch with a pre-submission laterality check against the operative or ED note.
• Incorrect 7th character for open fractures. The default in many EHR systems is character A for a closed fracture. When a physician documents an open wound at the fracture site without naming a Gustilo type, coders sometimes default to closed-fracture code A instead. An open fracture requires querying the physician for the Gustilo type before finalizing the code.
• Premature switch to subsequent encounter. Some coders transition to 7th character D or E at the first follow-up visit. Per ICD-10-CM guidelines, “initial encounter” covers the entire active treatment phase. A patient still receiving wound care and fracture monitoring at week three of treatment still carries a B encounter type, not E.
• Inferring Gustilo type from mechanism. A high-energy fracture mechanism (motorcycle accident, fall from height) does not automatically mean Gustilo type IIIA or above. Type classification requires physician documentation of wound size, contamination level, and soft tissue coverage status. Coders who upgrade to 7th character C without documentation are introducing an unsupported code.
• Omitting associated injury codes. An open fibula shaft fracture often presents with concomitant tibial fractures (S82.2xx) or soft tissue injuries. Per ICD-10-CM guidelines, code all conditions documented as present. Submitting only the fibula code when a tibial fracture is also documented leaves associated diagnoses uncaptured.

How Pabau supports accurate fracture coding and documentation

Many orthopedic and sports medicine practices still track the six S82.422B documentation elements across separate note fields. They then cross-check those fields against the CPT code by hand before a claim goes out. Consequently, that manual review is where a missing Gustilo type or an outdated encounter character slips through.

Instead, practice management software like Pabau replaces that manual check with structured clinical note templates. Those templates prompt for laterality, fracture pattern, displacement, and encounter type at the point of care. Pabau also pairs the resulting diagnosis code with the CPT codes the practice bills alongside it, so as a result the two records stay consistent.

The outcome is fewer queries back to the physician after the fact. Consequently, the documentation trail already answers the questions a payer or auditor asks about an open fibula fracture.

Keep fracture documentation audit-ready

Pabau's structured note templates prompt orthopedic and sports medicine practices for laterality, encounter type, and Gustilo classification. They then pair the result with the matching CPT code. See how it works in a live demo.

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Conclusion

The 7th character distinction between B and C is the single highest-risk decision point for S82.422B. Type I or II supports the character B, while type IIIA, IIIB, or IIIC calls for C instead. Therefore, query the physician for an explicit Gustilo type before assigning either one, rather than inferring it from the wound description. As a result, most preventable denials on this code disappear once that step is routine.

In short, documentation templates that prompt for all six required elements protect a practice more than post-denial appeals ever will. Pabau helps orthopedic and sports medicine practices keep that documentation organized alongside the procedure codes it pairs with. Book a demo to see how Pabau supports accurate fracture documentation.

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