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

Key takeaways

ICD-10 Code S82.422B describes 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 describes 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. In fact, 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 guide covers the full code breakdown, all valid 7th character options, and the Gustilo-Anderson classification mapped to ICD-10-CM 7th characters. In addition, it covers related sibling codes, documentation rules, and associated CPT codes. Of note, 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 also valid for filing on HIPAA-covered claims and appears in the CDC/NCHS ICD-10-CM web tool for FY2026. As a result, the table below provides the key reference data coders need before sending a claim.

What does S82.422B mean? Code breakdown

Every character in S82.422B carries a specific clinical meaning. For that reason, knowing what each letter and number in the code means helps coders check accuracy before filing and spot which part of the record to check when a claim is queried. For example.

The 5th character is where the fracture pattern is encoded. Specifically, a “2” in this position means transverse, where the fracture line runs straight across 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. Meanwhile, the 6th character “2” specifies left laterality. By contrast, 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 left out. Specifically, it captures the encounter type and, for initial encounters, whether the fracture was open or closed and which Gustilo-Anderson type applies. As a result, this is where most coding errors occur. For a comparison of how another injury-chapter code records its own encounter and severity details.

The “initial encounter” label (7th characters A, B, C) applies to every visit during the active treatment phase, not just the first physical visit. For example, 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 system is the clinical guide that determines whether a coder uses 7th character B or C for an open fracture. However, coders cannot assign the Gustilo type on their own. Instead, it must be clearly recorded by the treating physician in the operative or emergency department note. Per the CMS ICD-10 coding guidance, coders are bound by the clinical records. Therefore, they may not assume a Gustilo type from imaging or from how the injury happened.

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 records “open fracture, Gustilo type II” supports using 7th character B. However, if the physician records “Gustilo type IIIA” instead, the code requires 7th character C, making it S82.422C rather than S82.422B. In that case, the wrong character will trigger a denial.

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

S82.422B sits within a family of closely related codes. As a result, knowing the full sibling set helps coders check laterality, displacement, and fracture pattern before filing a claim. For example, the AAPC ICD-10-CM code lookup provides a searchable sibling view for the S82.42 subcategory. For those managing coding across multiple specialties.

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

Knowing the code structure helps coders navigate the tabular list when checking code selection and supports appeals records when a claim is questioned. In addition, the WHO ICD-10 browser provides the international coding framework. The Ottawa ankle rules calculator also supports this by guiding clinical decisions 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. Instead, 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. So, 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. The same documentation approach carries into recovery.

Per ICD-10-CM Official Guidelines, fractures not listed as open or displaced default to closed and displaced. However, relying on defaults raises audit risk. For that reason, practices should build note templates that remind physicians to record all six elements clearly.

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 used. In addition. The codes below reflect commonly used CPT codes for fibula shaft fractures. However, always check the AMA CPT 2026 manual and individual payer policies, since the right CPT code varies by treatment method and clinical context.

CPT 27784 is the most likely match for an open fibula shaft fracture requiring surgical treatment. In addition, for open fractures with serious 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. Therefore, always check 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 cause most claim denials and audit flags on S82.422B claims. In each case, there is a clear root cause and a simple fix. For that reason. Moreover, accurate encounter-type coding matters across the full care episode.

• 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 asking the physician for the Gustilo type before finalising 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 move 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 additional diagnoses uncoded.

Related ICD-10 codes

• ICD-10 code S83.241 — Other Tear of Medial Meniscus, Right Knee
• ICD-10 code S82.61XN — Lateral malleolus fracture, right fibula
• ICD-10 code S82.871G — Displaced pilon fracture, delayed healing
• ICD-10 Code S83.422A — Lateral collateral ligament sprain, left knee

How Pabau supports accurate fracture coding and documentation

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

Practice management software like Pabau replaces that manual check with set clinical note templates. Specifically, those templates prompt for laterality, fracture pattern, displacement, and encounter type at the point of care. In addition, Pabau pairs the resulting diagnosis code with the CPT codes the practice bills alongside it, so the two records stay in line.

The result is fewer queries back to the physician after the fact. In other words, the records already answer 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.

Book a demo

Conclusion

The 7th character choice between B and C is the single highest-risk decision point for S82.422B. Specifically, type I or II supports character B, while type IIIA, IIIB, or IIIC calls for C instead. Therefore, ask the physician for a clear Gustilo type before assigning either one, rather than assuming it from the wound description. In practice, most preventable denials on this code disappear once that step is routine.

Note templates that prompt for all six required elements protect a practice more than post-denial appeals ever will. As a result, Pabau helps orthopedic and sports medicine practices keep those records in order along with the procedure codes they pair with. Book a demo to see how Pabau supports accurate fracture records.

Continue your research

Need a validated screen for non-organic low back pain? Waddell sign test walks through the five categories, scoring, and clinical use.

Tracking recovery after a lower-limb injury? Knee outcome survey (KOS-ADLS) template gives coders and clinicians a standardized scoring guide for outcome documentation.

Assessing shoulder instability alongside a fracture workup? Clunk test covers the procedure, interpretation, and a documentation template.

Frequently asked questions