ICD code S82.90XB – Unspecified lower leg open fracture

Key takeaways

S82.90XB is billable for FY 2026. It covers an open Gustilo type I or II lower leg fracture when the record names neither the bone nor the side.

7th character B applies only to Gustilo type I and II open fractures. Types IIIA, IIIB, and IIIC all map to 7th character C, so a documented type III injury is coded S82.90XC.

When no Gustilo type is documented, ICD-10-CM guidelines assign the type I or II character, which is B at the initial encounter.

Before using S82.90XB, query the physician if the bone or side might be identifiable. A named tibia, fibula, or side requires a more specific code.

Pabau’s claims management software supports ICD-10 code entry, Claim.MD clearinghouse submission, and electronic remittance advice (ERA) reconciliation. Open fracture claims reach payers with the right diagnosis linked to the right CPT.

ICD-10 code S82.90XB at a glance

ICD-10 code S82.90XB is the billable code for an open Gustilo type I or II lower leg fracture at the initial encounter. It applies when the record names neither the bone nor the side. It sits at the end of a five-level path. Check each level for a more specific sibling code before you assign it.

What S82.90XB covers: Clinical definition and scope

S82.90XB records three clinical facts at once. The fracture is in the lower leg, below the knee, but the record doesn’t say which bone or which side. The wound is open, and the patient is in the initial period of active treatment for a Gustilo type I or II injury.

The two “unspecified” terms in the descriptor do different jobs. “Unspecified fracture” means the record doesn’t name the bone, so no tibia or fibula code can be chosen. “Unspecified lower leg” means it doesn’t name the side, because S82.91- covers the right leg and S82.92- the left.

The typical case is a heavily comminuted injury documented only as “lower leg fracture” in an early ED note. Orthopedic and physical therapy practices meet the code most often on trauma referrals, where the imaging report predates the surgeon’s notes.

• Open fracture: the skin is broken at the fracture site, which is the same as a “compound fracture.” Closed fractures take 7th character A (S82.90XA), not B. A fracture not documented as open or closed is coded as closed.
• Initial encounter: under ICD-10-CM Official Guidelines Section I.C.19.a, this covers the whole period of active treatment, which can span several visits. A patient transferred to a second facility for open reduction and internal fixation (ORIF) still gets 7th character B while surgical treatment continues.
• Gustilo type I or II: low-energy wounds with limited contamination. Type I is a clean wound under 1 cm. Type II is a laceration over 1 cm with moderate soft-tissue damage and no extensive stripping.

Understanding the 7th character B: Open fracture, initial encounter

The 7th character of an S82.90X code records two facts in one position: whether the fracture is open, and which encounter this is. Coders often get it wrong in one direction. They assign B when the note describes a type III injury, which belongs to character C.

Full 7th character table for S82.90X

The ICD-10-CM Official Guidelines base the open fracture characters on the Gustilo classification, so the grade comes from the physician’s note. When an open fracture has no Gustilo type documented, Section I.C.19.c.1 assigns the type I or II character, which is B here.

Query the physician only when the note describes type III damage, such as extensive soft-tissue loss or vascular injury, without naming the grade.

S82.90XB vs adjacent codes: Choosing the right code

The neighbors most often confused with S82.90XB split along four axes: fracture openness, encounter type, bone, and side. The table below gives the decision logic for each.

Laterality and specificity: When the side is unknown

S82.90XB records the side as unspecified. In the S82.9- subcategory, the 6th character carries laterality: 0 for unspecified, 1 for right, and 2 for left. Payers may flag an unspecified code when the record clearly identifies the injured limb. ICD-10-CM Official Guidelines also require the most specific code the documentation supports.

• When S82.90XB is appropriate: the record describes an open lower leg fracture but names neither the bone nor the side. A query can’t resolve either before the claim goes out, which is common with early imaging in multi-system trauma.
• When S82.90XB is not appropriate: the ED note says “right lower leg fracture.” Use S82.91XB if the bone is still unnamed, or a right-side tibia or fibula code if it is named. Bilateral fractures don’t belong here either, because the guidelines call for separate right and left codes when no bilateral code exists.
• Physician query first: before using S82.90XB, confirm with the treating provider that neither the side nor the bone can be identified. A documented query and answer become part of the medical record and hold up under audit.

Documentation requirements to support S82.90XB

Incomplete documentation drives many open fracture claim denials. Open fractures involve Gustilo grading, wound care, and often several specialties.

That makes the documentation behind S82.90XB more demanding than for a closed fracture code. Like any medical billing claim, it’s only as strong as the record behind it. Check each element below before you assign the code.

• Explicit documentation of an open (compound) fracture with broken skin at the fracture site
• The Gustilo type as stated by the physician, or no type at all, which defaults to type I or II
• Active treatment context: an ED visit, an operative report for ORIF or external fixation, or an inpatient admission for fracture care
• Anatomical site documented as the lower leg, without naming the tibia or fibula
• No side documented, or a physician’s answer to a query confirming the side can’t be determined
• An external cause code from V00-Y99 for the mechanism of injury, such as a fall, where your state or payer requires one

The CDC/NCHS ICD-10-CM tool shows the Chapter 19 instruction to add a Chapter 20 external cause code with injury codes. Under Section I.C.20, though, there’s no national mandate to report them. They become required where a state reporting rule or a payer’s claim edits ask for them.

Common claim denial reasons for S82.90XB

Open fracture claims attract more payer scrutiny than closed fracture claims. Six denial patterns come up again and again with S82.90XB, and each traces back to a specific documentation or coding error. Strong denial management workflows catch most of them before the claim leaves the practice.

Our guide to CARC denial codes explains CO-11, CO-16, and the other adjustment codes these rejections arrive with.

Coding workflow: Eight steps to assign S82.90XB correctly

Working through each case in the same order removes most of the denial triggers above. The decision path below condenses the eight steps into five checks, with the sibling code each wrong answer leads to.

1. Confirm the fracture is open. The record must state “open” or “compound,” or describe broken skin at the fracture site. A fracture not documented as open or closed is coded as closed, which routes to S82.90XA or a bone-specific closed code.
2. Identify the Gustilo type. Read the operative note or ED physician note. Type I or II supports character B, while types IIIA, IIIB, and IIIC support character C instead. When no type is stated, the guidelines assign B, so query the physician only when the note describes type III damage without a grade.
3. Check whether the tibia or fibula is named. If either bone is named, move to a bone-specific code, such as the S82.2- (tibial shaft) or S82.4- (fibular shaft) series. S82.90XB is valid only when the bone is unidentified.
4. Confirm the encounter is initial. Surgery, casting, ED management, and inpatient fracture care all count as active treatment. Outpatient wound checks after the fracture is stabilized may already be subsequent encounters.
5. Confirm the side can’t be specified. If the record or imaging report names a side, use S82.91XB or S82.92XB instead. Query the physician if the documentation is ambiguous.
6. Assign S82.90XB. All five conditions above must be met.
7. Add an external cause code. Select the V00-Y99 code for the mechanism of injury wherever your state or payer requires one.
8. Verify the linked CPT. The procedure code must fit an open lower leg fracture, such as ORIF, external fixation, or debridement. A mismatch between S82.90XB and a non-orthopedic CPT triggers an edit.

Associated CPT codes for open lower leg fractures

S82.90XB is most often paired with open treatment and wound management CPT codes. The table below lists the codes most often submitted with this diagnosis, with notes on bundling rules for same-day billing. Practices using orthopedic claims software can set claim rules that flag likely bundled pairs before submission.

Debridement and temporary fixation each come with their own documentation rules. The code pages for 11042 and 20690 spell out what the operative note needs for each one.

Open fracture claims often span several encounters, from ED care to definitive fixation and follow-up. Our guide to revenue cycle management shows how those visits fit into one billing workflow.

Excludes notes and other coding instructions

S82.90XB inherits every instructional note on category S82. Apply them before you confirm the code.

Excludes1 note (S82 category, never coded together)

• Traumatic amputation of lower leg (S88.-)

Excludes2 notes (S82 category, may be coded together when documented)

• Fracture of foot, except ankle (S92.-)
• Periprosthetic fracture around internal prosthetic ankle joint (M97.2-)
• Periprosthetic fracture around internal prosthetic implant of knee joint (M97.1-)

Other instructions that apply

• Chapter 19 instructs coders to add a secondary code from Chapter 20 (V00-Y99) to show the cause of injury.
• A fracture not documented as open or closed is coded as closed.
• The open fracture characters follow the Gustilo classification. An open fracture with no Gustilo type documented takes the type I or II character.

The AAPC ICD-10-CM code lookup shows these notes next to the code. Coders can review them at the point of assignment without opening the full tabular list.

How Pabau keeps open fracture claims accurate

Many orthopedic billing teams still check 7th characters by hand, key claims into a payer portal, and match remittances in a spreadsheet. Each handoff is another chance for a B to slip through where the operative note says type IIIB.

Pabau, the practice management and billing platform we build, links each ICD-10 code to its CPT on the claim. It submits 837P claims through the Claim.MD clearinghouse, with eligibility checked before the visit.

Remittances come back as ERA files with CARC denial reasons attached. Your team can correct an S82.90XB mismatch and resubmit while the case is still fresh. That keeps clean claim submission the norm for your practice.

Stop open fracture claims from denying on 7th character errors

Pabau integrates with Claim.MD to validate ICD-10 codes, submit 837P claims electronically, and reconcile ERAs. Your billing team catches character B vs C mismatches before the payer does.

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Conclusion

S82.90XB is a narrow code. It fits an open Gustilo type I or II lower leg fracture at initial treatment, when the record names neither the bone nor the side.

Most of the judgment sits in specificity. If a query can surface the bone or the side, the extra day it takes costs less than a CO-11 denial. If it can’t, S82.90XB is the defensible choice, and the record shows why.

Book a demo to see how Pabau catches 7th character and laterality mismatches before your open fracture claims reach the payer.

Continue your research

Managing claims across multiple payers? Claim.MD clearinghouse overview explains how Pabau routes 837P claims to 4,000+ US payers with real-time eligibility and ERA support.

Want to reduce denials upstream? Insurance eligibility verification outlines how pre-visit benefit checks catch coverage gaps before an open fracture claim is even submitted.

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