ICD-10 Code S62.181G: Trapezoid fracture with nonunion

Key Takeaways

S62.181G is the ICD-10-CM code for a displaced fracture of the trapezoid (smaller multangular) bone, unspecified wrist, at a subsequent encounter where the fracture has developed nonunion.

The 7th character G means subsequent encounter for fracture with nonunion, not delayed healing (H/J) or malunion (P). Confusing these characters is a common denial trigger.

“Unspecified wrist” reflects undocumented laterality. Use S62.181D for right wrist or S62.181F for left wrist when the treating side is documented in the record.

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ICD-10 Code S62.181G: code description and billable status

Most denied claims for wrist fracture follow-up visits share one root cause: the wrong 7th character. ICD-10 Code S62.181G covers a specific clinical scenario, and every component of that code must match what the chart documents before a payer will process the claim.

ICD-10 Code S62.181G is a billable ICD-10-CM diagnosis code valid for reimbursement in the current 2026 edition, which became effective October 1, 2025. It describes a displaced fracture of the trapezoid bone (also called the smaller multangular), at the unspecified wrist, presenting at a subsequent encounter where the fracture has developed nonunion. The code is not a placeholder. It is the specific terminal code used when a coder can confirm all three clinical elements: displacement, trapezoid site, and nonunion at a follow-up visit.

What does S62.181G mean? Breaking down each code segment

ICD-10-CM codes are structured rather than arbitrary. Breaking S62.181G into its components reveals exactly what clinical information each character encodes, and where a documentation gap can break the code assignment.

The absence of a laterality digit (right or left) in this code reflects the “unspecified wrist” qualifier. When the operative report, imaging, or progress note specifies a side, the correct code is S62.181D (right wrist, subsequent/nonunion) or S62.181F (left wrist, subsequent/nonunion). Using S62.181G when laterality is documented in the record is a common audit finding for orthopedic and hand surgery practices. You can verify current code validity against the CDC/NCHS ICD-10-CM web tool, which mirrors the official CMS tabular list.

About the trapezoid bone (smaller multangular)

The trapezoid bone sits in the distal row of the eight carpal bones, wedged between the trapezium (lateral), capitate (medial), and the base of the second metacarpal. It is the smallest bone in the distal row, which partly explains its alternate name: the smaller multangular. Because of its protected position, isolated trapezoid fractures are rare, and their diagnosis is frequently delayed on initial imaging.

Clinical relevance for coding: fractures that present initially as wrist injuries are sometimes coded at the broader wrist level, then reclassified once CT or MRI confirms the trapezoid as the specific site. Reaching a nonunion state (the clinical condition behind the G suffix) is more likely when the initial fracture went unrecognised and untreated for several weeks. Understanding this anatomical context helps coders justify S62.181G over a broader wrist fracture code when the record supports it. Physical therapists treating these injuries may find additional context in physical therapy EMR workflows that track wrist rehabilitation progress across visits.

• Location: Distal carpal row, between trapezium and capitate
• Alternate name: Smaller multangular (used in ICD-10-CM description brackets)
• Common injury mechanism: Axial load through the second metacarpal, direct crush, or high-energy wrist trauma
• Imaging: Often missed on plain radiograph; CT or MRI typically needed for confirmation
• Nonunion risk: Elevated when initial injury is missed or immobilisation is incomplete

Understanding the 7th character G: subsequent encounter for fracture with nonunion

Fracture nonunion is one of the most consequential distinctions in ICD-10 Code S62.181G assignment. The 7th character G does not mean a routine follow-up visit. It specifically means the fracture has failed to unite, meaning bony healing has not progressed as expected for the time elapsed since the injury. Coders and clinicians frequently confuse G with H, but they describe different clinical scenarios.

The table below lists every valid 7th character for the S62.181 subcategory. Each character changes the clinical meaning and the appropriate billing context, so selecting the correct one depends entirely on what the treating provider documents at each encounter.

Key distinction to commit to memory: G is nonunion for a closed fracture. P is malunion. Swapping these at claim submission sends the wrong clinical signal to the payer and opens the encounter to a medical necessity challenge. For ICD-10 coding questions across your practice, the AAPC ICD-10-CM code lookup allows searching by description or by code to verify character options. Always verify against the current-year CDC/NCHS ICD-10-CM tool before submitting.

S62.181G code hierarchy and classification

Every ICD-10-CM code exists within a hierarchy of parent categories. Knowing where S62.181G sits in that tree helps coders navigate related codes and understand what the broader grouping covers, which matters for DRG assignment in inpatient settings and for crosswalk queries between ICD-10-CM and CPT.

S62.181 without a 7th character is not a valid billing code. The 7th character is always required for this subcategory, and submitting S62.181 alone will result in a code validity rejection from most clearinghouses. You can verify the full ICD-10 hierarchy for S62 codes using the CMS ICD-10 codes page, which publishes annual tabular updates.

Related ICD-10 codes for trapezoid fractures

The S62.181 family covers displaced trapezoid fractures of the unspecified wrist across all encounter types and healing statuses. Coders working with hand surgery or orthopedic practices will encounter this entire group. The non-displaced equivalent, starting at S62.182, covers trapezoid fractures where the fragments have not shifted. See the adjacent section for the displaced vs non-displaced distinction. Practices dealing with fracture nonunion claims frequently also reference denial codes in medical billing to understand why these claims are rejected and how to correct submissions.

Displaced vs non-displaced fracture: ICD-10 coding distinction

Displacement is a clinical finding, not a coder judgment call. The treating provider must explicitly document whether the fracture fragments have separated or remain in anatomic alignment. When the chart is silent on displacement, ICD-10-CM guidelines direct coders to use the displaced code by default for most fracture categories. Practices with experience coding other ICD-10 conditions will recognise this default-displaced rule as consistent across multiple fracture categories.

The S62.182G code (non-displaced trapezoid fracture, nonunion, subsequent encounter) is less common in practice because non-displaced fractures have a lower nonunion rate. When a chart documents nonunion but does not specify displacement status, the displaced code (S62.181G) is the appropriate default.

Documentation requirements for ICD-10 Code S62.181G

Nonunion is a physician diagnosis, not a coder inference. Before assigning ICD-10 Code S62.181G, the documentation must affirmatively support three separate clinical elements. Missing any one of them creates an assignment error that can result in a denied claim or a postpayment audit finding. Practices looking to tighten their overall billing workflow can benefit from reviewing medical billing compliance guidance alongside fracture-specific documentation requirements.

• Confirmed trapezoid fracture: Imaging or operative documentation identifying the trapezoid (smaller multangular) as the specific fracture site. A general “wrist fracture” diagnosis without site specificity does not support this code.
• Displacement documented or unspecified: The provider must document displacement, or leave displacement unspecified (in which case the displaced code is the ICD-10-CM default). If non-displaced is explicitly documented, S62.182G applies instead.
• Subsequent (not initial) encounter: The visit must be a follow-up for an already-established fracture, not the first encounter for active fracture treatment. The distinction between initial and subsequent is determined by the purpose of the visit, not the time elapsed.
• Nonunion confirmed: The provider must explicitly diagnose nonunion, typically supported by serial imaging showing absence of bridging callus, hardware failure, or a clinical assessment noting failed union. Delayed healing alone does not support G; that would use character H (open fracture type I/II) or a delayed-healing character for the applicable encounter type.
• Laterality unspecified: The wrist side must not be documented, or documentation must be absent. If the chart specifies right or left, use the laterality-specific code instead of S62.181G.

When documentation is ambiguous, coders should query the provider rather than making a clinical inference. Using the ICD List reference tool alongside the official tabular supports accurate character selection when multiple similar codes are in play.

Coding guidelines and tips for wrist fracture ICD-10 codes

The ICD-10-CM Official Guidelines for Coding and Reporting (Section I.C.19.a) govern how fracture codes are sequenced and selected. Several specific rules affect ICD-10 Code S62.181G and the broader S62 category.

• Active treatment rule: The initial encounter character (A or B) applies for the entire period of active treatment, including fracture care, surgical management, and emergency visits. The shift to a subsequent character (D through S) occurs when the patient is receiving routine aftercare, not active fracture management.
• 7th character required: S62.181 without a 7th character is not a valid billing code. Every fracture code in category S62 requires the appropriate 7th character to be considered a billable, specific code.
• Nonunion vs malunion: These are mutually exclusive conditions. Nonunion means the fracture failed to heal; malunion means it healed in a deformed position. Assign G for nonunion, P for malunion. Assigning G when the chart documents malunion is an error that can trigger a clinical mismatch denial.
• Sequencing: When the nonunion is the reason for the visit, S62.181G is the principal diagnosis. Secondary codes for associated conditions (pain, functional limitation) follow.
• External cause codes: ICD-10-CM guidelines encourage but do not always require external cause codes (Chapter 20) to supplement S62.181G. They can provide payer context about the mechanism of injury, which matters for workers’ compensation and liability billing.

Orthopedic and hand surgery practices submitting claims for fracture nonunion cases benefit from electronic claim submission through a medical clearinghouse. Pabau integrates with Claim.MD, our clearinghouse partner for US payers, which supports electronic submission of ICD-10-coded claims to 4,000+ payers. The integration includes built-in CPT and ICD-10 code catalogues, real-time eligibility verification, and 837P claim submission, so coding accuracy at the point of documentation translates directly into cleaner electronic claims. Practices managing fracture claims can also explore Pabau’s claims management software for end-to-end billing workflow support, and our guide on how a medical claims clearinghouse works explains the submission and ERAs process in plain language.

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Approximate synonyms and alternate descriptions

Coders and providers may use alternate clinical terminology that maps to ICD-10 Code S62.181G. The following synonyms and alternate descriptions are accepted as equivalent for coding purposes. Recognising these in chart notes and operative reports reduces lookup time and supports faster, more accurate code selection. Practices that also code other complex injury presentations can refer to our ICD-10 codes for intraparenchymal hemorrhage for a parallel example of how multi-code injury scenarios are structured.

• Displaced fracture of smaller multangular bone, wrist, subsequent encounter with nonunion
• Displaced trapezoid bone fracture, nonunion, follow-up visit
• Fracture nonunion of trapezoid [smaller multangular], unspecified wrist
• Wrist carpal bone fracture (trapezoid), displaced, failed union, subsequent care
• S62.181G – displaced fracture of the carpal trapezoid, subsequent encounter, nonunion

The bracket notation “[smaller multangular]” within the ICD-10-CM description is the official synonym indicator. Both “trapezoid” and “smaller multangular” are clinically interchangeable when referring to this carpal bone, and either term in the chart supports assignment of codes within the S62.18 subcategory. For additional ICD-10 coding context across diagnostic categories, the ICD-10 code for autistic disorder article illustrates how code hierarchy and synonym lookups apply across different clinical areas. Additional lookup support is available through the AAPC ICD-10-CM reference tool, which allows code searches by both description and synonym terms.

Conclusion

Fracture nonunion claims are among the highest-scrutiny encounters in orthopedic billing. ICD-10 Code S62.181G is the right code only when all three clinical elements are present in the documentation: displaced trapezoid fracture, subsequent (not initial) encounter, and confirmed nonunion. Getting the 7th character wrong, using an unspecified laterality code when the chart specifies a side, or assigning G when the chart describes malunion creates denials that are entirely avoidable with accurate documentation review.

Pabau’s claims management software connects to Claim.MD to submit ICD-10-coded claims electronically to 4,000+ US payers, with real-time eligibility and ERA processing built in. To see how this fits your practice’s billing workflow, book a demo.

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