ICD code S92.316K – Nondisplaced second metatarsal fracture with nonunion

Key Takeaways

S92.316K codes a nondisplaced second metatarsal fracture at a subsequent encounter where nonunion is documented, not routine healing

7th character K requires radiographic or clinical evidence of nonunion; it cannot be used at the initial active-treatment visit

Selecting K instead of D (delayed healing) or P (malunion) without supporting imaging is the top denial trigger for this code

Pabau’s claims management software flags 7th-character mismatches and incomplete documentation before claims leave the practice

ICD-10 code S92.316K: Definition and code components

ICD-10 code S92.316K is a billable diagnosis code in the ICD-10-CM system, effective for encounters from October 1, 2015 onward. The official descriptor is: Nondisplaced fracture of second metatarsal bone, subsequent encounter for fracture with nonunion. According to the CMS ICD-10-CM tabular list, the code belongs to chapter 19 (Injury, poisoning and certain other consequences of external causes) and falls under the S92 block for fractures of the foot.

Each character in the code carries a specific clinical meaning. The quick-reference table below breaks each component down.

The code is unspecified for laterality. Where the payer’s local coverage determination requires left or right foot specificity, additional documentation noting the affected side must accompany the claim, though the ICD-10-CM code itself does not distinguish laterality at the .316 level.

Code breakdown: Anatomy, displacement, and encounter type

A nondisplaced second metatarsal fracture means the bone has fractured but the fragments have not shifted out of their normal anatomical alignment. This distinction matters for coding because the .316 designation (nondisplaced) is a separate code from .311 (displaced) and cannot be assumed from clinical notes alone. The operative or radiographic report must explicitly confirm that no displacement occurred.

The second metatarsal is the longest metatarsal bone and bears significant load during the push-off phase of gait, which is why it is the most common site of metatarsal stress fractures. Within the S92.3x block, the digit in position five identifies which metatarsal: .31x = second, .32x = third, .33x = fourth, .34x = fifth (Jones fracture area), and .35x = first.

The 7th character then layers the encounter type and healing status onto that anatomical specificity. For S92.316-series codes, the full 7th-character set is:

7th character K: Subsequent encounter with nonunion explained

The 7th character K in ICD-10 code S92.316K means the encounter is a subsequent visit (active treatment has already begun) and the fracture has failed to unite. Per ICD-10-CM Official Guidelines Section I.C.19.c, a subsequent encounter is any visit after the patient has received active/definitive treatment – whether by the original treating provider or a new one. The critical point: K does not describe an acute or surgical visit; it describes follow-up management of an established nonunion.

Nonunion is the failure of a fracture to heal within the expected timeframe, typically defined as no progressive bony bridging on serial radiographs over a clinically appropriate period (often 6 months for metatarsal fractures, though the AHA Coding Clinic does not specify a fixed time threshold – the radiographic and clinical evidence governs). It is distinct from:

• Delayed healing (G): Healing is progressing more slowly than expected but bony bridging is still occurring on imaging.
• Malunion (P): The fracture has healed, but in a faulty position causing deformity or functional impairment.
• Sequela (S): A late effect or residual condition that develops after the acute fracture phase is resolved.

The K suffix applies when both conditions are true simultaneously: The encounter is subsequent (not the first active-treatment visit) AND the fracture demonstrates nonunion on clinical or radiographic evidence. Using K at an initial encounter – even if the treating provider suspects future nonunion – is incorrect. 7th character A must be used for any visit that constitutes active treatment, including surgical intervention for a known nonunion.

Includes and excludes notes for S92.316K

Several Excludes1 and Excludes2 notes govern the S92 category and affect when S92.316K can appear on a claim. Coders must review these at both the category (S92) and subcategory (S92.3) levels before assigning the code.

The Excludes1 for ankle fractures is a hard rule: S92.316K and an S82.- code cannot appear on the same claim for the same fracture event. If a patient has concurrent ankle and metatarsal fractures from the same incident, both codes may be listed – but each describes a distinct fracture, not the same one.

Commonly confused codes: S92.316K vs. similar codes

The codes most frequently confused with S92.316K differ in either the healing status (7th character), the displacement status (5th character), or the metatarsal involved (4th character). The table below covers the most common confusion pairs seen in audit reviews.

The D-vs-K confusion is by far the most consequential. Payers auditing metatarsal fracture claims routinely flag claims where K appears without imaging reports confirming the absence of bony bridging. Auditors interpret the absence of imaging as unsupported coding, not as confirmed nonunion.

CPT codes commonly paired with S92.316K

The CPT codes that appear on the same claim as ICD-10 code S92.316K depend on whether the nonunion is being managed conservatively or surgically. Conservative subsequent-encounter management generates different procedural codes than surgical repair. Per AAPC coding resources, the following CPT pairings are commonly seen in podiatry and orthopedic practices managing second metatarsal nonunion.

For electronic claim submission and real-time payer eligibility verification, Pabau integrates with Claim.MD, our US clearinghouse partner, which carries a built-in CPT and ICD-10-CM catalogue for validating these pairings before claims are transmitted.

When surgical repair of a nonunion follows a prior fracture procedure, modifier -79 (unrelated procedure during the postoperative period) may be required if the original procedure’s global period is still active. Some payers also require modifier -58 (staged procedure). Confirm payer-specific modifier requirements before submitting.

Documentation requirements for S92.316K

Accurate documentation is what separates a clean S92.316K claim from one that attracts an audit or denial. The Pabau claims management platform can flag incomplete documentation before submission, but the clinical record itself must meet the following requirements.

1. Establish prior active treatment: The record must confirm this is a subsequent encounter. Prior visit notes, imaging reports, or prior-authorization records showing that active treatment was already initiated are required.
2. Radiographic evidence of nonunion: An X-ray or other imaging report documenting the absence of bony bridging or progressive callus at an appropriate time interval. Nonunion cannot be assumed; it must be demonstrated on imaging. The imaging report should explicitly describe the absence of healing or state “nonunion.”
3. Identify the bone and displacement status: The clinical note must confirm which metatarsal is fractured and whether displacement is present. “Second metatarsal, nondisplaced” in the assessment or imaging report maps directly to .316.
4. Document the nonunion treatment plan: The plan for managing the nonunion must be recorded – whether conservative (continued immobilization, bone stimulator, offloading) or surgical (ORIF, bone grafting). An unmanaged nonunion without a documented plan raises medical-necessity questions.
5. Laterality notation: Even though S92.316K does not encode laterality in the code itself, clinical notes must clearly state which foot is affected. Some Medicare Administrative Contractors and commercial payers require a modifier or supplemental documentation specifying left or right, particularly for orthotic and implant claims associated with the nonunion treatment.

Common claim denial reasons for S92.316K and how to avoid them

Claims for nonunion fracture management generate a predictable set of denial patterns. The most common denial codes in medical billing for this code cluster around encounter-type mismatches and missing documentation. Each denial below has a specific corrective action.

Effective denial management for metatarsal nonunion claims requires tracking which denial reason codes are appearing and whether they cluster around specific providers, CPT codes, or payers. Patterns in the denial data almost always reveal a correctable upstream documentation gap.

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Payer-specific requirements and coding guidelines

Medicare coverage for metatarsal nonunion treatment is governed by Local Coverage Determinations issued by Medicare Administrative Contractors. The MAC for a given region may publish an LCD for musculoskeletal fracture management that specifies documentation thresholds for nonunion claims, including minimum imaging requirements and time-since-fracture parameters. Practices should review the applicable MAC’s current LCD before submitting S92.316K claims for Medicare beneficiaries.

Key payer-specific considerations include:

• Medicare: Prior authorization is typically not required for conservative nonunion management, but surgical repair (ORIF, bone grafting) may require prior authorization through the MAC. Bone stimulator claims associated with nonunion treatment require a separate HCPCS code and their own LCD compliance.
• Medicaid: State-specific Medicaid programs vary considerably in coverage for nonunion management. Some state plans limit coverage to specific CPT codes or require the claim to be submitted by an orthopedic or podiatric specialist, not a general practitioner.
• Commercial payers (UHC, Aetna, BCBS): Major commercial payers generally follow AMA CPT and ICD-10-CM guidelines for encounter-type coding but may impose proprietary step-therapy requirements before approving surgical nonunion repair. Some commercial payers require a minimum duration of conservative management (commonly 3-6 months) before authorizing surgery for a metatarsal nonunion.
• Workers’ compensation: Occupational injury claims involving a second metatarsal fracture that progresses to nonunion require correlation with the original workers’ comp claim number. The external cause code for the work injury must remain consistent across all claims for the same episode of care.

Using S92.316K in physical therapy and rehabilitation billing

Physical therapists treating patients with a second metatarsal nonunion do not independently assign S92.316K – they use the referring or treating physician’s diagnosis code on their claims. Per ICD-10-CM Official Guidelines for outpatient rehabilitation services, the PT codes the confirmed diagnosis established by the physician or podiatrist managing the fracture. S92.316K appears on the PT claim as the reason for treatment, not as a code the therapist is independently diagnosing.

This distinction matters for physical therapy billing because a claim that lists S92.316K as the diagnosis code without a referring physician’s documentation of confirmed nonunion is an audit risk. The PT record should reference the treating physician’s diagnosis and include the physician’s most recent note or imaging report confirming active nonunion in the documentation package.

Common errors in PT billing with this code include:

• Using S92.316K when the physician’s current documentation shows D (routine healing) but the PT assumed the fracture is still not healed.
• Failing to update the diagnosis code when the physician transitions the patient from K to S (sequela phase) during the course of PT treatment.
• Billing S92.316K alongside PT evaluation codes when the physician has already discharged the patient from fracture management (at which point a sequela code or a different musculoskeletal diagnosis may be more appropriate).

Pabau’s clean claim workflow for multi-provider practices allows the treating physician’s diagnosis to flow through to therapy billing, reducing the risk of a PT claim arriving with an outdated or mismatched ICD-10 code. For practices submitting claims electronically through the medical billing workflow, Claim.MD’s real-time eligibility tools confirm payer acceptance of the diagnosis code before the claim is transmitted.

Conclusion

S92.316K is a precise code that only applies in a narrow clinical window: A subsequent encounter for a nondisplaced second metatarsal fracture where imaging has confirmed nonunion. The most expensive coding errors on this code – selecting K instead of D or G without supporting radiographs, or applying K at an initial encounter – are all preventable with a systematic pre-submission review against the documentation checklist above.

Practices managing high volumes of metatarsal fracture follow-up should build imaging-report verification into the billing workflow as a standing step before any K-suffix code is submitted.

To see how Pabau’s billing tools support this, explore our medical billing compliance resources or speak with our team.

Continue your research

Need to track denial patterns across metatarsal fracture claims? Denial management in healthcare covers how to build a systematic denial tracking and appeal workflow for high-volume musculoskeletal practices.

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Looking for CPT-to-ICD crosswalk guidance? Our Claim.MD clearinghouse guide explains how clearinghouse validation catches CPT-diagnosis mismatches before claims reach the payer.

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