ICD-10 Code S82.232M: Left tibial shaft fracture with nonunion

Key Takeaways

ICD-10 Code S82.232M describes a displaced oblique fracture of the shaft of the left tibia, subsequent encounter for an open fracture type I or II with nonunion.

The 7th character M is specific to nonunion: the original fracture must have been open type I or II, and the physician must document that the fracture site has failed to heal, not simply healed slowly.

S82.232M is only appropriate when the clinical record documents both the open fracture type (I or II) and a nonunion determination; using it without that documentation is a coding error that can trigger claim scrutiny.

Practice management software like Pabau helps orthopedic and physical therapy practices maintain the structured clinical documentation that supports accurate ICD-10 coding at every subsequent encounter.

ICD-10 Code S82.232M is a billable code for a displaced oblique fracture of the shaft of the left tibia, subsequent encounter for an open fracture type I or II with nonunion.

It applies once the fracture has stopped healing rather than simply healing slowly, which changes both the encounter type and the code itself. Getting the character-by-character detail right matters for orthopedic and physical therapy practices managing ongoing fracture care.

ICD-10 Code S82.232M is a billable ICD-10-CM diagnosis code. Its full official description, per the CDC/NCHS ICD-10-CM code tool, is: Displaced oblique fracture of shaft of left tibia, subsequent encounter for open fracture type I or II with nonunion. Every element of that description is encoded into the seven characters of the code itself.

ICD-10 Code S82.232M: definition and clinical description

This code sits within ICD-10-CM category S82, which covers fractures of the lower leg, including the patella, tibia, and fibula. Within that category, subcategory S82.23 covers displaced oblique fractures of the tibial shaft specifically, and the 6th character then narrows the code to a side.

Understanding the full character breakdown prevents the most common documentation and billing errors associated with this code.

Code details at a glance

The table below summarizes the key reference data for S82.232M. Verify validity against the current fiscal year release from CMS ICD-10 codes, as codes are updated annually on October 1.

Breaking down ICD-10 Code S82.232M character by character

ICD-10-CM codes encode clinical specificity into each character position. For S82.232M, every character has a precise meaning, and misreading any one of them produces a different code for a different clinical scenario.

Unlike some S82 subcategories where the sixth character combines displacement status and laterality, displacement for oblique tibial shaft fractures is fixed by the fifth character. S82.23_ codes are always displaced oblique fractures, while S82.24_ covers nondisplaced oblique fractures of the same shaft.

The sixth character in this family encodes side only. “1” is right, “2” is left, and “3” is unspecified side. Confirming which axis a given digit encodes is a common source of confusion when reading S82 codes quickly.

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

The 7th character is where most S82 coding errors occur. Choosing the wrong suffix changes both the clinical story and the documentation trail needed to support it. For the S82.232 base code, the valid 7th character options span initial treatment through late complications and sequela.

The distinction between K and M is the one coders most often get wrong. Both describe a subsequent encounter with nonunion, but the difference comes down to the original fracture type. K applies when the original fracture was closed, and M applies when the original fracture was open type I or II.

Using M on a fracture that was closed – or that defaults to closed because open/closed status was never documented – creates a clinically inconsistent record. Coders should confirm the original fracture classification before selecting the 7th character on any nonunion encounter.

Clinical significance and when to use S82.232M

Nonunion is not simply “taking longer than expected to heal.” Under ICD-10-CM guidelines, the clinical record must document that the fracture has failed to unite – the healing process has effectively stopped, not just slowed. This is a physician’s clinical assessment, not a coder’s determination.

The following criteria typically support a nonunion determination, though the treating physician makes the final clinical judgment:

• Absence of bridging callus and no radiographic progression toward union on serial imaging, well beyond the expected timeframe for fracture type and location
• Persistent motion, pain, or instability at the fracture site with no evidence of consolidation
• Physician documentation explicitly stating “nonunion,” “established nonunion,” or equivalent clinical language
• Consideration of, or progression to, revision surgery, bone grafting, or another intervention aimed at achieving union

Note that nonunion (M) is clinically distinct from delayed healing (H, for the same open type I/II fracture family). Delayed healing implies healing is still occurring but at a slower-than-normal rate. Nonunion implies the healing process has effectively ceased.

Using M before the physician has established that healing has stopped misrepresents the patient’s clinical trajectory and can affect treatment authorization decisions.

Who codes this encounter: S82.232M is used by orthopedic surgeons, orthopedic PAs and NPs, and physical therapists at follow-up visits where the treating provider has documented nonunion of an open type I or II tibial shaft fracture.

Physical therapy teams managing sports medicine fracture rehabilitation should flag encounters where the physician’s note documents nonunion so the correct 7th character is applied to the record.

S82.232M vs. related codes: key differences

Several codes sit adjacent to S82.232M in the tabular list. Coders regularly confuse these codes, particularly when laterality or union status shifts between encounters. The comparison below covers the most clinically relevant distinctions.

The K vs. M distinction is the most common error pattern for this code family. Both describe nonunion, and the choice depends entirely on whether the original fracture was open or closed.

If the treating physician’s notes from the initial encounter do not clearly state open vs. closed, ICD-10-CM guidelines default to closed, which points to K rather than M. Review the original encounter documentation before finalizing the 7th character on any nonunion follow-up visit.

Practices coding across a panel of orthopedic or sports medicine providers may benefit from structured patient care management workflows that carry fracture classification notes forward from the initial encounter into follow-up records.

Support accurate ICD-10 coding at every encounter

Practice management software like Pabau, including its clinical documentation tools, helps orthopedic and physical therapy practices capture the clinical detail needed to assign the right ICD-10 code at every encounter, not after a denial.

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Coding guidelines and documentation requirements

The ICD-10-CM official guidelines for fracture coding establish several rules that directly affect when and how S82.232M is used. Coders and clinicians should review Section I.C.19.c of the ICD-10-CM Official Guidelines for Coding and Reporting annually, as minor guidance revisions occur with each fiscal year update.

The core documentation requirements for S82.232M are:

• Encounter type must be subsequent: The patient must already have received active treatment for this fracture. “Active treatment” includes any surgical treatment, emergency department encounter, or evaluation and treatment by a new physician.
• Fracture must be open type I or II: The original fracture must be documented as an open fracture, Gustilo-Anderson type I or II. If open/closed status was never documented, ICD-10-CM Official Guidelines Section I.C.19.c instructs coders to default to closed, which points to a different code (K) rather than M.
• Nonunion must be explicitly documented: The physician’s note must state that the fracture has failed to unite. Coders should not infer nonunion from imaging alone without a physician’s clinical assessment.
• Open fracture severity must be type I or II (for M specifically): If the original fracture was open type IIIA, IIIB, or IIIC with nonunion, the correct code is S82.232N, not S82.232M.
• Sequencing: Fracture codes from category S82 are typically sequenced as the principal or first-listed diagnosis when the fracture is the primary reason for the encounter. Additional codes for associated injuries, complications, or external cause should follow.

Practices in physical therapy settings managing patients referred from orthopedic surgeons should confirm with the treating orthopedic physician which 7th character applies at each subsequent visit. The physical therapist does not make the nonunion determination; that assessment originates with the physician overseeing fracture care.

Billable status and reimbursement considerations for S82.232M

S82.232M is a fully specified, billable ICD-10-CM code. It satisfies CMS requirements for a complete, specific diagnosis code and can be reported on Medicare, Medicaid, and commercial claims without need for a more specific subcategory. The WHO ICD-10 classification provides the international framework underlying the CM adaptation.

As a diagnosis code, S82.232M does not itself carry a payment rate. Reimbursement is set at the procedure level: the CPT and HCPCS codes for the associated care, such as fracture care, revision surgery, bone grafting, imaging, or cast supplies like A4580, are priced under the CMS Physician Fee Schedule based on relative value units.

S82.232M’s role is to support the medical necessity of those procedure codes on the claim, not to set a reimbursement amount on its own.

Several documentation considerations are specific to nonunion codes:

• Prior authorization: Payers may require additional documentation when nonunion codes are submitted for imaging, revision surgery, bone grafting, or extended physical therapy. Clinical notes documenting the basis for the nonunion determination reduce authorization delays.
• Medical necessity: A nonunion diagnosis supports medical necessity for continued or escalated treatment beyond standard fracture care timelines. Without the code, payers may question why intervention is continuing beyond typical healing windows.
• Bilateral fracture exception: If both tibias are fractured (unusual but possible), separate codes for right (S82.231M) and left (S82.232M) must be reported. A single code cannot capture bilateral injury.
• External cause codes: When coding practice and payer requirements allow, adding an external cause code (from the V00-Y99 range) alongside S82.232M provides context for injury mechanism. This is optional on claims but recommended for complete clinical documentation.

Practices managing high volumes of orthopedic follow-up visits may find that structured clinical documentation workflows that flag nonunion codes for chart review before submission reduce denial rates on these encounters.

Reimbursement amounts for the associated procedure codes vary by payer, geographic locality, and facility type. Consult your payer contracts and the CMS Physician Fee Schedule for the specific CPT/HCPCS codes tied to the treatment provided.

Conclusion

Getting the 7th character right on tibial fracture codes is not a minor technical detail. It determines whether a claim accurately reflects the patient’s clinical status, whether it will survive payer scrutiny, and whether the documentation trail supports the care being delivered.

S82.232M is the correct code when the clinical record confirms a subsequent encounter for a displaced oblique left tibial shaft fracture that was originally open type I or II, with a physician-documented nonunion.

When that specificity is in the chart, the code is straightforward. When it is not, coders must go back to the physician before submission.

Practice management software like Pabau helps practices build documentation workflows that capture the specifics required for accurate ICD-10 coding at every encounter. To see how Pabau supports orthopedic and physical therapy practices, book a demo.

Continue your research

Managing fracture care documentation compliance? Compliance requirements for physiotherapy clinics covers documentation standards relevant to ongoing fracture rehabilitation and subsequent encounter coding.

Coding another tibial fracture encounter? S82.155P is a related left tibia code worth checking whenever a 7th-character selection needs a second look.

Handling nonunion in a different bone? S92.301K applies the same nonunion logic to a metatarsal fracture, a useful comparison for lower-extremity coding.

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