ICD code S82.199M – Other proximal tibia fracture with nonunion

Key takeaways

S82.199M codes a follow-up visit for an open type I or II fracture of the upper tibia that hasn’t united, with the side unspecified.

The 7th character M means open type I or II with nonunion. A closed nonunion takes K, and a type IIIA, IIIB or IIIC nonunion takes N.

The 5th character 9 means the fracture isn’t a tibial spine, condyle, bicondylar, tuberosity or torus fracture, since each of those has its own code.

Use the unspecified side only when no document in the encounter names the leg. Otherwise, code S82.191M (right) or S82.192M (left).

Pabau, the practice management software we build, submits claims through Claim.MD, posts electronic remittance and tracks denials for orthopedic practices.

ICD-10 code S82.199M covers an open upper tibia fracture that won’t heal

ICD-10 code S82.199M is a billable ICD-10-CM code for a follow-up visit for an open break near the knee that has stopped healing. Its official descriptor is other fracture of upper end of unspecified tibia, subsequent encounter for open fracture type I or II with nonunion. The record doesn’t say which leg, so the 6th character is 9.

“Other” has a narrow meaning here. S82.19- is the residual bucket after tibial spine (S82.11-), lateral condyle (S82.12-), medial condyle (S82.13-), bicondylar (S82.14-), tibial tuberosity (S82.15-) and torus (S82.16-) fractures. If the surgeon names one of those patterns, the fracture belongs in that subcategory instead. At the upper end of the right tibia, a buckle reviewed at a malunion follow-up codes to S82.161P. S82.199M stays behind only when none of those subcategories fits the documented pattern.

The code sits in Chapter 19 under category S82 and subcategory S82.1. It has no Excludes notes of its own, but it inherits the ones on category S82, as the CDC/NCHS ICD-10-CM web tool shows.

That means Excludes1 for traumatic amputation of the lower leg (S88.-). It also means Excludes2 for foot fractures (S92.-) and periprosthetic fractures around a knee or ankle implant (M97.1-, M97.2-).

• Full descriptor: Other fracture of upper end of unspecified tibia, subsequent encounter for open fracture type I or II with nonunion
• Billable: Yes, valid in the FY2027 ICD-10-CM code set
• Chapter: Chapter 19, Injury, poisoning and certain other consequences of external causes (S00-T88)
• Category: S82, Fracture of lower leg, including ankle
• Subcategory: S82.1, Fracture of upper end of tibia
• 7th character: M, subsequent encounter for open fracture type I or II with nonunion

Each character of S82.199M narrows the diagnosis

Read the code left to right and it answers six questions about the injury. The table shows what each position adds, which is the fastest way to spot a miscode.

The 7th character turns on the Gustilo classification of the original wound. Type I is an open wound under 1 cm with little contamination. Type II runs 1 to 10 cm without extensive soft-tissue damage. Both take M for nonunion.

Types IIIA, IIIB and IIIC involve heavy contamination, soft-tissue loss or an arterial injury, and they take N instead. What if the note says only “open fracture”? The Tabular List treats an open fracture with no type as type I or II, so a missing grade points to the M suffix.

Still, query the surgeon when the notes describe major tissue loss or vascular repair.

S82.199M fits follow-up visits for a nonunion

S82.199M applies when a patient returns for ongoing care of an open proximal tibia fracture, type I or II, that hasn’t united. The first visit was coded with B, for example S82.191B for the right leg. From then on, the 7th character follows the healing.

Typical visits include an orthopedic follow-up where imaging shows no bridging bone, or a bone graft planned after conservative care failed. Physical therapy after the surgeon documents nonunion also qualifies. Even the nonunion repair surgery takes M, because the guidelines treat care for a nonunion as subsequent care.

• Encounter type: Subsequent, never the first visit for the fracture
• Fracture site: Upper end of the tibia, not the shaft, ankle or fibula
• Wound type: Open, Gustilo type I or II, or open with no type documented
• Healing status: Nonunion, confirmed on imaging or stated by the surgeon
• Laterality: Not named anywhere in the encounter record, which is rare. Most cases code to S82.191M or S82.192M.

What S82.199M includes and what it sends elsewhere

Check both columns before you submit. Most miscodes on this code come from one of the swaps on the right.

Shaft fractures are the most common swap. If imaging places the break in the shaft, the code moves to S82.2-, as with S82.299K for a closed shaft nonunion in an unspecified leg.

S82.191M, S82.192M or S82.199M: Let the record pick the side

Laterality is the most common audit flag in this code family. The table compares S82.199M with its nearest neighbors, including other 7th characters for the same site.

Guideline I.B.13 says to assign the unspecified side only when the record doesn’t identify it. Guideline I.B.14 also lets you take laterality from other clinicians’ notes, such as a radiology report. So if the X-ray reads “right proximal tibia,” S82.199M is the wrong code.

The 7th character tracks the visit, the wound and the healing

Every S82.199 code shares the same site and side. Only the 7th character changes, and it records three facts at once: the visit type, the wound type and how healing is going. The matrix below lays out all 16 options.

The same options appear row by row below. Per the CMS ICD-10-CM coding guidelines, open or closed always reflects the wound at the original injury.

Six documentation checks that support S82.199M

Coders don’t diagnose, so every part of the code needs support in the record. Work through these six points before you assign it.

1. Fracture site: The note must state proximal tibia, with a fracture type that is not condylar, spinal or tuberosity. “Lower leg fracture” alone won’t support it.
2. Side not identified: No document in the encounter names the leg. If imaging or the operative note does, use S82.191M or S82.192M instead.
3. Open type I or II: The operative report, emergency note or wound assessment should give the Gustilo grade. A note that says only “open fracture” defaults to type I or II.
4. Subsequent encounter: The visit follows earlier treatment of the fracture. Nonunion surgery counts as subsequent care too, so A, B and C don’t apply.
5. Nonunion confirmed: You need imaging that shows no bridging bone, or a surgeon’s statement that the fracture hasn’t united. Delayed healing in an open type I or II fracture is coded differently (H suffix).
6. Care still ongoing: The visit treats the fracture itself. Once healing is complete and only residual effects remain, the S (sequela) suffix applies.

CPT codes that pair with a proximal tibia nonunion

Nonunion care usually bills as a repair, a graft or an office follow-up. The table pairs each CPT code with S82.199M and flags what to check. For payer-specific pairing edits, use the AAPC Codify ICD-10-CM lookup.

CPT 27720, 27722 and 27724 link most cleanly to S82.199M, because each one describes repair of a tibial nonunion. Coverage varies, so check each payer’s prior-authorization rules before you schedule the surgery.

Seven reasons S82.199M claims get denied

Denials on this code follow a short list of patterns. A structured approach to denial management catches most of them before the claim goes out. When one slips through, the medical billing denial codes reference maps each code to its fix.

1. Wrong 7th character: Delayed healing (H suffix for open type I or II) and nonunion (M suffix) need different support. Nonunion needs a surgeon’s statement or imaging. Coding M on notes that only support H invites a medical necessity denial.
2. Unspecified side when the record names it: If any note mentions “the right knee” or “left limb,” S82.199M is wrong. Auditors often pull the imaging report to check. Use S82.191M or S82.192M.
3. Conflicting Gustilo grade: An ungraded open fracture defaults to type I or II. If any note describes a type III wound, though, M is wrong and N applies.
4. Initial suffix on a follow-up: An A, B or C suffix on a post-op check or graft planning visit is an encounter-type mismatch. Catch it in pre-bill review.
5. Missing external cause code: Workers’ compensation and some commercial plans expect a W, V, X or Y code. On follow-ups it describes the original injury and carries 7th character D.
6. No imaging behind the nonunion: Payers may ask for the X-ray or CT report before paying a repair code. Keep it attached to the claim or ready in the file.
7. CPT site mismatch: Billing tibial shaft codes such as 27750 or 27758 against an upper-end diagnosis flags an anatomic conflict. The procedure must match the documented fracture site.

External cause codes follow the original injury

ICD-10-CM guidelines encourage external cause codes for injuries, but there’s no national rule requiring them. Workers’ compensation and many commercial payers expect them anyway.

On a follow-up, report the original mechanism with 7th character D, for example W18.30XD. The ICD List code browser shows the full W, V, X and Y hierarchy.

Place (Y92) and activity (Y93) codes are reported only once, at the initial encounter. They don’t go on an M-suffix claim. External cause status (Y99) works the same way, so a work injury’s Y99.0 rides on the first claim only.

How an S82.199M claim moves from note to payment

Most S82.199M claims follow the same five steps. Knowing where each one stalls tells you where to look first.

1. The surgeon documents the visit, including site, side, Gustilo grade and healing status.
2. The coder assigns S82.199M, the external cause code with D, and the CPT code for the service.
3. The claim goes to the clearinghouse, which rejects format errors before the payer sees them.
4. The payer adjudicates it and returns an electronic remittance advice (ERA) with any denial reason codes.
5. Your team posts the payment or works the denial, using the reason code to pick the fix.

On nonunion claims, three claim adjustment reason codes (CARCs) come up most. CARC 50 means not medically necessary, and CARC 167 means the diagnosis isn’t covered. CARC 252 asks for an attachment, which usually means the imaging report.

Before you submit: A five-point check

A clean claim passes payer edits the first time. Run these checks before an S82.199M claim leaves the practice.

• The note gives a Gustilo grade, or says “open fracture” with no type.
• The surgeon states nonunion, or imaging shows it.
• No document names the side. If one does, switch to S82.191M or S82.192M.
• The external cause code describes the original mechanism and ends in D.
• The CPT code matches the fracture site, and the imaging report is on file.

Keeping these records together also helps with medical billing compliance if a payer audits the claim later.

How Pabau keeps S82.199M claims moving

Many orthopedic practices track nonunion claims across a billing inbox, a clearinghouse portal and a denial spreadsheet. When a claim bounces, someone has to rebuild its history by hand.

With Pabau’s claims management software, the claim is submitted through Claim.MD, a US clearinghouse. Electronic remittance posts back against the patient, and each denial stays tracked until it’s resolved.

So when a CARC 252 lands, your team sees it the same day, attaches the imaging report and resubmits. Coding calls, like M versus H, stay with your coders.

Track every nonunion claim to payment

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Conclusion

S82.199M holds up at audit when three facts are on paper. The wound has a type I or II grade or no grade at all, the surgeon has stated nonunion, and no note names the leg.

If one of those is shaky, fix it before the claim goes out. A query to the surgeon takes minutes, while a denied nonunion repair can take weeks to unwind. Often the fix is simply switching to S82.191M or S82.192M.

Want fewer nonunion claims stuck in limbo? Book a demo to see how Pabau tracks each claim from submission to payment.

Continue your research

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