ICD-10 Code S72.435M: Left medial condyle fracture nonunion

Key takeaways

S72.435M covers a nondisplaced fracture of the medial condyle of the left femur, coded at a subsequent encounter with nonunion.

The 7th character M means open fracture type I or II with nonunion, so it never applies to a closed fracture.

Closed fracture nonunion at the same site takes K, and open type IIIA, IIIB, or IIIC nonunion takes N.

The 6th character carries displacement and laterality together, so 4 through 6 are the nondisplaced medial condyle codes.

Delayed healing takes H instead, so M needs a documented failure to unite rather than slow progress.

Pabau, our practice management platform, attaches diagnosis codes inside the patient record, so the claim matches the note.

ICD-10 Code S72.435M is a billable ICD-10-CM diagnosis code for a nondisplaced fracture of the medial condyle of the left femur. It applies at a subsequent encounter, once an open type I or II fracture has failed to unite.

The open fracture grade is where this code goes wrong most often. Coders reach for M whenever a note says nonunion, but closed fracture nonunion belongs to character K instead.

This guide covers the code hierarchy, the full 7th character set, sibling codes, documentation requirements, and the ICD-9 crosswalk.

ICD-10 Code S72.435M: Definition, billable status, and FY2026 validity

S72.435M is a billable and specific ICD-10-CM diagnosis code. The CDC/NCHS ICD-10-CM web tool confirms it is valid for the FY2026 code set, effective October 1, 2025. It maps to one well-defined clinical scenario, so payers accept it directly on a claim.

The CMS ICD-10-CM code files hold the tabular list and coding rules for this family. Additions and revisions land with each October update, so confirm the code is still valid before you apply it to a claim.

Code hierarchy: Parent codes for S72.435M

S72.435M sits at the bottom of a four-level hierarchy inside the fracture of lower end of femur classification. The parent chain decides your specificity, and it tells you which sibling code to pick when laterality or fracture grade differs.

The S72 category covers every femur fracture, from femoral neck injuries at the proximal end to the distal condylar fractures in S72.4. That subcategory groups the medial condyle, the lateral condyle, and the supracondylar region. S72.43 narrows it to the medial condyle alone.

The 6th character then carries displacement and laterality together. Characters 1, 2, and 3 are displaced right, left, and unspecified femur. Characters 4, 5, and 6 are the nondisplaced versions of the same three.

Sibling codes S72.451K and S72.442C show the same pattern in the supracondylar and lower epiphysis groups.

One rule trips coders up. S72.435 is not billable on its own, because the tabular list marks the whole S72.43 subcategory as requiring a 7th character. A five- or six-character stem submitted without that character rejects as an invalid code.

Understanding the 7th character M: Open type I or II with nonunion

The 7th character is where most S72 coding errors start. It carries three facts at once: the encounter type, whether the fracture was open or closed, and how it healed. All three have to be in the record before you use S72.435M.

Nonunion vs. delayed healing: nonunion means the fracture has stopped progressing toward union altogether. Delayed healing means it is still knitting, just slower than expected. On an open type I or II injury, delayed healing takes character H instead. Only the treating physician can draw that line, and radiographs usually anchor the call.

Nonunion vs. malunion: malunion means the bone united in the wrong position, bent, rotated, or shortened. Nonunion means it never united. Sibling code S72.431R shows the malunion end of the same family. For an open type I or II injury, nonunion takes M and malunion takes Q.

ICD-10-CM does simplify one thing. It collapses all three type III grades into a single character, so you never need to separate IIIA from IIIB or IIIC. The only grading question that changes the code is type I or II versus type III.

Clinical meaning: Nondisplaced medial condyle fracture of the left femur

The medial condyle is the rounded bony prominence on the inner side of the distal femur, and it forms part of the knee joint. It carries most of the axial load through the knee. Orthopedic surgeons and sports medicine clinicians see these fractures after high-energy trauma, such as a motor vehicle collision or a fall from height.

• Nondisplaced: the fragments stayed in anatomic alignment. Displacement and laterality share the 6th character, so 2 is displaced left and 5 is nondisplaced left. Nondisplaced condylar fractures are often managed without fixation.
• Medial condyle: the site on the inner side of the distal femur. Lateral condyle fractures are coded under S72.42x, and unspecified condyle fractures under S72.41x.
• Left femur: left is S72.435, right is S72.434, and unspecified is S72.436. Laterality has to come from the provider, never from the coder.
• Open type I or II: the original injury broke the skin. Type III injuries use a different 7th character. Type I means a clean wound under 1 cm, and type II means a moderate wound of 1 to 10 cm.
• Subsequent encounter: the patient is in follow-up care after active treatment of the acute fracture. That acute phase would have used 7th character B.
• Nonunion: the fracture has failed to consolidate within the expected window. A nondisplaced fracture is mechanically favorable, but poor vascularity, osteoporosis, or an infected open wound can still stall union.

Open fracture grading for S72.435M: Gustilo-Anderson types

S72.435M applies to open fracture type I or II only. Those types come from the Gustilo-Anderson classification, the accepted standard for grading open fracture wound severity. The grade must be documented by the treating surgeon. Reading it off a wound description is not acceptable coding practice.

If the operative or emergency record grades the injury IIIA, IIIB, or IIIC, S72.435M is the wrong code and S72.435N is right. Payers read the open fracture grade as a proxy for expected resource use. A grade that disagrees with the surgical record raises audit risk on the whole episode.

Related ICD-10 codes for medial condyle femur fractures

A patient moves through several sibling codes across one episode of care, as the encounter type and healing status change. The table below lists the codes most often confused with S72.435M. The same episode usually starts at S72.435B, the initial encounter code.

Use S72.436M for an unspecified femur only when the record genuinely does not state a side. Coding unspecified where the provider documented left is a specificity error, and it can trigger a claim edit even though the code is billable.

Documentation requirements for ICD-10 Code S72.435M

This code needs the medical record to support six clinical facts. If any one of them is absent, either a different code applies or the provider needs a query. A structured patient record system with encounter-type and fracture-status fields keeps all six in one place.

• Fracture site confirmed: the documentation names the medial condyle of the femur. A note that says only “condylar fracture” needs a provider query.
• Left side specified: the provider states the left femur. If the record says only “femur”, use S72.436M and query for clarification.
• Nondisplaced status: the provider or the imaging report describes the fragments as nondisplaced. Displaced fractures of the same condyle use S72.431 through S72.433 instead.
• Open type I or II confirmed: the 7th character M applies only to open fractures graded I or II. A closed fracture takes K, and an open type III fracture takes N.
• Subsequent encounter status: the visit is follow-up care after active treatment, not the initial emergency or surgical encounter.
• Nonunion clinically established: the provider states nonunion, ideally with imaging that shows absent or non-bridging callus. Digital clinical forms with a healing-status field help teams capture this at every visit.

Nonunion cases often run across many visits, and the same code repeats on claim after claim. Each of those claims needs its own healing-status statement in that visit’s note. A single nonunion entry from six months ago will not support the current one.

Billable status and reimbursement notes for S72.435M

S72.435M is valid for both inpatient and outpatient claims. MS-DRG 533 or 534 covers inpatient distal femur fractures in the S72.4 range, and CMS titles the pair Fractures of femur with and without MCC. The split depends on the patient’s documented complications and comorbidities.

On the outpatient side, the code supports medical necessity for follow-up radiographs, physical therapy authorization, and surgical consultation for nonunion.

Payers often want the matching procedure code on the same claim, such as bone grafting or revision internal fixation. Coverage for nonunion surgery can also require prior authorization, so check the current local coverage determination first.

Claims management software links the diagnosis code to the procedure code while the claim is being built. That check catches mismatched pairings before submission, which protects your clean claim rate.

Practices that submit to US payers can send those claims through the Claim.MD integration straight from the patient record. Anything that comes back rejected still needs working, so a defined denial management process keeps the rework contained.

ICD-9-CM to ICD-10-CM crosswalk: S72.435M and code 733.82

Practices holding legacy billing data will find the closest ICD-9-CM match for S72.435M is 733.82, nonunion of fracture. The mapping is approximate in both directions. The AAPC ICD-10-CM code lookup and the General Equivalence Mappings from CMS and NCHS are the references to trust here.

ICD-9-CM needed two codes to say what S72.435M says on its own. Coders paired the site code with 733.82 to record the failed union. The old site codes were split by fracture type rather than by side. Code 821.31 covered an open femoral condyle fracture, and 821.21 covered a closed one. Neither code carried laterality, so the side had to come from the chart notes.

733.82 was a broad nonunion code that maps forward to hundreds of ICD-10-CM codes. That one-to-many relationship means legacy data does not convert cleanly. Translating an old claim needs the original clinical record, not just the forward-mapping file. Site, side, and open fracture grade all have to come from somewhere.

Coding guidelines and common errors for S72.435M

Per ICD-10-CM Official Guidelines Section I.C.19 and CMS claim edits, the errors below surface most often in orthopedic coding audits.

• Treating M as a general nonunion character: this is the most frequent error on S72.435M claims. M commits the claim to an open type I or II injury, while closed fracture nonunion takes K.
• Skipping the Gustilo grade: open type IIIA, IIIB, and IIIC injuries take character N instead. Check the grade in the operative or ER record before you pick a 7th character.
• Coding nonunion from a slow-healing note: “healing slowly” and “callus forming” describe delayed healing, which takes H. A coder cannot upgrade that language to nonunion.
• Using an initial encounter character at follow-up: B belongs to the active treatment phase. Once that phase ends, the visit takes E, H, M, N, Q, or S.
• Confusing nonunion with malunion: M means the bone never united and Q means it united crooked. Each carries a different procedure code, so a mismatch puts diagnosis and procedure in conflict.
• Leaving laterality unspecified: choosing S72.436M when the record states left is not specific enough. The claim may still pay, but it can fail an audit later.
• Omitting the external cause code: S72.435M carries the site and healing status, not the mechanism. Add a code from the V00-Y99 range where payer rules call for it.

Most of these errors are made when the note is written, well before the claim goes out. An EHR that carries the code from the record into the claim removes the step where the character changes.

How Pabau supports ICD-10 coding and claim accuracy

Today a coder looks S72.435M up on a reference site, then retypes it into a separate billing system. That handoff is where a 7th character quietly becomes the wrong one, and where the claim stops matching the note behind it.

Practice management software like Pabau removes the retyping step. Staff search for the diagnosis code and attach it inside the patient record at the point of care. The code then flows into the claim unchanged, so laterality and 7th character errors have nowhere to enter.

Orthopedic, sports medicine, and rehabilitation teams often follow one fracture across a dozen encounters. Physical therapy EMR software keeps that episode record consistent from the initial encounter through discharge.

Pabau’s claims tools then show the attached code next to the clinical note, so you can confirm it matches what the provider documented.

For a nonunion case, that matters at every visit. The healing status can change between appointments, and the code has to change with it. Seeing both on one screen means you notice when the note says nonunion but the claim still says routine healing.

Keep ICD-10 codes and clinical notes in step

Pabau attaches diagnosis codes inside the patient record and carries them through to claim submission without re-keying. That keeps encounter type, laterality, and healing status consistent across every visit in a fracture episode.

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Conclusion

S72.435M rewards one habit above all others. Read the 7th character definition in full before you assign it. M looks like a generic nonunion marker, but it commits the claim to an open type I or II injury. The original operative record has to support that grade.

Practices that capture the Gustilo grade, the side, and the healing status at the point of care rarely revisit this code. Those that treat coding as a step after documentation end up choosing between K, M, and N from an incomplete note. The correction costs far more than the original query would have.

An integrated practice management platform keeps that decision inside the clinical record instead of a separate lookup. Book a demo to see how Pabau keeps fracture coding accurate across every encounter in an episode.

Continue your research

Coding a femur shaft nonunion instead? S72.309N walks through the same nonunion logic for an unspecified femur shaft fracture.

Working the initial encounter for the same condyle? S72.431C covers the acute treatment phase of a medial condyle fracture.

Coding the sequela phase after a distal femur fracture? S72.455S explains when the 7th character S replaces a subsequent encounter code.

Billing the graft that treats a nonunion? CPT 20900 covers a minor bone graft taken from any donor area.

Coding a knee fracture that healed crooked? S82.026R applies the malunion characters to the patella.

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