S42.309K — Unspecified fracture of shaft of humerus, unspecified arm, subsequent encounter for fracture with nonunion
S42.309K is a billable, specific ICD-10-CM code for unspecified fracture of shaft of humerus, unspecified arm, subsequent encounter for fracture with nonunion. It is valid for submission on a claim.
7th character "K" — subsequent encounter for fracture with nonunion
The appropriate 7th character is to be added to all codes from category S42
- A
- initial encounter for closed fracture
- B
- initial encounter for open fracture
- D
- subsequent encounter for fracture with routine healing
- G
- subsequent encounter for fracture with delayed healing
- K
- subsequent encounter for fracture with nonunion
- P
- subsequent encounter for fracture with malunion
- S
- sequela
Excludes1 inherited from the categories above S42.309K
These are not written on S42.309K, but they bind it: a note on a category applies to every code beneath it. Billing S42.309K with anything listed here is a denial.
Excludes2 inherited from the categories above S42.309K
Also inherited, and the opposite of Excludes1: these conditions are not part of S42.309K, but a patient can have both, so you may code both.
Written on S42.3 — Fracture of shaft of humerus
Other codes that can never be billed with S42.309K
These codes carry an Excludes1 note pointing at S42.309K. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading S42.309K alone.
Risk adjustment
S42.309K does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.
Medicare coverage
S42.309K is named in 1 Medicare coverage policy — 1 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A53065Billing and Coding: Outpatient Physical Therapy
Code history
S42.309K has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.
Related codes at this level
Codes that share S42.309. If S42.309K is not quite right, the correct code is usually one of these.
- S42.309AUnspecified fracture of shaft of humerus, unspecified arm, initial encounter for closed fracture
- S42.309BUnspecified fracture of shaft of humerus, unspecified arm, initial encounter for open fracture
- S42.309DUnspecified fracture of shaft of humerus, unspecified arm, subsequent encounter for fracture with routine healing
- S42.309GUnspecified fracture of shaft of humerus, unspecified arm, subsequent encounter for fracture with delayed healing
- S42.309PUnspecified fracture of shaft of humerus, unspecified arm, subsequent encounter for fracture with malunion
- S42.309SUnspecified fracture of shaft of humerus, unspecified arm, sequela
Questions about S42.309K
- Is S42.309K a billable ICD-10-CM code?
- Yes. S42.309K is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does S42.309K sit in the tabular list?
- Injury, poisoning and certain other consequences of external causes (S00-T88), in the block Injuries to the shoulder and upper arm (S40-S49).
- What cannot be coded together with S42.309K?
- S42.309K carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above S42.309K (S42) and apply to it just the same.