S52.399K Other fracture of shaft of radius, unspecified arm, subsequent encounter for closed fracture with nonunion

Billable ICD-10-CM code, FY2026.

Built from S52.399 with 7th character K (subsequent encounter for closed fracture with nonunion).

Applies from S52 Fracture of forearm

Excludes1 (never code together)

• traumatic amputation of forearm (S58.-)

Excludes2 (not included here)

• fracture at wrist and hand level (S62.-)
• periprosthetic fracture around internal prosthetic elbow joint (M97.4)

7th character note

• The appropriate 7th character is to be added to all codes from category S52

Notes

• A fracture not indicated as displaced or nondisplaced should be coded to displaced
• A fracture not indicated as open or closed should be coded to closed
• The open fracture designations are based on the Gustilo open fracture classification

7th character required

• A — initial encounter for closed fracture
• B — initial encounter for open fracture type I or II
• C — initial encounter for open fracture type IIIA, IIIB, or IIIC
• D — subsequent encounter for closed fracture with routine healing
• E — subsequent encounter for open fracture type I or II with routine healing
• F — subsequent encounter for open fracture type IIIA, IIIB, or IIIC with routine healing
• G — subsequent encounter for closed fracture with delayed healing
• H — subsequent encounter for open fracture type I or II with delayed healing
• J — subsequent encounter for open fracture type IIIA, IIIB, or IIIC with delayed healing
• K — subsequent encounter for closed fracture with nonunion
• M — subsequent encounter for open fracture type I or II with nonunion
• N — subsequent encounter for open fracture type IIIA, IIIB, or IIIC with nonunion
• P — subsequent encounter for closed fracture with malunion
• Q — subsequent encounter for open fracture type I or II with malunion
• R — subsequent encounter for open fracture type IIIA, IIIB, or IIIC with malunion
• S — sequela

Medicare Code Edits (MCE v43.1 (April 2026))

• Unspecified code (laterality): Unspecified codes for which a more specific code identifying laterality (right, left, bilateral) exists within the same code family.

Code annotations containing back-references to S52.399K

Back-references to S52.3

• Type 2 Excludes: S52.1 Fracture of upper end of radius ("fracture of shaft of radius (S52.3-)")

Back-references to S52

• Type 1 Excludes: M84.3 Stress fracture ("traumatic fracture (S12.-, S22.-, S32.-, S42.-, S52.-, S62.-, S72.-, S82.-, S92.-)")
• Type 1 Excludes: M84.4 Pathological fracture, not elsewhere classified ("traumatic fracture (S12.-, S22.-, S32.-, S42.-, S52.-, S62.-, S72.-, S82.-, S92.-)")
• Type 1 Excludes: S51 Open wound of elbow and forearm ("open fracture of elbow and forearm (S52.- with open fracture 7th character)")
• Type 2 Excludes: S62 Fracture at wrist and hand level ("fracture of distal parts of ulna and radius (S52.-)")

Nearby codes

• S52.399E Other fracture of shaft of radius, unspecified arm, subsequent encounter for open fracture type I or II with routine healing
• S52.399F Other fracture of shaft of radius, unspecified arm, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with routine healing
• S52.399G Other fracture of shaft of radius, unspecified arm, subsequent encounter for closed fracture with delayed healing
• S52.399H Other fracture of shaft of radius, unspecified arm, subsequent encounter for open fracture type I or II with delayed healing
• S52.399J Other fracture of shaft of radius, unspecified arm, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with delayed healing
• S52.399K Other fracture of shaft of radius, unspecified arm, subsequent encounter for closed fracture with nonunion (this code)
• S52.399M Other fracture of shaft of radius, unspecified arm, subsequent encounter for open fracture type I or II with nonunion
• S52.399N Other fracture of shaft of radius, unspecified arm, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with nonunion
• S52.399P Other fracture of shaft of radius, unspecified arm, subsequent encounter for closed fracture with malunion
• S52.399Q Other fracture of shaft of radius, unspecified arm, subsequent encounter for open fracture type I or II with malunion
• S52.399R Other fracture of shaft of radius, unspecified arm, subsequent encounter for open fracture type IIIA, IIIB, or IIIC with malunion