S89.399K Other physeal fracture of lower end of unspecified fibula, subsequent encounter for fracture with nonunion

Billable ICD-10-CM code, FY2026.

Built from S89.399 with 7th character K (subsequent encounter for fracture with nonunion).

Applies from S89 Other and unspecified injuries of lower leg

Excludes2 (not included here)

• other and unspecified injuries of ankle and foot (S99.-)

7th character note

• The appropriate 7th character is to be added to each code from subcategories S89.0, S89.1, S89.2, and S89.3

Notes

• A fracture not indicated as open or closed should be coded to closed

7th character required

• A — initial encounter for closed 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

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 S89.399K

Back-references to S89

• Type 2 Excludes: M23 Internal derangement of knee ("current injury - see injury of knee and lower leg (S80-S89)")

Nearby codes

• S89.392S Other physeal fracture of lower end of left fibula, sequela
• S89.399 Other physeal fracture of lower end of unspecified fibula
• S89.399A Other physeal fracture of lower end of unspecified fibula, initial encounter for closed fracture
• S89.399D Other physeal fracture of lower end of unspecified fibula, subsequent encounter for fracture with routine healing
• S89.399G Other physeal fracture of lower end of unspecified fibula, subsequent encounter for fracture with delayed healing
• S89.399K Other physeal fracture of lower end of unspecified fibula, subsequent encounter for fracture with nonunion (this code)
• S89.399P Other physeal fracture of lower end of unspecified fibula, subsequent encounter for fracture with malunion
• S89.399S Other physeal fracture of lower end of unspecified fibula, sequela
• S89.8 Other specified injuries of lower leg
• S89.80 Other specified injuries of unspecified lower leg
• S89.80XA Other specified injuries of unspecified lower leg, initial encounter