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ICD-10-CM 2027 diagnosis code

S66.5Injury of intrinsic muscle, fascia and tendon of other and unspecified finger at wrist and hand level

Not billable — use a more specific codeRequires 7th character

S66.5 is a header code, so it can't be reported by itself. Choose one of the 4 more specific codes beneath it and add the required 7th character.Short description: Inj intrinsic musc/fasc/tend and unsp finger at wrs/hnd lv

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About S66.5

S66.5 is the ICD-10-CM diagnosis code for injury of intrinsic muscle, fascia and tendon of other and unspecified finger at wrist and hand level. It belongs to category S66 (injury of muscle, fascia and tendon at wrist and hand level), block S60-S69 (injuries to the wrist, hand and fingers) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is a header code, so it can't be reported by itself; one of its 4 subcodes must be used instead.

Within S66, choose S66.5 (intrinsic muscle, fascia and tendon of other and unspecified finger at wrist and hand level) only when documentation doesn't support a more specific option: long flexor muscle, fascia and tendon of thumb at wrist and hand level (S66.0), flexor muscle, fascia and tendon of other and unspecified finger at wrist and hand level (S66.1), extensor muscle, fascia and tendon of thumb at wrist and hand level (S66.2), extensor muscle, fascia and tendon of other and unspecified finger at wrist and hand level (S66.3), intrinsic muscle, fascia and tendon of thumb at wrist and hand level (S66.4), other specified muscles, fascia and tendons at wrist and hand level (S66.8) and unspecified muscle, fascia and tendon at wrist and hand level (S66.9).

Codes in this range require a 7th character: A for initial encounter, D for subsequent encounter and S for sequela. Use placeholder "X" characters to fill any empty positions before the 7th character.

The conditions in its Excludes2 note aren't part of S66.5, but may be coded alongside it if the patient has both: injury of intrinsic muscle, fascia and tendon of thumb at wrist and hand level (S66.4-).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

7th character

The appropriate 7th character is to be added to each code from category S66

  • Ainitial encounter
  • Dsubsequent encounter
  • Ssequela

Coding notes

Excludes2Not included here — may be reported together if both conditions exist
  • injury of intrinsic muscle, fascia and tendon of thumb at wrist and hand level (S66.4-)

Notes that apply from higher levels

Instructions written at a parent level also apply to S66.5.

› From S66 Injury of muscle, fascia and tendon at wrist and hand level
Excludes2
  • sprain of joints and ligaments of wrist and hand (S63.-)
Code also
  • any associated open wound (S61.-)

Broader instructions also apply from S60-S69 Injuries to the wrist, hand and fingers and Chapter 19: Injury, poisoning and certain other consequences of external causes.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about S66.5

Is S66.5 billable?

No. S66.5 is a header code. Report one of its more specific subcodes instead.