S66.316 Strain of extensor muscle, fascia and tendon of right little finger at wrist and hand level

ICD-10-CM Code S66.316: Strain of extensor muscle, fascia and tendon of right little finger at wrist and hand level

ICD-10-CM code S66.316 identifies a strain affecting the extensor muscle, fascia, and tendon of the right little finger at the wrist and hand level. This active diagnosis concept is a specific terminology record with no narrower child concepts. It is distinct from other specified finger extensor strains. 1 5

Plain-language overview

Code S66.316 represents an injury or poisoning event specifically involving a strain of the right little finger's extensor structures at the wrist and hand level. 1

What this code represents

The official preferred name for S66.316 is the strain of the extensor muscle, fascia, and tendon of the right little finger at the wrist and hand level. 1

S66.316 is an active terminology record that has no narrower child concepts within the ICD-10-CM version 2026 system, establishing it as a specific concept. 1

Coding details

The parent concept for S66.316 is S66.31, which covers strains of the extensor muscle, fascia, and tendon of other and unspecified fingers at the wrist and hand level. 1

While S66.316 specifies the right little finger, related codes in the same category distinguish other fingers, such as S66.311 for the left index finger. 4 6

Documentation considerations

The terminology record for S66.316 explicitly defines the anatomical elements of the diagnosis as the extensor muscle, fascia, and tendon of the right little finger at the wrist and hand level. 1

Related finger extensor strain codes listed in Medicare articles include encounter characters, such as A for initial or D for subsequent, within their full code formats. 4 6

What the sources add

National injury surveillance frameworks classify muscle and tendon injuries into a specific nature-of-injury category, separating them from sprains and strains. 2

Terminology records list S66.316 as a specific right little finger strain, while Medicare billing articles list related finger extensor strain codes during tendon injection discussions, showing distinct operational uses. 1 4

Sources

1. ICD-10-CM S66.316 terminology record — National Cancer Institute Enterprise Vocabulary Services; accessed 2026-07-27.
2. National Health Statistics Reports — cdc.gov; accessed 2026-07-27.
3. Bookshelf — ncbi.nlm.nih.gov; accessed 2026-07-27.
4. Article - Billing and Coding: Injections - Tendon, Ligament, Ganglion Cyst, Tunnel Syndromes and Morton's Neuroma (A57201) — cms.gov; accessed 2026-07-27.
5. EVS Explore — evsexplore.semantics.cancer.gov; accessed 2026-07-27.
6. Article - Billing and Coding: Injections - Tendon, Ligament, Ganglion Cyst, Tunnel Syndromes and Morton's Neuroma (A57079) — cms.gov; accessed 2026-07-27.