S66.124 Laceration of flexor muscle, fascia and tendon of right ring finger at wrist and hand level

ICD-10-CM Code S66.124: Laceration of flexor muscle, fascia and tendon of right ring finger at wrist and hand level

ICD-10-CM code S66.124 identifies a laceration of the flexor muscle, fascia, and tendon of the right ring finger at the wrist and hand level. Flexor tendons are cord-like tissues on the palm side that bend the fingers. Injuries to these tendons complicate palmar lacerations and restoring digital function after such an injury remains a challenging clinical dilemma in hand surgery. 3 6 2

Plain-language overview

Flexor tendons are cord-like tissues on the palm side of the hand that attach muscles to bones, allowing the fingers to bend. An injury to these tendons frequently complicates lacerations to the palmar surface of the digit and hand. 6 2

What this code represents

Code S66.124 is assigned the semantic type of injury or poisoning and specifically denotes a laceration of the flexor muscle, fascia, and tendon of the right ring finger at the wrist and hand level. 3

Coding details

The base code S66.124 expands into encounter-specific variants including S66.124A for initial encounter, S66.124D for subsequent encounter, and S66.124S for sequela. A distinct left ring finger code, S66.125, also exists. 5

The code tree distinguishes this right ring finger laceration from an unspecified injury of the same anatomical structure, S66.104, and from a strain of the right ring finger at the wrist and hand level, S66.114D. 5

Documentation considerations

Clinical assessment of a flexor tendon injury involves correlating the laceration, overlying skin injury, and mechanism of injury. The position of the finger during injury, such as flexion or extension, helps determine the actual level of the tendinous insult relative to the skin wound. 2

Clinical context

Flexor tendon lacerations can be subcategorized as partial lacerations, complete lacerations, and tendon avulsion injuries. Restoration of satisfactory digital function after an unrepaired flexor tendon laceration or failed repair remains a challenging operative dilemma. 2

What the sources add

While S3 defines the specific diagnosis of a right ring finger flexor laceration, S2 provides broader clinical context that flexor tendon injuries complicate palmar lacerations and involve subcategories like partial or complete lacerations. 3 2

The coding reference S5 provides the specific hierarchical structure and encounter variants for S66.124, whereas the clinical reference S6 explains the anatomical function of the involved flexor tendons in bending the fingers. 5 6

Coverage and utilization context

A Centers for Medicare and Medicaid Services article references an adjacent but distinct code, S56.115D for a strain of the right ring finger flexor muscle at the forearm level, within the context of billing and coding for tendon injections. 4

Sources

1. Bookshelf — ncbi.nlm.nih.gov; accessed 2026-07-25.
2. Bookshelf — ncbi.nlm.nih.gov; accessed 2026-07-25.
3. EVS Explore — evsexplore.semantics.cancer.gov; accessed 2026-07-25.
4. Article - Billing and Coding: Injections - Tendon, Ligament, Ganglion Cyst, Tunnel Syndromes and Morton's Neuroma (A57079) — cms.gov; accessed 2026-07-25.
5. ICD-10-CM 2024 | S66.1 - Injury of flexor muscle, fascia and tendon of other and unspecified finger at wrist and hand level — unboundmedicine.com; accessed 2026-07-25.
6. Hand and Wrist Care - Princeton Orthopaedic Associates — princetonorthopaedic.com; accessed 2026-07-25.