Spontaneous rupture of flexor tendons, left forearm

This code describes the non-traumatic tearing or breaking of one or more flexor tendons in the left forearm. This rupture occurs without an external force or injury, often due to underlying degenerative changes, inflammatory conditions, or systemic diseases.

Apply this code when documentation clearly indicates a spontaneous (non-traumatic) rupture of a flexor tendon in the patient's left forearm. This typically involves a sudden onset of pain, weakness, and loss of function in the affected digits or wrist, without a history of acute injury.

• Ensure documentation specifies "spontaneous" or "non-traumatic" to differentiate from traumatic ruptures.
• Verify the laterality is explicitly stated as "left forearm."
• Do not use for ruptures due to acute injury; those would be coded under S66.3- for flexor tendons at wrist and hand level.