Spontaneous rupture of flexor tendons, left hand

This code signifies a non-traumatic tear of a flexor tendon in the left hand. This rupture occurs without an external force or injury, often due to underlying degenerative changes, inflammatory conditions, or chronic overuse. It results in an inability to actively flex the affected digit(s).

Use this code when documentation clearly indicates a spontaneous (non-traumatic) rupture of one or more flexor tendons in the patient's left hand. This diagnosis is typically supported by physical examination findings demonstrating loss of active flexion, and may be confirmed by imaging such as ultrasound or MRI.

• Ensure documentation specifies "spontaneous" or "nontraumatic" to differentiate from traumatic ruptures.
• Verify the laterality is explicitly stated as "left hand."
• Do not confuse with M66.341 (right hand) or M66.349 (unspecified hand).