Spontaneous rupture of flexor tendons, unspecified hand

This code signifies a non-traumatic tear of the flexor tendons in an unspecified hand, occurring without an external force or injury. It typically results from underlying degenerative changes, inflammatory conditions, or chronic impingement rather than an acute event.

Apply this code when documentation clearly indicates a spontaneous (atraumatic) rupture of a flexor tendon in the hand, and the specific hand (right or left) is not specified. This diagnosis is often supported by physical examination findings, patient history ruling out trauma, and imaging studies like ultrasound or MRI confirming the tendon tear.

• Ensure the documentation explicitly states "spontaneous" or "atraumatic" to differentiate from traumatic ruptures.
• Avoid using this code if the specific hand (right or left) is documented; instead, use the more specific M66.341 or M66.342.
• Consider co-reporting with codes for underlying conditions (e.g., rheumatoid arthritis, chronic tenosynovitis) if they are documented as contributing factors.