Spontaneous rupture of flexor tendons, unspecified thigh

This code signifies a non-traumatic tear or break in the flexor tendons located in an unspecified thigh. This condition typically results from degenerative changes within the tendon rather than an acute injury or external force. Patients often present with sudden pain, weakness, or loss of function in the affected thigh.

Assign this code when documentation clearly indicates a spontaneous (atraumatic) rupture of a flexor tendon in the thigh, and the specific thigh (right or left) is not documented. This code is appropriate when the rupture is not due to an external injury, overuse, or a surgical complication. Supporting documentation should specify "spontaneous," "atraumatic," or "non-traumatic" rupture.

• Avoid using this code if the rupture is due to a traumatic event; instead, refer to the S76 category for injury of muscle, fascia, and tendon at thigh level.
• Do not use this code if the specific thigh (right or left) is documented; instead, select M66.351 for right thigh or M66.352 for left thigh.
• Ensure the documentation explicitly states "flexor tendons" to differentiate from extensor tendon ruptures.