Spontaneous rupture of extensor tendons, left forearm

This code signifies a non-traumatic, sudden tearing of the extensor tendons located in the left forearm. This condition typically results from underlying degenerative changes within the tendon itself, rather than an acute injury. It leads to an inability to extend the fingers or wrist.

Apply this code when documentation explicitly states a spontaneous rupture of extensor tendons affecting the left forearm. This diagnosis is often supported by physical examination findings demonstrating loss of active extension and imaging studies confirming tendon discontinuity without evidence of acute trauma.

• Differentiate from traumatic ruptures, which are coded differently (e.g., S66.312A).
• Ensure the laterality (left forearm) is clearly documented and matches the code.
• Look for documentation of underlying conditions that may predispose to spontaneous rupture, such as rheumatoid arthritis, which would be coded additionally.