Varus deformity, not elsewhere classified, left ankle

This code describes an inward angulation of the left ankle joint, where the distal part of the limb deviates towards the midline of the body. This deformity can affect gait, weight-bearing, and overall foot and ankle mechanics. It is a structural abnormality not attributable to specific conditions classified elsewhere.

Apply this code when documentation specifies a varus deformity of the left ankle that is not congenital, post-traumatic, or due to a specific disease process with its own ICD-10-CM code. Clinical notes should clearly indicate "varus deformity" and specify the "left ankle." This code is appropriate for idiopathic or unspecified causes of varus angulation.

• Ensure the documentation explicitly states "varus" deformity, not "valgus" (which is an outward angulation).
• Verify the laterality is "left ankle." Use M21.171 for the right ankle or M21.173 for bilateral.
• Confirm that no more specific code exists for the underlying cause (e.g., congenital, post-traumatic, or arthritic). If a cause is identified, code that first.