ICD-10-CM > M00-M99 > M60-M63 > M63 > M63.8 > M63.86 M63.86 Disorders of muscle in diseases classified elsewhere, lower leg Non-Billable/Non-Specific Codes M63.861Disorders of muscle in diseases classified elsewhere, right lower legM63.862Disorders of muscle in diseases classified elsewhere, left lower legM63.869Disorders of muscle in diseases classified elsewhere, unspecified lower leg