ICD-10-CM > M00-M99 > M65-M67 > M66 > M66.8 > M66.86 M66.86 Spontaneous rupture of other tendons, lower leg Non-Billable/Non-Specific Codes M66.861Spontaneous rupture of other tendons, right lower legM66.862Spontaneous rupture of other tendons, left lower legM66.869Spontaneous rupture of other tendons, unspecified lower leg