ICD-10-CM > M00-M99 > M65-M67 > M66 > M66.2 > M66.25 M66.25 Spontaneous rupture of extensor tendons, thigh Non-Billable/Non-Specific Codes M66.251Spontaneous rupture of extensor tendons, right thighM66.252Spontaneous rupture of extensor tendons, left thighM66.259Spontaneous rupture of extensor tendons, unspecified thigh