ICD-10-CM > M00-M99 > M65-M67 > M66 > M66.3 > M66.34 M66.34 Spontaneous rupture of flexor tendons, hand Non-Billable/Non-Specific Codes M66.341Spontaneous rupture of flexor tendons, right handM66.342Spontaneous rupture of flexor tendons, left handM66.349Spontaneous rupture of flexor tendons, unspecified hand