ICD-10-CM > S00-T88 > S80-S89 > S80 > S80.2 > S80.22 > S80.221 S80.221 Blister (nonthermal), right knee Non-Billable/Non-Specific Codes S80.221A..., initial encounterS80.221D..., subsequent encounterS80.221S..., sequela