ICD-10-CM > S00-T88 > S50-S59 > S56 > S56.5 > S56.59 S56.59 Other injury of other extensor muscle, fascia and tendon at forearm level Non-Billable/Non-Specific Codes S56.591Other injury of other extensor muscle, fascia and tendon at forearm level, right armS56.591A..., initial encounterS56.591D..., subsequent encounterS56.591S..., sequelaS56.592Other injury of other extensor muscle, fascia and tendon at forearm level, left armS56.592A..., initial encounterS56.592D..., subsequent encounterS56.592S..., sequelaS56.599Other injury of other extensor muscle, fascia and tendon at forearm level, unspecified armS56.599A..., initial encounterS56.599D..., subsequent encounterS56.599S..., sequela