ICD-10-CM > S00-T88 > S60-S69 > S66 > S66.3 > S66.39 > S66.391 S66.391 Other injury of extensor muscle, fascia and tendon of left index finger at wrist and hand level Non-Billable/Non-Specific Codes S66.391A..., initial encounterS66.391D..., subsequent encounterS66.391S..., sequela