Prosthetics
CMS description
Addition to lower extremity, below knee/above knee, custom fabricated socket insert for congenital or atypical traumatic amputee, silicone gel, elastomeric or equal, for use with or without locking mechanism, initial only (for other than initial, use code l5673 or l5679)
In the order to send them
Why these codes
Prosthetic devices have their own STC; DME is the fallback.
If a payer returns nothing
Payers don't all answer every service type. Send 30 (Health Benefit Plan Coverage) for the plan's general benefits.
Sources
CMS HCPCS Level II descriptor; X12 HIPAA 5010 service type code definitions; VerifyTX billing practice

