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    v1.0.28
    OpenPayerBilling CodesProsthetic ProceduresHCPCS hcpcs-l8420-prosthetic-sock-below-knee-multiple-ply
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    HCPCS L8420: Prosthetic Sock, Multiple Ply, Below Knee, Each

    HCPCS Level II code L8420 describes a single below-knee prosthetic sock, specified as a multiple-ply sock used with a lower-limb prosthesis; the service is durable medical equipment for prosthetic socket interface/liner needs and the typical site of service is an outpatient orthotics/prosthetics clinic or durable medical equipment supplier where prosthetic fitting and supply occur.

    For related coverage guidance, see recent payer policy updates: Clinical Review Criteria — Lymphedema Therapy and Training (Complete Decongestive Therapy; LVA), Therapy Services — Electric Stimulation for Pain, Swelling and Function in a Clinic Setting, Site of Care: Outpatient Hospital Setting for Physical and Occupational Therapy.

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    Table of contents

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    Clinical & Coding Specifications

    Clinical Context

    A 68-year-old patient with a transtibial (below-knee) amputation due to peripheral arterial disease presents to a prosthetics clinic for routine follow-up and socket fit assessment. The prosthetist evaluates volume fluctuations in the residual limb and determines the patient requires one or more prosthetic socks to improve socket fit and comfort. A single L8420 item (prosthetic sock, multiple ply, below knee, each) is supplied and documented in the durable medical equipment record. The clinical workflow includes: initial assessment by the prosthetist, measurement of residual limb circumference, selection of appropriate sock ply and quantity, fitting with the prosthetic socket, patient education on sock use and wear schedule, and documentation of the item, diagnosis code(s), supplier details, and any applicable modifier (for laterality or billing circumstance). Typical site of service is an outpatient prosthetics clinic or durable medical equipment supplier location.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    97760Orthotic(s) management and training, upper and/or lower extremity, initial encounter, 15 minutesUsed for patient education and training on prosthetic sock use and donning/doffing techniques
    97763Orthotic(s)/prosthetic(s) management and training, initial encounter, each additional 15 minutesUsed for extended training sessions beyond the initial time unit
    99213Office or other outpatient visit for the evaluation and management of an established patient, low to moderate complexityUsed when the prosthetist or clinician performs a focused follow-up visit addressing socket fit and supply needs
    99456Work related or medical disability examination services (including completing forms)May be used when documentation for work-related prosthetic supply justification is required
    L4364Insert, supplemental, interface (e.g., gel liner), below knee, eachOften furnished in conjunction with prosthetic socks as part of socket interface management

    Related Modifiers

    5 rows

    ModifierDescriptionWhen to Use
    52Modifier ‑52 (Reduced Services) indicates that a service or procedure was partially reduced or omitted at the provider’s discretion, allowing reporting of the basic procedure number with a qualifier…- Use modifier -52 when a physician or qualified health professional electively reduces or omits part of a procedure or service (for example, performing fewer required views or omitting a portion of…
    59Modifier 59 indicates a distinct procedural service when two procedures that are not normally billed together are clinically and procedurally separate. The CPT definition (as reiterated by CMS)…- Use modifier -59 to report a distinct procedural service when documentation supports that the procedure reported is not normally billed together with another service on the same day because of a…
    [object Object]
    3PThe CPT Category II modifier -3P denotes a performance‑measure exclusion when a required quality action was not performed because of system‑level constraints. It is appended only to Category II…- When to apply: Use CPT Category II modifier 3P only with Category II (‘‘F’’) codes when a specific quality measure’s specifications allow a system‑level exclusion — append 3P to indicate the…
    23Modifier -23 (Unusual Anesthesia) is used on anesthesia service CPT codes when a procedure that normally requires no anesthesia or only local anesthesia must be performed under general anesthesia…- Use modifier -23 only on anesthesia CPT codes (00100–01999) when a procedure that normally requires no anesthesia or only local anesthesia must be performed under general anesthesia because of…

    Related Provider Taxonomies

    8 rows

    Taxonomy CodeSpecialtyNotes
    332B00000XDurable Medical Equipment & Medical SuppliesA supplier of medical equipment such as respirators, wheelchairs, home dialysis systems, or monitoring systems, that are prescribed by a physician for…
    208M00000XHospitalist PhysicianHospitalists are physicians whose primary professional focus is the general medical care of hospitalized patients. Their activities include patient ca…
    207L00000XAnesthesiology PhysicianAn anesthesiologist is trained to provide pain relief and maintenance, or restoration, of a stable condition during and immediately following an opera…
    207K00000XAllergy & Immunology PhysicianAn allergist-immunologist is trained in evaluation, physical and laboratory diagnosis, and management of disorders involving the immune system. Select…
    103TM1700XDeactivated - Psychologist Men & Masculinity
    261QC1500XCommunity Health Clinic/CenterAmbulatory Health Care Facilities · Clinic/Center
    251K00000XPublic Health or Welfare AgencyAgencies · Public Health or Welfare
    152WX0102XOccupational Vision OptometristOptometrists who work in Occupational Vision, the branch of environmental optometry, consider all aspects of the relationship between work and vision,…

    Related ICD-10-CM Codes

    23 rows

    ICD-10-CM CodeDescription
    B86Scabies
    E11.621Type 2 diabetes mellitus with foot ulcer
    G54.6Phantom limb syndrome with pain
    G57.61Lesion of plantar nerve, right lower limb
    G62.9Polyneuropathy, unspecified
    I83.10Varicose veins of unspecified lower extremity with inflammation
    I83.90Asymptomatic varicose veins of unspecified lower extremity
    L97.102Non-pressure chronic ulcer of unspecified thigh with fat layer exposed
    L97.303Non-pressure chronic ulcer of unspecified ankle with necrosis of muscle
    L97.401Non-pressure chronic ulcer of unspecified heel and midfoot limited to breakdown of skin

    Showing 1–10 of 23

    Related Payer Policy Updates

    Specialty: Physical Medicine, Rehab & Therapies1 / 2

    10 rows

    PolicyPayerEffective Date
    Clinical Review Criteria — Lymphedema Therapy and Training (Complete Decongestive Therapy; LVA)Kaiser Permanente2026-09-01
    Therapy Services — Electric Stimulation for Pain, Swelling and Function in a Clinic SettingCigna2026-08-15
    Site of Care: Outpatient Hospital Setting for Physical and Occupational TherapyCigna2026-08-15
    Habilitation and Rehabilitation Therapy (Occupational, Physical, and Speech)Colorado Rocky Mountain Health Plans2026-08-01
    Cognitive Rehabilitation and Coma Stimulation (for Tennessee Only)UnitedHealthcare2026-08-01
    Habilitation and Rehabilitation Therapy (Occupational, Physical, and Speech) (for Kentucky Only)UnitedHealthcare2026-08-01
    Home Traction Therapy (for Pennsylvania Only)UnitedHealthcare2026-08-01
    Habilitation and Rehabilitation Therapy (Occupational, Physical, and Speech) (for Florida Only)Colorado Rocky Mountain Health Plans2026-08-01
    Habilitation and Rehabilitation Therapy (Occupational, Physical, and Speech) (for Pennsylvania Only)UnitedHealthcare2026-08-01
    Habilitation and Rehabilitation Therapy (Occupational, Physical, and Speech) (for North Carolina Only)UnitedHealthcare2026-08-01

    Related Codes

    HCPCS-L5000-PARTIAL-FOOT-SHOE-INSERT-LONGITUDINAL-ARCH-TOE-FILLER

    HCPCS Level II L5000: Partial Foot Shoe Insert with Longitudinal Arch, Toe Filler

    HCPCS-L5010-PARTIAL-FOOT-MOLDED-SOCKET-ANKLE-HEIGHT-TOE-FILLER

    HCPCS L5010: Partial Foot Molded Socket, Ankle Height, With Toe Filler

    HCPCS-L5020-PARTIAL-FOOT-MOLDED-SOCKET-TIBIAL-TUBERCLE-TOE-FILLER

    HCPCS L5020: Partial Foot Molded Socket with Toe Filler

    HCPCS-L5050-ANKLE-SYMES-MOLDED-SOCKET-SACH-FOOT

    HCPCS L5050: Ankle/Symes Molded Socket with SACH Foot

    HCPCS-L5060-ANKLE-SYMES-METAL-FRAME-MOLDED-LEATHER-SOCKET-ARTICULATED-ANKLE-FOOT

    HCPCS L5060: Ankle/Symes Metal Frame with Molded Leather Socket

    HCPCS-L5100-BELOW-KNEE-MOLDED-SOCKET-SHIN-SACH-FOOT

    HCPCS Level II L5100: Below-Knee Molded Socket with Shin and SACH Foot

    HCPCS-L5105-BELOW-KNEE-PLASTIC-SOCKET-SACH-FOOT

    HCPCS L5105: Below-Knee Plastic Socket Prosthesis with SACH Foot

    HCPCS-L5150-KNEE-DISARTICULATION-MOLDED-SOCKET-EXTERNAL-KNEE-SACH-FOOT

    HCPCS L5150: Knee Disarticulation Molded Socket with External Knee and SACH Foot

    HCPCS-L5160-KNEE-DISARTICULATION-MOLDED-SOCKET-BENT-KNEE-SACH-FOOT

    HCPCS Level II L5160: Knee Disarticulation Molded Socket, Bent Knee Configuration

    HCPCS-L5200-ABOVE-KNEE-MOLDED-SOCKET-SINGLE-AXIS-KNEE-SACH-FOOT

    HCPCS Level II L5200: Above-knee Prosthesis with Molded Socket and Single-axis Knee

    Showing 1–10 of 472

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    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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