Summary & Overview

HCPCS L5590: Preparatory Above-Knee Ischial-Level Socket, Non-Alignable

HCPCS Level II code L5590 denotes a preparatory above-knee/knee-disarticulation ischial-level socket prosthesis built as a non-alignable system with a pylon (no cover), SACH foot, and a laminated socket molded to a model. This code captures an interim prosthetic device used during the rehabilitation and fitting process after an above-knee or knee-disarticulation amputation. Nationally, standardized coding for preparatory prostheses supports continuity of care across prosthetics providers and payers and informs utilization of temporary devices that enable early mobility and gait training.

Key payers in scope include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise explanation of what the code represents, the clinical context for use, and the typical site of service. The publication covers billing benchmarks and reimbursement context where available, relevant policy updates affecting prosthetic coding, and clinical considerations tied to preparatory prosthesis use. Data not available in the input will be noted explicitly where gaps exist. The content is intended for national audiences including prosthetists, billing specialists, rehabilitation clinicians, and policy analysts seeking a clear summary of L5590 and its role in post-amputation care pathways.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicareL5590HCPCS Level IIprostheticsabove-knee amputationpreparatory prosthesisprosthetic fabricationoutpatient rehabilitationSACH foot

Billing Code Overview

HCPCS Level II code L5590 describes a preparatory, above knee to knee disarticulation ischial level socket prosthetic component. The code specifies a non-alignable system with pylon no cover, a SACH foot, and a laminated socket molded to model. This represents a fabricated transtibial/above-knee preparatory prosthesis intended for use following an above-knee or knee-disarticulation amputation.

Service type: Prosthetic fabrication and fitting (preparatory prosthesis)

Typical site of service: Prosthetics and orthotics clinic, outpatient rehabilitation center, or hospital-based prosthetics lab

Clinical & Coding Specifications

Clinical Context

A 58-year-old male with a history of peripheral arterial disease and chronic non-healing right lower-extremity wounds undergoes a transfemoral (above-knee) amputation at the distal femur/knee-disarticulation level. After surgical healing and residual limb stabilization, the patient is evaluated by a prosthetist in an outpatient orthotics and prosthetics clinic for fabrication of a preparatory above-knee (knee-disarticulation/ischial-level) socket prosthesis. The service described by L5590 is for a non-alignable system with a laminated socket, pylon without cover, and a SACH foot; the socket is molded to a positive model.

The clinical workflow includes:

Referral from the surgical team or physical medicine and rehabilitation physician to a certified prosthetist.
A prosthetic evaluation visit to assess limb volume, skin integrity, range of motion, strength, functional goals, and gait potential.
Casting or scanning of the residual limb and fabrication of a laminated socket molded to the model as the preparatory device.
Alignment and bench fitting with the pylon and SACH foot attached; initial adjustments for comfort and suspension.
Follow-up visits for fitting adjustments, gait training with a physical therapist, and documentation of functional progress.
Typical site of service: outpatient prosthetics clinic, orthotics and prosthetics facility, or hospital outpatient department for prosthetic fabrication and fitting.
Typical patient scenario: post-amputation rehabilitation phase requiring a preparatory prosthesis to enable early mobility, limb shaping, and progression toward a definitive, alignable prosthetic system.

Coding Specifications

Modifier	Description	When to Use
`LT`	Left side	Use when the preparatory prosthesis is for the left lower extremity.
`RT`	Right side	Use when the preparatory prosthesis is for the right lower extremity.
`KA`	Data not provided in the input.	Data not available in the input.
`52`	Reduced service	Use when the prosthesis is provided with reduced components or scope compared with the full service.
`59`	Data not provided in the input.	Data not available in the input.
`80`	Assistant surgeon	Use when a qualified assistant participates in surgical procedures related to limb amputation (applies to related surgical claims, not to prosthetic fabrication).
`62`	Two surgeons	Use when two surgeons are necessary for the related operative procedure (applies to related surgical claims).
`59`	Data not provided in the input.	Data not available in the input.
`78`	Return to OR	Use if the patient returns to the operating room for revision of the amputation prior to prosthetic fitting (applies to surgical claims).
`KX`	Necessity on file	Use when payer requires documentation of medical necessity for prosthetic components/services.
`AS`	Physician assistant, nurse practitioner, or clinical nurse specialist services	Use when the service is provided by a qualifying non-physician practitioner under applicable rules.
`NU`	New equipment	Use when the preparatory prosthesis is new equipment rather than repair or replacement.
`RR`	Recovery room	Use for billing related to facility recovery services when applicable (facility coding contexts).

Taxonomy Code	Specialty	Notes
`207L00000X`	Prosthetics/Orthotics	Certified prosthetist responsible for socket design and fitting.
`2080P0206X`	Physical Medicine & Rehabilitation	Physiatrist overseeing rehabilitation goals and prosthetic prescription.
`207P00000X`	Orthotist	Orthotist/prosthetist involved in component selection and alignment.
`208000000X`	Physical Therapist	Provides gait training and functional rehabilitation after fitting.
`207R00000X`	Prosthetist-Orthotist Assistant	Assists with fabrication and adjustments under the prosthetist's direction.

ICD-10 Code	Description	Clinical Relevance
`Z43.21`	Encounter for fitting and adjustment of lower limb prosthesis	Primary encounter code used when fitting a preparatory above-knee prosthesis.
`Z89.612`	Acquired absence of right leg above knee	Identifies the amputation level relevant to above-knee/proximal prosthetic fabrication.
`Z89.611`	Acquired absence of left leg above knee	Identifies the amputation level for left-sided prosthetic fabrication.
`I70.213`	Atherosclerosis of native arteries of right leg with ulceration	Common vascular etiology leading to amputation and need for prosthesis.
`T79.A11`	Traumatic amputation of right leg, initial encounter	Traumatic cause of limb loss requiring preparatory prosthesis.

CPT Code	Description	Relationship to This Procedure
`97760`	Orthotic management and training, initial encounter (including assessment and fit, with training in use of device)	Used for prosthetic training and functional mobility instruction after delivery of the preparatory prosthesis.
`97763`	Assistive technology evaluation(s) (e.g., seating, positioning, mobility device), initial or follow-up	Used when a comprehensive mobility-device evaluation is performed to determine appropriate prosthetic components and functional needs.
`11720`	Debridement of nail(s) or `99070`	Data not provided in the input.

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