Summary & Overview
HCPCS L5321: Above-Knee Molded Socket with SACH Foot, Single-Axis Knee
HCPCS Level II code L5321 identifies a complete above-knee prosthetic assembly featuring a molded, open-end socket with a SACH foot, endoskeletal support, and a single-axis knee. This code matters nationally as it specifies a common prosthetic configuration used in post-amputation mobility care and is central to coverage, pricing, and clinical decision pathways for lower-limb prosthetic services. Payers commonly engaged in coverage for this code include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare.
Readers will find an overview of clinical context for L5321, how the item aligns with typical prosthetic service lines and sites of care, and what to expect in claims handling and payer coverage discussions. The publication summarizes benchmark considerations, common modifier usage and billing practice notes, and highlights policy or coding guidance relevant to prosthetic device billing. Where payer-specific policy details are available, the analysis outlines coverage criteria and documentation expectations. Data not available in the input is identified plainly.
Billing Code Overview
HCPCS Level II code L5321 describes a prosthetic component: above knee, molded socket, open end, SACH foot, endoskeletal system, single axis knee. This item represents a laminated or molded transtibial/ transfemoral prosthetic socket built for an above-knee amputation and configured with an open-end design, incorporating a Solid Ankle Cushion Heel (SACH) foot, an endoskeletal pylon or support system, and a single-axis knee joint.
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Service type: Prosthetic device fabrication and fitting for an above-knee prosthesis
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Typical site of service: Outpatient prosthetics and orthotics clinic or specialty prosthetic fabrication shop
Clinical & Coding Specifications
Clinical Context
A 68-year-old male patient with a transfemoral (above-knee) amputation presents to a specialty prosthetics clinic for fabrication and fitting of a definitive above-knee prosthesis. The patient has a well-healed residual limb with stable volume, intact skin, and demonstrated ability to bear weight on the socket during pre-prosthetic training. The prosthetic prescription calls for an above-knee, molded socket with an open end, endoskeletal system, a SACH (solid ankle cushioned heel) foot, and a single-axis knee joint, corresponding to the HCPCS Level II code L5321.
The clinical workflow includes: initial evaluation by a prosthetist with review of medical history and surgical notes; measurement and casting or digital scanning of the residual limb; fabrication of a custom molded socket and endoskeletal pylon and components; bench alignment and assembly of the SACH foot and single-axis knee; fitting appointment with static and dynamic alignment checks; gait training with a physical therapist; and follow-up adjustments for socket comfort and function. Typical documentation includes the prosthetic order, limb measurements or scan, component manufacturer and model, alignment notes, patient's functional level, goals, and justification for component selection.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
LT | Left side | Applied when the prosthesis is for the left lower extremity |