Summary & Overview
HCPCS L1846: Custom Double‑Upright Knee Orthosis with Adjustable Joint
HCPCS Level II code L1846 identifies a custom-fabricated double-upright knee orthosis with adjustable flexion-extension joint and medial-lateral and rotational control. The code covers devices designed for complex knee instability, deformity correction, or postoperative protection where a custom fit and adjustable joint mechanics are required. Nationally, this code matters because custom orthoses can represent significant device cost, influence mobility and rehabilitation outcomes, and trigger specific coverage and documentation requirements across payers.
Key payers included in this analysis are Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of clinical indications and typical sites of service, a summary of payer coverage patterns and common modifiers used in billing for custom orthoses, and guidance on documentation elements commonly required by payers. The publication also summarizes benchmarks and policy considerations relevant to authorization, custom-fabrication justification, and claims adjudication workflows. Where input data is incomplete, the text notes "Data not available in the input." The content is intended for a national audience of billing managers, orthopedic device suppliers, and health policy analysts seeking a concise reference on coding, service context, and payer considerations for L1846.
Billing Code Overview
HCPCS Level II code L1846 describes a knee orthosis, double upright, thigh and calf, with adjustable flexion and extension joint (unicentric or polycentric), medial-lateral and rotation control, with or without varus/valgus adjustment, custom fabricated. This device is custom fabricated to provide mechanical stabilization and controlled range of motion for the knee joint, addressing complex instability, deformity, or postoperative protection.
Service type: Durable medical equipment — custom-fabricated knee orthosis
Typical site of service: Outpatient orthopedic clinics, prosthetics and orthotics facilities, rehabilitation centers, and specialty orthopedic device fabrication labs
Clinical & Coding Specifications
Clinical Context
A 62-year-old patient with post-traumatic instability of the knee presents to an orthopedic surgeon and a certified orthotist for evaluation. The patient reports recurrent episodes of giving way and pain after a complex tibial plateau fracture treated surgically one year prior. Examination demonstrates significant medial-lateral laxity and limited active knee control. The care team documents the need for a custom-fabricated knee orthosis with double upright construction and an adjustable flexion-extension joint to control rotation and varus/valgus forces.
The clinical workflow includes an orthopedic evaluation with gait and stability assessment, standing measurements and cast or 3D scan by the orthotist, fabrication of a custom L1846 orthosis, fitting and dynamic adjustment of the unicentric/polycentric joint for range limits, patient education on donning and doffing, and follow-up visits for device tuning and monitoring skin integrity and function. Typical sites of service are the orthotics/prosthetics clinic, outpatient orthopedic clinic, or ambulatory surgery center for complex fittings requiring minor procedures under local anesthesia (if needed for skin measures or adjustments).
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
LT | Left side | Use when the orthosis is furnished for the left lower extremity |