Summary & Overview
HCPCS L5855: Endoskeletal Hip Prosthesis Addition, Mechanical Extension Assist
HCPCS Level II code L5855 represents an addition to an endoskeletal prosthetic system for patients with hip disarticulation, specifically a mechanical hip extension assist. This code is used when a component is added to an existing endoskeletal hip prosthesis to aid hip extension during standing, gait, and transfers. Nationally, the code is relevant to prosthetics coverage, durable medical equipment policy, and clinical management of high‑level lower‑extremity amputees.
Key payers covered include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical context and service setting, along with payer coverage considerations, common modifiers, and where to find related coding guidance. The publication provides benchmarking context and policy implications for coverage determination, prior authorization, and documentation requirements, and summarizes practical coding notes for billing departments and prosthetics providers.
The content is organized to help administrators, billing professionals, and clinicians understand the code’s clinical purpose, typical site of service, and the aspects of reimbursement and documentation most commonly associated with prosthetic component additions. Data not available in the input will be noted where applicable.
Billing Code Overview
HCPCS Level II code L5855 describes an addition to an endoskeletal prosthetic system for hip disarticulation that provides a mechanical hip extension assist. The code denotes a component added to an existing endoskeletal prosthesis designed for patients with hip disarticulation amputation to assist with hip extension during gait and transfers.
Service type: Prosthetic component addition (endoskeletal hip prosthesis)
Typical site of service: Prosthetics and orthotics clinic or outpatient prosthetic fitting center
Clinical & Coding Specifications
Clinical Context
A patient with a prior hip disarticulation amputation presents for prosthetic component augmentation to improve limb alignment and gait function. Typical candidates are adults with transfemoral-level or hip-disarticulation-level limb loss who have an existing endoskeletal prosthesis and require an added mechanical hip extension assist to restore hip stability and extension during stance and swing. The clinical workflow includes: pre-prosthetic evaluation by a prosthetist and physiatrist or orthopedic surgeon; gait analysis and measurement of the residual limb and socket interface; selection of an appropriate mechanical hip extension assist (addition to the endoskeletal system); fabrication and bench testing of the component; in-clinic fitting and alignment; iterative gait training with physical therapy; documentation of baseline function, limb measurements, component serial number, and objective outcome measures (e.g., walking distance, timed-up-and-go); and follow-up visits for adjustments and maintenance. Typical site of service is an outpatient prosthetics clinic, orthotics and prosthetics facility, or rehabilitation hospital prosthetics lab. Typical modifiers that may appear on claims include LT/RT for laterality, RR/RT when billing Rental-related services, and payer-specific service modifiers such as UE for unusual prosthetic componentry when required by the payer.
Coding Specifications
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