Microprocessor-Controlled Prostheses for the Lower Limb

POLICY NUMBER

A.1.04.05

DESCRIPTION

Microprocessor-controlled prostheses use feedback from sensors to adjust joint movement on a real-time as-needed basis. Active joint control is intended to improve safety and function, particularly for patients who can maneuver on uneven terrain and with variable gait.

Lower-Extremity Prosthetics

More than 100 different prosthetic ankle-foot and knee designs are currently available. The choice of the most appropriate design may depend on the patient’s underlying activity level. For example, the requirements of a prosthetic knee in an elderly, largely homebound individual will differ from those of a younger, active person. Key elements of a prosthetic knee design involve providing stability during both the stance and swing phase of the gait. Prosthetic knees vary in their ability to alter the cadence of the gait, or the ability to walk on rough or uneven surfaces. In contrast to more simple prostheses, which are designed to function optimally at one walking cadence, fluid and hydraulic-controlled devices are designed to allow amputees to vary their walking speed by matching the movement of the shin portion of the prosthesis to the movement of the upper leg. For example, the rate at which the knee flexes after “toe-off” and then extends before the heel strike depends in part on the mechanical characteristics of the prosthetic knee joint. If the resistance to flexion and extension of the joint does not vary with gait speed, the prosthetic knee extends too quickly or too slowly relative to the heel strike if the cadence is altered. When properly controlled, hydraulic or pneumatic swing-phase controls allow the prosthetist to set a pace adjusted to the individual amputee, from very slow to a race-walking pace. Hydraulic prostheses are heavier than other options and require gait training; for these reasons, these prostheses are prescribed for athletic or fit individuals. Other design features include multiple centers of rotation, referred to as “polycentric knees.” The mechanical complexity of these devices allows engineers to optimize selected stance and swing-phase features.

According to the manufacturers, microprocessor-controlled prostheses are considered a class I device by the U.S. Food and Drug Administration (FDA) and are exempt from 510(k) requirements. This classification does not require submission of clinical data regarding efficacy, but only notification of the FDA prior to marketing.

POLICY

A microprocessor-controlled knee may be considered medically necessary in individuals with transfemoral amputation who meet the following requirements: 

• Demonstrated need for long distance ambulation at variable rates (use of the limb in the home or for basic community ambulation is not sufficient to justify provision of the computerized limb over standard limb applications) OR demonstrated patient need for regular ambulation on uneven terrain or for regular use on stairs (use of the limb for limited stair climbing in the home or employment environment is not sufficient evidence for prescription of this device over standard prosthetic application); AND

• Physical ability, including adequate cardiovascular and pulmonary reserve, for ambulation at faster than normal walking speed; AND 

• Adequate cognitive ability to master use and care requirements for the technology.

A microprocessor-controlled knee is considered investigational in individuals who do not meet these criteria. 

A powered knee is considered investigational.

A microprocessor-controlled or powered ankle-foot is considered investigational.

POLICY EXCEPTIONS

Federal Employee Program (FEP) may dictate that all devices, drugs or biologics approved by the FDA may not be considered investigational and thus, these devices may be assessed only on the basis of their medical necessity.

POLICY GUIDELINES

The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.

Amputees should be evaluated by an independent, qualified professional to determine the most appropriate prosthetic components and control mechanism. A trial period may be indicated to evaluate the tolerability and efficacy of the prosthesis in a real-life setting. Decisions about the potential benefits of microprocessor knees involve multiple factors including activity levels, as well as the individual's physical and cognitive ability. An individual's need for daily ambulation of at least 400 continuous yards, daily and frequent ambulation at variable cadence or on uneven terrain (e.g., gravel, grass, curbs), and daily and frequent use of ramps and/or stairs (especially stair descent) should be considered as part of the decision. Typically, the daily and frequent need of two or more of these activities would be needed to show benefit.

Individual Selection and Identification

For individuals in whom the potential benefits of the microprocessor knees are uncertain, individuals may first be fitted with a standard prosthesis to determine their level of function with the standard device.

The following are guidelines from the Veterans Health Administration Prosthetic Clinical Management Program Clinical Practice Recommendations for Microprocessor Knees.

1. Contraindications for the use of the microprocessor knee should include the following:

   • Any condition that prevents socket fitting, such as a complicated wound or intractable pain which precludes socket wear

   • Inability to tolerate the weight of the prosthesis

   • Medicare level K0—no ability or potential to ambulate or transfer

   • Medicare level K1—limited ability to transfer or ambulate on level ground at fixed cadence

   • Medicare level K2—limited community ambulator who does not have the cardiovascular reserve, strength, and balance to improve stability in stance to permit increased independence, less risk of falls, and potential to advance to a less restrictive walking device

   • Inability to use swing and stance features of the knee unit

   • Poor balance or ataxia that limits ambulation

   • Significant hip flexion contracture (>20°)

   • Significant deformity of remaining limb that would impair the ability to stride

   • Limited cardiovascular and/or pulmonary reserve or profound weakness

   • Limited cognitive ability to understand gait sequencing or care requirements

   • Long distance or competitive running

   • Falls outside of recommended weight or height guidelines of the manufacturer

   • Specific environmental factors—such as excessive moisture or dust, or inability to charge the prosthesis

   • Extremely rural conditions where maintenance ability is limited.

2. Indications for the use of the microprocessor knee should include the following:

   • Adequate cardiovascular and pulmonary reserve to ambulate at variable cadence

   • Adequate strength and balance in stride to activate the knee unit

   • Should not exceed the weight or height restrictions of the device

   • Adequate cognitive ability to master technology and gait requirements of the device

   • Hemi-pelvectomy through knee-disarticulation level of amputation, including bilateral; lower-extremity amputees are candidates if they meet functional criteria as listed

   • The individual is an active walker and requires a device that reduces energy consumption to permit longer distances with less fatigue

   • Daily activities or job tasks that do not permit full focus of concentration on knee control and stability—such as uneven terrain, ramps, curbs, stairs, repetitive lifting, and/or carrying

   • Medicare level K2—limited community ambulator, but only if improved stability in stance permits increased independence, less risk of falls, and potential to advance to a less restrictive walking device, and the individual has the cardiovascular reserve, strength, and balance to use the prosthesis. The microprocessor enables fine-tuning and adjustment of the hydraulic mechanism to accommodate the unique motor skills and demands of the functional level K2 ambulator.

   • Medicare level K3—unlimited community ambulator

   • Medicare level K4—active adult athlete who needs to function as a K3 level in daily activities

   • Potential to lessen back pain by providing more secure stance control, using less muscle control to keep the knee stable

   • Potential to unload and decrease stress on remaining limb

   • Potential to return to an active lifestyle.

3. Physical and Functional Fitting Criteria for New Amputees:

   • New amputees may be considered if they meet certain criteria as outlined above

   • Premorbid and current functional assessment important determinant

   • Requires stable wound and ability to fit the socket

   • Immediate postoperative fit is possible

   • Must have potential to return to an active lifestyle.

Medically Necessary is defined as those services, treatments, procedures, equipment, drugs, devices, items or supplies furnished by a covered Provider that are required to identify or treat a Member's illness, injury or Mental Health Disorders, and which Company determines are covered under this Benefit Plan based on the criteria as follows in A through D:

A.  consistent with the symptoms or diagnosis and treatment of the Member's condition, illness, or injury; and

B.  appropriate with regard to standards of good medical practice; and

C.  not solely for the convenience of the Member, his or her Provider; and

D.  the most appropriate supply or level of care which can safely be provided to Member. When applied to the care of an Inpatient, it further means that services for the Member's medical symptoms or conditions require that the services cannot be safely provided to the Member as an Outpatient.

For the definition of medical necessity, “standards of good medical practice” means standards that are based on credible scientific evidence published in peer-reviewed medical literature generally recognized by the relevant medical community, and physician specialty society recommendations, and the views of medical practitioners practicing in relevant clinical areas and any other relevant factors. BCBSMS makes no payment for services, treatments, procedures, equipment, drugs, devices, items or supplies which are not documented to be Medically Necessary. The fact that a Physician or other Provider has prescribed, ordered, recommended, or approved a service or supply does not in itself, make it Medically Necessary.

Investigative is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized as a generally accepted standard of good medical practice for the treatment of the condition being treated and; therefore, is not considered medically necessary. For the definition of Investigative, “generally accepted standards of medical practice” means standards that are based on credible scientific evidence published in peer-reviewed medical literature generally recognized by the relevant medical community, and physician specialty society recommendations, and the views of medical practitioners practicing in relevant clinical areas and any other relevant factors. In order for equipment, devices, drugs or supplies [i.e, technologies], to be considered not investigative, the technology must have final approval from the appropriate governmental bodies, and scientific evidence must permit conclusions concerning the effect of the technology on health outcomes, and the technology must improve the net health outcome, and the technology must be as beneficial as any established alternative and the improvement must be attainable outside the testing/investigational setting.

POLICY HISTORY

7/27/2006: Approved by Medical Policy Advisory Committee (MPAC).

7/20/2007: Policy reviewed, description updated. Policy statement revised; microprocessor-controlled knee prosthesis changed from investigational to may be considered medically necessary in amputees who meet criteria as outlined in policy. Non-covered codes table removed. Covered codes table added. HCPCS L5856, L5857, and L5858 moved to covered. ICD-9 codes 897.2-897.7 and V43.65 added.

11/15/2007: Revised policy approved by MPAC.

4/27/2010: Title changed from "Prosthetic Knees" to "Prostheses for the Lower Limb." Description section revised to include ankle-foot prostheses information. Policy statement section was revised to add two new policy statements regarding ankle-foot and powered knee prostheses; these are considered investigational. FEP verbiage was added to the Policy Exceptions section. Code Reference section was revised to add the following language: "*Some covered procedure codes may have multiple descriptions. Coverage will only be made for covered codes when used for services outlined within the policy statement."

04/20/2011: Policy reviewed; no changes.

04/26/2012: Policy reviewed; no changes.

12/21/2012: Added the following new 2013 CPT code to the Code Reference section: L5859.

04/19/2013: Policy reviewed; no changes.

04/24/2014: Policy reviewed; description updated regarding available devices for microprocessor-controlled prosthetic knees and ankle-foot prostheses. Policy statement unchanged.

08/27/2015: Code Reference section updated to add ICD-10 codes.

09/10/2015: Policy description updated regarding devices. Policy statements unchanged. Policy guidelines section updated regarding the evaluation of amputees; added medically necessary and investigative definitions.

05/31/2016: Policy number A.1.04.05 added.

10/26/2017: Policy description updated regarding devices. Investigational statement updated to change "powered foot" to "powered ankle-foot."

04/27/2018: Policy description updated regarding outcome measures for microprocessor-controlled lower-limb prostheses. Policy statements unchanged. Policy Guidelines updated regarding patient selection and identification.

04/11/2019: Policy description revised to remove devices. Medically necessary policy statement updated to change "amputees" to "individuals with transfemoral amputation."

12/20/2019: Code Reference section updated to add new HCPCS code L2006 effective 01/01/2020.

04/14/2020: Policy reviewed; no changes.

04/01/2022: Policy reviewed. Policy statements unchanged. Policy Guidelines updated to change "Nervous/Mental Conditions" to "Mental Health Disorders" and "Medically Necessary" to "medical necessity." Code Reference section updated to add HCPCS code K1014.

08/15/2023: Policy reviewed. Policy statement updated to change "not medically necessary" to "investigational." Policy Guidelines updated to change "patients" to "individuals." Code Reference section updated to add HCPCS code L5973 as investigational.

12/21/2023: Code Reference section updated to add new 2024 HCPCS code L5615, effective 01/01/2024.

04/17/2024: Policy reviewed; no changes.

01/01/2025: Code Reference section updated to remove HCPCS code L2006 and deleted code K1014.

04/01/2025: Code Reference section updated to add new HCPCS code L5827, effective 04/01/2025.

04/16/2025: Policy reviewed; no changes.

SOURCE(S)

Blue Cross Blue Shield Association Policy # 1.04.05

CODE REFERENCE

This may not be a comprehensive list of procedure codes applicable to this policy.

The code(s) listed below are ONLY medically necessary if the procedure is performed according to the "Policy" section of this document.

Covered Codes

Investigational Codes

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