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Microprocessor-Controlled Prostheses for Lower-Extremity Amputees
11.14.21l

Policy

MEDICALLY NECESSARY​

MICROPROCESSOR-CONTROLLED PROSTHETIC KNEES
The microprocessor-controlled prosthetic knee system is considered medically necessary and, therefore, covered as a component fitting in a lower-limb prosthesis for individuals who meet all of the following criteria:
  • The individual is motivated to ambulate.
  • The individual has high mobility and stance stability needs and is at a functional level of 3 or 4 according to Medicare's classification scale of patient potential functional ability as described below:
    • Level 0: Does not have the ability or potential to ambulate or transfer safely with or without assistance, and a prosthesis does not enhance their quality of life or mobility (Level K0).
    • Level 1: Has the ability or potential to use a prosthesis for transfers or ambulation on level surfaces at fixed cadence. Typical of the limited and unlimited household ambulator (Level K1).
    • Level 2: Has the ability or potential for prosthetic ambulation with the ability to traverse low-level environmental barriers such as curbs, stairs, or uneven surfaces. Typical of the limited community ambulator (Level K2).
    • Level 3: Has the ability or potential for prosthetic ambulation with variable cadence. Typical of the community ambulator who has the ability to traverse most environmental barriers and may have vocational, therapeutic, or exercise activity that demands prosthetic utilization beyond simple locomotion (Level K3).
    • Level 4: Has the ability or potential for prosthetic ambulation that exceeds basic ambulation skills, exhibiting high impact, stress, or energy levels. Typical of the prosthetic demand of the child, active adult, or athlete (Level K4).
NOT MEDICALLY NECESSARY

All other uses for a microprocessor-controlled prosthetic knee not meeting the above criteria are considered not medically necessary and, therefore, not covered because the available published peer-reviewed literature does not support their use in the treatment of illness or injury. 

ENHANCEMENTS, DELUXE SUPPLIES, CONVENIENCE FEATURES 

Enhancements or deluxe supplies or convenience features that do not serve or contribute towards any clinically established physiological and/or functional improvements are benefit contract exclusions for most plans, and, therefore, not eligible for reimbursement consideration. Individual benefits must be verified. 

For plans that do not have a benefit contract exclusion for enhancements or deluxe supplies or convenience features that do not serve or contribute towards any clinically established physiological and/or functional improvements,​ the use of these features for a microprocessor-controlled prosthetic knee are considered not medically necessary and, therefore, not covered because the available published peer-reviewed literature does not support their use in the treatment of illness or injury. 

Examples of these enhancements or deluxe supplies or convenience features include, but are not limited to: 

  • Duplication or upgrade of a functional prosthesis; or
  • Prosthetic devices or prosthetic components that are primarily for cosmesis; or
  • Prosthetics used for activities other than normal daily living, including, but may not be limited to, those utilized for leisure or sporting activities such as skiing or swimming; or
  • Repair or replacement of a prosthesis for appearance, comfort, convenience or individual abuse, misuse or neglect; or
  • Repair or replacement of parts of a duplicate prosthesis; or
  • Test sockets for an immediate prosthesis; or
  • Water prosthesis (designed to be used for showering, swimming, etc.).   
  • Passive/restorative devices (such as silicone devices) to make the limb more life-like;
  • Custom-shaped prosthetic covers unless there is medical function and documentation of medical need. Custom-made prosthetic covers are typically made of foam that is cosmetically shaped to the person's limb.
EXPERIMENTAL/INVESTIGATIONAL

POWERED AND PROGRAMMABLE FLEXION/EXTENSION ASSIST-CONTROL PROSTHETIC KNEES
A powered and programmable flexion/extension assist-control prosthetic knee is considered experimental/investigational and, therefore, not covered because the safety and/or effectiveness of this service cannot be established by review of the available published peer-reviewed literature.

MICROPROCESSOR-CONTROLLED PROSTHETIC ANKLE-FOOT SYSTEMS
The microprocessor-controlled prosthetic ankle-foot system is considered experimental/investigational and, therefore, not covered because the safety and/or effectiveness of this device have not been established by review of the available published peer-reviewed literature.

POWER-ASSIST ANKLE-FOOT PROSTHETIC SYSTEMS
The power-assist ankle-foot prosthetic system is considered experimental/investigational, and, therefore, not covered because the safety and/or effectiveness of this device have not been established by review of the available published peer-reviewed literature.

REPAIR AND REPLACEMENT

For information on the repair and/or replacement of prostheses, refer to the Company's policy on the repair and replacement of external prosthetic devices.

REQUIRED DOCUMENTATION

Reimbursement for devices will be made only if there is sufficient documentation in the individual's medical record showing current functional capabilities and functional need for the technological or design features. Documentation should also include expected functional potential and an explanation if there is a difference between the individual's current status and expected potential. This information must be retained in the professional provider's or prosthetist's files, and be available upon request.

Documentation should also include identification and compliance with all the qualifications for utilization of a microprocessor-controlled prosthetic knee listed in this policy, which conform with the recommendations of the Veterans Health Administration Prosthetic Clinical Management Program Clinical Practice Recommendations for Microprocessor Knees (2000).

The prosthetist must retain documentation in the medical record of the prosthesis or prosthetic component replaced, the reason for replacement, and a description of the labor involved. It is recognized that there are situations where the reason for replacement includes but is not limited to: changes in the residual limb; functional need changes; or irreparable damage or wear and tear due to excessive patient weight or prosthetic demands of highly mobile amputees.

The Company may conduct reviews and audits of services to our members regardless of the participation status of the provider. Medical record documentation must be maintained on file to reflect the medical necessity of the care and services provided. These medical records may include but are not limited to: records from the professional provider’s office, hospital, nursing home, home health agencies, therapies, and test reports.

PRESCRIPTION (ORDER) REQUIREMENTS
Before submitting a claim to the Company, the supplier must have on file a timely, appropriate, and complete order for each item billed that is signed and dated by the professional provider who is treating the member. Requesting a provider to sign a retrospective order at the time of an audit or after an audit for submission as an original order, reorder, or updated order will not satisfy the requirement to maintain a timely professional provider order on file.

PROOF OF DELIVERY
Medical record documentation must include a contemporaneously prepared delivery confirmation or member’s receipt of supplies and equipment. The medical record documentation must include a copy of delivery confirmation if delivered by a commercial carrier and a signed copy of delivery confirmation by member/caregiver if delivered by the supplier/provider. All documentation is to be prepared contemporaneous with delivery and be available to the Company upon request.

CONSUMABLE SUPPLIES
The durable medical equipment (DME) supplier must monitor the quantity of accessories and supplies an individual is actually using. Contacting the individual regarding replenishment of supplies should not be done earlier than approximately 7 days prior to the delivery/shipping date. Dated documentation of this contact with the individual is required in the individual’s medical record. Delivery of the supplies should not be done earlier than approximately 5 days before the individual would exhaust their on-hand supply.

If required documentation is not available on file to support a claim at the time of an audit or record request, the DME supplier may be required to reimburse the Company for overpayments.

BILLING REQUIREMENTS

Inclusion of a code in this policy does not imply reimbursement. Eligibility, benefits, limitations, exclusions, precertification/referral requirements, provider contracts, and Company policies apply.

There are specific HCPCS codes that describe microprocessor-controlled knee prostheses. Reimbursement for additional features, functions, or components of a microprocessor-controlled knee prosthesis are included in the allowance of the existing specific HCPCS codes described in this policy. For example, there is no separate payment for a component or feature of a microprocessor-controlled knee, including but not limited to real-time gait analysis, continuous gait assessment, or electronically controlled static stance regulator.

For any microprocessor-controlled knee system, the use of additional HCPCS codes other than the existing HCPCS codes described in this policy that are used to represent microprocessor-controlled prosthetic knees, and/or the use of a not otherwise classified code, are not eligible for reimbursement consideration.

When submitting a claim, the billed HCPCS code for a microprocessor-controlled prosthesis must be submitted with functional level modifiers K0 -​ K4 and laterality modifiers RT or LT.

Guidelines

A microprocessor-controlled prosthesis is prescribed with the goal of enabling an individual with a lower-limb amputation to return to, and engage in, their activities of daily living. This entails the procurement of a prosthetic device that is appropriate for their individual level of activity, ability, and weight.

Qualifications for utilization of microprocessor-controlled prosthetic knees should include all of the following:
  • The individual is an active walker (e.g., more than 3 miles per day) and requires a device that reduces energy consumption to permit longer distances with less fatigue.
  • The individual requires a prosthesis that can accommodate sudden changes in direction and speed for work or home activities, with the potential or ability for improved gait quality and speed (e.g., faster than 3 miles per hour).
  • The individual participates in daily activities or job tasks that do not permit full attention on knee control and stability (e.g., repetitive lifting and/or carrying, frequent negotiation of uneven terrain, ramps, curbs, and stairs).
  • The prosthesis should not be initially prescribed or utilized primarily for athletic purposes.
  • The individual has adequate cognitive ability to master the technology and gait requirements of the prosthesis.
  • The individual has adequate cardiovascular and pulmonary reserve to ambulate at variable cadence while using the prosthesis.
  • The individual does not have a documented comorbid condition that would interfere with maintaining functional level 3 or 4 (e.g., peripheral vascular, neuromuscular, or musculoskeletal [other than amputation]).
  • The individual has adequate strength, balance, and stride to activate the knee unit.
  • The individual does not exceed the weight or height restrictions of the device.
  • Use of the prosthesis gives the individual the potential to return to an active lifestyle.
  • Individuals with a hemipelvectomy through knee disarticulation level of amputation, including bilateral lower-extremity amputees, are candidates if they meet the functional medically necessary criteria.
BENEFIT APPLICATION

Subject to the terms and conditions of the applicable benefit contract, a microprocessor-controlled prosthetic knee is covered under the medical benefits of the Company’s products when the medical necessity criteria listed in this medical policy are met.

However, devices that are identified in this policy as experimental/investigational are not eligible for coverage or reimbursement by the Company.

REPAIR OR REPLACEMENT
Coverage of the repair or replacement of prosthetic devices and associated supplies and components (parts) may vary by product and/or group contract. Therefore, individual member benefits must be verified.

US FOOD AND DRUG ADMINISTRATION (FDA) STATUS

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

MANDATES

For members enrolled in New Jersey products, refer to the applicable Orthotic and Prosthetic mandate.

Description

Following a lower-limb amputation and after the appropriate healing of the surgical site, an individual may consider the use of a prosthetic leg to begin rehabilitation efforts in learning to ambulate.


More than 100 different prosthetic ankle-foot and knee designs are currently available. The choice of the most appropriate design may depend on the individual'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 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 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.


MICROPROCESSOR-CONTROLLED PROSTHETIC KNEES


Multiple prosthetic devices are available that use varying degrees of computer technology to enhance basic mechanical knee designs. Recently, prosthetic devices with a microprocessor-controlled knee have become available, including the C-Leg® and Genium™ Bionic Prosthetic System (Otto Bock Orthopedic Industry, Minneapolis, MN), the Intelligent Prosthesis (IP) (Blatchford & Sons, UK), the Rheo Knee® (Össur, Iceland), and Seattle Powered Knees (three models include Single Axis, 4-bar and Fusion, from Seattle Systems). These devices are equipped with a sensor that can detect when the knee is in full extension and automatically adjust the swing phase of the individual's gait, allowing for a more natural walking pattern at varying speeds. The C-Leg® is also designed to improve stance control. In addition, sensors may be able to detect a stumble and stiffen the knee to avoid a fall.


Microprocessor-controlled prosthetic knees have been developed, including the Intelligent Prosthesis (Blatchford); the Adaptive (Endolite); the Rheo Knee® (Össur); the C-Leg®, Genium™ Bionic Prosthetic System, and the X2 and X3 prostheses (Otto Bock Orthopedic Industry); and Seattle Power Knees (three models include Single Axis, 4-bar, and Fusion, from Seattle Systems). These devices are equipped with a sensor that detects when the knee is in full extension and adjusts the swing phase automatically, permitting a more natural walking pattern of varying speeds. The prosthetist can specify several different optimal adjustments that the computer later selects and applies according to the pace of ambulation. Also, these devices (except the Intelligent Prosthesis) use microprocessor control in both the swing and stance phases of gait. (The C-Leg Compact provides only stance control.) By improving stance control, such devices may provide increased safety, stability, and function. For example, the sensors are designed to recognize a stumble and stiffen the knee, thus avoiding a fall. Other potential benefits of microprocessor-controlled knee prostheses are improved ability to navigate stairs, slopes, and uneven terrain and reduction in energy expenditure and concentration required for ambulation. In 1999, the C-Leg was cleared for marketing by the US Food and Drug Administration (FDA) through the 510(k) process (K991590). Next-generation devices such as the Genium Bionic Prosthetic system and the X2 and X3 prostheses use additional environmental input (e.g., gyroscope and accelerometer) and more sophisticated processing that is intended to create more natural movement. One improvement in function is step-over-step stair and ramp ascent. They also allow the user to walk and run forward and backward. The X3 (Genium X3) is a more rugged version of the X2 that can be used in water, sand, and mud. The X2 and X3 were developed by Otto Bock as part of the Military Amputee Research Program.


Microprocessor-controlled prosthetic knees may provide incremental benefits for individuals who meet the need for the technological or design features of the device. Individuals who are considered most likely to benefit from this prosthesis have both the potential and the need for frequent ambulation at variable cadence, frequent negotiation of uneven terrain, and/or recurrent usage of stairs. The potential to achieve a high functional level with a microprocessor-controlled prosthetic knee requires the appropriate physical and cognitive abilities to utilize the advanced technology.


In 2000, the Veterans Administration Technology Assessment Program issued a report on computerized lower-limb prostheses. This report offered the following observations and conclusions:

  • Energy requirements of ambulation (vs. requirements with conventional prostheses) are decreased at walking speeds slower or faster than the amputee's customary speed but do not differ significantly at customary speeds.
  • Results on the potentially improved ability to negotiate uneven terrain, stairs, or inclines are mixed. Such benefits, however, could be particularly important to meeting existing deficits in the reintegration of amputees to normal living, particularly those related to decreased recreational opportunities.
  • Users' perceptions of the microprocessor-controlled prosthesis are favorable. Where such decisions are recorded or reported, most study participants choose not to return to their conventional prosthesis or to keep these only as a backup to acute problems with the computerized one.
  • Users' perceptions may be particularly important for evaluating a lower-limb prosthesis, given the magnitude of the loss involved, along with the associated difficulty of designing and collecting objective measures of recovery or rehabilitation. However resilient the human organism or psyche, loss of a limb is unlikely to be fully compensated. A difference between prostheses sufficient to be perceived as distinctly positive to the amputee may represent the difference between coping and a level of function recognizably closer to the preamputation level.

Systematic Reviews​


Thibaut et al. (2022) conducted a systematic review including studies of microprocessor prosthetic knees in individuals with lower limb amputation. The authors identified 18 studies (seven randomized controlled trials (RCTs) [later determined five RCTs were the same study reporting different outcomes], six cross-sectional studies, and five follow-up studies). All RCTs were cross-over studies. Overall, the authors found better functional status and mobility with microprocessor prosthetic knees, but it remains unclear whether there are differences among various models of microprocessor prosthetic knees.


In a systematic review and meta-analysis of microprocessor prosthetic knees in limited community ambulators, Hahn et al. (2022) identified 13 studies (N=2366; n=704 limited community ambulators). In limited community ambulators, microprocessor prosthetic knees had improved outcomes in terms of falls, fear of falling, risk of falling, and mobility grade when compared with nonmicroprocessor prosthetic knees.


Nonrandomized Trials


The primary literature consists of small (sample range, 7–50 individuals) within-subject comparisons of microprocessor-controlled with nonmicroprocessor-controlled prostheses in transfemoral amputees. Medicare Functional Level K2 describes a limited community ambulator who is able to traverse low barriers, such as curbs, and walk with a fixed cadence. Medicare Functional Level K3 describes a community ambulator who is able to traverse most barriers at variable cadence and may have activities beyond basic locomotion. Medicare Functional Level K4 exceeds basic ambulation skills and includes activities with high impact or stress that would be performed by a child, athlete, or active adult. The C-Leg compact provides stance control only and has been tested primarily in the more limited Medicare Functional Level K2 amputees. The C-Leg, which provides both stance and swing control, has been tested in Medicare Functional Level K3 and K4 amputees, in addition to Medicare Functional Level K2 amputees.


About half of the studies first tested participants with their own nonmicroprocessor prosthesis followed by an acclimation period and testing with the microprocessor-controlled knee. The other studies used an alternating or randomized order, with more than one test session for each type of prosthesis. Most studies compared performance in laboratory activities and about half also included a period of home use.


Results of these studies can be summarized as such:

  • In K2 ambulators, the C-Leg and C-Leg compact improved performance on simulated activities of daily living that required balance, for walking on level ground and ramps, and led to a faster time to stand up from a seated position and move forward (Timed Up & Go test). In the single study that measured activity levels at home, use of a microprocessor-controlled knee did not increase objectively measured activity.
  • In studies that included K2 to K3 ambulators, use of a microprocessor-controlled knee increased balance, mobility, speed, and distance compared with performance using the participant's prosthesis. In studies that included independent or proficient community ambulators, the greatest benefit was for the descent of stairs and hills. Normal walking speed was not increased. In a study that primarily included K2 ambulatory, there was a reduction in falls demonstrated by the change from baseline while using a microprocessor knee and an increase in falls with reversion to a nonmicroprocessor knee.
  • In studies that included K3 to K4 ambulators, use of a prosthesis with a microprocessor-controlled knee resulted in a more natural gait, and an increase in activity at home. Participants voiced a strong preference for the microprocessor knee.
  • Irrespective of the Medicare Functional Level from K2 to K4, all studies reported that participants preferred the C-Leg or C-Leg compact over their nonmicroprocessor prosthesis.

A cross-sectional study by Alzeer et al. (2022) identified 38 individuals who had been fitted with microprocessor prosthetic knees (Genium) and 38 individuals fitted with various nonmicroprocessor prosthetic knees. Individual-reported outcomes were measured with the Prosthesis Evaluation Questionnaire (PEQ). Total average PEQ scores were higher among individuals with microprocessor prostheses (82.14 vs. 73.53; P=0.014). Utility (78.41 vs. 68.20; P=0.025) and ambulation (75.61 vs. 59.11; P=0.003) were also significantly improved. This study indicates improved quality of life outcomes in individuals with microprocessor prosthetic knees compared with nonmicroprocessor varieties, but is limited by its small size and observational nature.


Overall, the literature consists of systematic reviews and a number of small within-subject comparisons of microprocessor-controlled knees with nonmicroprocessor-controlled knee joints. Studies of prostheses with microprocessor knees in Medicare Functional Level K3 and K4 amputees have shown objective improvements in function on some outcome measures and strong individual preference for the microprocessor-controlled prosthetic knees. The evidence in Medicare Functional Level K2 ambulators suggests that a prosthesis with stance control only can improve activities that require balance and improve walking in this population.


POWERED AND PROGRAMMABLE FLEXION/EXTENSION ASSIST-CONTROL PROSTHETIC KNEES


In development are lower-limb prostheses that also replace muscle activity in order to bend and straighten the prosthetic joint. For example, according to the manufacturer, the Power Knee™ (Ossur Foothill Ranch, CA), is designed to replace muscle activity of the quadriceps. It is proposed that the Power Knee™ delivers active lifting power for stairs, resistance for downhill slopes, and gentle propulsion for level ground walking. These devices use artificial proprioception with sensors similar to the Proprio Foot® (Ossur, Alsio Viejo, CA) in order to anticipate and respond with the appropriate movement required for the next step in time and space. The Power Knee™ is currently in the initial launch phase in the United States.


MICROPROCESSOR-CONTROLLED PROSTHETIC ANKLE-FOOT SYSTEMS

​​

Microprocessor-controlled prosthetic ankle-foot systems for lower-extremity amputees are devices designed to adjust to environmental impediments such as uneven terrain, inclines, and stairs. The device usually consists of four parts: a power storing foot, a lithium battery and charger, a battery-powered prosthetic flexing ankle, and a microprocessor with Terrain Logic™ that controls both dorsiflexion and plantarflexion in response to changing landscape conditions. The Proprio Foot® (Ossur, Alsio Viejo, CA) is currently available for low- to moderate-impact use for transtibial amputees who are classified as Level K3 (i.e., community ambulatory, with the ability or potential for ambulation with variable cadence). Available published peer-reviewed literature evaluating the use of microprocessor-controlled prosthetic ankle-foot systems is limited and consists mainly of pilot studies and case series involving small samples sizes (Fradet et al., 2010; Alimusaj et al., 2009, Wolf et al 2009).


POWER-ASSIST ANKLE-FOOT PROSTHETIC SYSTEMS


Power-assist ankle-foot prosthetic systems replace muscle activity of the foot, Achilles tendon, and calf muscle in order to bend and straighten the prosthetic joint. For example, transtibial amputees use muscle activity from the remaining limb for the control of ankle movement. Power-assist ankle-foot prosthetic systems are designed to propel the foot forward as it pushes off the ground during the gait cycle, which is proposed to improve efficiency, and has the potential to reduce hip and back problems arising from an unnatural gait with use of passive prostheses. This power-assist technology may be limited by the size and the weight required for a motor and batteries in the prosthesis.


The limited evidence with small sample size in available published peer-reviewed literature does not support an improvement in functional outcomes with a power-assist ankle-foot prosthetic system compared to standard prostheses (Gates et al. 2013; Ferris et al., 2012).


SUMMARY


The evidence includes a number of within-subject comparisons of microprocessor-controlled knees versus nonmicroprocessor-controlled knee joints and systematic reviews of these studies for individuals who have a transfemoral amputation who receive a prosthesis with a microprocessor-controlled knee. Relevant outcomes are functional outcomes, health status measures, and quality of life. For K3- and K4-level amputees, studies have shown an objective improvement in function on some outcome measures, particularly for hill and ramp descent, and strong patient preference for microprocessor-controlled prosthetic knees. Benefits include a more normal gait, increased stability, and a decrease in falls. The evidence in Medicare level K2 ambulators suggests that a prosthesis with stance control only can improve activities that require balance and improve walking in this population. For these reasons, a microprocessor-controlled knee may provide incremental benefit for these individuals. The potential to achieve a higher functional level with a microprocessor-controlled knee includes having the appropriate physical and cognitive ability to use the advanced technology. The evidence is sufficient to determine that the technology results in an improvement in the net health outcome.​


For individuals who have a transfemoral amputation who receive a prosthesis with a powered knee, the evidence includes no data. Relevant outcomes are functional outcomes, health status measures, and quality of life. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.


For individuals who have a tibial amputation who receive a prosthesis with a microprocessor-controlled ankle-foot, the evidence includes limited data. Relevant outcomes are functional outcomes, health status measures, and quality of life. The limited evidence available to date does not support an improvement in functional outcomes using microprocessor-controlled ankle-foot prostheses compared with standard prostheses, although quality of life improvements were noted in one small study. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.


For individuals who have a tibial amputation who receive a prosthesis with a powered ankle-foot, the evidence includes limited data. Relevant outcomes are functional outcomes, health status measures, and quality of life. The limited evidence available to date does not support an improvement in functional outcomes using powered ankle-foot prostheses compared with standard prostheses. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

References

Alimusaj M, Fradet L, Braatz F, et al. Kinematics and kinetics with an adaptive ankle foot system during stair ambulation of transtibial amputees. Gait Posture. 2009;30(3):356-363. 


Alzeer AM, Bhaskar Raj N, Shahine EM, et al. Impacts of Microprocessor-Controlled Versus Non-microprocessor-Controlled Prosthetic Knee Joints Among Transfemoral Amputees on Functional Outcomes: A Comparative Study. Cureus. 2022;14(4):e24331. ​


Au S, Berniker M, Herr H. Powered ankle-foot prosthesis to assist level-ground and stair-descent gaits. Neural Netw. 2008;21(4):654-666. 

Bellmann M, Schmalz T, Ludwigs E et al. Immediate effects of a new microprocessor-controlled prosthetic knee joint: a comparative biomechanical evaluation. Arch Phys Med Rehabil. 2012;93(3):541-549.

Buckley JG, Spence WD, Solomonidis SE. Energy cost of walking: Comparison of “intelligent prosthesis” with conventional mechanism. Arch Phys Med Rehabil. 1997;78(3):330-333.

Burnfield JM, Eberly VJ, Gronely JK, et al. Impact of stance phase microprocessor-controlled knee prosthesis on ramp negotiation and community walking function in K2 level transfemoral amputees. Prosthet Orthot Int. 2012;36(1):95-104. 

Cacciola CE, Kannenberg A, Hibler KD, Howell J. Impact of a Powered Prosthetic Ankle-Foot Component on Musculoskeletal Pain in Individuals with Transtibial Amputation: A Real-World Cross-Sectional Study with Concurrent and Recalled Pain and Functional Ratings. J Prosthet Orthot. 2024;36(1):2-9.

Carse B, Scott H, Brady L, et al. Evaluation of gait outcomes for individuals with established unilateral transfemoral amputation following the provision of microprocessor controlled knees in the context of a clinical service. Prosthet Orthot Int. 2021;45(3):254-261. ​

Colas-Ribas C, Martinet N, Audat G, et al. Effects of a microprocessor-controlled ankle-foot unit on energy expenditure, quality of life, and postural stability in persons with transtibial amputation: An unblinded, randomized, controlled, cross-over study. Prosthet Orthot Int. 2022;46(6):541-548. 

Darter BJ, Wilken JM. Energetic consequences of using a prosthesis with adaptive ankle motion during slope walking in persons with a transtibial amputation. Prosthet Orthot Int. 2014;38(1):5-11.

Datta D, Heller B, Howitt J. A comparative evaluation of oxygen consumption and gait pattern in amputees using Intelligent Prostheses and conventionally damped knee swing-phase control. Clin Rehabil. 2005;19(4):398-403.

Datta D, Howitt J. Conventional versus microchip controlled pneumatic swing phase control for trans-femoral amputees: User’s verdict. Prosthet Orthot Int. 1998;22(2):129-135.

Darter BJ, Wilken JM. Energetic consequences of using a prosthesis with adaptive ankle motion during slope walking in persons with a transtibial amputation. Prosthet Orthot Int. 2014;38(1):5-11.

Delussu AS, Brunelli S, Paradisi F, et al. Assessment of the effects of carbon fiber and bionic foot during overground and treadmill walking in transtibial amputees. Gait Posture. 2013;38(4):876-882.

Eberly VJ, Mulroy SJ, Gronley JK, et al. Impact of a stance phase microprocessor-controlled knee prosthesis on level walking in lower functioning individuals with a transfemoral amputation. Prosthet Orthot Int. 2014;38(6):447-455.

Ferris AE, Aldridge JM, Rábago CA, et al. Evaluation of a powered ankle-foot prosthetic system during walking. Arch Phys Med Rehabil. 2012;93(11):1911-1918.

Flynn K. Short Report: Computerized lower limb prosthesis (VA Technology Assessment Program). No. 2. Boston, MA: Veterans Health Administration; 2000.​

Fradet L, Alimusaj M, Braatz F, et al. Biomechanical analysis of ramp ambulation of transtibial amputees with an adaptive ankle foot system. Gait Posture. 2010;32(2):191-198.

Gailey RS, Gaunaurd I, Agrawal V, et al. Application of self-report and performance-based outcome measures to determine functional differences between four categories of prosthetic feet. J Rehabil Res Dev. 2012;49(4):597-612. 

Gates DH, Aldridge JM, Wilken JM. Kinematic comparison of walking on uneven ground using powered and unpowered prostheses. Clin Biomech. 2013;28(4):467-472.

Hafner BJ, Smith DG. Differences in function and safety between Medicare Functional Classification Level-2 and -3 transfemoral amputees and influence of prosthetic knee joint control. J Rehabil Res Dev. 2009;46(3):417-433. ​

Hafner BJ, Willingham LL, Buell NC, et al. Evaluation of function, performance, and preference as transfemoral amputees transition from mechanical to microprocessor control of the prosthetic knee. Arch Phys Med Rehabil. 2007;88(2): 207-217.

Hahn A, Bueschges S, Prager M, et al. The effect of microprocessor controlled exo-prosthetic knees on limited community ambulators: systematic review and meta-analysis. Disabil Rehabil. 2022;44(24):7349-7367. 

Herr HM, Grabowski AM. Bionic ankle-foot prosthesis normalizes walking gait for persons with leg amputation. Proc Biol Sci. 2012;279(1728):457-464. 

Highsmith MJ, Kahle JT, Bongiorni DR, et al. Safety, energy efficiency, and cost efficacy of the C-Leg for transfemoral amputees: A review of the literature. Prosthet Orthot Int. 2010;34(4):362-377.

Highsmith MJ, Kahle JT, Miro RM, et al. Ramp descent performance with the C-Leg and interrater reliability of the Hill Assessment Index. Prosthet Orthot Int. 2013;37(5):362-368.

Hofstad C, Linde H, Limbeek J, et al. Prescription of prosthetic ankle-foot mechanisms after lower limb amputation. Cochrane Database Syst Rev. 2004;2004(1):CD003978. ​

Howard CL, Wallace C, Perry B, et al. Comparison of mobility and user satisfaction between a microprocessor knee and a standard prosthetic knee: a summary of seven single-subject trials. Int J Rehabil Res. 2018;41(1):63-73. 

Johansson JL, Sherrill DM, Riley PO, et al. A clinical comparison of variable-damping and mechanically passive prosthetic knee devices. Am J Phys Med Rehabil. 2005;84(8):563-575. ​

Kannenberg A, Zacharias B, Pröbsting E. Benefits of microprocessor-controlled prosthetic knees to limited community ambulators: Systematic review. J Rehabil Res Dev. 2014;51(10):1469-1496. Available at: http://www.rehab.research.va.gov/jour/2014/5110/jrrd-2014-05-0118.html. Accessed November 16, 2020.

Kaufman KR, Levine JA, Brey RH, et al. Gait and balance of transfemoral amputees using passive mechanical and microprocessor-controlled prosthetic knees. Gait Posture. 2007;26(4):489-493. 

Kaufman KR, Levine JA, Brey RH, et al. Energy expenditure and activity of transfemoral amputees using mechanical and microprocessor-controlled prosthetic knees. Arch Phys Med Rehabil. 2008;89(7):1380-1385. 

Kaufman KR, Bernhardt KA, Symms K. Functional assessment and satisfaction of transfemoral amputees with low mobility (FASTK2): A clinical trial of microprocessor-controlled vs. non-microprocessor-controlled knees. Clin Biomech (Bristol). 2018;58:116-122.​

Kirker S, Keymer S, Talbot J, et al. An assessment of the intelligent knee prosthesis. Clin Rehabil.1996;10(3):267-273.

Klute GK, Berge JS, Orendurff MS, et al. Prosthetic intervention effects on activity of lower-extremity amputees. Arch Phys Med Rehabil. 2006;87(5):717-722. ​

Mancinelli C, Patritti BL, Tropea P, et al. Comparing a passive-elastic and a powered prosthesis in transtibial amputees. Annu Int Conf IEEE Eng Med Biol Soc. 2011;2011:8255-8258. ​

New Jersey (NJ) Legislature. P.L. 2007, Chapter 345. Senate No. 502. Requires health benefits coverage by health insurers and SHBP for orthotic and prosthetic appliances and provides reimbursement. [NJ State Legislature Web site]. 01/13/08. (N.J.S.A. 17:48E-35.30, effective April 11, 2008). Available at: https://www.nj.gov/dobi/bulletins/blt08_10.pdf​. Accessed December 05, 2023.

Noridian. Local Coverage Determination (LCA). A52946: Lower limb prostheses. [Noridian website]. Original 10/01/2015. (Revised 08/01/2020). Available at: https://med.noridianmedicare.com/documents/2230703/7218263/Lower+Limb+Prostheses+LCD+and+PA/d3244c51-74d3-4214-a789-7481bc2e03d5. Accessed November 16, 2020.

Noridian. Local Coverage Determination (LCD). L33787: Lower limb prostheses. [Noridian website]. Original 10/01/2015. (Revised 01/01/2020). Available at: https://med.noridianmedicare.com/documents/2230703/7218263/Lower+Limb+Prostheses+LCD+and+PA/d3244c51-74d3-4214-a789-7481bc2e03d5. Accessed November 16, 2020.

Orendurff MS, Segal AD, Klute GK, et al. Gait efficiency using the C-Leg. J Rehabil Res Dev. 2006;43(2):239-246. 

Prinsen EC, Nederhand MJ, Olsman J, et al. Influence of a user-adaptive prosthetic knee on quality of life, balance confidence, and measures of mobility: a randomised cross-over trial. Clin Rehabil. 2015;29(6):581-591.

Seymour R, Engbretson B, Kott K, et al. Comparison between the C-leg microprocessor-controlled prosthetic knee and non-microprocessor control prosthetic knees: A preliminary study of energy expenditure, obstacle course performance, and quality of life survey. Prosthet Orthot Int. 2007;31(1):51-61.

Swanson E, Stube J, Edman P. Function and body image levels in individuals with transfemoral amputations using the C-Leg. J Prosthet Orthot. 2005;17(3):80-84.

Taylor MB, Clark E, Offord EA, Baxter C. A comparison of energy expenditure by a high level trans-femoral amputee using the Intelligent Prosthesis and conventionally damped prosthetic limbs. Prosthet Orthot Int.1996;20(2):116-121.

Theeven P, Hemmen B, Rings F, et al. Functional added value of microprocessor-controlled knee joints in daily life performance of Medicare Functional Classification Level-2 amputees. J Rehabil Med. 2011;43(10):906-915. 

Theeven PJ, Hemmen B, Geers RP, et al. Influence of advanced prosthetic knee joints on perceived performance and everyday life activity level of low-functional persons with a transfemoral amputation or knee disarticulation. J Rehabil Med. 2012;44(5):454-461. ​

Thibaut A, Beaudart C, Maertens DE, et al. Impact of microprocessor prosthetic knee on mobility and quality of life in patients with lower limb amputation: a systematic review of the literature. Eur J Phys Rehabil Med. 2022;58(3):452-461. 

Thomas-Pohl M, Villa C, Davot J, et al. Microprocessor prosthetic ankles: comparative biomechanical evaluation of people with transtibial traumatic amputation during standing on level ground and slope. Disabil Rehabil Assist Technol. Jan 2021; 16(1): 17-26. PMID 31535903.​

US Department of Veterans Affairs, Veterans Health Administration. Office of Research and Development, Health Service Research and Development Service, Management Decision and Research Center, Technology Assessment Program. Computerized lower limb prosthesis. VA Technology Assessment Program Short Report No. 2. 2000. Available at: https://www.research.va.gov/resources/pubs/docs/ta_short_3_00.pdf. Accessed November 16, 2020.

US Food and Drug Administration (FDA). Center for Devices and Radiological Health. C-Leg® (3C100). 510(k) summary. [FDA Web site]. 07/08/99. Available at:
http://www.accessdata.fda.gov/cdrh_docs/pdf/k991590.pdf. Accessed November 16, 2020.

VA/DoD Clinical Practice Guideline for Rehabilitation of Individuals with Lower Limb Amputation (2017). Available at: https://www.healthquality.va.gov/guidelines/Rehab/amp/VADoDLLACPG092817.pdf. Accessed November 16, 2020.

Veterans Health Administration. Prosthetic clinical management program (PCMP). Clinical practice recommendations: Microprocessor knees. 2004. See: Berry D. Microprocessor prosthetic knees. Phys Med Rehabil Clin N Am. 2006;17:91-113.

Webster JB, Crunkhorn A, Sall J, et al. Clinical Practice Guidelines for the Rehabilitation of Lower Limb Amputation: An Update from the Department of Veterans Affairs and Department of Defense. Am J Phys Med Rehabil. 2019;98(9):820-829. ​

Williams RM, Turner AP, Orendurff M, et al. Does having a computerized prosthetic knee influence cognitive performance during amputee walking? Arch Phys Med Rehabil. 2006;87(7):989-994. 

Wolf SI, Alimusaj M, Fradet L, Siegel J, Braatz F. Pressure characteristics at the stump/socket interface in transtibial amputees using an adaptive prosthetic foot. Clin Biomech (Bristol). 2009 Dec;24(10):860-5.

Coding

CPT Procedure Code Number(s)
N/A
ICD - 10 Procedure Code Number(s)
N/A
ICD - 10 Diagnosis Code Number(s)
N/A
HCPCS Level II Code Number(s)
MEDICALLY NECESSARY

THE FOLLOWING CODES ARE USED TO REPRESENT A MICROPROCESSOR-CONTROLLED PROSTHETIC KNEE:

L5615 Addition, endoskeletal knee-shin system, 4 bar linkage or multiaxial, fluid swing and stance phase control

L5856 Addition to lower extremity prosthesis, endoskeletal knee-shin system, microprocessor control feature, swing and stance phase, includes electronic sensor(s), any type

L5857 Addition to lower extremity prosthesis, endoskeletal knee-shin system, microprocessor control feature, swing phase only, includes electronic sensor(s), any type

L5858 Addition to lower extremity prosthesis, endoskeletal knee-shin system, microprocessor control feature, stance phase only, includes electronic sensor(s), any type

NOT MEDICALLY NECESSARY

THE FOLLOWING CODE IS USED TO REPRESENT THE ENHANCEMENTS OR DELUXE SUPPLIES OR CONVENIENCE FEATURES:

L5999 Lower extremity prosthesis, not otherwise specified

EXPERIMENTAL/INVESTIGATIONAL

THE FOLLOWING CODE IS USED TO REPRESENT POWERED AND PROGRAMMABLE FLEXION/EXTENSION ASSIST CONTROL PROSTHETIC KNEE:

L5827 Endoskeletal knee-shin system, single axis, electromechanical swing and stance phase control, with or without shock absorption and stance extension damping
L5859 Addition to lower extremity prosthesis, endoskeletal knee-shin system, powered and programmable flexion/extension assist control, includes any type motor(s)

THE FOLLOWING CODE IS USED TO REPRESENT A POWER ASSIST ANKLE-FOOT PROSTHETIC SYSTEM:

L5969 Addition, endoskeletal ankle-foot or ankle system, power assist, includes any type motor(s)

THE FOLLOWING CODE IS USED TO REPRESENT A MICROPROCESSOR-CONTROLLED ANKLE-FOOT SYSTEM:

L5973 Endoskeletal ankle foot system, microprocessor controlled feature, dorsiflexion and/or plantar flexion control, includes power source
Revenue Code Number(s)
N/A

Modifiers

FUNCTIONAL LEVEL MODIFIERS

K0 Lower extremity prosthesis functional level 0-does not have the ability or potential to ambulate or transfer safely with or without assistance and a prosthesis does not enhance their quality of life or mobility

K1 Lower extremity prosthesis functional level 1 - has the ability or potential to use a prosthesis for transfers or ambulation on level surfaces at fixed cadence, typical of the limited and unlimited household ambulator.

K2 Lower extremity prosthesis functional level 2 - has the ability or potential for ambulation with the ability to traverse low level environmental barriers such as curbs, stairs or uneven surfaces. typical of the limited community ambulator.

K3 Lower extremity prosthesis functional level 3-has the ability or potential for ambulation with variable cadence, typical of the community ambulator who has the ability to traverse most environmental barriers and may have vocational, therapeutic, or exercise activity that demands prosthetic utilization beyond simple locomotion

K4 Lower extremity prosthesis functional level 4 - has the ability or potential for prosthetic ambulation that exceeds the basic ambulation skills, exhibiting high impact, stress, or energy levels, typical of the prosthetic demands of the child, active adult, or athlete.

LATERALITY MODIFIERS

LT - Left side

RT - Right side

Coding and Billing Requirements

Policy History

Revisions From 11.14.21l:
10/01/2025

This version of the policy will become effective on 10/01/2025.​

​The policy has been reviewed and reissued to communicate the Company’s continuing position on microprocessor-controlled prostheses for lower-extremity amputees. ​
​04/01/2025
​​Inclusion of a policy in a Code Update memo does not imply that a full review of the policy was completed at this time.

This policy has been identified for the HCPCS code update, effective 04/01/2025.
The following HCPCS code has been added to the experimental/investigation section of this policy:
  • ​L5827  Endoskeletal knee-shin system, single axis, electromechanical swing and stance phase control, with or without shock absorption and stance extension damping​

Revisions From 11.14.21k:
10/28/2024
This policy version will become effective on 10/28/2024.

This version of policy continues to communicate Company's published positions for Microprocessor-Controlled Prostheses for Lower-Extremity Amputees​.

Additional clarifications in terms of examples and language were added to communicate that enhancements or deluxe supplies or convenience features for a microprocessor-controlled prosthetic knee, which do not serve or contribute towards any clinically established physiological and/or functional improvements, are an existing benefit exclusion. For plans that do not have this benefit contract exclusion, they are considered not medically necessary and, therefore, not covered because the available published peer-reviewed literature does not support their use in the treatment of illness or injury.

The following HCPCS code was added as not medically necessary when it is used to represent a prosthesis with enhancements or deluxe supplies or convenience features:

L5999 Lower extremity prosthesis, not otherwise specified

Revisions From 11.14.21j:
01/01/2024
This policy has been identified for code update, effective 01/01/2024.

The following procedure code is being DELETED from this policy because​ it is a termed code:
K1014

The following code is being ADDED to this policy: ​
L5615​​

Revisions From 11.14.21i:
04/01/2021
Inclusion of a policy in a Code Update memo does not i​mply that a full review of the policy was completed at this time.​

This policy has been identified for the HCPCS code update, effective 04/01/2021.

The following HCPCS code has been added to this policy:

K1014 Addition, endoskeletal knee-shin system, 4 bar linkage or multiaxial, fluid swing and stance phase control​

​Revisions From 11.14.21h:
​12/16/2020

​The policy has been reviewed and reissued to communicate the Company’s continuing position on Microprocessor-Controlled Prostheses for Lower-Extremity Amputees​.
12/09/2019 This version of the policy will become effective 12/09/2019. The intent of this policy remains unchanged; however, billing requirements have been incorporated into this policy to convey the following:
  • the use of additional HCPCS codes other than the existing HCPCS codes described in this policy that are used represent microprocessor-controlled prosthetic knees and/or the use of a not otherwise classified code (miscellaneous code) are not eligible for reimbursement consideration.
  • to submit the functional level modifiers K0-K4 and laterality modifiers RT or LT with the billed HCPCS code for a microprocessor-controlled prosthesis when submitting a prosthetic​ claim for a microprocessor-controlled prosthesis.

Revisions From 11.14.21g:
01/14/2019This version of the policy will become effective 01/14/2019.

The intent of this policy has not changed. Billing requirements have been incorporated to clarify reimbursement for additional features, functions, or components of a microprocessor-controlled knee prosthesis.

Effective 10/05/2017 this policy has been updated to the new policy template format.
4/1/2025
4/1/2025
10/1/2025
11.14.21
Medical Policy Bulletin
Commercial
No
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