Response to Comments: Lower Limb Prostheses - DL33787

Most commenters expressed their support of the proposed expansion of coverage for fluid, pneumatic, and electronic/microprocessor knees to a subset of beneficiaries with lower limb amputations requiring a prosthetic knee who function at a K2 level. Supportive comments noted the stability, safety, and enhanced ambulation capabilities of advanced knees would likely result in improved function, independence, and quality of life for Medicare beneficiaries. Additionally, many commenters noted that beneficiaries would be less likely to fall and require hospitalization with the use of microprocessor knees, which may result in overall cost savings to the Medicare program.

The DME MAC Medical Directors would like to thank the clinicians, associations, Medicare beneficiaries, and their families for offering their support for the proposed Lower Limb Prostheses (LLP) Local Coverage Determination (LCD) (DL33787). 

One commenter disagreed with the proposed expansion of Medicare coverage of electronic/microprocessor knees to a subset of beneficiaries with lower limb amputations requiring a prosthetic knee who function at a K2 level. The following topics were addressed in the commentor’s letter:

• Outlined the history of Medicare coverage and manufacturers’ initial indications for microprocessor knees.
• Asserted that independent clinical research is lacking and questioned “what evidence has been presented in peer reviewed studies that creates the need for the vast majority of amputees (K2) to get a microprocessor knee system?”
• Stated that most beneficiaries want a microprocessor knee system because of fear of falling or fall prevention and Medicare does not provide devices for prevention.
• Suggested that amputees should receive better training with their mechanical knees in lieu of advanced technology.
• Referenced the findings of the 2017 CMS Lower Limb Prosthetic Workgroup Consensus and the requirements for development of evidence-based LCDs based on CMS Program Integrity Manual (PIM) (CMS Pub. 100-08), Chapter 13, Section 13.7.1.

The DME MACs based the proposed and now final LLP LCD on the best currently available published evidence. The LCD includes a detailed summary of evidence and an associated bibliography that outline the relevant clinical studies and additional resources reviewed and considered during the LCD development process. These resources included the 2017 CMS Lower Limb Prosthetic Workgroup Consensus document. Since the publication of the Workgroup Consensus document and the determination of initial manufacturer indications for microprocessor knees, multiple peer-reviewed studies have been published and represent an update to the evidence base. No literature was submitted by the commenter to refute the conclusions made by the DME MACs, or to support the commenter’s assertion that additional training with mechanical knees result in equivalent safety and mobility outcomes as advanced knee systems.

It should also be noted that the use of advanced technology to improve functional health outcomes for beneficiaries requiring an LLP is not precluded by the definition of a prosthetic in statute or regulation.

Additionally, the PIM Chapter 13 section referenced by the commenter was removed from the manual in 2019 and has been replaced with new requirements for assessing evidence. The current requirements for evidentiary content are located in the Program Integrity Manual (CMS Pub. 100-08), Chapter 13, Section 13.5.3. 

Many commenters shared their personal experience and anecdotal evidence supporting the use of microprocessor knees by beneficiaries with lower limb amputations requiring a prosthetic knee functioning at a K2 level.

The DME MAC Medical Directors would like to thank the clinicians, associations, Medicare beneficiaries, and their families/caretakers for sharing their stories and experiences. We acknowledge that all were earnestly conveying their personal or loved ones' experiences with the use of advanced knees. However, when determining if a treatment is “reasonable and necessary” for purposes of Medicare reimbursement, CMS instructs the DME MACs to rely on published peer-reviewed clinical evidence.

Per CMS Program Integrity Manual (CMS Pub. 100-08), Chapter 13, Section 13.5.3 (in relevant part):

“In conducting a review, MACs shall use the available evidence of general acceptance by the medical community, such as published original research in peer-reviewed medical journals, systematic reviews and meta-analyses, evidence-based consensus statements and clinical guidelines.”

Many commenters requested clarification on the prosthetist’s role in assigning a functional level and requested confirmation that the prosthetist’s role in assigning the functional level has not changed based on the proposed verbiage. The commenters requested the addition of statutory language requiring consideration of the prosthetist’s records be added to the LLP LCD (L33787). 

The prosthetist’s role in assigning a functional level has not changed. Consistent with Social Security Act §1834(h)(5), orthotists and prosthetists records are considered part of an individual’s medical record to support documentation created by the treating practitioner. Therefore, a prosthetist may assign a functional level as long as the functional level chosen is supported by and is not in conflict with medical records from the treating practitioner. Additional clarification and statutory language have been incorporated into the LLP LCD-related Policy Article (PA) (A52496).

Many commenters requested clarification on how to document the rationale for choosing a microprocessor knee. Some of the commenters questioned whether documentation from the prosthetist is sufficient to meet this requirement. 

Specific documentation requirements are outlined in the LLP LCD-related PA (A52496). Consistent with Social Security Act §1834(h)(5), orthotists and prosthetists records are considered part of a beneficiary’s medical record to support documentation created by the treating practitioner. Therefore, a prosthetist may document the rationale for choosing the MPK within their chart notes, as long as the documentation is supported by and is not in conflict with medical records from the treating practitioner. 

One commenter indicated that “documentation and instructions for criteria to justify a microprocessor system should be revised and strengthened.”

The specific documentation requirements for microprocessor knee systems are located in the LLP LCD-related PA (A52496).

Many commenters requested clarification on what documentation must be present to support the following coverage criterion from the proposed LLP LCD (DL33787):

“All lower-level knee systems (e.g., knee systems which exclude use of fluid, pneumatic, or microprocessor) have been considered and ruled out based on the beneficiary’s specific functional and medical needs.”

The commenters further questioned whether all 200 plus knees must be specifically ruled out. Some of these commenters feel that this criterion is unnecessary since the medical record needs to establish the reason for the specific knee chosen.  

The DME MACs would not expect 200 plus knees to be specifically ruled out, but would expect a discussion in the medical record about the rationale for why lower-level knee systems would not be sufficient to meet the beneficiary’s specific functional and safety needs, and why the chosen knee system can meet the beneficiary’s needs. The coverage criterion has been updated in the final LLP LCD and now reads:

“Lower-level knee systems (e.g., knee systems which exclude use of fluid, pneumatic, or microprocessor) have been considered and ruled out based on the beneficiary’s specific functional and medical needs.”

The specific documentation requirements are outlined in the LLP LCD-related PA (A52496). 

Many commenters stated they were opposed to a “fail first” policy which would require a trial of lower-level prosthetic knees prior to providing a fluid, pneumatic, or microprocessor knee. 

There is no requirement for a trial and failure of a lower-level prosthetic knee system prior to coverage of a fluid, pneumatic, or microprocessor knee for a beneficiary with lower limb amputation requiring a prosthetic knee functioning at a K2 level. The medical records need to support that the coverage criteria outlined in the LLP LCD (L33787) are met, including documentation of the rationale for why lower-level knee systems would not be sufficient to meet the beneficiary’s specific functional and safety needs. 

Two commenters suggested specific verbiage which could be used to clarify the coverage criteria and/or documentation requirements for ruling out lower-level prosthetic knees.

The DME MACs thank the commenters for the suggested verbiage. The language has been considered. Documentation requirements are outlined in the associated LLP LCD-related PA (A52496).

Several commenters requested clarification on the following coverage criterion for electronic/microprocessor knees:

“The electronic/microprocessor knee is indicated for functional level 2.”

The commenters were unsure if Pricing, Data Analysis, and Coding (PDAC) contractor verification would be required to prove a microprocessor knee was indicated for functional level 2 patients.

PDAC responsibilities are limited to pricing, data analysis, and coding. The PDAC is not responsible for determining the proper indications for a product. Satisfaction of this criterion is based solely on the manufacturer’s indications for the specific knee. 

One commenter suggested adding the following language to the LLP LCD to clarify the requirement for a microprocessor knee to be indicated for K2 functional level:

“To be indicated for functional level 2, the medical record must contain information validating that the electronic/microprocessor knee (a) has a stumble recovery function, and (b) adjusts knee resistance in stance and swing phase in real-time based on the patient’s gait. The need for the electronic/microprocessor knee must also be corroborated in the prescribing physician’s medical records.”

The DME MACs thank the commenter for the suggested verbiage. Documentation requirements are not traditionally included in the LCD but are outlined in the associated LLP LCD-related PA (A52496).

One commenter requested coverage criterion 2a for a fluid, pneumatic, control addition, or electronic/microprocessor knee be modified to include mobility as a qualifying reason for coverage. The commenter suggested the following verbiage:

“Improve/preserve the beneficiary’s functional health outcomes (including but not limited to mobility and safety)”

The commenter noted patients using “K3 knees” will benefit from the additional mobility the knees provide and argued that the Medicare functional levels are based solely on mobility related factors and not stability/safety. They felt this change would align the policy with the K levels. 

The DME MACs thank the commenter for the suggested verbiage. The language has been considered. Criterion 2a under the knee subheading in the proposed and now final LLP LCD requires documentation of the rationale for selection of a fluid, pneumatic, or electronic/microprocessor-controlled knee, including how the selected knee with improve the beneficiary’s functional health outcomes. The parenthetical statement provides examples of functional health outcomes, but is not all inclusive.  

Three commenters raised safety concerns about the use of non-MPK fluid stance knees (L5828) in individuals with lower limb amputation requiring a prosthetic knee and functioning at a K2 level since the hydraulic stance control provides good functional support but offers low stability. Two of these commenters mentioned the same concern for pneumatic knees without microprocessor control. 

While the DME MACs are sensitive to these concerns, we believe the decision regarding the most appropriate knee for the safety and mobility of a beneficiary is best made by the prosthetist, treating practitioner, and other clinicians involved in the beneficiary’s care. Any safety concerns should be addressed when determining the appropriate knee for each beneficiary. Documentation requirements are outlined in the associated LLP LCD-related PA (A52496). Additionally, operationalization of such a limitation would be difficult with the current HCPCS coding system which requires use of the same HCPCS codes by more than one type of knee system.  

One commenter raised safety concerns about covering microprocessor (MP) swing control only knees (L5857). The commenter noted, “MP swing only knees usually use pneumatic or small (miniature) hydraulic units to provide superior speed and cadence adaptation without adding substantial weight to the knee. However, these swing control units are unable to provide the knee flexion resistance necessary to allow for loading the knee with the full body weight in case of a trip or stumble. Therefore, MP swing only knees (L5857) do not provide stumble recovery or comparable technology.”

The commenter was concerned that manufacturers may claim existence of stumble recovery with the stroke of a pen since MPKs are not regulated by the FDA.

The DME MAC Medical Directors are aware that the swing-only microprocessor knees currently available on the market do not include integrated technology that allows the knee to detect when the user trips or stumbles; however, the coverage criteria are clear that in order for a microprocessor knee system to be considered for coverage for a beneficiary with a lower limb amputation requiring a prosthetic knee who is functioning at a K2 level it must include integrated technology that allows the knee to detect when the user trips or stumbles (e.g., stumble recovery).

Coverage criterion number 2 outlines the following for coverage of an electronic/microprocessor knee for a beneficiary functioning at a K2 level:

“The electronic/microprocessor knee has integrated technology that allows the knee to detect when the user trips or stumbles and can automatically adjust to stabilize the knee unit (e.g., stumble recovery);”  

One commenter is concerned that “manufacturers may simply ‘expand’ the indication for their MPKs to functional level 2 with the stroke of a pen without proper technical testing and clinical research to prove clinical benefits in this population.” The commenter suggested adding a requirement that “the electronic/microprocessor knee has been subjected to at least one published clinical study or product-specific sub-analysis that proves clinical benefits in beneficiaries whose functional level is 2.”

The commenter suggested using the PDAC contractor to enforce this requirement. 

The DME MACs understand the concerns of the commenter but are unable to develop product specific coverage criteria or documentation requirements. The DME MACs considered the best currently available published evidence for the entire class of devices when developing the proposed criteria. PDAC responsibilities are limited to pricing, data analysis, and coding. The PDAC is not responsible for determining the proper indications for a product. 

Two commenters indicated they do not support requiring that each brand name MPK prosthetic component conduct a clinical study or trial to affirmatively demonstrate it is indicated for K2 amputees. The comments included concerns about beneficiary access to technology and stifling competition to the advantage of the larger manufacturers. 

The DME MACs have not proposed nor have finalized a requirement that each manufacturer conduct clinical studies to add an indication for beneficiaries functioning at a K2 functional level. The DME MACs considered the best currently available published evidence for the entire class of devices when developing the proposed criteria. 

One commenter requested the following language be added to clarify the documentation requirements for providing higher-level feet (i.e., functional level 3):

“To satisfy this requirement, the supporting documentation must specify both (a) what functions of the proposed fluid, pneumatic, or microprocessor knee are absent from lower-level knee systems, and (b) how those functions specifically address documented clinical issues in the beneficiary’s medical record. These conclusions must be corroborated by information contained in the prescribing physician’s medical record.”

The DME MACs thank the commenter for the suggested language. The documentation requirements are outlined in the associated LLP LCD-related PA (A52496).

One commenter stated the following in response to the methodological limitations about the literature included in the summary of evidence:

“We think it is important to note that there is no such thing as “perfect” evidence in the medical realm and that the methodological quality of the MPK studies, especially the use of randomized cross-over designs and bigger sample sizes, has considerably improved in the past 10 years.”

The DME MACs agree the literature has improved and shows consistency in results, but stand behind the conclusions made regarding the limitations of the evidence. 

One commenter suggested revisions to the functional level classification system and indicated it is not supported by “sound clinically accepted studies.” 

This comment is outside of the scope of this reconsideration which is limited to Medicare coverage of prosthetic knees and feet that were previously limited to beneficiaries with lower limb amputations requiring a prosthetic knee and functioning at a K3 (or higher) level.

One commenter suggested requiring the functional level assessment be completed by a licensed or certified medical professional including physicians, physician’s assistants, nurse practitioners, or physical therapists and exclude functional assessments conducted by the orthotist or prosthetist. The commenter also recommended mandatory physical therapy assessments and provided a suggested list of criteria for the assessments/evaluations. 

This comment is outside the scope of this reconsideration request and is potentially in conflict with Social Security Act §1834(h)(5), which states the following:

“For purposes of determining the reasonableness and medical necessity of orthotics and prosthetics, documentation created by an orthotist or prosthetist shall be considered part of the individual’s medical record to support documentation created by eligible professionals.”

One commenter indicated their company has developed an all-mechanical knee that provides automatic stability and stumble control without pneumatics, hydraulics, or electronics. The commenter stated their mechanical knee will provide many of the same benefits as an MPK at a fraction of the cost. 

The DME MACs are required to follow an evidence-based approach in development of our LCDs as outlined in the CMS Program Integrity Manual (CMS Pub. 100-08), Chapter 13, Section 13.5.3. A thorough analysis of the best currently available published evidence was conducted and included in the summary of evidence outlined in the proposed and now final LLP LCD. The commenter did not submit literature to support their assertion or refute the conclusions made in the summary of evidence.  

One commenter, who manufactures and distributes an activity monitor, suggested the use of a daily life activity monitor to better understand patient mobility needs rather than using perception of fall risk or fall rate to determine the need for advanced technology.  

The LLP LCD does not stipulate the method used for assessing a beneficiary’s functional level or risk of falling. The beneficiary’s potential functional level is determined by the prosthetist, treating practitioner, and other clinicians involved in their care. These clinicians may use a tool, such as an activity monitor, to assist in the assessment of the beneficiary’s potential functional level or their risk of falling. However, coverage of an activity monitor is outside the scope of this reconsideration request. 

One commenter requested that the final LLP LCD include language that is as clear as possible and reflects the realities of the disparate continuum of care (i.e., multiple clinicians from non-affiliated facilities documenting medical need) in order to prevent beneficiaries from uncertainty regarding whether they qualify to receive a microprocessor knee or other advanced technology. 

The LLP LCD-related PA (A52496) includes comprehensive documentation requirements which must be met in order to meet the coverage criteria outlined in the LLP LCD. Additionally, most microprocessor control additions and other advanced componentry are subject to the Prior Authorization process. Submitted medical record documentation from clinicians involved in the beneficiary’s care, regardless of health system/facility affiliation, will be reviewed during this process. Therefore, a beneficiary will know in advance if they meet Medicare coverage criteria to receive the advanced technology.

One commenter discussed their experience with the use of prosthetics over the past 49 years and their inability to receive needed technologies under Social Security and Medicaid. They also shared their dissatisfaction with the cost of prosthetic socks compared to regular socks. 

This comment is outside of the scope of this reconsideration which was limited to Medicare coverage of prosthetic knees and feet that were previously limited to beneficiaries with lower limb amputations requiring a prosthetic knee functioning at a K3 (or higher) level.

One commenter submitted two comments concerning potential Medicare coverage of the VGK-X knee manufactured by Orthomobility of England. The commenter privately purchased the VGK-X knee which is purportedly lightweight and includes stumble recovery at a fraction of the cost of microprocessor knees. The commenter would like this knee to be an available option for amputees residing in the U.S. 

This comment is outside of the scope of this reconsideration because the VGK-X knee is not currently available in the United States. 

One commenter noted transitioning patients from K2 to a K3 status should not be overly burdensome for healthcare practitioners.  

The DME MACs would like to clarify that the functional level classification system has not changed. However, the proposed and now final LLP LCD expands coverage of certain prosthetic knees and feet that were previously limited to beneficiaries with lower limb amputations functioning at a K3 (or higher) level to some K2 level ambulators when medically appropriate. Not all beneficiaries with lower limb amputations functioning at a K2 level will be eligible for advanced componentry, as it will be based on the assessment of the prosthetist and treating practitioner to determine the most appropriate knee system for the beneficiary. 

One commenter outlined their experience and satisfaction with the use of an all-terrain mechanical knee. 

The DME MAC Medical Directors would like to thank the individual for sharing their experience with a mechanical knee.  

One below knee amputee questioned if they would be eligible for a microprocessor-controlled leg in the future. 

This comment is outside of the scope of this reconsideration which was limited to Medicare coverage of prosthetic knees and feet that were previously limited to beneficiaries with lower limb amputations requiring a prosthetic knee functioning at a K3 (or higher) level.  

Two commenters, representing orthotic and prosthetic associations, offered to assist with educational efforts regarding the revised coverage criteria and the associated documentation requirements. 

The DME MACs appreciate the support and offers for assistance in education.