mp-083
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Microprocessor-Controlled Prostheses for the Lower Limb

Policy Number: MP-083

Latest Review Date: March 2021

Category: DME 

POLICY:

 A microprocessor-controlled knee may be considered medically necessary in individuals with transfemoral amputation and ALL the following indications are met:

  • The patient is fit and active with at least a potential Functional Level 3 or 4;
  • The patient has the appropriate cognitive abilities to master use and care requirements for the technology;
  • The patient does not have additional medical problems that would interfere with maintaining Functional Level 3 or 4: i.e., disabling cardiovascular, neuromuscular, peripheral vascular, or musculoskeletal (other than amputation) conditions.

Refer to Coding Section for guidelines regarding the Ottobock Genium® MPK

 A microprocessor-controlled knee is contraindicated when:

  • Patient is historically non-ambulatory or has a potential Functional Level below 3.
  • Patient has demonstrated a lack of proper care for existing equipment.
  • Patient is not motivated.
  • Patient lives or works in a wet environment.

Coverage may be provided for one microprocessor-controlled knee per limb per five years when medically indicated. Coverage will not be provided if the prosthesis is functioning properly and in good general condition.

A high activity knee control frame (L5930) is only covered for patients whose functional level is K4.

A power knee is considered investigational.

A microprocessor-controlled or powered foot is considered investigational. 

A combination microprocessor-controlled powered foot and microprocessor-controlled knee prosthesis is considered investigational.

A combination microprocessor-controlled knee/ankle/foot (i.e. Linx) is considered investigational.

Additions or upgrades to the prosthetic for convenience, sports or recreational activities are considered not medically necessary.

DESCRIPTION OF PROCEDURE OR SERVICE:

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 have the capability to 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 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.

KEY POINTS:

The most recent literature update was performed through January 25, 2021.

SUMMARY OF EVIDENCE:

For individuals who have a transfemoral amputation who receive a prosthesis with a microprocessor-controlled knee, the evidence includes a number of within-subject comparisons of microprocessor-controlled knees vs non-microprocessor-controlled knee joints. 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, an increase in stability, and a decrease in falls. 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 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 a powered knee prostheses with standard prostheses. 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. 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 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.

PRACTICE GUIDELINES AND POSITION STATEMENTS:

The Veteran’s Affairs Prosthetic and Sensory Aids Strategic Healthcare Group established a Prosthetic Clinical Management Program to coordinate the development of clinical practice recommendations for prosthetic prescriptive practices. A subgroup of the Pre-Post National Amputation Workgroup met in 2004 to define the patient selection and identification criteria for microprocessor prosthetic knees. Their proposal was based on recommendations arising from the 2003 Microprocessor Prosthetic Knee Forum.

Veterans Affairs/Department of Defense Clinical Practice Guideline for Rehabilitation of Individuals with Lower Limb Amputation

In 2019, the Veterans Affairs/Department of Defense Clinical Practice Guideline for Rehabilitation of Individuals with Lower Limb Amputation made the following recommendations:

We suggest offering microprocessor knee units over non-microprocessor knee units for ambulation to reduce risk of falls and maximize patient satisfaction. There is insufficient evidence to recommend for or against any particular socket design, prosthetic foot categories, and suspensions and interfaces.

U.S. Preventive Services Task Force Recommendations

Not applicable.

KEY WORDS:

C-leg, microprocessor control prostheses, computerized leg, computerized lower limb prosthesis, bionic leg, Proprio Foot®, Power Foot, microprocessor-controlled foot, power knee, powered foot, iPED, Intelligent Prosthesis,  Symbionic® Leg, PowerFoot Biom, Genium, Otto Bock®, Rheo Knee, Linx system (endolite), knee/ankle/foot/prosthesis system, ALLUX

APPROVED BY GOVERNING BODIES:

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.

BENEFIT APPLICATION:

Coverage is subject to member’s specific benefits.  Group specific policy will supersede this policy when applicable.

ITS: Home Policy provisions apply

FEP contracts: Special benefit considerations may apply.  Refer to member’s benefit plan.  FEP does not consider investigational if FDA approved and will be reviewed for medical necessity.

CURRENT CODING:

HCPCS codes:  

K1014 Addition, endoskeletal knee-shin system, 4 bar  linkage or multiaxial, fluid swing and stance phase control (Effective 4/1/21)

L5828

Addition, endoskeletal, knee-shin system, single axis, fluid swing and stance phase control

L5930

Addition, endoskeletal system, high activity knee control frame

L5845

Stance extension, damping, adjustable

L5848

Addition to endoskeletal knee-shin system, fluid stance extension, dampening feature, with or without adjustability

L5850

Addition, endoskeletal system above knee or hip disarticulation, knee extension assist

L5859

Addition to lower extremity prosthesis, endoskeletal knee-shin system, powered and programmable flexion/extension assist control, includes any type motor(s)

L5969

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

There are specific HCPCS codes that describe the microprocessor-controlled knee prosthesis:

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

There is a specific HCPCS code for ankle-foot system with a microprocessor control feature:

L5973

Endoskeletal ankle foot system, microprocessor controlled feature, dorsiflexion and/or plantar flexion control

Ottobock Genium® MPK:

There is no separate billing and reimbursement for any other features or functions performed by the on-board microprocessors and/or sensors (e.g. L5999 “real-time gait assessment”, “electronically controlled static stance regulator, adjustable”, “predicted proprioceptive input” or programming necessary for use), since the allowance for all functions and features is included in the payment for codes recommended (L5828, L5845, L5848, L5856).

REFERENCES:

  1. Affairs DoV. VA Prosthetics and Sensory Aids. 2006; montgomery.md.networkofcare.org/veterans/library/article.aspx?id=1684. Accessed February, 2015.
  2. 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):356-63.
  3. American Orthotic and Prosthetic Association Functional Levels.
  4. Au S, Berniker M, Her H.  Powered ankle-foot prosthesis to assist level-ground and stair-descent gaits. Neural Netw 2008; 21(4):654-66.
  5. Berry D. Microprocessor prosthetic knees. Phys Med Rehabil Clin N Am. Feb 2006; 17(1):91-113, vii.
  6. 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):541-9.
  7. Blue Cross and Blue Shield Association.  Microprocessor-controlled prosthetic knees.  Medical Policy Reference Manual, March 2007.
  8. 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.
  9. Chin T, Machida K, et al.  Comparison of difference microprocessor controlled knee joints on the energy consumption during walking in trans-femoral amputees: Intelligent knee prosthesis (IP) verus C-leg. Prosthet Orthot Int 2006; 30(1): 73-80.
  10. 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.
  11. 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):129-35.
  12. 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.
  13. 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):876-82.
  14. 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 2013.
  15. Ferris AE, Aldridge JM, Rabago CA et al. Evaluation of a powered ankle-foot prosthetic system during walking. Arch Phys Med Rehabil 2012; 93(11):1911-8.
  16. Flynn K. Short Report: Computerized lower limb prosthesis (VA Technology Assessment Program). No. 2. Boston, MA: Veterans Health Administration; 2000.
  17. 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):191-8.
  18. 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.
  19. Hafner BJ, Willingham LL, Buell NC et al. Evaluation of function, performance, and preference as transfemoral amputee’s transition from mechanical to microprocessor control of the prosthetic knee. Arch Phy Med Rehabil 2007; 88(2):207-17.
  20. Hafner BJ, Smith DB.  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):417-33.
  21. Herr HM, Grabowski AM. Bionic ankle-foot prosthesis normalizes walking gait for persons with leg amputation. Proc Biol Sci 2012; 279(1728):457-64.
  22. 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):362-77.
  23. 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 Oct; 37(5):362-8.
  24. Hofstad C, Linde H, Limbeek J et al. Prescription of prosthetic ankle-foot mechanisms after lower limb amputation.  Cochrane Database Syst Rev 2004; (1):CD003978.
  25. 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. Mar 2018; 41(1):63-73
  26. 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; 87(7):989-94.
  27. Kaufman, KK, Bernhardt, KK, Symms, KK. 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, Avon), 2018 Aug 5; 58:116-122.
  28. 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):489-93.
  29. 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):1380-5.
  30. Kirker S, Keymer S, Talbot J, et al. An assessment of the intelligent knee prosthesis. Clin Rehabil 1996 1996; 10(3):267-273.
  31. Klute GK, Berge JS, Orendurff MS et al. Prosthetic intervention effects on activity of lower-extremity amputees. Arch Phys Med Rehabil 2006; 87(5):717-22.
  32. LCD for Lower Limb Prostheses (L11464). www.medicarenhic.com/viewdoc.aspx?id=1649. Accessed February, 2015.
  33. Mancinelli C, Patritti BL, Tropea P, et al. Comparing a passive-elastic and a powered prosthesis in transtibial amputees. Conf Proc IEEE Eng Med Biol Soc. Aug 2011; 2011:8255-8258.
  34. Noridian Healthcare Solutions. Notification of Service Specific Targeted Review of Lower Limb Prostheses (HCPCS L5980). 2018; https://med.noridianmedicare.com/web/jddme/cert-review/mr/complex-notificationsresults/lower-limb-prostheses-l5980-targeted. Accessed April 9, 2018.
  35. Orendurff Michael S, Segal AD, et al. Gait efficiency using the C-leg.  Journal of Rehabilitation Research & Development, March/April 2006, Vol. 43, No. 2, pp. 239-246.
  36. Otto Bock Orthopedic Industry, Inc. Otto Bock C-Leg. 510(k) Summary of Safety and Effectiveness. 510 (k) no K99150. Minneapolis, MN: Otto Bock, May 6, 1999. Available online at www.fda.gov/cdrh/pdf/k991590.pdf.
  37. 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 randomized cross-over trial. Clin Rehabil. Oct 6 2014.
  38. Rosenblatt N, Brauer A, Rotter D et al. Active dorsiflexing prostheses may reduce tri-related fall-risk. AAOP Journal of Proceedings 2014, www.oandp.org/publications/jop/2014/2014-50pdf.
  39. Seymour R, Engbrestson 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.
  40. 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):80-4.
  41. 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. May 2012; 44(5):454-461.
  42. 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):906-15.
  43. United States Department of Veterans Affairs. VA technology assessment program project report – Patient summary on computerized lower limb prostheses. Available online at www.va.gov/VATAP/patientinfo/prosteticlimb.htm. Last accessed August 2013. 
  44. United States Department of Veterans Affairs Fact Sheet. VA’s prosthetics and sensory aids.  February 2006.
  45. U.S. 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 online at www.va.gov/VATAP/docs/ComputerizedLowerLimbProsthese2000tm.pdf. Last accessed August, 2013.
  46. VHA 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.
  47. Williams RM, Turner AP, Orendurff M et al. Does having a computerized prosthetic knee influence cognitive performance during amputee walking? Arch Phy Med Rehabil 2006; 87(7):989-94.
  48. Wilson M.  Computerized prosthetics. Ptmagazine 2001; 35-38.
  49. Wolf, SI et al. Pressure characteristics at the stump/socket interface in transtibial amputees using an adaptive prosthetic foot. J. Clin. Biomech. 2009, www.ncbi.nlm.nih.gov/pubmed/19744755.

POLICY HISTORY:

Medical Policy Group, September 2002

Medical Policy Group, November 2002 (2)

Medical Policy Administration Committee May 2003

Available for comment May 23-July 7, 2003

Medical Policy Group, April 2004

Medical Policy Group, November 2005 (2)

Medical Policy Group, May 2007 (1)

Medical Policy Group, August 2007 (1)

Medical Policy Administration Committee, August 2007

Available for comment August 13-September 27, 2007

Medical Policy Group, February 2009 (2)

Medical Policy Administration Committee, March 2009

Available for comment March 4-April 17, 2009

Medical Policy Group, February 2010 (2)

Medical Policy Administration Committee February 2010

Medical Policy Group, November 2012: Added new 2013 Code L5859 effective 1/1/13; Deleted Code K0670 which deleted 1/1/06.

Medical Policy Panel, March 2013

Medical Policy Group, August 2013 (2): Policy updated with literature review through July 2013.  Added an investigational statement for combination microprocessor knee and power foot prostheses.  Description, Key Words, Key Points, Codes, and References updated.

Medical Policy Administration Committee, September 2013.

Available for comment September 19 through November 2, 2013

Medical Policy Group, December 2013 (5):  2014 Coding Update – added new code L5969 to current coding effective 01/01/2014

Medical Policy Group, February 2014 (5): Update to Policy statement to only cover code L5930 for functional level of K4.  Key Points and References also updated.

Medical Policy Administration Committee, February 2014

Available for comment February 5 through March 21, 2014

Medical policy Group, June 2014 (5): Updated description, Key Points and References; Policy statements unchanged.

Medical Policy Group, February 2015 (6): Updated References; no change to policy statement.

Medical Policy Panel, April 2015

Medical Policy Group, April 2015 (6): Updates to Description, Key Points, Key Words and References; no change to policy statement.

Medical Policy Group, November 2016 (6): Updates to coding section:L5848: Addition to endoskeletal knee-shin system, fluid stance extension, dampening feature, with or without adjustability.

Medical Policy Panel, November 2017

Medical Policy Group, November 2017 (6): Removed old policy statement. Added “A combination microprocessor-controlled knee/ankle/foot (i.e. Linx) does not meet Blue Cross and Blue Shield medical criteria for coverage and is considered investigational.” to policy statement from existing investigational listing. Updates to Key Points, Governing Bodies, Key Words and References.

Medical Policy Panel, April 2018

Medical Policy Group, May 2018 (6): Updates to Description, Key Points, Practice Guidelines and References.

Medical Policy Panel, March 2019

Medical Policy Group, April 2019 (6): Updates to Description, Key Points, References and Title name changed to Microprocessor-Controlled Prostheses for the Lower Limb. No change to policy statement.

Medical Policy Group, June 2019 (6): Updates to Coding to include guidelines for the Ottobock Genium MPK.

Medical Policy Panel, March 2020

Medical Policy Group, March 2020 (6): Updates to Key Points, Practice Guidelines and References. Updated policy verbiage to include "microprocessor controlled knee" and "transfemoral amputation".

Medical Policy Panel, March 2021

Medical Policy Group, March 2021 (6): Updates to Key Points. Policy statement updated to remove “not medically necessary,” no change to policy intent.

Medical Policy Group, March 2021: Quarterly Coding Update.  Added new code K1014 to Current Coding. Added Key Word ALLUX.

Medical Policy Group, September 2021 (6): Added clarification statement to include non-coverage for convenience items.

This medical policy is not an authorization, certification, explanation of benefits, or a contract. Eligibility and benefits are determined on a case-by-case basis according to the terms of the member’s plan in effect as of the date services are rendered. All medical policies are based on (i) research of current medical literature and (ii) review of common medical practices in the treatment and diagnosis of disease as of the date hereof. Physicians and other providers are solely responsible for all aspects of medical care and treatment, including the type, quality, and levels of care and treatment.

This policy is intended to be used for adjudication of claims (including pre-admission certification, pre-determinations, and pre-procedure review) in Blue Cross and Blue Shield’s administration of plan contracts.

The plan does not approve or deny procedures, services, testing, or equipment for our members. Our decisions concern coverage only. The decision of whether or not to have a certain test, treatment or procedure is one made between the physician and his/her patient. The plan administers benefits based on the member’s contract and corporate medical policies. Physicians should always exercise their best medical judgment in providing the care they feel is most appropriate for their patients. Needed care should not be delayed or refused because of a coverage determination.

As a general rule, benefits are payable under health plans only in cases of medical necessity and only if services or supplies are not investigational, provided the customer group contracts have such coverage.

The following Association Technology Evaluation Criteria must be met for a service/supply to be considered for coverage:

1. The technology must have final approval from the appropriate government regulatory bodies;

2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes;

3. The technology must improve the net health outcome;

4. The technology must be as beneficial as any established alternatives;

5. The improvement must be attainable outside the investigational setting.

Medical Necessity means that health care services (e.g., procedures, treatments, supplies, devices, equipment, facilities or drugs) that a physician, exercising prudent clinical judgment, would provide to a patient for the purpose of preventing, evaluating, diagnosing or treating an illness, injury or disease or its symptoms, and that are:

1. In accordance with generally accepted standards of medical practice; and

2. Clinically appropriate in terms of type, frequency, extent, site and duration and considered effective for the patient’s illness, injury or disease; and

3. Not primarily for the convenience of the patient, physician or other health care provider; and

4. Not more costly than an alternative service or sequence of services at least as likely to produce equivalent therapeutic or diagnostic results as to the diagnosis or treatment of that patient’s illness, injury or disease.