functional considerations for prosthetic candidacy

Lisa U. Pascual, MD

Assistant Clinical Professor

Department of Orthopaedic Surgery

University of California, San Francisco

Functional Considerations for

Prosthetic Candidacy

“Will My Patient Be Able to Walk?” (And What Should I tell Her to Expect?)

What do I Tell My Patient?

65 yo M, now s/p R AKA

DM, HTN, ESRD, CAD, h/o mi, h/o previous BKA on same side

Wheelchair bound for short distances on level surfaces

Transfers with assist

Limited ambulation prior to recent surgery as had difficulty with ulcer to RLE

Objectives

To be able to understand the impact of:

Premorbid Medical Concerns – Comorbidities

– Age

– Psychosocial Concerns

Premorbid Functional Status – Gait

– Energy Expenditure

The Interdisciplinary Team

“When am I getting a prosthesis?”

Assumes “when,” not “if.”

Is the patient a prosthetic candidate?

Prosthetic Candidacy: Premorbid Medical Concerns

Comorbidities

Age

Psychosocial Status


Comorbidities:

Ischemic Heart Disease, or

Hemiplegia, or

Bronchitis, or

Bilateral amputation

performed worse than amputees without these diseases in the Walking Ability Index

Siriwardena, et al 1991


Comorbidities:

Severe Cardiopulmonary Disease – May be a major consideration for withholding prosthetic

use given the energy expenditure required for ambulation

Compromise of the Contralateral Foot – Relative contraindication


Comorbidities:

Dialysis – Previously shown to perform worse

– Similar outcomes for dysvascular amputees with ESRD compared to those without

Czyrny, et al. 1994


Comorbidities:

Obesity – BMI did not correlate with functional outcome in a

dysvascular amputee

– Obesity did not predict a poorer prognosis Kalbaugh, et al. 2006

– However, obesity may have an impact on musculoskeletal pain


Comorbidities:

Compliance is a significant criteria for successful prosthetic use

Muellar, et al. 1985


Age: Fit Trends Throughout the Years 1959: 55.3% were fit with prostheses, only 2-3% were older

Chapman, et al. 1959

1986: Increased age associated unfavorably with social dependence and physical ability

Helm, et al. 1986

1991: 87% (N=26) were fit with prostheses Harris, et al. 1991

1993: 1846, 80% fit with prostheses (majority elderly) Stewart, et al. 1993


Age: Fit Trends Throughout the Years

Poorer outcomes vs. successful rehabilitation

– 25 yrs + ago, more AKAs in older dysvascular patient to ensure healing: higher energy demands

– More recently, less AKAs, more BKAs


Age

Schoppen et al, 2003

• >60 year oldlower level of function after 1 year

• Most predictive: 2 weeks post amputation:

• Age

• 1 leg balance on unaffected limb

• Cognitive impairment


Age

• Fletcher et al, 2001

• Wanted to determine the rate of successful prosthetic fit in

geriatric amputees and determine predictors

• Success rates vary for fit of elderly:

• “selected group” for fit

• “unselected” group for fit

• Selected individuals can be successfully fit

• Factors that adversely affected fit: increased age,

cerebrovascular disease, dementia, AKA


Age

Age alone is not a contraindication for prosthetic use, careful consideration of other factors is needed


Psychosocial Concerns

Varied results/different populations: – Return to home varied 20-80%

– Decrease in need for help at home post amputation

– Improved health as less pain post amputation

– Decrease in quality of life the higher the amputation


Psychosocial Concerns

Limited or lack of studies on: – Quality of Life

– Social network and other environment factors

• Although re-operation and social dependency appears to

negatively affect outcome


Morbidity and Mortality: Dysvascular Amputees

15-20% risk of losing contralateral limb 2 years post amputation

– Risk increases to 40% at 4 years

5 year survival for lower limb dysvascular amputees averages 30-40% overall

Patients with diabetes vs. peripheral vascular disease:

– Shorter survival

– Related to level of amputation

Survival: BKA > AKA (presumably due to more widespread involvement)


In summary:

Adequate data still not available to:

– Reliably identify all predictors of outcome

– Look at predictive factors when series include combinations of amputations due to trauma with dysvascular causes (pooled populations)

– Look at “unselected” populations

Prosthetic Candidacy: Premorbid Functional Status

Was the patient ambulating prior to surgery?

Was the patient transferring on own prior to surgery?

What type of amputation is being considered?

What are the energy expenditure factors that need to be considered?

Prosthetic Candidacy: Gait


Documented kinematics

of gait

Prosthetic Candidacy: Energy Expenditure

•Normal Gait: 3 METs

•Waters, Perry, et al. 1976

Energy Cost of Ambulation

Increase (%) MET

No prosthesis, with crutches 50 4.5

Unilateral BK with prosthesis 9-28 3.3-3.8

Unilateral AK with prosthesis 40-65 4.2-5.8

Bilateral BK with prosthesis 41-100 4.2-6.0

BK plus AK with prosthesis 75 5.3

Bilateral AK with prosthesis 280 11.4

Unilateral hip disarticulation with prosthesis 82 5.5

Hemipelvectomy with prosthesis 125 6.75

Prosthetic Candidacy: Energy Expenditure

Normal Ambulation: 3 METS DeLisa, PM&R Principles and Practice.

Correlation of Energy Cost of Ambulation According to Level of Amputation with

Estimated Work Capacity According to Cardiac Functional Class

Cardiac Class MET Amputee Ambulation MET

Class IV <2 --- ---

Class III <2 to <5 Wheelchair 2.0-3.0

Unilateral BK with prosthesis 3.3-3.8

Class II >5 to <7 No prosthesis with crutches 4.5

Unilateral AK with prosthesis 4.2-5.0

Bilateral AK with prosthesis 4.2-6.0

BK plus AK with prosthesis 5.3

Hip disarticulation with

prosthesis

5.5

Hemipelvectomy with

prosthesis

6.75

Class I >7 Bilateral AK with prosthesis 11.4


Schoppen et al, 2003.

Unilateral leg stance significant predictor of functional outcome

Memory most important mental predictor for function


Possible factors:

Strong motivation to walk

Level of physical fitness as measured by maximal oxygen consumption after amputation


Functional Independence Measure (FIM) as a predictor of functional outcome:

Muecke et al,1992: – FIM scores a poor predictor

– FIM scores in lower level amputees had potential for greater change in score

Leung et al, 1996: – FIM not useful as a predictor of outcome

– Only motor subscore at discharge correlated with use of a prosthesis


Gailey et al, 2002. – Amputee Mobility Predictor: designed to measure an

amputee’s functional capacities and predict ability to ambulate with a prosthesis

– Can be performed with or without a prosthesis

– Looks at sitting, transfers, sit to stand, standing balance, gait activities

– Can be performed with and without a prosthesis

– Can assist in assigning an Medicare Functional Classification Level (MFCL)

Managing Expectations

“What kind of prosthesis am I going to get?”

Dependent of pre-morbid level of functioning

The prosthesis that is on TV may not be the appropriate one for them


Goal of Prosthetic Prescription:

To provide the amputee with the ability to return to participating in activities that are important to them in society

To provide a prosthesis that is appropriate for their level of activity, ability and weight


Energy Storing Feet: Highly subjective satisfaction rates Limited biomechanical evidence of significant benefit Trends suggest increased walking speed, greater

stride length, slight decrease in metabolic expenditure at high speeds – no superiority for level walking


K Levels

K0 Does not have the ability or potential to ambulate or transfer safely with or without assistance and a prosthesis does not enhance the quality of life or mobility.

K1 Has the ability or potential to use a prosthesis for transfers or ambulation on levels surfaces at fixed cadence. Typical of the limited and unlimited household ambulator.

K2 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 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 use beyond simple locomotion.

K4 Has the ability or potential for prosthetic ambulation that exceeds basic ambulation skill, exhibiting high impact, stress, or energy levels. Typical of the prosthetic demands of the child, active adult, or athlete.


Microprocessor knees:

Controls postural stability

Varies step cadence

Enhances ability to walk on uneven surfaces


K Level Description Medicare-Covered Prosthesis

K0 Nonambulatory None

K1 Household ambulator Constant-friction knee

K2 Limited community ambulator Constant-friction knee

K3 Unlimited community ambulator Fluid-control knee

K4 Very active Fluid-control knee

Source: Region B Medicare Supplier Bulletin


K Level Description Medicare-Covered Prosthesis

K0 Nonambulatory None

K1 Household ambulator Constant-friction knee

K2 Limited community ambulator Constant-friction knee

K3 Unlimited community ambulator Fluid-control knee

K4 Very active Fluid-control knee


What do I Tell My Patient?

65 yo M, now s/p R AKA

DM, HTN, ESRD, CAD, h/o mi, h/o previous BKA on same side

Wheelchair bound for short distances on level surfaces

Transfers with assist

Limited ambulation prior to recent surgery as had difficulty with ulcer to RLE

It Takes a Village: The Interdisciplinary Team

Key element for successful amputee care program

Surgeon, Internist, Nurse, Prosthetist, Physical Therapist, Occupational Therapist, Social Worker, Nutritionist, Psychologist, Primary Care

Peer Support, vocational rehabilitation, recreational activities

Physical Medicine and Rehabilitation (Physiatry): Role on the Interdisciplinary Team

A physiatrist may assist the team in determination of amputation level as it relates to function, especially when uncertainty exists

Involve the physiatrist during the perioperative period

Utilize the physiatrist during the post op period to assist in the prosthetic prescription

Utilize the physiatrist when the amputee is in the community

Thank You

functional considerations for prosthetic candidacy

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