Transfemoral Considerations

Question 1

TF Amputation and Energy Expenditure

Answer 1

• weight of prosthesis
• quality or socket
• accuracy alignment prosthesis
• fucntional characteristics of the prosth components
• on average: TF AMPUTATION (double amount of energy when walking 1/2 as fast, they need more rest breaks, more encouragement)
  *

Question 2

Biomechanics - Length/ROM

Answer 2

• ROM - arthritis in hip
• Length - hip flexion contractures
• surface area
• RL condition/Surgical techniques - myodesis/myoplasty
  *

Question 3

Funding Complications with TF amputations

Answer 3

• Medicare K Levels
  
  • prescription factors K level mediates knee and foot componentry
  • other design criteria

Question 4

Quadrilateral Socket Design

Answer 4

MORE MEDIAL/LATERAL WIDTH - TOTAL CONTACT

Posterior wall and brim

• wall - flat, slants ant to provide initial flex 15 deg, countoured to hamstrings
• brim - horizontal parallel to floor, seat for ischial tuberosity

Medial Wall and Brim

• wall - relief channel ant.med for add long, high to prevent add roll, prevents medial mvmnt of limb in socket
• brim - same height as post brim SHOULD NOT press on pubic ramus

Anterior Wall

• 2.5 in higher than medial wall-counter pressure for post wall
• SCARPAS BULGE = maintains ischial tub on ishcial seat by providing counter pressure (scarpas triangle = satrorius, inguinal lig, add long)

Lateral Wall

• higher than ant, inclines medially as it goes distally, set in 10 deg adduction

Easier to DON/DOFF

Question 5

NOrmal Shape Normal Alignment NSNA

AKA Iscial Containment

Answer 5

• More Anterior/Posterior Width
• Ischial Tuberosity is contained w/in socket
• lateral wall is higher and contains greater trochanter
• Lateral wall set in 10-15 deg ADD
• made with laminate hard socket interface
• also known as: ischial containment, CAT CAM, Sabolich socket, Hanger Comfortflex
• some contain both ischium and ramus therefor creating a boney lock with the femur
• CAT CAM = flexible socket, harder don
• Sabolich = rot stab & side/side control, comfortable
• Hanger = contoured to lock the pubic ramus and ischium within socket, harder to don

Question 6

Endoskeleton Design Critera TF

Answer 6

• vast componentry options
• post fabircation adjustability
• light weight
• more anatomical/soft/cosmetic with outer shell

Question 7

Exoskeleton Design TF

Answer 7

• traditional hard finish fabricated method
• durability/heavy
• limited componentry
• non-adjustable

Question 8

Suction Pull-In Suspension for TF

Answer 8

• Best primary suspension if possible
• provides greatest feedback - no sock is worn
• DIFFICULT TO DON
• Not indicated for individuals with:
  
  • fluctuating volume
  • heart conditions
  • balance problems

Question 9

Roll on Suspension Liner

Answer 9

• shuttle lock or pin system
• lanyard system - cord pulls residual limb into socket and then attaches to external aspect of socket
• cushion liner - with air expulsive valve - sometimes vaccumm suspension

Question 10

Suction: Roll on silicone liner with shuttle cock and lanyard

Answer 10

• liners now being used for TF applications
• used with pts who have difficulty donning a traditional suction suspension
• extra guidance needed to get pin in shuttle
• lanyard used to solve this problem
• HAND DEXTERITY is important
• makes socket longer than normal

Question 11

Suction: Roll on Seal in Liner

Answer 11

• provides a suction socket
• easier to don than traditional true suction
• relatively new and have had good results
• has an air expulsion valve in socket to create negative pressure

Question 12

suction: roll on liner with coyote summit suspension

Answer 12

• relatively new
• prevents rotation in the socket**
• easy to apply
• works like a ski boot lock

Question 13

Silesian Band or Belt

Answer 13

• a webbing belt used as auxillary suspension
• does not control rotation in the socket
• simple
• made of cotton/dacron webbing
• relatively low profile
• DOES NOT CONTROL ROTATION WELL

Question 14

Total Elastic Suspension TES belt

Answer 14

• Another type of auxillary suspension
• very simple to use
• sort of bulky
• Moderate rotation control
• prosthesis may telescope

Question 15

Osseointegration

Answer 15

Advantages

• less feling of weight
• more control of prosthesis
• no persperation, pain from socket
• easy don/doff

Disadvantages

• 2 surgeries req’d (fixed to skeleton, re-expose and implant fixture)
• long rehab period
• deep infection risk
• rejection - amp at higher level

Question 16

Knees - Axis

Single Axis

Answer 16

• simple
• low maintenance
• single speed
• swing phase control
• not appropriate for some one who does not have good muscular control of knee**

Question 17

Knees - Axis

PolyCentric

Answer 17

• multiple centers of rotation
• provides added stability during stance**
• indicated for anyone with especially long residual limbs as well as those with less hip extensor strength/control

Question 18

Knees - Swing Resistance

Answer 18

Constant Friction

• single speed ambulator K1 or K2

Fluid Resistance

• hydraulic or air
• variable speed ambulators K3 or K4
• permits swing phase that more closely simulates normal gait
• increased weight, higher maintenance and higher cost
• may be less responsive in cold weather

Question 19

Other Features of Knees

Answer 19

• extension assist = at terminal swing
• stance control = locked, friction brake activated, mechanical, hydraulic
• computer controlled
• rotator
• torque absorber

Question 20

Single Axis Constant Friction Knee

Answer 20

• uses weight activated friction brake
• restricts more flexion when wt is put on 15-20 deg of flexion
• for K1 or K2
• up to 220lbs
• comes in child size

Question 21

SNS Stance and Swing Control Knee

Answer 21

• provides increasing resistance to flexion as knee flexes more and more to prevent falling in stance
• in swing, as knee is flexed more than 20 deg the foot is lifted and the knee extends

Question 22

Computer Controlled Hydra Knee

(C-Leg)

Answer 22

• intelligent knee by endolite
• rheo knee
• controls resistance to flexion and extension
• does not provide acive flexion/ extension

Question 23

Rotator Knee

Answer 23

located proximal to knee joint

allow pt to sit with legs crossed

Question 24

Torque Absorber

Answer 24

may be specific unit on shank or integral with foot

absorbs torque and thereby decreases shear force at RL/Socket Interface

Question 25

TF and Foot Prosthesis

Answer 25

• K0 = Non Ambulator - no coverage
• K1 = Household ambulator
  
  • SACH, Constant friction knee
• K2 = limited community ambulator
  
  • flexible keel foot, constant friction knee
• K3 = unlimited community ambulator
  
  • dynamic response foot, fluid friction knee
• K4 = high activity
  
  • dynamic response foot, fluid friction knee

Question 26

Knee Disarticulation Designs

Answer 26

advantage:

• end bearing RL
• self suspending
• long lever arm
• less surgically traumatic

disadvantage:

• component limitations
• cosmetic concerns

Question 27

Transfemoral Biomechanics

Answer 27

• must provide ML stability of pelvis during mid stance on prosthetic side - lateral wall of socket ADD
• provide AP stability of prosthetic knee between heel contact and heel off
• socket aligned in flexion approx 5-10 deg of flexion
• knee joint posteiror to TKA line
• TKA line = trochanteric knee ankle
• TKA line - socket forward of knee, knee posterior to trochanter and ankle if drop a plumb line - causes extensor moment = stabilization during stance

Question 28

Hip Disarticulation Endoskeletal Prosthesis

Answer 28

• pts can walk unassisted but with noticable deviations
• suspension socket that encompasses the waist to contain LE for providing more support to the lower kinetic chain
• requires A LOT of gait training in order to learn proper method of hip, knee, ankle control

Question 29

Bilateral Amputees

Answer 29

• limbs shorter so easier to control
• begin to train with stubbies
• lowers COM
• makes it easier to learn - start getting control and balance for gait