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56 Cards in this Set
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Review of prostheses for partial foot amputations and symes amputations
Dynamic response footplate to prevent toe break and to provide a more responsive prosthesis Shoe will break right where the foot is. So put a metal piece down the shoe so it does not happen. |
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Symes
Def: ankle/foot disarticulation, malleoli are partially shaved for cosmesis; heel pad reserved and anchored to distal end of tibia & fibula Limitation – type of feet, getting foot all the way down |
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A Complete Transtibial Prescription
Foot-ankle assembly Shank = shin Socket = the bucket Interface = what is between residual limb and hard shell Suspension = how it is held on to the person |
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Feet Classifications
Remember that all foot motions occur ___ in response to the load applied by the amputee Have to do w/ person’s body weight |
Remember that all foot motions occur passively in response to the load applied by the amputee
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Dynamic Response
Improved plastics & composite engineering have resulted in stronger and responsive internal keels. Includes the Seattle Foot & Seattle II, OWW Carbon Copy II, Otto Bock Dynamic, Flex Foot, Flex Walk, Freedom innovations FS 1000, and others Energy storing = materials, allow it return some energy when the person walks Flex foot = the curved metal foot = energy storing or dynamic response feet |
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Dynamic Response or Energy Storing
Advantages: Lower energy consumption for moderate to high activity patients Better roll-off and support through late stance More normal gait Disadvantage: Cost = higher level, more expensive |
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Feet-articulating
Foot that allows for plantar and dorsi-flexion via some mechanism of bumpers and an axis pin Simulates actions of the Gastoc/Soleus and Anterior Tibialis Reduces flexion torque at the knee at initial contact Multi or single axis Non-articulating foot = like the high energy foot Articulating foot = DF, PF, Inv, Ev, allow uneven surface – body weight moves it |
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Feet-articulating
Advantages: Reduced torque on knee and therefore decreased pressure on the RL Accommodates uneven terrain Disadvantages: Weight Mechanical complexity Noisy Cosmesis - ugly |
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Articulated
Multiple-axis Feet Gressinger Foot Endolite Multiflex Foot College Park Foot (Tru-Step) Endolite = has a bumper, allow motion in all directions, cover allows you to put on sock and shoes easier. |
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Proprio Foot by Ossur
Samples ankle motion over 1000 times/second Makes walking on inclines easy Plantarflexes and dorsiflexes like a real foot Not for someone who does sports, or jumping. Nice gait pattern |
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Proprio Foot
Selection criteria: Transtibial amputees Low to medium impact US K3 ambulator (all daily activities) EU M2 - M4 (exclude high impact) Patient weight range: 100 - 250 lb (45 - 116 kg) Clearance 7" (18cm) |
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Non-articulated Feet
SACH Solid-ankle-cushioned-heel Cheap, for people that are not very active Stiffness of heel cushion is what gives a roll off (?) during gait |
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SAFE—Stationary Attachment Flexible Endoskeletal
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Seattle
Released in early 1980’s and was considered a dynamic response foot Energy storing, non-articulating Light weight, has plastic inside |
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Carbon Copy II
Considered to be a moderate dynamic response foot |
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Flex Foot—by OSSUR
Variations: Variflex Symes Reflex Flex walk Split toe Sprint flex Talux Ceterus Returns a lot of energy, 2-3K per piece, good for playing sports, shock absorbing |
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OSSUR Ceterus Flex-Foot
Provides natural, responsive rotation |
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Springlite Foot
Dynamic response foot |
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Pathfinder Foot
Dynamic response foot with air pump to adjust heel resistance and shock attenuation |
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Some Feet Manufacturers
Flexfoot by OSSUR Ohio Willow Wood Seattle Systems Freedom Innovation Springlite Century XXII Dycor Otto Bock College Park Kingsley Endolite |
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Energy return percentages
SACH 0 % - returns no energy Seattle 70 % Flex 90% - high end foot Human 260 % |
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Medicare K-levels
K0 - Does not have ability or potential to ambulate safely with or without assistance and a prosthesis does not enhance their quality of life or mobility. K1 - 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. |
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Medicare K-levels
K2 - Has the ability or potential for ambulation with the ability to traverse low level environmental barriers such as curbs, stair or uneven surfaces. Typical of limited community ambulator. K3 - Has the ability or potential to ambulate with variable cadence. Typical of the community ambulator who has the ability to traverse most environmental barriers and may have vocational, therapeutic, or exercise activities that demands prosthetic utilization beyond simple locomotion. TF |
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Medicare K-levels
K4 - Has the ability or potential for prosthetic ambulation that exceeds basic ambulation skills, exhibiting high impact, stress or energy levels. Typical of the prosthetic demands of the child, active adult, or athlete. Someone who can run, play a sport (golf, tennis) |
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Feet covered by Medicare
K0 none K1 SACH, Single Axis K2 Flexible Keel, Multi Axial K3 Energy Storing Feet including Flex foot or equal K4 All feet |
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Shanks
Endoskeletal: Interchangeability Component options Post fabrication adjustable Strength Weight Covering options Exoskeletal: Durability – for construction worker Endoskeletal = could cover w/ cosmetic covering if you want to, the pipe |
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Pylons—narrow vertical support connecting the socket to the ankle/foot assembly
Shock and torque absorption pylons can be added for additional responsiveness, stress, shear & torque reduction |
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SOCKETS
HARD: Direct contact between socket and residual limb SOFT: A liner is incorporated as a cushion between socket and residual limb—in some cases, provides suspension (goes inside the hard socket) Ply – weighted socks, 1 ply sock thin, 8 ply sock thick. As shrink, must keep getting socks, until remake it b/c limb too small. Must keep a sock with you at all times, because of fluctuating edema. Everyone wears a sock w/ TT prosthesis |
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Socket Design
patellar tendon bearing design (PTB socket) wt. bearing areas vs. non-wt. bearing areas total contact design variations: Joint & Corset Supracondylar (SC) Supracondylar- Suprapaterllar (SCSP) All sockets are total contact – all parts of the residual limb are contacting this socket. If not, break down, edema. If bottom doesn’t touch, pool blood You can’t WB on end of TT limb. Its touching, but not WB. PTB – held on w/ external means SC – if just over condyles (med and lat) SCSP = if over condyles and over patella |
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Socket Design Joints & Corset
Everyone got one pre WWII Usually suspended with a waist belt Advantages: Offers maximal ML and AP stability Large surface area on the thigh allows for residual limb de-loading Disadvantages: Hot & heavy Causes thigh musculature atrophy Ligaments & tendons may become lax due to lack of use. Thigh corset – someone w/ knee instability(no lig in knee) – hot, heavy, ugly |
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Socket Design
Hydrostatic Total Surface Bearing Advantages: Evenly distributes forces across the RL Liner offers good shear and friction reduction Enhanced comfort Pascal's law of fluids. This states that a confined fluid transmits externally applied pressure uniformly in all directions. It further states that the resultant forces act perpendicular to the container's surface. |
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Socket Design
Disadvantages: Skin irritations Some hypersensative areas cannot tolerate the “even” pressure PTB prosthesis, can be uncomfortable, some don’t have that anymore. WB is on the side and soft tissues – never on the end. |
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Interface:
socks/hard sockets Foam “pelite” liner Vicsoelastic gel liners |
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“Hard” Socket/Sock
Indicated for mature limbs only Minimizes bulk Reportedly “cooler” than with liners Properly contoured socket required Requires some means of suspension |
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Foam “Pelite” liners
Advantages: Adds cushion Easily modifiable Suspension can be incorporated Disadvantages: Adds bulk Increases friction Insulative properties Skill required for donning |
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Custom Liners:
Indicated for uniquely shaped and/or scarred limbs Were the first silicone liners available Advantages: Reduce friction and shear Suspension mechanisms may be included Disadvantages: Expensive and hot at first Potential for skin problems Add bulk |
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Off the Shelf Liners
Most manufacturers now have their own line Advantages: Reduces friction and shear --is in vogue Suspension may be included Different thicknesses and styles Silicone, mineral oil gels, even with aloe! Customizable Disadvantages: May be hot Add bulk Potential for skin problems |
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Suspension:
cuff strap thigh corset/lacer supracondylar or SCSP wedge locking pin suction suspension sleeve waist belt |
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Suspension Systems-cuff strap: (leather strap thing - see slide 52)
Advantages: Simple & effective means of suspension Suspends over the condyles Attachment points approximate knee center Leather or leather & elastic Disadvantages: Does not provide AP or ML stability May impede circulation and knee flexion > 90 degrees Not very cosmetic |
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Waist Belt & Fork Strap Suspension Systems
Advantages: Removes all suspension burden from the limb Usually added as an auxiliary suspension Disadvantages: Hot Allows for piston action (residual limb move up and down socket = bad) Bulky |
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Suspension Systems-Supracondylar (PTB-SC)
May be SC or Supracondylar Suprapatellar (PTB-SCSP) |
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Suspension Systems-Supracondylar (PTB-SC or SCSP)
Advantages: Added ML stability Some recurvatum control (SCSP only) Increased socket surface area lowers overall pressure One piece design Disadvantages: Higher trim lines Requires dexterity to don |
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Pin Suspension Systems:
Locking pin and shuttle mechanism Foam gummy thing with screw at end rolls over sock. It is hot. Feeling of sucking bottom of limb Donning and doffing = putting on and off prosthesis |
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Pin Suspension Systems
Pin is incorporated into the distal end of the gel liner and must be guided into the “shuttle” at the distal end of the socket. May or may not have audible clicking with donning Doffing is accomplished by pushing a button on the outside of the prosthesis that disengages the pin/shuttle |
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Pin Suspension Systems
Advantages: Pistoning reduced Secure suspension Disadvantages: Suspension forces concentrated distally Mechanical complications Flexion limitations |
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Sleeve Suspension:
Advantages: Improved cosmesis Suspension is not concentrated on the RL Disadvantages: Durability Knee flexion limitations Heat Skin Irritations Suction suspension – really good, some people feel it is too tight |
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Suction Sleeve Suspension Systems
Consists of incorporation of a one way valve into the socket that allows air to escape in conjunction with a gel suspension sleeve that “seals” the top of the socket preventing air from coming in. Can be used with pin and non pin liners |
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Suction Sleeve Suspension Systems
Advantages: Best suspension available Improved cosmesis Suspension is not concentrated on the RL Disadvantages: Durability Knee flexion limitations Heat Skin irritations Mechanical noises |
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Biomechanics of Transtibial Prostheses (PTB)
Socket design Maximize wt-bearing capacity of RL Incorporate total contact Use pressure-tolerant areas (socket build-up) Avoid pressure-sensitive areas (socket relief) Use flexion in interface (5-8 degrees) |
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Biomechanics of Transtibial Prostheses (PTB)
Alignment Maintain ML stability at midstance on prosthetic side Initial foot placement inset ½ inch with respect to socket Increases compression of tissues distal-lateral and proximal-medial |
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Biomechanics of Transtibial Prostheses (PTB)
Encourage knee flexion throughout stance on prosthetic side Initial foot placement 1 ½ inches posterior to midpoint of socket at medial tibial plateau level Reduces length of keel, encouraging knee flexion from midstance to toe off Initial flexion in prosthesis of 5-8 degrees maintains floor reaction posterior to knee throughout stance Correct heel durometer (SACH) firm=increased flexion moment & soft=increased extension moment |
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Normal expectations
Patient comfortable when walking Base of support 2-4 inches between heel centers Knee flexion approx. 10-15 degrees after initial contact Foot moves smoothly into loading response Socket should not gap at lateral brim, not increased pressure at medial brim (should be total contact all the time) |
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Knee should extend throughout MS and flex again through TS & Pre-swing
Swing should have normal knee flexion with minimal piston action between RL and socket plus adequate toe clearance |
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Heel lever arm
Distance from end of prosthetic heel to midpoint of shoe Provides support from initial contact to mid stance to allow smooth descent of the prosthetic foot and controlled knee flexion |
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Toe lever arm
Distance from midpoint of shoe to toe Provides support from mid stance to terminal stance and allows the patient to roll over the foot in a smooth manner |
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Too short a toe lever arm is caused by placement of the socket too far forward on the foot
Short toe lever, long heel lever. |
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