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What are the 2 types of transfemoral sockets?
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What is the shape of the quadrilateral socket?
- square/rectangular
- bigger medial/lateral
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What is the shape of the CAT-CAM?
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How is the ishium supported with a quadrilateral socket?
rests on socket on posterior shelf (ishcial seat)
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How is the ishium supported with a CAT-CAM?
ischial tuberosity and part of the ischiopubic ramus are contained inside the walls
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With what socket type is the inguinal pressure increased with sit->stand?
quadrilateral
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What type of gait deviations are seen with a quadrilateral socket?
increased trendelenburg
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What is the fit/alignment of the transfemoral socket like?
- should be total contact with good contact on every area of the limb
- distributes load over max area
- reduces pressure
- provides counter pressure to assist venous return and prevent distal edema
- enhances sensory feedback to foster better control
- designed to emphasize loading on pressure tolerant structures (ishial tuberosity, gluteal musculature, sides of thigh, somewhat the distal end of the limb)
- must avoid excessive pressure on pubic symphysis and perineum
- slight flexion
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Why do transfemoral sockets have a slight flexion aspect?
- facilitate extensors
- reduce lumbar lordosis
- allows for approx equal step length
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What is stance phase knee ext and stability created by aligning the knee joint posterior to the vertical knee axis line?
alignment stability
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What are components?
parts of the prosthesis
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What is dynamic alignment?
- slight mvmt of the foot or knee component in relationship to the socket to provide the client with an optimum gait
- can only be done after the client has learned to walk with the prosthesis
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What is a lightweight metal tube to connect the components?
- endoskeletal
- soft foam cover that matches the color and configuration of the other leg covers the shank
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What is a wood or rigid polyurethane covered with a rigid plastic lamination?
exoskeletal
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What is pistoning?
- dropping of prosthesis away from the residual limb during swing phase of gait
- usually occurs with inadequate suspension
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What is the part of the prosthesis corresponding to the lower leg of the unamputated limb, or the part that connects the foot to the socket/knee unit?
- shank
- includes the pylon and cosmetic cover of the endoskeletal and is the finished part of the exoskeletal
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What is the component into which the residual limb is inserted?
socket
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What is static alignment?
- placing the prosthetic components in proper relationship to each other in the standing position
- the socket, knee component, and foot are placed to duplicate the trochanter, knee, and ankle relationships of the nonamputated leg
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What is the stance phase stability of the transfemoral prosthesis that is controlled by the clients extension of the residual limb against the posterior wall of the socket?
voluntary knee control
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What are 4 possible features of knees?
- axis
- friction mechanism
- extension aid
- mechanical stabilize
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What are the advantages of a single axis knee?
- simple
- less costly
- most common
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What do polycentric knee axis's provide?
efficient glide-slide motion
- varying stability through stance by placing the line of force for knee rotation posterior to wearers weight line
- shortens shank during swing phase for better toe clearance
- allows shank to rotate under knee when sitting
- increased weight/bulk
- complex, less durable
- less common
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What modifies the pendular action of the knee?
friction mechanism
- constant friction device
- variable friction device
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What is a constant friction device?
- most popular
- friction remains constant at all phases of gait
- pt can alter the amt of friction by tightening or loosening the clamp
- clamp grabs the knee bolt
- simple
- durable
- low maintenance
- *only constant swing phase control
- *no stance control
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What is a variable friction device?
- friction changes during swing phase to accommodate to varying gait speeds
- hydraulic
- better knee for more active ppl
- when wearer walks faster, knee friction increases instantly
- increases symmetry in the limbs
- can be affected by temperature
- hydraulic swing control:high cost, heavy
- hydraulic swing and stance control: has braking mechanism for stance phase control, high cost, heavy, may need more maintenance
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What is a pneumatic knee?
- air
- more responsive to changes in gait speed than constant friction
- higher cost
- may need more maintenance
- heavy
- less friction than hydraulic
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What is a microprocessor knee?
- C leg (name brand)
- programmed to achieve optimal gait (speed and quality)
- can analyze pts gait and adjust accordingly
- costly
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What is an extension aid (kick strap)?
elastic webbing placed along the front of the knee axis, elastic stretches when the knee flexes in early swing and recoils to extend the knee in late swing
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What are the advantages/disadvantages of an extension aid?
- adv: simplest method, external aid, easily ajusted
- dis: knee tends to extend in sitting
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What type of extension aid allows the knee to remain flexed in sitting?
internal elastic strap or coiled spring
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What are some characteristics of a manual lock knee?
- security all pahses of gait and total stability in stance
- knee wont flex when locked
- shank will be shortened to accommodate for lack of flexion
- can lead to hip hiking and circumduction gait
- no swing phase
- good for those with significant knee instability/weakness
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What are the characteristics of a weight activted stance control (stance control knee)?
- knee is locked during stance only, when weight is through the prosthesis
- bock safety knee
- good for single speed ambulators
- during stance if knee is flexed <10-15 degrees, knee is locked
- contraindicated: bilateral amputees
- possible hip hiking, circumduction
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What are the characteristics of a SACH foot?
- solid ankle cushion heel
- most prescribed
- posterior portion has a cushion with variable densities (softer for lighter pt, harder for bigger pt)
- no propulsion at terminal stance
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What type of foot prosthesis is more flexible than a SACH?
- SAFE
- solid ankle flexible endoskeleton
- posterior heel cushion
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What motions do single axis articulated ankles allow for?
- DF/PF
- has 2 rubber bumpers:
- post bumper controls amt of PF; ant bumper controls amt of DF
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What motions do a multi axis articulated ankle allow for?
- DF/PF - has ant/post bumpers
- INV/EVER - has medial/lateral bumpers
- medial controls amt of INV
- lateral controls amt of EVER
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What is dynamic response?
- energy is stored in a flexible shank and keel and is released at toe off
- use plastic or carbon fiber foot-ankle-shank
- propulsion at terminal stance
- run, jump
- lightweight
- reduces fatigue
- costly
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