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15 Cards in this Set
- Front
- Back
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What population are polycentric knees indicated for? why?
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1) short limbs
2) Weak hip ext 3) long limbs Stability found in linkage system. Centrode. Instantaneous center of rotation starts posterior/ proximal giving it the most stability. As the knee bends, the centrode moves anterior and distal moving closer to the knee access and allowing the knee to bend. This hinges are good for longer limbs because they are able to fold under, making them shorter during sitting and for foot clearence in swing phase |
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what phase of gait is MECHANICAL friction control in Px knees used?
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SWING PHASE. controls rate of knee flexion and extension.
Limits heel rise and prevents terminal impact |
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what phases of gait is FLUID friction control used?
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Swing phase or swing and stance phase
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Describe how a weight activated stance control knee works?
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Locks upon weight bearing at 10-15 degrees, patient must totally "unload" for swing phase.
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Name 2 advantage and 2 disadvantages of a weight activated stance control knee
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Adv: stance phase stability, friction break
Disadv: no shock absorption at initial contact. no knee flexion in terminal stance in order to prepare limb for swing These result in gait deviations: vaulting and hip hiking in order to unweight the leg |
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Describe the difference between Stance phase control/"stumble recovery" and stance flexion
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"stumble recovery" is if a Pt is falling down the yield/ resistance to flexion will increase. This feature also allows the Pt to go step over step while going down stairs by providing a yield to the knee flexing.
Stance phase flexion is the ability to have the knee flex slightly at heel strike in order to provide shock absorption. |
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Describe what the extension assist feature will do on a knee unit
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It provides for stability at initial contact. Helps position the leg. Readies the leg for stance phase.
These can be found internally in the knee unit or externally. All knees that we fit have some sort of extension assist |
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What knee unit is indicated for a knee disarticulation?
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Polycentric - endoskeletal
Outside Hinges- exoskeletal |
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Name the 5 types of possible knee units for a TF socket in the order of STABILITY.
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1) Outside hinges
2) Single axis- constant friction -3) Weight activated stance control 4) Polycentric 5) Manuel locking |
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Name 3 ways to adj a polycentric knee in order to make it flex more easily
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1) Linear slide
2) Adj extension stop 3) Tip knee anteriorly. NOT the socket but the knee unit. This drops the ICOR (centrode lines intersect closer the the knee center) allowing the knee to flex more easily. |
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Why would you recommend a polycentric knee joint v. a weight activated stance control knee?
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Polycentric= good HE, good voluntary control
Stance control weight activated= Poor balence. They need mechanical knee security |
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How does a Pt control a single axis knee?
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Hip extensor strength and by shifting weight line anterior to the knee
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What are the benefits of flexing a TF socket and why do we accomidate a HF contracture?
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In order to take a normal step length on the sound side.
Puts the HE on stretch. Loads the posterior femur/soft tissue- which is a an area that tolerates load bearing well |
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What is the advantage of a pelvic jt/belt?
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increases coronal stabiltiy at the hip
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where is the axis of the hip joint on a TF socket with a pelvic belt?
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12mm anterior/ 25 mm proximal
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