prosthetics and orthotics video

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Thursday, March 4, 2010

Knee Disarticulation Amputation/Knee Disarticulation Prosthesis


Knee Disarticulation Prosthesis in alignment jig.

For the fitting of lower limb Prosthesis there are different level of amputation such as,
(i) Hip disarticulation
(ii) Transfemoral
(iii) Knee disarticulation
(iv) Trans tibial

Note; the above mentioned level of amputation are mostly found during Prosthesis fitting, for the starting let us learn a bit about knee disarticulation.

Knee disarticulation amputation – Is an amputation done between bone surfaces (femur and tibia) rather than by cutting bone.



Advantages of knee disarticulation amputation
-Has good end weight bearing
-No cut bone
-good muscular stabilation
-has long lever arm
-Epiphysis retained
-There is no terminal over growth of the bone.
-Patient can kneel without the prosthesis.
-Soft tissue adapted to weight bearing
-femoral condyles intact of which do help to control rotation and suspension.

Disadvantage to knee disarticulation Amputation
-Knee center difficult to match
-Socket must allow for femoral condyles (sometimes patella)
-has limited choice of knee mechanisms
-always are bulky in appearance
-poor cosmetics.

When we come to its biomechanics functions we find that;

Has greater control
-due to its intact at thigh musculature
-the stump has good weight bearing at distal area.
-maximum rotational control
-due to its suspension at its condyles
-due to its extended lever arm

Center of rotation
When we compare the center of rotation (COR) of knee disarticulation to transfemoral we found that:
COR of transfemoral is about the ischial tuberocity while COR of knee disarticulation is about the distal end

NOTE;
In prosthesis fabrication ,knee disarticulation is an excellent weight bearing stump.
-Its most often used in children and young adult.
-Its nearly always avoided in the elderly and patient with ischemic disease.






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