Hesperian Health Guides

Above-Knee Artificial Limbs

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HealthWiki > Disabled Village Children > Chapter 67: Artificial Legs > Above-Knee Artificial Limbs


Children who are growing quickly need a low-cost limb that can be easily replaced or lengthened. Small children usually learn to walk well with a straight leg limb that does not have a knee joint.

A bamboo or PVC plastic tube above-knee limb can be made in much the same way as for the below-knee limb.
BACK
VIEW
FRONT
VIEW
The top edge of the socket should be rounded to form a wide lip on the back, where the butt can sit. Weight bearing should be on the butt bone and over the entire stump—and not just on the end of the stump.
Back view and front view of bamboo or PVC plastic tube above knee limb.
NOTE: In some countries, thin plastic cuffs the right shape for socket tops can be purchased in different sizes from orthopedic suppliers. They can be placed around the leg before casting and can be re-used. Ask for ‘prefabricated ishial weightbearing cuffs’.
Thin plastic cuff to shape socket top
2. A leather and metal rod limb (adapted from Simple Prosthesis Manufacture).
MEASUREMENTS
Pictures of two boys, one with limb, the other with stump, and horizontal lines showing where to take measurements.
stand with hips level
distance
around hip
leg length
and
across hip

Note: The socket is open at the bottom of the stump. This makes it cooler than the one above, and also allows for growth.



Three pictures showing the different parts of a leather metal and rod limb, with arrows on each signaling measurements, characteristics, materials used.
padded soft leather cuff
5 mm. metal ring
15 degrees
length to crotch
bolt heads sunk into wood
weld joints
metal plate
hard wood
car tire rubber
bolt
lace
eyelet
thick leather sleeve
8 mm. or 5 mm. metal rod
To make sleeve, draw on paper a design like this based on A, B, and C stump measurements. Then copy onto leather and cut it out.
Design on paper for sleve using stump measured in three places
A
B
C


Above-knee limb with knee joint (for older children and adults)


SIDE VIEW FRONT VIEW
Side view of the above knee limb with knee joint, arrows pointing materials used and places where parts are attached.
Socket piece of leather (see below). (It can also be made of plaster, resin, or wood.)
support strips of metal
flat metal bars
knee joint
wood
wood and rubber foot
Front view of above knee limb with knee joint including the inner piece for very short stumps.
To help keep knee from bending when weight is on it, stretch a piece of rubber across front of knee.
strip of car tire inner tube
leather
(for very short stumps only)
Adapted from the OHI Manual: Simple Above-knee Prosthesis Manufacture.


Making the knee joint:

Note: This is a simple design for a knee joint. Knee joints that work well are hard to make and you may need to experiment a lot. Perhaps you can re-use a joint from an old limb that is not being used.


Four pictures that show how different parts are put together to form the knee joint.
1. Mark and round the top of the post.
2. Drill hole at exact center of circle.
3. Weld or rivet angle piece at right angle. (Use flat metal bar.)
4. Round back of post.
bolt
DVC Ch67 Page 634-4.png
DVC Ch67 Page 634-9.png
5. Drill hole in post and attach bolt with wire (to lock knee straight, when necessary).
6. Ledge prevents knee from bending backward. Small strip of car tire acts as cushion.
7. Add an angled piece to allow joint to stop in a squatting position.

FEET

Putting feet on artificial legs makes them look better (with shoes, sandals, or boots). Also, the wide base helps prevent the leg from sinking into mud or sand. A well-made, flexible foot can make walking easier. Here are 2 possibilities.

DVC Ch67 Page 634-5.png
lightweight spongy rubber
wood block (Use strong wood that will not crack.)
leg pole
old car tire (one piece)

Note: By putting the pole through the foot, if the foot breaks off the person can keep walking.


DVC Ch67 Page 634-6.png
The sponge rubber over the heel and toe lets the foot bend for smoother walking.
To mount a foot on a plastic PVC tube, use a flat metal pipe base like this.
A foot can also be made for a metal-rod leg. Here is one possibility.
Illustration showing metal foot
metal plate
weld
Leave open space above bottom sole for flexible heel.
3 or 4 layers of car tire, cut to allow flexibility of toes and heel.
Bolts should pass through all but the last layer of rubber.



This page was updated:19 Jan 2018