Hesperian Health Guides

Plaster and Bamboo Below-Knee Artificial Leg

Every day 20,000 people visit the HealthWiki for lifesaving health information. A gift of just $5 helps make this possible!

Make a giftMake a gift to support this essential health information people depend on.


HealthWiki > Disabled Village Children > Chapter 67: Artificial Legs > Plaster and Bamboo Below-Knee Artificial Leg


Man sitting adjusts bamboo limb of man using crutches.
A village rehabilitation worker fits a young man with a bamboo limb. (PROJIMO)

This simple, low-cost leg was developed for refugee amputees in Thailand by Operation Handicap Internationale. It is most useful as a temporary limb for learning to walk. However, if the inner (plaster) part of the socket is made with waterproof glue, or is protected from getting wet, the leg can last for a long time.

Steps for making the plaster socket

1. Make a thick ‘cup’ or ‘cap’ of sponge or folded cloth and tape it over the end of the stump (to give it a little extra length).
Stump below the knee and a plaster cap-looking socket.
2. Put a thick, tight-fitting stocking—without seams if possible—over the stump and knee. (Several thin layers of stocking can be used instead of a thick one.) Pull tight to avoid wrinkles. Girl puts sock on stump below the knee.
Putting holes near the top of the stocking makes it easy for the child to pull it up tight against the skin while the cast is put on.
Sock with two large holes on each side, near the top.
3. Put a thin plastic bag over the stocking.
Plastic bag put on the sock that covers the stump.
4. Put a thin cotton stocking or stockinette over the plastic bag and also pull tight to avoid wrinkles.
Sock being pulled onto stump below the knee.
5. With the stocking stretched tight, mark the important places with a ‘grease pencil’. The pencil marks will ‘print’ onto the inside of the plaster cast when it is removed.

Note: If you do not have a stocking, you can mold the socket directly on the stump. Shave any hair off the stump and cover it with vegetable oil (for example, coconut or palm oil).


Bottle of palm oil.



Mark all these places:



Two stumps with arrows pointing to characteristics.
FRONT
VIEW
SIDE
VIEW
top of smaller leg bone
bottom end of smaller leg bone
kneecap
middle of kneecap tendon
bump of shin bone where tendon attaches
spot where shin bone gets wider
front edge of shin bone (each side)
bottom end shin bone, front edge
6. Wrap the stump and knee with plaster bandage. Be very careful to put the bandage on evenly and smoothly. (Elastic plaster bandage works best, but is very costly. To reduce costs you can make your own plaster bandages for casting.
Cast the knee with the stump slightly bent.
knee and stump wrapped with plaster bandage.
Keep the knee at about this angle.
7. As the plaster dries, hold the stump firmly below the knee.
DVC Ch67 Page 629-3.png
Press your thumbs on each side of the tendon just below the kneecap.
FRONT VIEW
BACK VIEW
With the ball of the hand, press gently on the muscles on both sides of the leg.
With the 2 middle fingers of each hand, press into the hollow behind the knee.
Hold the stump like this until the plaster is hard enough to hold its shape.
8. When the cast becomes hard, mark where to cut the top edge (see below).
SIDE VIEW BACK VIEW
marking the plaster in a straight line on the side and in a U shape behind the knee
9. When the cast becomes hard, mark where to cut the top edge (see below).
DVC Ch67 Page 629-5.png
It may be necessary to cut the cast behind the knee, like this, to get it off.
10. Cut the cast along the line you drew.
DVC Ch67 Page 629-6.png
1 cm.
3 to 4 cm.
The dip behind the knee should reach at most ½ cm. above a line passing through the mid-point of the kneecap tendon.

Preparing the bamboo post

1. Select a piece of strong, green bamboo a little longer than the good leg from the knee to heel.
DVC Ch67 Page 630-1.png
bamboo 4 cm. to 6 cm. thick
The joint in the bamboo should be about 2 cm. below the end of the stump.
2. Split the bamboo to a little below the level of the stump end. Split into thin strips— each about ¾ cm. wide.
DVC Ch67 Page 630-2.png
Hold the post up firmly in a vise or a log with a hole in it — or however you can.
3. Remove the softer inner layer from each of the thin strips. DVC Ch67 Page 630-3.png
4. Spread the bamboo strips around the plaster socket.
DVC Ch67 Page 630-4.png
5. Position the socket as correctly as you can. Then, with a thin wire, wrap the bamboo tightly against the socket.
DVC Ch67 Page 630-5.png
6. Put the limb on the stump and have the child stand on it. Check the length. If necessary, cut some off the post.
DVC Ch67 Page 630-6.png
Cover stump with cotton stocking.
Make sure the post is straight or at the same angle as the other leg. If not, loosen the wire and re-adjust until you get it right.

Note: If child uses a shoe or sandal, be sure to have her wear it when measuring the height of the limb.


7. After trimming the tops of the bamboo strips, cover the outside of the socket with several layers of glue, sawdust, and gauze bandage:
  • Brush on one layer of glue.
  • Press sawdust on the glue (with gloves).
  • Wrap tightly with gauze bandage. Let it dry.
  • Repeat 5 or 6 times.
DVC Ch67 Page 630-7.png
glue
sawdust
8. Smooth the outside of the socket with sandpaper. Also smooth and round the inner edges at the top.
showing
CROSS SECTION
9. Make a ‘cuff’ to hold the limb on. (If attached correctly, it should also help keep the knee from over-straightening.)
DVC Ch67 Page 631-1.png
Fit cuff just above kneecap.
Rivet cuff to socket slightly behind mid-line (Mark rivet points with tabs pulled tight when knee is a little bent.)
10. Make a rubber ‘heel’—a piece of thick truck tire works well. If you can, cut the tire so that a ‘plug’ fits inside the bamboo. Cut off bamboo as much as the heel is thick. (Be sure to allow for height of sandal or shoe on other foot.)



11. Have the child stand and walk on the limb for several minutes. Then remove it and look for sore spots on the child’s skin, or signs of too much pressure. Check especially over bony spots. An area that looks pale when the limb is removed and then turns red or dark, is a sign of too much pressure.
DVC Ch67 Page 631-4.png
bony spurs
12. Scrape shallow pits into the socket from the inside, at the points where it presses over bones. You may also need to build up around the area where pressure occurs.
DVC Ch67 Page 631-3.png
rasp
(file)
(To help you find the right points, it helps to have marked ‘bony spots’ before casting. They will then be ‘printed’ inside the socket — see "Mark all these places" above.)
If stump presses on bottom of socket, you may need to build up.


DVC Ch67 Page 631-5.png
the top edge,
behind the knee,
SIDE VIEW CROSS SECTION
showing places to dig out pits
under the kneecap,
under the inner side of the knee,
and on each side of the shin bone.
To build up these spots, dig a few pits into the socket surface so new material will grip better. Fill with a paste of fresh plaster mixed with glue.
BACK VIEW CROSS SECTION
If socket presses on the end of the bone, scrape out a hollow here.


Artificial leg using PVC plastic pipe instead of bamboo

Where plastic PVC water pipe is available, it can be used instead of bamboo. Use a
3 cm. (1¼ inch) thick-walled PVC.

1. Measure the tube the same as bamboo, and cut it to form 4 strips. 2. Heat the PVC in an oven until it gets a little soft. 3. Fit the hot PCV around the socket piece and wrap it tightly with a long strip of cloth or rubber until it cools.
DVC Ch67 Page 632-1.png
DVC Ch67 Page 632-2.png
DVC Ch67 Page 632-3.png
4. Fasten PVC firmly to socket with wire or rivets (or both). It is best to attach it temporarily with wire and to have the child try it before you fix it permanently. 5. Cover with sawdust and glue, or with resinbase casting bandage (very expensive) or with fiberglass and resin (also expensive).
DVC Ch67 Page 632-4.png
DVC Ch67 Page 632-5.png


Note: For a stronger, water-resistant limb, the socket can also be made with resin-based casting bandage. But this is also expensive.



Lengthening the PVC leg to allow for growth of the child

1. Cut through PVC pipe. DVC Ch67 Page 632-7.png 2. Cut a strong hardwood rod or plastic tube that just fits inside the PVC. DVC Ch67 Page 632-9.png
3. Cut a ring of PVC pipe as long as the additional leg length needed. (Make it a little extra long to allow for more growth.) DVC Ch67 Page 632-10.png 5. Drill holes and screw or bolt leg together tightly.
4. Put the wood rod inside the PVC with the new ring of PVC .
6. When an even longer limb is needed, replace the short ring with a longer one. DVC Ch67 Page 632-11.png 7. If necessary, to make the joint stronger, cut a piece of PVC lengthwise, heat it, put it over the leg tube, and attach it tightly. DVC Ch67 Page 632-12.png


IMPORTANT! For both below-knee and above-knee limbs, try to line up the limb as well as possible so that its angle is similar to the other leg and ‘feels right’ when the child stands and steps. Often this requires repeated tries and adjustments. Getting the limb to line up right is the key to successful limb fitting. It helps to learn this from someone skilled at fitting limbs.



This page was updated:19 Jan 2018