Responses: Squaring up joints
Jeremiah Uronis
Description
Collection
Title:
Responses: Squaring up joints
Creator:
Jeremiah Uronis
Date:
10/24/2018
Text:
Sorry for the delay, been swamped. Thanks for all the feedback everyone. Lots of good info. I think I have captured all the responses here:
1) Drill a hole through your cast at knee center axis. Select a long threaded rod that fits your joints female section. Protect threaded rod with tubing and insert in cast then fill cast. Make it about an inch or so too long on both sides. Bend uprights and make sure both female sections screw in the joints to ensure square.
2)If these are once in a blue moon I would make my own. Had to make a joint and lacer (which no body does anymore) .....so I took an ML caliper drilled out the side on the extensions and used that - worked well and I can still use the caliper.
3)This information came from one of our technicians.
As long as he has something on the joint axis that makes the componentry parallel to the other side he can bend with confidence. The best way to do that is to have a rod or something straight through the axis from side to side that the componentry can rest on in the same place in all planes. There are lots of objects that can be used, like threaded rod, cross-bow arrows, tube, otto bock has AB foam squared knee axis blocks.
And no. I don't believe all companies provide jigs. However, I have heard of people using VFJs, ottobock has it's universal kit for their own joints, and becker might sell something too.
4)becker has knee jigs one time buy
5) I use regular carpenter metal square. It is literally impossible to explain in written language. By far, works great. I have much better success with it than with any jig. You lay it flat on a joint side, right across the axis center. Then watch, what happens to the other joint. If there is gap, joints are toed out', if square edge hits the joint, they are toed in. Then you repeat same with square laid as vertical on the joint, as possible. Do same for stirrups. I bet, the very moment you lay square on a joint, you WILL see it, as it creates two nice 90 degree lines, makes very easy to see which way joints point.
6)I purchased drill rod about a foot long in the diameter of the joint nuts. It is very rigid and so remains accurate if you don't abuse it.
After your rough assembly, just remove the screw and nut from one side, slide the drill into the hole, then bend/twist the upright until the end of rod hits the center of the other nut. Then switch sides. It's very fast and accurate. The only disadvantage is you can't use it when the brace is on a cast or patient. It's also great when doing repairs and you're facing maligned joints.
7)There are numerous ways to undo this depending on what type of KAFO you are making. If you are making a polypropylene brace from a full leg cast get a universal alignment fixture (both Becker and Fillauer make them) They are specifically made for fracture bracing but you can adapt them both for thermoplastic KAFO construction. I mount the knee joints to the inside of the arms of the alignment fixture by leaving the nut insert in the joint and replacing the main screw with a longer screw that will reach thru the arm of the alignment fixture and secure the knee joint to its side temporarily while fabricating. Then take the central pin of the alignment fixture which a has a round plate on one end (to rest on the knee cap when Fx bracing) and turn it over using the other end, which you sharpen to a point and gently hammer it into the knee cap of the cast right. Hammer right on the round plate. So you mounted the knee joints to the arms of the fixture, inverted the knee cap rest in the the middle of the fixture and hammered the entire unit(fixture and knee joints) into the front of the cast with each knee joint and upright coming down the sides of the cast. You do this while you continually checking to see that you like the position of the joint and uprights in relation to the cast. Once it is secure you can draw the knee joints closer to the front of the cast or push them posterior by loosening the thumb screw on the fixture and slide the cross bar up or down the pin, then retighten it. Really tighten it.. Now you are ready to shape the joints. slide both joints close to the cast as you can. Pick one side and slide the arm off of the fixture, make your bend(s) and then slide it back on, check, remove and bend again and then replace it and over and over until you are happy with its shape. You can also cut them down to length during this process. Then repeat on the other side. Check to make sure the joints are in full extension periodically. If you are doing this over an already vacuum formed plaster mold of the leg cut out a square over the knee cap before hammering the pin into the cast or you will fracture the polypro. When you are all done and happy withe uprights check to make sure they are in extension and mark where you want the rivets to be on the uprights. Take one side off at a time and drill out the holes for the uprights then replace it on the cast and drill into the polypro thru the holes in the uprights one at a time and after drilling each hole lightly tap a copper rivet into the upright thru the poly and into the plaster to temporarily hold it in place while doing the other holes. That way they never shift and always will line up during final construction. Leave the rivets in place while doing the other upright as well. then do the other upright on the opposite side of the leg. Now draw your trim lines on the polypro. Remove the joints and alignment fixture, cut off the polypro and clean up each piece to do a trial assembly. You can use 8-32 screws with nuts or Cleco’s. Trial assemble the brace, mark any adjustments to the trim lines that you want and then finish the polypro shells, finish the metal uprights (sand and polish, or sand blast, etc..) and you are ready to final assemble. When you are all done the joints should be perfectly aligned, if not occasionally a very slight bend might be needed to square one of the upper or lower heads, but not usually.
8)A carpenter square worked really well for me!
9) If you have bilateral joints use a rod long enough to go through both joints an a washer that just fits the size of the rod
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1) Drill a hole through your cast at knee center axis. Select a long threaded rod that fits your joints female section. Protect threaded rod with tubing and insert in cast then fill cast. Make it about an inch or so too long on both sides. Bend uprights and make sure both female sections screw in the joints to ensure square.
2)If these are once in a blue moon I would make my own. Had to make a joint and lacer (which no body does anymore) .....so I took an ML caliper drilled out the side on the extensions and used that - worked well and I can still use the caliper.
3)This information came from one of our technicians.
As long as he has something on the joint axis that makes the componentry parallel to the other side he can bend with confidence. The best way to do that is to have a rod or something straight through the axis from side to side that the componentry can rest on in the same place in all planes. There are lots of objects that can be used, like threaded rod, cross-bow arrows, tube, otto bock has AB foam squared knee axis blocks.
And no. I don't believe all companies provide jigs. However, I have heard of people using VFJs, ottobock has it's universal kit for their own joints, and becker might sell something too.
4)becker has knee jigs one time buy
5) I use regular carpenter metal square. It is literally impossible to explain in written language. By far, works great. I have much better success with it than with any jig. You lay it flat on a joint side, right across the axis center. Then watch, what happens to the other joint. If there is gap, joints are toed out', if square edge hits the joint, they are toed in. Then you repeat same with square laid as vertical on the joint, as possible. Do same for stirrups. I bet, the very moment you lay square on a joint, you WILL see it, as it creates two nice 90 degree lines, makes very easy to see which way joints point.
6)I purchased drill rod about a foot long in the diameter of the joint nuts. It is very rigid and so remains accurate if you don't abuse it.
After your rough assembly, just remove the screw and nut from one side, slide the drill into the hole, then bend/twist the upright until the end of rod hits the center of the other nut. Then switch sides. It's very fast and accurate. The only disadvantage is you can't use it when the brace is on a cast or patient. It's also great when doing repairs and you're facing maligned joints.
7)There are numerous ways to undo this depending on what type of KAFO you are making. If you are making a polypropylene brace from a full leg cast get a universal alignment fixture (both Becker and Fillauer make them) They are specifically made for fracture bracing but you can adapt them both for thermoplastic KAFO construction. I mount the knee joints to the inside of the arms of the alignment fixture by leaving the nut insert in the joint and replacing the main screw with a longer screw that will reach thru the arm of the alignment fixture and secure the knee joint to its side temporarily while fabricating. Then take the central pin of the alignment fixture which a has a round plate on one end (to rest on the knee cap when Fx bracing) and turn it over using the other end, which you sharpen to a point and gently hammer it into the knee cap of the cast right. Hammer right on the round plate. So you mounted the knee joints to the arms of the fixture, inverted the knee cap rest in the the middle of the fixture and hammered the entire unit(fixture and knee joints) into the front of the cast with each knee joint and upright coming down the sides of the cast. You do this while you continually checking to see that you like the position of the joint and uprights in relation to the cast. Once it is secure you can draw the knee joints closer to the front of the cast or push them posterior by loosening the thumb screw on the fixture and slide the cross bar up or down the pin, then retighten it. Really tighten it.. Now you are ready to shape the joints. slide both joints close to the cast as you can. Pick one side and slide the arm off of the fixture, make your bend(s) and then slide it back on, check, remove and bend again and then replace it and over and over until you are happy with its shape. You can also cut them down to length during this process. Then repeat on the other side. Check to make sure the joints are in full extension periodically. If you are doing this over an already vacuum formed plaster mold of the leg cut out a square over the knee cap before hammering the pin into the cast or you will fracture the polypro. When you are all done and happy withe uprights check to make sure they are in extension and mark where you want the rivets to be on the uprights. Take one side off at a time and drill out the holes for the uprights then replace it on the cast and drill into the polypro thru the holes in the uprights one at a time and after drilling each hole lightly tap a copper rivet into the upright thru the poly and into the plaster to temporarily hold it in place while doing the other holes. That way they never shift and always will line up during final construction. Leave the rivets in place while doing the other upright as well. then do the other upright on the opposite side of the leg. Now draw your trim lines on the polypro. Remove the joints and alignment fixture, cut off the polypro and clean up each piece to do a trial assembly. You can use 8-32 screws with nuts or Cleco’s. Trial assemble the brace, mark any adjustments to the trim lines that you want and then finish the polypro shells, finish the metal uprights (sand and polish, or sand blast, etc..) and you are ready to final assemble. When you are all done the joints should be perfectly aligned, if not occasionally a very slight bend might be needed to square one of the upper or lower heads, but not usually.
8)A carpenter square worked really well for me!
9) If you have bilateral joints use a rod long enough to go through both joints an a washer that just fits the size of the rod
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OANDP-L is a forum for the discussion of topics
related to Orthotics and Prosthetics.
Public commercial postings are forbidden. Responses to inquiries
should not be sent to the entire oandp-l list. Professional credentials
or affiliations should be used in all communications.
Citation
Jeremiah Uronis, “Responses: Squaring up joints,” Digital Resource Foundation for Orthotics and Prosthetics, accessed November 1, 2024, https://library.drfop.org/items/show/209199.
