One of Tyler’s comments which was posted to me got me wondering whether there might be a easier way to possibly do the Lateral Synovial Joint Loading. The clamps we might buy operates on a rather easily understood principle. Two blunt, rather flat surfaces is compressive down upon bone tissue to try to create bone modification. Most people have legs that are about 3-4 inches in diameter and the knee is often slightly smaller in width.

[The exact location we are supposed to load the clamp is the protruding bumps on the side of our limb synovial joints. There are 5 locations that I can think of from the top of my head, the wrist area, the elbow area of the forearm, above the knee where the distal femur epiphysis is, below the knee where the proximal tibia and fibula are, and the ankle area where the tibia is connected to the feet bones.]

This means that any device that is build must be able to at least clamp around 4 inches of material. We know that we can try using weights/ dumbbell but that is hard to aim and really compress/load in the right area. Plus, the other side using a dumbbell would have the hard floor to load on.

What I propose in this post is to build an automatic LSJL device for less than $600 in cost, using material one can find from EBay and speciality shops on the internet.

When I first started on the idea, I envisioned in my head a device that was similar to a piston that push in a axial direction with sinusoidal behavior. When I called and around and did some research, most people at a hardware store or electronic store could not even give a name what such a device would look like.

I have worked in building robots before so I know that if the device could not be bought as an intact device, then it could be built, because I know exactly which parts are needed. Eventually I found the right suppliers and parts to make the device.

These are the parts needed

1. We need to buy two linear actuators. The two types I would suggest is get either the electro-mechanical or the linear motor, which can give one some speed. The actuators are what would allow one to control the stroke action, where one stroke compresses and load, while the alternate stroke releases the loading. A website to use is Progressive Automations. For the actual thing to buy, we would be looking for the strongest ones since I am almost positive to scale up the loading from the original experiments done on mice hindleg bone, we might have to multiple the loading force by at least 10,000X.

Note three factors of the actuators,

• 1. stroke size – this is the maximum stroke or actual length that can happen. This also determines the both the size of the actual device and the range one can put the actuators apart from each other.
• 2. force – the amount of loading that is being exerted.
• 3. speed – the amount of change that the stroke can change by per second.

2. We need to buy a field-programmable gate array (FPGA). FPGAs are integrated circuits which you can plug to your own computer and program to send specific signals out. For more information on FPGA check out the wikipedia article on it HERE. For a company where you can buy a very nice easy to use FPGA board you can try Digilent Inc HERE. You can get a Nexys-3 Spartan-6 for $200 but also discount it for $120 if you are a student. This should handle simultaenous devices. Remember that if you are using the board to control the stroking movement, you have to get the digital actuators which I haven’t looked into.

3. You need a board and a mounting bracket sold HERE to hold the electro-mechanical actuators in place, at about 6 inches apart from each other in their standard resting distance. depending on what size of stroke you buy, you may have to put the devices either further apart or closer together to account for both the stroke size and your leg width.

4. You need a computer with knowledge on embedded systems to program the FPGA board. This part I have no knowledge on. It would take me at least 3 months to learn how to program using the original language I used which was Assembly. Most people seem to suggest using C or Java these days. Almost any Electrical Engineering major in university would know how to do this part.

5. It might be helpful if on the ends you put some types of plastic plug or covering to avoid skin chafing or stretching when the loading is happening.

Alternatively, if you don’t want to get the stuff for 2 and 4, you can get the control box for the actuators HERE. There is a nice video on the website to show how easy it is to just use the control box. You want to buy the one AC controller with 2 motors with simultaneous function which costs $186. However, the issue is that they seem to only have one speed, but we would need to test the leg bone’s response to different frequencies and speeds. That is why we can modulate the speed of the actuator with the FPGA board.

Actual construction: So you basically just mount the two linear actuators facing each other, screw or bolt the devices on a board or plane which will not be moving, plug the actuator cord into the board, and program the board to send specific wave function signals to the actuator to either stoke in or out. The simpler method would be to remove the Board completely and just go with a controller board but one might have to replace and switch actuators if the speed and force are not right for the bone lengthening effect we desire. No matter what, you need at least 4 parts, the two actuators, something to control it, and the mounting parts to hold the actuators down to a flat solid surface. The combined total is around the $600 range for the weaker loading devices and around $800 for the stronger loading devices.