This paper discusses a lateral bone loading device.  It mentions a capacity of 40N which I think won’t be enough for lengthening purposes as since lengthening post growth plate senesence is an abnormal task it probably requires very abnormal stimuli.  It’s interesting to look at the device though.

The study mainly mentioned the technical design of the device and no analysis of the applications.

A Mechatronic Loading Device to Stimulate Bone Growth via a Human Knee

“This paper presents the design of an innovative device that applies dynamic mechanical load to human knee joints. Dynamic loading is employed by applying cyclic and periodic force on a target area. The repeated force loading was considered to be an effective modality for repair and rehabilitation of long bones that are subject to ailments like fractures, osteoporosis, osteoarthritis, etc. The proposed device design builds on the knowledge gained in previous animal and mechanical studies. It employs a modified slider-crank linkage mechanism actuated by a brushless Direct Current (DC) motor and provides uniform and cyclic force.”

Here’s an example of what slider crank linkage looks like:

“The functionality of the device was simulated in a software environment and the structural integrity was analyzed using a finite element method for the prototype construction. The device is controlled by a microcontroller that is programmed to provide the desired loading force at a predetermined frequency and for a specific duration. The device was successfully tested in various experiments for its usability and full functionality.  The device works according to the requirements of force magnitude and operational frequency. This device is considered ready to be used for a clinical study to examine whether controlled knee-loading could be an effective regimen for treating the stated bone-related ailments{Hopefully bone length is one of those bone-related ailments unfortunately Ping Zhang’s name is not on this paper and he was always the one more interested in bone length}.”

“When a specific loading force is applied to the epiphyses of the femur and tibia, the trabecular bone tissue, which is characterized by axial stress resistance, resists this force from the opposite direction. This results in deformations in that area. These deformations create a variation of the fluid pressure in the intramedullary cavity. This pressure gradient allows the flow of fluids that carry essential nutrients to the bone cortex initiating osteoblast differentiation and osteogenesis, thus helping in repair and regeneration of the bone tissue. This unique reaction makes this procedure an effective treatment for bone rehabilitation. It helps in reduction of healing time of bone fractures and hastens recovery from bone-related injuries and diseases. The lateral stress application is also less strenuous to the knee bone and reduces the amount of force that needs to be applied to get this result.”

B is the force we’re looking for.  The pressure generated by fluid flow not just on the bone but on the stem cells to initiate chondrogenic differentiation.  The pressure on the intact bone may also allow the creation of cartilage canals to enable that requirement for a neo growth plate.

It’s also interesting to note that in the proposed knee loading device the load the entire lateral area of the epiphysis this may be a way to reduce slippage.

” it was decided that the proposed device should be robust enough to produce different magnitudes of linear force up to a maximum of 40 N”<-Since lengthening is not being considered in this study forces required for lengthening may be higher.

The device doesn’t look wide enough for the knee really.  The dimensions of the device listed are:

There are about 39 inches in a meter so about 3.9 inches in width.  I don’t know if that’s enough.

Also the device looks more like this kind of clamp:

Then the other clamps we’ve been using.    Although you’d have to make new pads to actually adjust to knee.  Well actually more like:

But the pipe gets in the way of getting around the knee.  Although I’m not really sure that a pipe clamp is superior to the other clamps.  I’m just pointing out that it’s the clamp that looks most like the design mentioned in the study.

Here’s some more details on the device:

Here’s an actual physical prototype: