Dog Orthotics and Pet Leg Braces - Types of Joints discussed.
We have seen several discussions as to which is better, and we will continue to add to this page as we get more information.
Rubber hinge on a carbon fiber support
The use of metal hinges and the method of control that they give to a patient have been used since the 1800's. The use of a single band of metal/leather below a joint, connected to a band above a joint by a metal hinge has its pros/cons just like anything else.
Pet Orthotic with a metal hinge on a plaster cast made by a with a casting kit.
The primary disadvantage of a metal hinge you do not replicate that soft tissues ability to store and return ground reaction forces or energy. This was a major problem that took many years to overcome. When a stifle joint is flexing during the propulsive phase, there is a tremendous amount of kinetic energy being exerted to the flexor muscle group. Meanwhile the extensor muscle group is gaining potential energy. When the paw is lifted off the ground, the process reverses itself.
Not until the mid 1950’s did the Orthotic/Prosthetic/therapy/M.D. profession have the knowledge or ability to understand, much less replicate that energy delivery system.
Rubber joints represent an entire revolution in the human field of Orthotics. They are flexible enough to articulate with a joint that actually travels, rather than move like a hinge across a few millimeters. Also, a rubber loint is like a “living” mechanical joint. As the animal moves, the joint acts like the soft tissue…i.e.…ligaments, tendons, muscle tissue and so forth, it stores and releases energy during the gait cycle.
Therefore, you get the control your after as well as a remarkable ability to ambulate through the use of the orthotic.
The use of a metal hinge has its place and its value. When a limb no longer has the muscular or nervous system available to control and support the weight bearing movement or requirement for ambulation, a metal joint is very appropriate. If those indications are present, then there are choice between various plastic/rubber/metal/carbon/ and composite joint materials.
In the human world, we use metal joints for large patients, or when there is a muscle deficiency or you need to limit motion down to just one plane of movement.
You can look at a variety of human knee braces. They will almost certainly be made out of a metal hinge at the knee and carbon fiber material for the frame. If you were to look at an ankle brace, you might see any material for the joint possible. It would depend on the healthcare requirements.
Metal hinges have an adjustable range of motion. This is critical when you need to create a resist or an assist moment during the gait cycle.
