human biomechanics orthotic




		Theta-Orthotics

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	Theta: Orthotics Quantified

Orthotics are used by many different types of physicians to treat a variety of medical conditions caused or aggravated by standing and walking.

Clinical benefits with use of orthotics have been documented for almost 200 years. Unfortunately, studies are not well defined and clinical benefits are obviously limited as many patients get some help, but still require invasive treatment to address remaining symptoms.

A four year process that resulted in a mathematical definition of the part of any foot control device that relates directly to function of the device was just the beginning. More than twenty years of clinical research with orthotics quantified using this definition has yielded many important findings.

When a plastic orthotic was tilted, so as to increase the height of the wedge and stabilize it in that position with a combination of extrinsic and intrinsic posts, the function of the foot control device was in fact improved. What proved to be far more difficult was to accurately measure the wedge. Choosing the points that determined the angular measurement was difficult,as the portion of the device that corresponds to the high point of the arch of the foot is a hyperbolic curve. When the proper points of the curve were finally defined, the clinical benefits were observed to correlate directly with the height of the wedge.




		Theta = ABC = 40 degrees


		tan(theta) A-C = A-B

	Theta is measured in a frontal plane section, taken where the device lines up with the talo-navicular joint (high point of the arch). If this section is divided into 4 parts from inside (medial) to outside (lateral), only the center 50 percent of the curve is used to plot the points that define theta. This definition places the medial flange portion of the wedge outside the definition of theta.




		Theta = 20 degrees

Two things were learned very early in the clinical trials:

First was that every time the angular correction (Theta) was increased by 5 degrees, there was a significant decrease in symptoms, as reported by patients.

Second, the technique used to define and measure Theta was applied to hundreds of other foot control devices. It was clear that the actual correction provided from hundreds of different devices was between 10 and 22 degrees. In general, prescription orthtoics had about 5 degrees more correction than most over the counter prefab orthotic devices. This clearly supported the claims that most podiatric physicians made, suggesting that prescription devices were in fact better than most non-prescription devices. The exception to this was a device designed by a German researcher, Dr. Alzner, that had 22 degrees of correction.


		Good, supportive shoes have about 5 degrees of theta support. Birkenstock sandals have 10 degrees of theta angular control. Foot Levelers and Phase IV orthotics have 15 degrees of theta. Prescription Orthotics from your local physician have up to 20 degrees of theta. Alzners are next best to Theta-Orthotics with 23 degrees of theta. Theta-Orthotics have *seven different corrections:* 10-40 degrees of theta.

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		Theta-Orthotics PO Box 1574 Riverton Ut. 84065