The Difference Between Traditional and Silicone Dynamic Orthotics (SDO)
Traditional rigid and semi-rigid orthotics have been around a long time. The theories and principles of biomechanics upon which they were conceived have also been around a long time (about 100 years). The SDO is new technology.
The idea of the traditional orthosis has been to control the foot when it first makes heel contact to the ground. It does so by confining the foot to a pre-set position, then to allow the foot only so much motion (called pronation) in order to complete the gait cycle while keeping it at or near its "neutral position".
The silicone dynamic orthotic (SDO) works on a principle of "fluid mechanics"-"fluid moves to the area of least resistance and greatest need". So the SDO moves with the motion of the foot, it actually "catches" the motion (pronation) at the arch and begins to slow it down and then "cushions" the motion to a full stop preventing and restricting excessive movement, just before the foot begins to propel itself away. It is easy and comfortable to wear in most shoe styles for men and women and therefore it is easy to wear ALL the time, even around the house.
The traditional supports are not usually as comfortable or easy to wear because instead of working "with the foot", they act more like an intermediary between the foot and shoe and stops the motion (pronation) rather abruptly. It is for this reason that a very high percentage of people give up or wear their supports with difficulty.