Motion characteristics of motorized knee splints

The authors have tested the qualities of eight different motor devices. The following aspects were examined: Correspondence between motion of the motor device and of the limb placed on it. Actual transformation of the range of motion set on the motor device onto the knee joint. Changes in contact forces of the limb during passive motion. With aid of a special measuring device the X- and Y-coordinates of hip-, knee- and ankle joints of the probationer and the motor device are determined. From these coordinates the distances between the centres of rotation of hip-, knee- and ankle joint of the motor device and of the probationer are calculated; so are the degrees of hip- and knee flexion of the motor device and of the limb. For better representation and comparison of the results the authors introduce the notion of the "device quotient" (DQ). This value states which percentage of the amplitude of motion of the motor device is transformed onto the limb and at the same time takes into account the differences of centres of rotation between device and limb. The bigger DQ the better the congruence of device- and limb motion. Only two of the eight examined motor devices guarantee a next to harmonic motion (DQ of 65 to 100 for the knee and 27 to 63 for the hip). They differ from the other devices in that they have the possibility to adjust the centre of rotation of the hip joint to the anatomic centre of rotation of the hip.(ABSTRACT TRUNCATED AT 250 WORDS)