Triaxial electrogoniometric examination of the pivot shift sign for rotatory instability of the knee.

The precise nature of the motion of the knee during a pivot shift is of interest when types of knee instability are correlated with specific injuries. Ten subjects with anterior cruciate ligament injuries and demonstrable pivot shift instabilities were examined with a triaxial electrogoniometer to detect angular motion at the joint during the performance of a pivot shift test. By varying the method of test performance and observing the patterns of motion by eye and in the electrogoniometric data, the pivot shift was shown to be a dominantly translational event during nonstressed knee testing and a dominantly rotational event during stressed knee testing.