[Three-dimensional testing of the stability of spinal implants]

In the field of spinal fixation devices, biomechanical evaluation is often done in a nonstandardized manner, which makes it difficult to compare the results of one researcher with those of another for the same device or for different devices. There is a need for uniform and comprehensive evaluation of these devices. There are three basic biomechanical tests: strength, fatigue and stability. In contrast to the first two test, which are destructive to the device., the stabilitytest is nondestructive. It measures the capability of the device to provide multidirectional stability to the injured spine. Such measurements may characterize the device for its potential for handling fracture healing and fusion. A biomechanical concept for the evaluation of multidirection stability of spinal fixation devices and guidelines for designing the necessary experiments are suggested.