Cardan joint

The cardan joint plays a vital role in some advanced external fixation applications. Its characteristics allow it to be used both as a multidirectional joint and in a one-way mode, according to specific needs.

Use in multidirectional mode in pairs

It represents the main mode of use for the construction of a hinge in circular external fixation. This use creates a center of rotation of the fixator which represents the correction fulcrum, a fundamental concept for the use of the fixator in the progressive treatment of deformities. The rationale for the correct positioning of the fixator fulcrum goes beyond the description of the joint here.

Use in single multidirectional mode

This use is typical of the construction of the motor bar of circular fixators when the complexity of the fixator does not allow a straight connection of the bar, e.g. when the angle of inclination between the rings is very high.

Use in one-way mode

The use in unidirectional mode requires the blocking of one of the two pins of the joint. In this way, the joint can only move on the plane of the other pin, effectively becoming a hinge on the selected plane. Very useful in transarticular mountings with linear fixation, to allow joint movement and simultaneously protect the joint on planes other than the one selected.