Evaluation of an Image Intensifier Supported Technique to Identify the Center of Rotation of the Humero-Ulnar Hinge Joint - An Anatomical Study

The use of a hinged elbow fixator has become a standard technique in traumatized and unstable elbow joints. It is still a challenge to identify the best fitting axis of rotation. A well described and frequently used technique uses the image intensifier. A K-wire is place into the center of capitulum and trochlea. There is yet no experimental proof that this technique does reliably allow to align the external fixator according to the natural center of rotation. A total of 15 cadaver specimens were used. The center of rotation was identified according to the intraoperatively used technique. Afterwards the specimens were embedded in resin and cut into slices. Evaluation of the geometry revealed a minor error of the K-wire position that was more prominent on the ulnar side. In summery the K-wire position was found in an area of 2 mm radius from the center of the slice. The center in each slice was directly determined by the shape of the cartilage surface. The indirect technique is a valuable Method to determine the axis of rotation. Even if the technique is applied accurately, a minor error is unavoidable but may be neglected for surgical purposes.