Improved external skeletal fixation for unstable fractures.

A novel external fixation device (EX-FI-RE) is described with which it is possible to manipulate fracture fragments under complete control of stability. EX-FI-RE is a unilateral, telescopic, single-frame device, consisting of two functionally separate components, the correction unit and the fixation unit. The correction unit allows reduction of angular, parallel, and longitudinal dislocations. Sustained transverse compression of an oblique fracture is a special feature. After reduction has been achieved, pin retainers and transcutaneous pins can be transferred to the fixation unit without change of position of the fracture fragments. Its mechanical behavior under load is analyzed and compared with that of a Hoffman-Vidal Adrey quadrilateral system. In axial loading, the two systems were similar within the loading range of 0-1000 N. In the anteroposterior plane, the stiffness ratio of the EX-FI-RE was significantly higher. In lateral bending and axial loading, the two systems were comparable. The turning moment required to induce a 5 degree angular deformation of the quadrilateral system was 4.8 +/- 0.6 Nm; the corresponding figure for the unilateral system was 8.8 +/- 0.4 Nm. After more than two years of clinical experience with this new device, closed atraumatic reduction, sustained transverse compression, and early weight-bearing were found to promote union. There were no pin tract infections or mechanical failures in more than 70 cases treated.