Improvement of external fixator performance in type C pelvic ring injuries by plating of the pubic symphysis: an experimental study on 12 external fixators.

BACKGROUND

In an earlier study, we introduced a pelvic ring stability criterion for weightbearing stabilization. In a loading test, however, current external fixation systems alone did not meet this criterion. Internal fixation of the dorsal ring can significantly increase stability, but the condition of severely injured patients is often a contraindication for major surgery. The aim of this study is to optimize external pelvic ring fixation without dorsal ring stabilization to allow weightbearing in early mobilization of patients with unstable pelvic ring injuries.

METHODS

The stiffness of external fixation systems alone and in combination with one or two anterior plates was measured by using a pelvic replica with a type C pelvic ring injury. Endpoints were 15 mm of dislocation or tolerance of 560 N.

RESULTS

Addition of one plate at least doubles stiffness, whereas two-plate fixation results in at least a fourfold stiffer configuration. Frame configurations profit more than single-bar systems, and all but one system resist the weightbearing load after double-plating of the pubic symphysis.

CONCLUSION

The choice of double-plate fixation of the anterior ring in addition to external fixation results in weightbearing capacity.