Abstract
Objectives
The additive use of an external modular device may improve dorsal compression forces in pelvic external fixation. This would improve the efficiency of indirect reduction and stabilization with an anterior pelvic external fixator. The purpose of this study was to determine the forces of the posterior pelvis achieved by a new device improving the application of a supraacetabular anterior external fixator compared with other constructs.
Material and Method
Synthetic pelvic models were used. Complete pelvic ring instability was created by symphyseal and unilateral sacroiliac joint disruption. Four different constructs of fixation were tested. A pressure-sensitive film was placed in the sacroiliac joint. The constructs were applied in a standardized way. The maximum sacroiliacal compression loads (N) of each trial was recorded. Statistics was performed with the student t-test.
Results
Standard supraacetabular two-pin external fixator achieved a dorsal compression load of 13.84 (SD 8.13). The new dorsal pelvic compression device delivered 177.05N (SD 32.32) of load across the sacroiliac joint when the pins were inserted half way and 183.58N (SD 46.64) with full pin insertion. Both the half- and full-pin construct demonstrated a significant dorsal load improvement with the pelvic compressor (p<0.05) compared with the standard supraacetabular fixator group. The C-clamp revealed compression forces of 384.88N (SD 22.95), which was significantly greater than all the other groups (p<0.05).
Conclusion
We tested a simple and new modular device for improved application of pelvic external fixation. The centres of rotation of supra-acetabular pins were determined and used to achieve greater dorsal compression forces in disrupted pelvic ring injuries. The compression load is less than with a C-Clamp, but significantly greater than the familiar technique of standard external supra-acetabular fixation. This improves the initial stability in acute management of unstable, disrupted and life threatening pelvic ring fractures.
