Abstract
Acetabular fractures are amongst the most complex fractures to treat. It has been suggested that pre-contouring the fixation plates may save intra-operative time, blood loss, reduce intra-operative fluoroscopy and improve the reduction. The purpose of this study was to assess if the contouring could be done reliably using the mirror image of the uninjured hemipelvis.
Using the CT data of 12 specimens with no bony abnormality 3D models were reconstructed. Using computer software (AMIRA, Visage Imaging) the mirror image of the left hemipelvis and the right hemipelvis were superimposed based on landmarks. The distances between the surfaces were then calculated.
The results were collected in the form of mean distance and colour maps. The mean difference between surfaces ranged from 1.76mm and 8.47mm. The colour maps demonstrated that for the areas around were acetabular fixation plated would be placed the differences were small. For the anterior column plate 6 (50%) of the specimens had differences of less than 1mm, which based on the work of Letournel and Judet would represent an anatomical reduction. (None had a difference of more than 6mm.) For the posterior column plate 7 (58%) had differences of less than 1mm. (None had a difference of more than 3mm.
This study demonstrates that there is considerable symmetry between both hemipelvises and that precontouring on the mirror image of the uninjured side is an accurate, quick and reliable method for precontouring. However the symmetry is not exact and the operating surgeon needs to be aware that fine-contouring may be required intra-operatively.
