The Study of Screw Placement Parameters for Ogawa Type I Acromial Fractures by 3D Technology

Abstract

Background: Acromial fractures are rare and there is no consensus on fixation, but more and more studies have reported using two screws to fix Ogawa type I acromial fractures. The objective of this study was to obtain the ideal length, diameter, insertion point and angle of the screw using a novel 3D technology. Methods: Scapula CT data of 100 human subjects were obtained to reconstruct 3D models. The transparency of 3D models was then downgraded along the axial perspective (the view perpendicular to the cross section of the acromial axial) to find the maximum translucent area. Two virtual screws were placed from the anterior edge of the acromial until they penetrated the posterior cortical bone. The largest diameters and lengths of the screw were measured, and the direction and insertion point of the screw were observed.Results: The mean maximum lengths of medial and lateral screws were 43.33±6.17mm and 39.23±6.01mm, respectively. The mean maximum diameters of medial and lateral screws were 4.71±1.23 mm and4.97±1.07mm, respectively. The study found differences in screw length, diameter and insertion point between males and females. The differences sexes in screw angle were not statistical significance.Conclusions: Using the 3D model, we demonstrated that the distal acromial can be safely placed with two screws and provide valuable guidance for screw fixation of Ogawa type I acromial fractures.