Fractures of the clavicle are relatively common, occurring mostly in younger patients and have historically been managed non-operatively. Recent studies have shown an advantage to surgical reduction and stabilisation of clavicle fractures with significant displacement. Currently, fracture displacement is measured using simple anterior-posterior two-dimensional x-rays of the clavicle. Since displacement can occur in all three-dimensions, however, evaluation of the amount displacement can be difficult and inaccurate. The purpose of this study was to determine the view that provides the most accurate assessment. Nine CT scans of acute displaced clavicle fractures were analysed with AmiraDEV5.2.2 Imaging software. Measurements for degrees of shortening and fracture displacement of the fracture clavicle were taken. Using a segmentation and manipulation module (ITK toolkit), five digitally reconstructed radiographs (DRRs) mimicking antero-posterior x-rays were created for every CT, with each differing by projection angle (ranging from 20° upwards tilt to 20° downwards tilt). Measurements were taken on each DRR using landmarks of entire clavicle length, distance from vertebrae to fracture (medial fragment length), distance from fracture to acromium (lateral fragment length), and horizontal shortening, and then compared to the true measurement obtained from the original CT. For all 9 samples, after comparing the measurements of clavicle fracture displacement in each 2D image, we found that an AP view with a 20° downward tilt yielded displacement measurements closest to the 3D (“gold standard”) measurements. The results agree with previous data collected from cadaveric specimens using physical X-ray film images. DDRs enable creation of multiple standard AP radiographs from which accurate tilt can be measured. The large deviation in measurements on different DRR projections motivates consideration of standardising X-ray projections. A uniform procedure would allow one to correctly evaluate the displacement of clavicular fractures if fracture displacement information is to be utilized in motivating surgical decision-making.
Based on a structure function relationship, bone density distribution has been described as being representative of skeletal loading. As such, computed tomography (CT) may be used to visualize the structure of femoral head subchondral bone to allow in vivo quantification of joint mechanics without the need for implanted hardware. This study aims to characterize the distribution of subchondral bone density in the femoral head. We hypothesize that a non-uniform distribution of bone density will be observed, with correlation between left and right sides for a given patient. Femoral head surfaces were created bilaterally for thirty patients through semi-automatic segmentation of reconstructed CT data and used to map bone density, by shrinking them into the subchondral bone and averaging the grey values (linearly related to bone density) within five millimeters of the articular surface. Density maps were then oriented with the center of the head at the origin, the femoral mechanical axis (FMA) aligned with the vertical, and the posterior condylar axis (PCA) aligned with the horizontal. Twelve regions were created by dividing the density maps into three concentric rings at increments of thirty degrees from the horizontal, then splitting into four quadrants along the anterior-posterior and medial-lateral axes. Average bone density within each region was then calculated using histogram analysis. All analysis was performed with AmriaDEV 5.2.2 image analysis software (Visage Imaging, Carlsbad USA).Purpose
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