Influence of radiographic projection and patient positioning on shortening of the fractured clavicle

Background: Radiographic measurements of shortening and vertical displacement in the fractured clavicle are subject to a variety of factors such as patient positioning and projection. The aims of this study were (1) to quantify differences in shortening and vertical displacement in varying patient positions and X-ray projections, (2) to identify the view and patient positioning indicating the largest amount of shortening and vertical displacement, and (3) to identify and quantify the inter- and intraobserver agreement. Methods: A prospective clinical measurement study of 22 acute Robinson type 2B1 clavicle fractures was performed. Each patient underwent 8 consecutive standardized and calibrated X-rays in 1 setting. Results: In the upright patient position, the difference of absolute shortening was 4.5 mm (95% confidence interval [CI]: 3.0-5.9, P <.0001) larger than in the supine patient position. For vertical displacement, the odds of being scored a category higher in the upright patient position were 4.7 (95% CI: 2.2-9.8) times as large as the odds of being scored a category higher in supine position. The odds of being scored a category higher on the caudocranial projection were 5.9 (95% CI: 2.8-12.6) times as large as the odds of being scored a category higher on the craniocaudal projection. Conclusion: Absolute shortening, relative shortening, and vertical displacement were found to be the greatest in the upright patient positioning with the arm protracted orientation on a 15° caudocranial projection. No statistically significant differences were found for a change in position of the arm between neutral and protracted.