Effects of Upright and Supine Radiograph on Shortening and Displacement of Middle Clavicle Fracture

Abstract

Objective: To compare the difference in degree of shortening and displacement in middle clavicle fracture between upright and supine radiograph. Materials and Methods: Two hundred fifty-nine patients with a median age of 36 years old and between 18 to 80 years with acute displaced clavicular fractures that occurred within two weeks were included in the present study. Standardized upright and supine AP radiograph of bilateral clavicles were obtained. The fractures were classified into three subtypes, simple for 85 patients, wedge for 123 patients, and complex for 51 patients. Shortening and displacement were measured and compared between the two positions. Results: Shortening was higher in upright radiograph at 10.00 mm (–7.60 to 33.20) compared to supine radiograph at 6.90 mm (–11.80 to 21.40). Median difference of shortening was significant at 2.60 mm (–8.30 to 21.10) (p<0.001). The differences of shortening were also significant, in the three subtypes with simple at 2.40 mm (–5.60 to 11.70) (p<0.001), wedge at 2.20 mm (–8.30 to 21.10) (p<0.001), and complex at 4.60 mm (–7.40 to 13.80) (p<0.001). Displacement was greater when measured on upright radiograph at 18.30 mm (4.40 to 36.40) compared to supin radiograph at 8.20 mm (2.00 to 29.30). Median difference of displacement was significant at 8.10 mm (0.10 to 23.50) (p<0.001). The differences of displacement were significant also the three subtypes with simple at 7.20 mm (0.10 to 20.40) (p<0.001), wedge at 8.70 mm (0.50 to 21.70) (p<0.001), and complex at 12.20 mm (2.90 to 23.50) (p<0.001). The intraclass correlation was 0.91 (95% CI 0.88 to 0.93) for shortening, 0.86 (95% CI 0.75 to 0.92) for displacement, and 0.88 (95% CI 0.84 to 0.93) for OTA fracture classification, all indicating excellent agreement. The number of patients who met operative indication, which was a shortening or displacement greater than 20 mm, in upright position were greater than those in supine position. Conclusion: Significant discrepancies in shortening and displacement of middle clavicle fracture among the positions were obtained in all fracture subtypes. The ability of upright radiograph to demonstrate maximal shortening and displacement may influence the decision on the treatment courses. Keywords: Clavicle fracture; Displacement; Shortening; Upright radiograph; Supine radiograph