Geometry of the clavicle and reliability of measurement using PACS. 
To investigate the geometry of the clavicle and to assess the reliability of Picture Archiving Communication System (PACS) for its measurement.  One hundred pairs of dry clavicles from 78 males and 22 females were measured on radiographs using PACS.  Measurements included all of the following parameters: length, width, medial and lateral angulation.  The intraclass correlation coefficient (ICC) for the inter-observer and intra-observer reliability was calculated.  The mean left clavicle length among males and females was 149.25 ± 9.64 and 133.30 ± 8.32 mm, respectively.  The respective mean right clavicle length among the males and females was 147.77 ± 9.99 and 132.08 ± 6.92 mm.  The clavicles from male cadavers were significantly longer, wider and thicker than those from females, on both the left and right (P < 0.05).  Among both the male and female clavicles, the left side was significantly longer than the right (P < 0.05).  There was good to excellent intra-observer reliability (ICC > 0.70) for all parameters.  Inter-observer reliability was also found good to excellent for all parameters except for medial clavicular angulation; for which there was fair reliability (ICC = 0.697).  The geometry of the clavicle is influenced by sex and side.  Use of PACS as a measurement tool is reliable.  Data from this study will be useful for pre-contouring plate or improving future designs of the anatomical plate of the clavicle.