The dermatoglyphic pattern of human palms and soles is individually unique and unchanging. Their prints show the course of the papillary ridges as papillary lines. Case reports and a few older studies of repeatedly taken fingerprints could, however, show that so-called interpapillary lines can develop between the papillary lines. The questions of this study were: How often do interpapillary lines occur? Can the differences between papillary and interpapillary ridges be quantified?
Five-hundred and two ink prints of the palms and fingers from the archive of the Bochum Police Department were examined retrospectively. In 121 volunteers, the appearance of interpapillary lines was examined prospectively. From the later collective, the fingerprints of 13 people with interpapillary lines and nine people without were examined further by taking two silicon prints and measuring them with laser profilometry
In 215 of the 502 ink prints (42.8%) interpapillary lines could be demonstrated. In those subjects younger than 20 years they were less frequently observed (34.1%) than in those above the age of 20 (51.8%). In all cases using laser profilometry the interpapillary lines could be related to a corresponding interpapillary ridge. The interpapillary ridge heights were 24.9 ± 10.0 µm, significantly lower than the papillary ridges, which measured 59.0 ± 19.2 µm. Interpapillary ridge widths were with 194.8 ± 65.1 µm significantly narrower as compared to 435.5 ± 57.4 µm in the papillary ridge. Those papillary ridges, between which interpapillary ridges were found, were significantly further apart from each other (610.5 ± 78.9 µm) than those without interpapillary ridges (484.9 ± 70.6 µm).
During the course of a lifetime new ridges between the regular papillary ridges can develop or manifest. The fact that interpapillary lines are more frequently found on the right hands in men and those with increasing age is consistent with the theory that they correspond to degenerative changes and with sensitivity of touch.