The identification and reliability of static and dynamic barefoot impression measurements: A systematic review

Barefoot impressions collected from crime scenes can be used in forensic analysis. The reliability of the measurement method employed during comparison of these foot impressions is paramount to prevent incorrect conclusions being made. A number of methods of obtaining measurements from barefoot impressions have been described in the research literature; however there has been no comprehensive review of their reliability. Therefore, the aim of this systematic review was to determine the reliability of measurements used to describe footprint morphology obtained from static and dynamic barefoot impressions.

Four electronic databases were searched from inception to 23 November 2017. Eligible studies were required to report either the test-retest, intra or inter-rater reliability of measurements taken from barefoot impressions for the purposes of identification or classification of foot morphology. Methodological quality was assessed using the COSMIN checklist.

Eleven studies were identified that reported the reliability of 10 measurements (Reel method, arch index, Chippaux-Smirak index, footprint angle, Staheli index, contact area, Martirosov's K index, toe score and metatarsal ridge-to-toe measurement). High intra-rater reliability has been established for the Reel method (ICC=0.98-0.99), arch index (ICC=0.96-0.99), Chippaux-Smirak index (ICC=0.98-0.99), footprint angle (ICC=0.97-0.98), Staheli index (ICC=0.98-0.99) and footprint index (ICC=0.96-0.97). High inter-rater reliability has been established for the Reel method (ICC=0.99) and footprint angle (ICC=0.99). Overall methodological quality was rated as 'Poor' to 'Fair'.

The measurement developed by Reel et al. has both its intra- and inter-rater reliability established to be high. However, the findings of this review were unable to inform a recommendation of one specific technique based on reliability data due to a small body of research at this time. Furthermore, there is a lack of data on the reliability of footprint measurement and comparison techniques in real-world scenarios. Overall, the findings regarding reliability of the techniques covered in this systematic review are to be interpreted with caution due to the methodological quality of reliability testing conducted within the included studies.