Measuring the Intercondylar Shelf Angle Using Radiographs: Intra- and Inter-Observer Error Tests of Reliability

• NCJ Number: 220409
• Journal: Journal of Forensic Sciences Volume: 52 Issue: 5 Dated: September 2007 Pages: 1020-1024
• Author(s): Gregory E. Berg M.A.; Sabrina C. Ta'ala M.A.; Elias J. Kontanis Ph.D.; Sardiaa S. Leney B.S.
• Date Published: September 2007
• Length: 5 pages
• Publication Format: Article
• Publication Type: Report (Study/Research)
• Language: English
• Country: United States of America

Annotation

This study tested intraobserver and interobserver measurement error rates of the intercondylar shelf angle of the distal femur as measured on lateral radiographs, which is the central feature of a method for determining racial affiliation.

Abstract

Statistically, significant differences were found for both intraobserver and interobserver error. Three principal areas of potential methodological error were attributed to observer error. First, the femur positioning in the radiographs tended to be slightly different between observers. A "true lateral" position is difficult to achieve consistently with dry bone specimens. Two sources of error stemmed from a degree of subjectivity when judging "best-fit" positioning of lines through Blumensaat's line and a line parallel to the posterior cortex of the distal one-third of the femur. The most conspicuous source of intraobserver and interobserver error was variation in the placement of the line parallel to the posterior cortex of the distal femur. In nearly every case, determination of a parallel position varied between trials per observer and between observers on a single radiograph. This problem was particularly pronounced in instances of highly curvlinear femora. The aforementioned sources of error had a far greater effect on the measurements than the experience of the investigator. These results indicate that continued reliance on this method (the "Craig" method) for determining racial ancestry requires further experimentation in order to develop refined measurement techniques that will improve standardization and reduce observer error. Four observers independently radiographed a set of 33 complete and partial femora from collections housed at the Joint POW/MIA Accounting Command, Central Identification Laboratory. Each observer then measured the intercondylar shelf angles in each radiograph, following the original method's guidelines. A supplementary interobserver error test was conducted by four additional observers on one set of radiographs. 5 tables, 2 figures, and 9 references