The purpose of this study was to quantify  interexaminer reliability of a standardized supine leg check procedure  used to screen for leg-length inequality.


Two doctors of chiropractic used a standardized  supine leg check procedure to examine 50 volunteers for leg-length  inequality. The order of examination was randomized. The side and  magnitude of leg-length inequality were determined to the nearest 1/8  in. Subjects and examiners were blinded. Interexaminer reliability was  assessed with a Bland-Altman plot, tolerance table of absolute  differences, a quadratic weighted κ statistic for quantitative scores,  and a Gwet’s first-order agreement coefficient for dichotomous ratings.


The quadratic weighted κ statistic to quantify the  reliability of the rating scale was 0.44 (95% confidence interval,  0.21-0.67), indicating moderate reliability. The 2 examiners agreed  exactly 32% of the time, within 1/8 in 58% of the time, within 3/16 in  72% of the time, and within 3/8 in 92% of the time. The Bland-Altman  plot revealed possible heterogeneity in reliability that requires  additional study. The examiners agreed on the presence of a leg-length  inequality of at least 1/8 in in 40 (80%) of 50 subjects (first-order  agreement coefficient, 0.76), suggesting good agreement for this  diagnostic category.


The examiners showed moderate reliability in  assessing leg-length inequality at 1/8-in increments and good  reliability in determining the presence of a leg-length inequality.
J Manipulative Physiol Ther. 2011 May;34(4):239-46. [PMID:21621725] Author information: Woodfield HC, Gerstman BB, Olaisen RH, Johnson DF. Upper Cervical Research Foundation, Raleigh, NC, USA.