Intra-observer reliability in three-dimensional kinematic analysis of sacroiliac joint mobility

[Purpose] Physical therapists, osteopathic practitioners, and chiropractors often perform manual tests to evaluate sacroiliac joint (SIJ) mobility. However, the available evidence demonstrates an absence of reliability in these tests and in investigations with kinematic analysis. The aim of this study was to verify the three-dimensional kinematic reliability in SIJ movement measurements. [Subjects] This cross-sectional study analyzed 24 healthy males, aged between 18 and 35 years. [Methods] Three-dimensional kinematic analysis was performed for measurements of posterior superior iliac displacement and greater trochanter (femur) displacement during hip flexion movement in an orthostatic position. The distance variations were measured from a reference point in 3 blocks. The intra-observer reliability was compared with the mean of three 3 blocks using the interclass correlation coefficient (ICC) and a 99% significance level. [Results] The measurements indicated a strong correlation among blocks: ICC = 0.94 for right side SIJ and ICC = 0.91 for left side SIJ. The mean displacement between the reference points was 7.7 mm on the right side and 8.5 mm on the left side. [Conclusion] Our results indicate that three-dimensional kinematic analysis can be used for SIJ mobility analyses. New studies should be performed for subjects with SIJ dysfunction to verify the effectiveness of this method.