Computerized back postural assessment in physiotherapy practice: Intra-rater and inter-rater reliability of the MIDAS system

Background and purpose: Assessment of spinal posture during physiotherapy practice is routine, yet few objective measures exist to this end. The Middlesbrough Integrated Digital Assessment System (MIDAS) is a low cost portable system able to record 3D information on posture. The purpose of this study was to assess both the intra-rater and inter-rater reliability of the MIDAS system. Methods: Twenty-five healthy subjects were recruited. A repeated measures design was used to record fifteen pre-palpated landmarks on the back of each subject. To limit the sources of variability, the principal researcher palpated the landmarks for each subject. Each of three raters took two measurements on each subject in a standardized upright posture. X (medio-lateral), Y (antero-posterior) and Z (height) landmark positions were recorded via a computer interface. Results: Both intra-rater agreement (mean ICCs - rater 1 r = 0.970, rater 2 r = 0.965 and rater 3 r = 0.965, p < 0.001) and inter-rater agreement (mean ICCs r = 0.967, p< 0.001) was very high between repeated measures and between markers. Error values for the z-axis (height) were the lowest. Conclusions: The MIDAS demonstrated both high inter-rater and intra-rater reliability and provides an objective method for the assessment of posture in physiotherapy practice.