Interrater reliability of a passive physiological intervertebral motion test in the mid-thoracic spine

Objective: To examine the interrater reliability of a passive physiological intervertebral motion (PPIM) test of a mid-thoracic spine motion segment. Methods: Nineteen males and 22 females with a mean age of 22.7 years (range, 19-40 years) and no known spinal pathologies were tested independently by 3 certified manual therapy instructors. Investigators performed 3-dimensional segmental mobility testing at a preselected thoracic motion segment. Interrater reliability was assessed with Cohen's K statistics, using 3 pairwise comparisons for determination of the direction of lateral flexion leading to the greatest amount of segmental rotation. Results: Percent agreement ranges were 63.4% to 82.5%, with K scores ranging from 0.27 to 0.65. Conclusion: The PPIM testing demonstrated fair to substantial interrater reliability. A majority of females (91%) demonstrated greatest segmental PPIM motion in contralateral rotation with lateral flexion, whereas a majority of males (90%) demonstrated greatest segmental PPIM motion in ipsilateral rotation with lateral flexion. These findings are applicable to asymptomatic subjects of the same age category. Interrater reliability of 3-dimensional PPIM testing is fair to substantial for assessing passive segmental mobility of the mid-thoracic spine.