Comparison of force development strategies of spinal manipulation used for thoracic pain.

INTRODUCTION: To date, there is a paucity of comparative analysis of manual therapeutic procedures for the treatment of pain in the same spinal region. This paper examines the cross correlation of force-time histories across three distinct strategies of force production for the same thoracic spine procedure. Secondary analysis includes examination of the characteristics that account for potential differences.
METHODS: A homogeneous sample of 21 male volunteers and three clinicians were selected as a convenience sample. The force-time histories were recorded using a table mounted force plate (AMTI model number OR6-7-2000, London, ON), and cross-correlation analysis was applied by strategy type, for analysis between group data. Secondary parameters included: peak force, preload force, slope of the thrust, instantaneous loading rate and thrust duration, of the total force magnitude.
RESULTS: Primary results indicate strong correlations among all strategies but with notably different cross-correlation coefficients (0.894 ≤ r ≤ 0.946) based on individual comparisons. Classical descriptive components of the force-time curves (e.g. preload, peak force, slope) for each strategy group were examined. Significant differences in the raw data were noted on slope and loading rate (adjusted p < 0.01). One strategy of force development was significantly different from the others in four of the five characteristics. The effects of clinician stature were evaluated by normalizing force to body mass.
CONCLUSION: Quantitative biomechanical differences in procedures may be responsible for differences in outcomes based on the method of treatment selected. This data set begins a basis for translational research to assist in identifying populations of thoracic spine pain patients for whom one procedure or other may be more effective.