RESPONSIVENESS OF LEG ALIGNMENT CHANGES ASSOCIATED WITH ARTICULAR PRESSURE TESTING TO SPINAL MANIPULATION - THE USE OF A RANDOMIZED CLINICAL-TRIAL DESIGN TO EVALUATE A DIAGNOSTIC-TEST WITH A DICHOTOMOUS OUTCOME

Objective: A study was undertaken to assess the stability of leg align ment reaction to a pressure challenge and its responsiveness to an adj ustive intervention. Design: Prospective, double-blind clinical trial of a diagnostic test. Setting: Laboratory: Center for Technique Resear ch. Participants: Forty-two chiropractic college students, faculty and staff. Interventions: A high-velocity, low-amplitude, short lever adj ustment of a single vertebra from among C1 and T3-T7; or a sham adjust ment similar to a manual diagnostic pressure test at C1, T3-T7 or T9-T 10. Main Outcome Measures: Leg alignment reactivity: An increase in le g alignment discrepancy (yes or no) following a metered pressure chall enge to a vertebra. Results: On average, stability was poor at T3-T7 ( Kappa = 0.04), moderate at C1 (K = 0.47), and fair for sham pressure t ests (K = 0.30). Responsiveness: The proportion of positive baseline l eg alignment reactions that responded (became negative) to sham adjust ment was 95% at T3-T7 and 55% at Cl. Further analysis was untenable si nce too few vertebrae were implicated for an adjustment. Conclusions: For the population investigated, the majority of the responsiveness of the leg alignment diagnostic test to a rotatory adjustment appears to be a diagnostic illusion (i.e., background noise unrelated to a treat ment intervention). Further research with different subject population s, regions of investigation, leg alignment measurement techniques and vertebral challenge techniques are indicated.