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 alignment reaction to a pressure challenge and its responsiveness to an adjustive intervention. DESIGN: Prospective, double-blind clinical trial of a diagnostic test. SETTING: Laboratory: Center for Technique Research. PARTICIPANTS: Forty-two chiropractic college students, faculty and staff. INTERVENTIONS: A high-velocity, low-amplitude, short lever adjustment of a single vertebra from among C1 and T3-T7; or a sham adjustment similar to a manual diagnostic pressure test at C1, T3-T7 or T9-T10. MAIN OUTCOME MEASURES: Leg alignment reactivity: An increase in leg alignment discrepancy (yes or no) following a metered pressure challenge 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 tests (K = 0.30). Responsiveness: The proportion of positive baseline leg alignment reactions that responded (became negative) to sham adjustment was 95% at T3-T7 and 55% at C1. Further analysis was untenable since 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 treatment intervention). Further research with different subject populations, regions of investigation, leg alignment measurement techniques and vertebral challenge techniques are indicated.

Reactivity of leg alignment to articular pressure testing: evaluation of a diagnostic test using a randomized crossover clinical trial approach.

OBJECTIVE: A study was undertaken to assess the reliability of detecting leg alignment changes (reactivity) and to determine if the observed leg alignment reactivity can be attributed to a rotatory articular pressure challenge. DESIGN: Prospective double-blind crossover trial of a diagnostic test. SETTING: Laboratory: Center for Technique Research. PARTICIPANTS: Forty-two chiropractic college students, faculty and staff. INTERVENTIONS: A standardized force of 2 or 3 kg was applied with a 1 cm2 rubber-tipped pressure algometer on the lateral aspect of the T3-T7 spinous processes and the posterior aspect of the lateral masses of C1. MAIN OUTCOME MEASURES: Leg alignment reactivity: an increase in leg alignment discrepancy (yes or no) following a diagnostic intervention. RESULTS: The reliability for detecting leg alignment reactivity was poor: on average, Kappa = 0.05 in the thoracics and 0.06 at C1. On average, the attributable risk of leg alignment reactivity (pressure test risk--sham test risk) was less than 4%. In many cases, the sham rate was greater than the pressure test rate. CONCLUSIONS: For the population investigated, leg alignment reactivity to rotatory pressure testing can, in the majority of cases, be attributable to background noise. This procedure was not found to be viable for identifying vertebrae for adjustment. Further research with different subject populations, regions of investigation, leg alignment measurement techniques and vertebral challenge techniques are indicated.