Immediate Effects of Bilateral Sacroiliac Joint Manipulation on Plantar Pressure Distribution in Asymptomatic Participants

Objective: To investigate the immediate effects of manipulation of bilateral sacroiliac joints (SIJs) on the plantar pressure distribution in asymptomatic participants in the standing position. Design: Randomized, controlled, double-blind clinical trial. Participants: Sixty-two asymptomatic men and women (mean age, 20.66±2.56 years) randomly assigned to 2 groups. Interventions: The experimental group underwent mobilization without tension of the hips in the supine position and high-velocity, low-amplitude manipulation in the SIJs bilaterally. The control group underwent only mobilization, without tension of the hips in supine position. Outcome Measures: Pre- and postintervention outcomes measured by an assessor blinded to the treatment allocation of the participants included a baropodometric analysis performed by using a force platform. Baseline between-group differences were examined with a Kolmogorov-Smirnov test. A chi-square test was used for categorical data. Analysis of covariance (ANCOVA) was used to assess differences between groups, with the preintervention value as covariant (95% confidence level). Results: At baseline, no variables significantly differed between groups. Baropodometric analysis showed statistically significant differences in the location of the maximum pressure point in the experimental group ( p =0.028). Pre- and postintervention analysis with ANCOVA showed statistically significant differences between both groups in the left hindfoot load percentage (interaction p =0.0259; ANCOVA p =0.0277), right foot load percentage (ANCOVA p =0.0380), and surface of the right forefoot (interaction p =0.0038). There was also a significant effect in the variables that analyze the entire foot (left foot: surface [interaction p =0.0452], percentage of load [ANCOVA p =0.0295]) and between both groups (right foot: weight [interaction p =0.0070; ANCOVA p =0.0296]). Conclusions: Sacroiliac joint manipulation applied bilaterally in asymptomatic persons resulted in immediate changes in load distribution on plantar support in the standing position. Study limitations and suggestions for future studies are discussed.