Force-displacement relationship during anteroposterior mobilization of the ankle joint

The purpose of this study was to determinate the correlation between force and displacement during passive anteroposterior mobilization of the talus and the effect of this treatment technique on ankle dorsiflexion range of motion (ROM).

This is an exploratory, methodological study. Maitland grades III and IV mobilization were applied on the right ankle of 25 healthy subjects (mean age +/- standard deviation, 25.08 +/- 3.01 years) by 2 randomized raters (A and B). Applied forces were measured using a small force plate and displayed for the rater on a computer monitor. Linear displacement of the ankle joint was quantified by a motion analysis system. Synchronization of these 2 systems was obtained by software. Dorsiflexion active ROM, before and after mobilization, was assessed using a biplane goniometer. Statistical analysis was performed using the Pearson correlation coefficient for force and displacement variables and the paired t test to compare dorsiflexion ROM mean values.

A fair positive correlation was found between force range and displacement (r = 0.370; P = .049, 1-tailed), and a fair negative correlation was found between minimum forces and displacement (r = 0.404; P = .035, 1-tailed), only for rater A data. Significant increase in dorsiflexion was found in the right ankle (P = .035), comparing ROM before and after mobilization, which did not occur in the left ankle.

These data do not support a linear force-displacement relationship during Maitland grades III and IV passive joint mobilization, although they confirmed an increase in ankle dorsiflexion ROM immediately after joint mobilization. The use of visual feedback may increase interrater reliability of forces applied during ankle joint mobilization.