Relationship between positive clinical outcomes of foot orthotic treatment and changes in rearfoot kinematics.

BACKGROUND Previous two-dimensional kinematic studies that assessed the effect of foot orthoses on rearfoot motion have yielded mixed results regarding whether control of rearfoot motion is related to symptom relief. METHODS We sought to determine the effect of foot orthoses on rearfoot motion and to correlate these changes with the degree of symptom improvement in 22 individuals with excessive rearfoot pronation (17 women and 5 men; mean +/- SD age, 44.3 +/- 16.7 years; mean +/- SD weight, 74.9 +/- 15.9 kg). Two-dimensional motion-analysis software was used to assess frontal plane rearfoot motion with and without foot orthoses. The mean +/- SD Foot Posture Index of the left foot was 8.83 +/- 3.54 and of the right foot was 9.22 +/- 3.64). The pain and function subscales of the Foot Health Status Questionnaire were then used to determine the degree of symptom relief associated with the orthoses at baseline and 4 weeks later. RESULTS Orthoses had a small but statistically significant effect on rearfoot motion, although no significant correlations were found between differences in rearfoot motion with and without foot orthoses and the improvements demonstrated in the Foot Health Status Questionnaire subscales of pain and function. CONCLUSIONS The effect of orthoses on frontal plane rearfoot motion is considered small and probably insufficient to account for the extent of symptom reduction found in this study. Other parameters of orthotic function, such as kinetic and neuromechanical variables, should be further investigated.