The mechanical relationship between the rearfoot, pelvis and low-back.

The purpose of this study was first to investigate whether foot pronation (measured as calcaneal eversion) induced an anterior tilt of the pelvis and increased the degree of lumbar lordosis. Second the study investigated whether foot supination (measured as calcaneal inversion) induced a posterior pelvic tilt and a decreased lumbar lordosis. Participants placed their feet in 18 different foot positions while standing on a rigid platform. Seven of these positions ranged from 15 degrees of foot eversion to 15 degrees of foot inversion and 11 positions ranged from 40 degrees of external foot rotation to 40 degrees of internal foot rotation. Pelvic tilt and lumbar lordosis were estimated using a 3D motion analysis system. Foot pronation and supination did not have a significant relationship with pelvic tilt (r=0.3) and lumbar lordosis (r=0.05). Internally rotating the legs caused the pelvis to tilt anteriorly and externally rotating the legs caused the pelvis to tilt posteriorly (r=0.58). There was no relationship between leg rotation and lumbar lordosis (r=0.24). Since the effects of pelvic tilt on the lumbar spine were only noticeable when pelvic tilt was exaggerated beyond values seen this study it seems unlikely that there is a link between induced foot pronation and an increase in lumbar lordosis.