Altered patterns of pelvic bone motion determined in subjects with posterior pelvic pain using skin markers

Objective. To determine whether the pattern of pelvic bone motion, determined by skin markers, differs between control subjects and subjects with posterior pelvic pain. Design. Cross-sectional study of three-dimensional angular and translational motion of the innominates relative to the sacrum in two subject groups. Background. Comparative in vivo analysis of the 3D patterning of pelvic motion in subjects with posterior pelvic pain and controls is limited. Methods. Fourteen males with posterior pelvic pain and healthy age and height matched controls were studied. A 6-camera motion analysis system was used to determine 3D angular and translational motion of pelvic skin markers during standing hip flexion. Results. Posterior rotation of the innominate occurred with hip flexion in control subjects and pelvic pain subjects as previously reported in the literature. On the supporting leg, the innominate rotated posteriorly in controls and anteriorly in symptomatic subjects. Conclusion. Posterior rotation of the innominate, as measured using skin markers during weight bearing in controls may reflect activation of optimal lumbo-pelvic stabilisation strategies for load transfer. Anterior rotation occurred in symptomatic subjects, suggesting failure to stabilise intra-pelvic motion for load transfer. Relevance This study found that posterior rotation of the innominate occurred during weight bearing in controls. This movement pattern is thought to optimise stability of the pelvic girdle during increased loading. Conversely, anterior rotation occurred in symptomatic subjects during weight bearing. This is a non-optimal pattern and may indicate abnormal articular or neuromyofascial function during increased vertical loading through the pelvis.