Changes in pelvic tilt related to body position measured with Smart Navigated Ultrasound mobile system

Abstract The aim of the study was to assess the changes of pelvic tilt between standing and supine position with the Smart Navigated Ultrasound (SNU) mobile system. In this prospective study, the pelvic tilt in the standing and supine pelvis was recorded in 16 orthopedically healthy female volunteers, mean age 37.5 years. All measurements were performed with SNU mobile system, consisting of a smartphone-based optical tracking device, medical-grade tablet, an ultrasound device with a transducer, and two rigid body optical markers. Anterior pelvic tilt was noted in all but two patients in the standing position and in all but one in the supine position. For 13 subjects, the pelvis rotated posteriorly during movement from the supine to standing position, in three cases, the change was in the opposite direction. Mean anterior pelvic tilt significantly reduced from lying down (-9.8) to (-4.9) standing (p = 0.04). The study showed that pelvic tilt is different in supine and standing position and is changing from anterior to more posterior, respectively in most cases. The SNU navigation system may be a useful to prevent complications related to cup position due to differences in pelvic tilt between those positions and could be used for large-scale screening purposes.