An Easy-to-Use Portable Ultrasound Based Device for the Measurement of the Pelvic Tilt

Abstract

The orientation of the cup in Total Hip Arthroplasty plays a major role on the post- operative results. It has been considered for several decades that the cup should be oriented according to the safe zone defined by Lewinnek. However, this safe zone is not always suitable because of the inter-individual variability of the pelvic tilt during daily activities. We propose in this paper a non-invasive ultrasound based solution which can easily measure this patient specific parameter in order to thereafter otimise the cup orientation. The accuracy of this system was assessed with a specific pelvic phantom. A clinical pilot study was also performed on ten patients. The pelvic tilt was measured in three daily positions: the supine, sitting and standing positions. The average error was 1.15°±0.82°. The average pelvic tilt was -97.1°±28.6°, -46.3°±12.8° and -9.0°±8.3° for respectively the supine, the sitting and the standing positions. The high inter-individual variability of the pelvic tilt in different daily positions highlight the need to have a suitable device for the measurement of this patient specific parameter for THA. The proposed system is easy-to-use, portable and allows the pelvic tilt measurement in different positions without any additional x-ray radiation.

In-vivo precision of a non-invasive ultrasound-based device to measure pelvic tilt for THA

“…This study shows therefore that besides the accuracy, which has been studied last year (Dardenne et al, 2018), the inter and intra-observer precision of our system meets the clinical requirement.…”

“…A non-invasive ultrasound (US) based device has been recently proposed which allows the acquisition of the pelvic tilt, i.e. the angle between the Anterior Pelvic Plane (APP) and the vertical, in several daily positions: in the supine, standing and sitting positions (Dardenne et al, 2018). The accuracy of this system has been analyzed according to a mechanical test bench.…”