The Effects of Body Position on Pelvic Tilt Angles Measured with a Smartphone-Based Navigated Ultrasound System in Symptom-Free Young Adults

Frank Lampe,Viktor Breul,Josef Kozak,Tobias Martin,Mathias Weber,Carlos Marques,Franziska Fiedler

doi:10.3390/jfmk3010018

Abstract

The study aimed to investigate whether pelvic tilt (PT) angles differ between the supine and upright position in symptom-free young adults. Additionally, the concurrent validity of the measurement system was tested on a pelvis phantom against a digital inclinometer. A new smartphone-based navigated ultrasound system was used to perform the measurements. The sample consisted of 12 symptom-free young adults. A multivariate regression model was used to analyze the data. The subjects’ pelvis in supine position was significantly more tilted anteriorly (mean PT = −7.3°, 95% C.I.: −10.6 to −3.9) than in upright position (mean PT = 0.8°, 95% C.I.: −2.5 to 4.1) (mean. diff. 8.1°; p < 0.001). Rater and trial order had no significant effects on the measured PT angles (p = 0.5). The accuracy of the system when measuring PT angles on the pelvis phantom was 0.3° (0.1° to 0.7°) and 0.2° (−0.09° to 0.6°) for the supine and upright positions respectively. Pelvic tilt angles differed significantly between the supine and the upright position in symptom-free young adults. Concurrent validity showed no differences for measurements in the upright position and small (under 0.4°) significant differences for measurements in the supine position.

Highlights

Hip dislocation is one of the most common complications following primary total hip arthroplasty (THA) with prevalence rates ranging from 0.3% to 3% [1]
The prevalence rate of THA dislocations is affected by multiple factors that can be grouped in patient-specific [3,4], surgeon-specific [5] and factors related to the implant design [6,7], implant alignment [8], and surgery technique [9]
Post hoc analysis showed that pelvic tilt (PT) angles measured in the supine position significantly differed from PT angles measured in the upright position (p < 0.001)

Summary

Introduction

Hip dislocation is one of the most common complications following primary total hip arthroplasty (THA) with prevalence rates ranging from 0.3% to 3% [1]. According to the annual report of the Swedish hip register (2014), dislocation was the second cause for reoperation, responsible for 25% of all revisions within the first year after surgery [2]. The prevalence rate of THA dislocations is affected by multiple factors that can be grouped in patient-specific [3,4], surgeon-specific [5] and factors related to the implant design [6,7], implant alignment [8], and surgery technique [9]. Acetabular component alignment is considered to play an important role in THA dislocations [10].

Methods

Results

Conclusion