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Applied Bionics and Biomechanics
Volume 2017 (2017), Article ID 4370649, 8 pages
Research Article

Reliability of an Integrated Ultrasound and Stereophotogrammetric System for Lower Limb Anatomical Characterisation

1Department of Mechanical Engineering and INSIGNEO Institute for in silico Medicine, University of Sheffield, Sheffield, UK
2Research & Development, Aesculap AG, Tuttlingen, Germany
3Department of Orthopaedic Surgery, Physical Medicine & Rehabilitation, Campus Grosshadern, Ludwig Maximilians University Munich, Munich, Germany

Correspondence should be addressed to Frederick Greatrex

Received 3 February 2017; Revised 28 April 2017; Accepted 29 May 2017; Published 19 June 2017

Academic Editor: Adrien Baldit

Copyright © 2017 Frederick Greatrex et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Background. Lower extremity analysis for preoperative total knee and hip arthroplasty routines can increase surgery success rate and hence reduce associated costs. Current tools are limited by being invasive, limited to supine analysis, or too expensive. This study aimed to propose and validate a device, OrthoPilot®, based on the combined use of a stereophotogrammetric and ultrasound system which can in vivo and noninvasively measure varus/valgus, flexion/extension, femur and tibia torsion, and femur and tibia lengths. Methods. A phantom was measured by four operators to determine the resolution of the system. Interoperator variability was measured on three operators who measured the above six variables on both legs of three subjects in standing and supine positions. Intraoperator variability was assessed on data from three repeats from 9 subjects (18 legs). Results. All 6 variables were reliably detected on a phantom, with a resolution of 1 mm and 0.5°. Inter- and intraoperator consistency was observed for varus/valgus, flexion/extension, and length measurements on the healthy subjects in standing and supine positions (all ICC > 0.93). For torsion measurements, there was a considerable variation. Conclusion. The proposed system, when used on healthy subjects, allowed reliable measurements of key parameters for preoperative procedures in both supine and standing positions. Accuracy testing and further validation on patient populations will be the next step toward its clinical adoption.