Accuracy of Component Orientation and Leg Length Adjustment in Total Hip Arthroplasty Using Image-free Navigation

Yu Takeda*, Shigeo Fukunishi, Shoji Nishio, Yuki Fujihara, Shinichi Yoshiya
Hyogo College of Medicine, Department of Orthopedic Surgery 1-1, Mukogawa-cho, Nishinomiya, Hyogo, Japan

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© 2017 Takeda et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Hyogo College of Medicine, Department of Orthopedic Surgery 1-1, Mukogawa-cho, Nishinomiya, Hyogo, Japan, 663-8501; Tel: 81-798-45-6452; E-mail:



The purpose of this study was to examine the accuracy of implant orientation and leg length in total hip arthroplasty (THA) with an image-free navigation system based on a comparison of the intraoperative navigation and postoperative CT evaluations.

Material and Methods:

A consecutive series of 111 patients (118 hips) who underwent THA using the current version of the image-free navigation system constituted the basic study population. Subsequently, a total of 101 patients (108 hips) meeting the inclusion and exclusion criteria were selected as study subjects for the analysis. THA was performed using an image-free navigation system that was capable of adjusting both the prosthetic position and leg length. Postoperative CT examination was performed for all study subjects, and the prosthetic position and leg length were measured on CT images using the image analysis software. Subsequently, the intraoperative navigation results and the corresponding values obtained from the postoperative CT measurements were compared to test the accuracy of the navigation system.


The average discrepancies between the intra- and postoperative assessments were 6.8°, 3.7°, and 5.7° for cup anteversion, cup inclination, and stem anteversion, respectively. The corresponding value in leg length averaged 4.1 mm.


Average discrepancies between the intra- and postoperative measurements were less than 10° in all prosthetic alignment parameters and less than 5 mm in leg length. Intraoperative assessments with the use of the image-free navigation in THA could afford satisfactory result.

Keywords: Component orientation, CT evaluations, Leg length, Total Hip Arthroplasty, Image-free, Navigation.