Abstract
Purpose: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.Results: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.Conclusion: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.
Highlights
Previous studies have indicated that implant positioning is an important factor influencing the postoperative outcome in Total Hip Arthroplasty (THA)
Based on a review of our clinical experiences using previous versions of image-free navigation systems (Orthopilot ver1.1 and Orthopilot THAplus B/BRAUN-Aesculap, Germany), the co-author of the present study has reported satisfactory accuracy and consistency in the assessment of cup positioning [5, 6]
The purpose of this study was to assess the accuracy of the current version of the image-free navigation system in detail using a 3D template system by comparing measurement values obtained from intraoperative navigation to a postoperative Computed Tomography (CT) evaluation with a 3D template system
Summary
Previous studies have indicated that implant positioning is an important factor influencing the postoperative outcome in Total Hip Arthroplasty (THA). Based on a review of our clinical experiences using previous versions of image-free navigation systems (Orthopilot ver1.1 and Orthopilot THAplus B/BRAUN-Aesculap, Germany), the co-author of the present study has reported satisfactory accuracy and consistency in the assessment of cup positioning [5, 6]. Since December 2011, the authors have used a revised version (Orthopilot THAPro), which is capable of navigating stem anteversion alignment and leg length including cup orientation. Achieving an improvement in overall alignment can be expected; there have been studies examining and reporting the accuracy of intraoperative navigation, an accuracy assessment for this revised version has not been reported in previous literature. The purpose of this study was to assess the accuracy of the current version of the image-free navigation system in detail using a 3D template system by comparing measurement values obtained from intraoperative navigation to a postoperative CT evaluation with a 3D template system. It was hypothesized that reasonable accuracy would be attained with the use of this system
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