Retrospective Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. Dec 18, 2017; 8(12): 929-934
Published online Dec 18, 2017. doi: 10.5312/wjo.v8.i12.929
Acetabular cup version modelling and its clinical applying on plain radiograms
Anton Denisov, Stanislav Bilyk, Anton Kovalenko
Anton Denisov, Stanislav Bilyk, Anton Kovalenko, Orthopedic Department, Vreden Russian Research Institute of Traumatology and Orthopedics, St. Petersburg 195427, Russia
Author contributions: Kovalenko A designed the study and analyzed data; Bilyk S performed three-dimensional modeling part; Denisov A revised the manuscript for important intellectual content and in couple with expert-doctor from United States made the translation in English.
Institutional review board statement: The study “Acetabular cup version modelling and its clinical applying on plain radiograms” was approved by the Institutional Review Board (IRB) of the Vreden Scientific Orthopedic Institute, Saint- Petersburg, Russian Federation.
Informed consent statement: Patients were not required to give informed consent to the study because in retrospective analysis were used anonymous data that were obtained after each patient agreed to treatment by written consent.
Conflict-of-interest statement: Dr. Denisov has nothing to disclose. Dr. Kovalenko has nothing to disclose. Dr. Bilyk has nothing to disclose.
Data sharing statement: No additional data are available. No data are shared with another study as this manuscript and related data were not published elsewhere.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Anton Denisov, Academic Fellow, Orthopedic Department, Vreden Russian Research Institute of Traumatology and Orthopedics, Baykova Street 8, St. Petersburg 195427, Russia. denisov1993@gmail.com
Telephone: +7-812-6708687 Fax: +7-812-6708688
Received: August 1, 2017
Peer-review started: August 25, 2017
First decision: September 20, 2017
Revised: October 20, 2017
Accepted: November 8, 2017
Article in press: November 8, 2017
Published online: December 18, 2017
ARTICLE HIGHLIGHTS
Research background

Correct cup positioning is one of the crucial factors of preventing hip luxation after total hip arthroplasty (THA). It can be estimated using simple radiographic views (AP of pelvis and hip) and calculating of the cup inclination angle.

Research motivation

Some techniques can provide calculation of cup version, however none of these techniques can differentiate cup ellipse appearance in patients with same degree of anteversion vs retroversion. It can be resolved by using a cross-table lateral view or CT scan, both of which are seldom used due to challenge with patient position in the early postoperative period and concerns for radiation exposure and sometimes not available in orthopedic practice.

Research objectives

The authors measured the sensitivity and specificity of the cup version assessment by using AP hip and pelvis views, evaluated the incidence of inadequate version in patients with repeated dislocations after THA. The authors believe that estimation of simple radiographic anteversion sign can be used for screening assessment for further obtaining of additional examinations in case of cup malposition and repeated dislocations (as one of the provoking factor).

Research methods

Cup shadows in retroversion and anteversion were reproduced on AP hip and pelvis views using Autodesk 3ds Max software (Autodesk, Inc., San Rafael, CA, United States). Difference in angles of cup version, which may be seen as a result of difference between X-ray beams centered on AP hip and pelvis views, were subsequently analyzed. Acquired data was used for analysis of 2 groups of patients, with follow up of 6-60 mo, after undergoing primary THA.

Research results

The value of the χ2 yates was 10.668 (P < 0.01). A sign of retroversion was also noted when true anteversion angle did not exceed 1/2 of the angle between X-ray beam in different views (AP hip and AP pelvis). Sensitivity of SAI was 29% (95%CI: 9%-46%), and specificity was 92% (95%CI: 88%-96%). Relative risk of dislocation in patients with SAI was 3.4 (95%CI: 1.8-6.3).

Research conclusions

Results of our study showed high specificity of the sign of anteversion inclination 92% and low sensitivity (29%) due to other risk factors of hip dislocation.

Research perspectives

In this article were not studied other factors provoking hip dislocation. That is way for future perspectives, the authors want to determine the current role of the cup malposition in comparison with other factors of hip luxation.