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
Processing time: 115 Days and 16.6 Hours
Abstract
AIM

To measure the sensitivity and specificity of the cup version assessment by using only anteroposterior hip and pelvis views, evaluate the incidence of inadequate cup version in patients with repeated dislocations after total hip arthroplasty (THA).

METHODS

Radiographic retrospective analysis of 2 groups of patients, with follow up of 6-60 mo, after undergoing primary THA. First group of 32 patients (20 female, 12 male) with unilateral THA (32 hips) required early revision arthroplasty for reasons of dislocation. The mean age and mode were 59 (from 38 to 83) and 66 ages respectively. The average body mass index (BMI) was 24.2 (from 17.7 to 36.3), mode 23.9. Second group was consisted of 164 patients (101 female, 63 male) without dislocations during the follow-up period (170 hips). Among them 6 patients required bilateral THA. The mean age was 60 (from 38 to 84) and mode 59. BMI was 24.8 (17.2-36.8), mode 25.2. Clinical significance of the cup anteversion sign was estimated with cross tabulation 2 × 2.

RESULTS

The value of the χ2 yates was 10.668 (P < 0.01). Sensitivity of SAI (sign of anteversion insufficiency) 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).

CONCLUSION

This method provides the surgeons with the ability to perform a reliable and simple qualitative assessment of the acetabular component version. It can be useful during patient examination with early loosening of the implant, dislocations, and impingement. Additionally, it can provide necessary information during planning of revision surgery, especially when considering question about cup replacement, although final assessment of the cup position should be done with a computed tomography scan.

Keywords: Hip arthroplasty; Acetabular component; Retroversion; Dislocation

Core tip: The acetabular cup position is a crucial factor of normal function and implant survival. Several methods to determine cup anteversion are described. Among them are mathematical methods based on a standard anteroposterior (AP) view, modifications of a cross-table lateral views, and computed tomography-scan. Latter two methods are not always available or practical in outpatient setting. The purpose of our study was to estimate sensitivity, specificity of the cup version assessment by using only AP hip and pelvis views. Our findings suggest that inadequate anteversion sign appears when the anteversion angle is less than half the angle between X-ray beams in the AP hip and pelvis views.