Basic Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. Feb 18, 2016; 7(2): 117-122
Published online Feb 18, 2016. doi: 10.5312/wjo.v7.i2.117
Effect of elbow position on radiographic measurements of radio-capitellar alignment
Emilie Sandman, Fanny Canet, Yvan Petit, G-Yves Laflamme, George S Athwal, Dominique M Rouleau
Emilie Sandman, Fanny Canet, Yvan Petit, G-Yves Laflamme, Dominique M Rouleau, Hôpital du Sacré-Cœur de Montréal, Montreal, Quebec H4J 1C5, Canada
George S Athwal, the Hand and Upper Limb Centre, Ontario N6A 4L6, Canada
Author contributions: Sandman E, Canet F and Rouleau DM performed the majority of experiments and analysed the data; Sandman E and Canet F performed the radiographic investigations; Petit Y, Athwal GS and Rouleau DM participated equally in the design of the research; all the authors contributed to the drafting of the paper.
Supported by Fondation de Recherche et d’Éducation en Orthopédie de Montréal.
Institutional review board statement: Comité d’éthique de la recherche de l’HSCM, CÉR 2010-04-32. Each individual was asked to give informed consent.
Informed consent statement: Each individual was asked to give informed consent.
Conflict-of-interest statement: The authors declare no conflicts of interest regarding this manuscript.
Data sharing statement: No data were created so no data are available.
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: Dominique M Rouleau, MD, MSc, FRCSC, Hôpital du Sacré-Cœur de Montréal, 5400 Boul Gouin O, Montreal, Quebec H4J 1C5, Canada. dominique.rouleau@umontreal.ca
Telephone: +1-514-3382222 Fax: +1-514-3383542
Received: May 15, 2015
Peer-review started: May 15, 2015
First decision: September 29, 2015
Revised: November 18, 2015
Accepted: December 3, 2015
Article in press: December 4, 2015
Published online: February 18, 2016
Processing time: 277 Days and 13.5 Hours
Abstract

AIM: To evaluate the effect of different elbow and forearm positions on radiocapitellar alignment.

METHODS: Fifty-one healthy volunteers were recruited and bilateral elbow radiographs were taken to form a radiologic database. Lateral elbow radiographs were taken with the elbow in five different positions: Maximal extension and forearm in neutral, maximal flexion and forearm in neutral, elbow at 90° and forearm in neutral, elbow at 90° and forearm in supination and elbow at 90° and forearm in pronation. A goniometer was used to verify the accuracy of the elbow’s position for the radiographs at a 90° angle. The radiocapitellar ratio (RCR) measurements were then taken on the collected radiographs using the SliceOmatic software. An orthopedic resident performed the radiographic measurements on the 102 elbows, for a total of 510 lateral elbow radiographic measures. ANOVA paired t-tests and Pearson coefficients were used to assess the differences and correlations between the RCR in each position.

RESULTS: Mean RCR values were -2% ± 7% (maximal extension), -5% ± 9% (maximal flexion), and for elbow at 90° and forearm in neutral -2% ± 5%, supination 1% ± 6% and pronation 1% ± 5%. ANOVA analyses demonstrated significant differences between the RCR in different elbow and forearm positions. Paired t-tests confirmed significant differences between the RCR at maximal flexion and flexion at 90°, and maximal extension and flexion. The Pearson coefficient showed significant correlations between the RCR with the elbow at 90° - maximal flexion; the forearm in neutral-supination; the forearm in neutral-pronation.

CONCLUSION: Overall, 95% of the RCR values are included in the normal range (obtained at 90° of flexion) and a value outside this range, in any position, should raise suspicion for instability.

Keywords: Elbow subluxation; Radiocapitellar ratio; Elbow; Elbow dislocation

Core tip: Assessing radial head alignment after injury and obtaining perfect lateral radiographs with the elbow at 90° and the forearm in neutral may be difficult. Therefore we designed this study to assess whether the radiocapitellar ratios (RCR) calculated from true lateral radiographs at different positions of elbow flexion and forearm pronosupination differ from those taken in 90° flexion and neutral position. The paper shows that the RCR measurement continues to be an overall valid and reliable method throughout different elbow and forearm positions. However, values in the negative range, > 5% regardless of forearm rotation, should raise suspicion for elbow instability.