Observational Study
Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. Dec 18, 2018; 9(12): 292-299
Published online Dec 18, 2018. doi: 10.5312/wjo.v9.i12.292
Humeral retroversion and shoulder muscle changes in infants with internal rotation contractures following brachial plexus birth palsy
Fabian van de Bunt, Michael L Pearl, Tom van Essen, Johannes A van der Sluijs
Fabian van de Bunt, Tom van Essen, Johannes A van der Sluijs, Department of Orthopedics, Amsterdam UMC, VU University Medical Center, Amsterdam 1081 HV, Netherlands
Michael L Pearl, Department of Shoulder and Elbow Surgery, Kaiser Permanente Medical Center, Los Angeles, Ca 90027, United States
Author contributions: van de Bunt F designed the study, and performed data collection, analysis and interpretation of data, writing of (the first draft) of the manuscript, critical evaluation of the intelligent content of the final version; Pearl ML designed the study and performed data interpretation, writing of the manuscript, critical evaluation of the intelligent content of the final version; van Essen T performed data collection, analysis and interpretation of data, writing of (the first draft) manuscript; van der Sluijs JA designed the study and performed data interpretation, writing of the manuscript, and critical evaluation of the intelligent content of the final version; all authors made significant contributions to the manuscript, conforming to the standard proposed by the ICMJE.
Institutional review board statement: We are pleased to confirm that the Medical Research Involving Human Subjects Act (WMO) does not apply to the above-mentioned study and that an official approval of this study by our committee is not required.
Informed consent statement: We received an IRB waiver from the Institutional review board since this was a retrospective observational study, utilizing MRI scans made strictly for clinical purposes. MRIs were all anonymized by the Radiology department before conducting our study. See the attached IRB statement.
Conflict-of-interest statement: The authors whose names are listed immediately below certify that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.
STROBE statement: The authors have read the STROBE Statement-checklist of items, and the manuscript was prepared and revised according to the STROBE Statement-checklist of items.
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/
Corresponding author to: Fabian van de Bunt, MD, MSc, Doctor, MD, Department of Orthopedics, Amsterdam UMC, VU University Medical Center, De Boelelaan 1117, Amsterdam 1081 HV, Netherlands. fabianvdbunt@gmail.com
Telephone: +31-64-8482593
Received: August 22, 2018
Peer-review started: August 22, 2018
First decision: October 4, 2018
Revised: October 16, 2018
Accepted: November 15, 2018
Article in press: November 15, 2018
Published online: December 18, 2018
Processing time: 118 Days and 14.8 Hours
ARTICLE HIGHLIGHTS
Research background

The existing common treatment options for children suffering from brachial plexus birth palsy all strive for better function of the upper extremity through an improved position of the hand in space. This position is directly related to the humeral version angle.

Research motivation

Since earlier studies did not reveal a correlation between age and decreased retroversion on the involved side, the question remained at what age this anatomic change may occur.

Research objectives

Our objective was to elucidate the timing that decreased retroversion may occur; therefore, we included our youngest patient population (2-7 mo old).

Research methods

We measured humeral version relative to two proximal axes and one distal axis (transepicondylar axis). The proximal axes were: (1) the perpendicular line to the borders of the articular surface (humeral centerline), and (2) the longest diameter through the humeral head. Additionally, cross-sectional areas of the infraspinatus (IS) and subscapularis (SSc) muscles were measured. The difference in retroversion was correlated with the ratio of muscle sizes.

Research results

Retroversion on the involved side was significantly decreased, 1.0° vs 27.6° (1) and 8.5° vs 27.2° (2), (P < 0.01), as compared to the uninvolved side. SSc and IS muscle size on the involved side was significantly decreased, 2.26 cm² vs 2.79 cm² and 1.53 cm² vs 2.19 cm², respectively (P < 0.05). Additionally, muscle ratio (SSc/IS) on the involved side was significantly smaller compared to the uninvolved side (P = 0.007), but was not related to alterations in humeral version.

Research conclusions

Our results show that altered humeral development can occur very early in life in a population where internal rotation contractures are apparent.

Research perspectives

A large reduction in humeral retroversion at a very young age could be a predictor (or an argument when apparent at an older age), for the necessity of a humeral derotational osteotomy, to provide adequate improvement of hand and possibly elbow function. A prospective study analyzing changes in humeral version over time would be of interest to assess the predictive value of decreased retroversion at such a young age, concerning various treatment options (soft-tissue and bony).