Retrospective Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Radiol. Sep 28, 2017; 9(9): 359-364
Published online Sep 28, 2017. doi: 10.4329/wjr.v9.i9.359
Reliability of the pronator quadratus fat pad sign to predict the severity of distal radius fractures
Julia Loesaus, Isabel Wobbe, Erik Stahlberg, Joerg Barkhausen, Jan Peter Goltz
Julia Loesaus, Isabel Wobbe, Erik Stahlberg, Joerg Barkhausen, Jan Peter Goltz, Department for Radiology, Neuroradiology and Nuclear Medicine, University Hospital of Schleswig-Holstein, 23538 Lübeck, Germany
Author contributions: Loesaus J and Goltz JP contributed to study conception and design; Loesaus J and Goltz JP contributed to acquisition of data; Loesaus J and Stahlberg E contributed to analysis and interpretation of data; Loesaus J and Goltz JP contributed to drafting of manuscript; Wobbe I and Barkhausen J contributed to critical revision.
Institutional review board statement: This study was reviewed and approved by the University Hospital of Schleswig-Holstein.
Informed consent statement: All study participants, or their legal guardian, provided informed written consent prior to study enrollment.
Conflict-of-interest statement: The authors certify that they have no affiliations with or involvement in any organization or entity wwith any financial interest, or any non-financial interest in the subject matter or materials discussed in this manuscript.
Data sharing statement: Thchinical ppendix, statistical code, and dataset available from the corresponding author at j.loesaus@gmail.com. Participants gave informed consent for data sharing.
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: Julia Loesaus, MD, Department for Radiology, Neuroradiology and Nuclear Medicine, University Hospital of Schleswig-Holstein, Campus Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany. loesausj@klifue.de
Telephone: +49-451-50017001 Fax: +49-451-50017004
Received: January 19, 2017
Peer-review started: January 20, 2017
First decision: May 22, 2017
Revised: June 26, 2017
Accepted: July 14, 2017
Article in press: July 17, 2017
Published online: September 28, 2017
Abstract
AIM

To evaluate the reliability of pronator quadratus fat pad sign to detect distal radius fracture and to predict its severity.

METHODS

Retrospectively we identified 89 consecutive patients (41 female, mean age 49 ± 18 years) who had X-ray (CR) and computed tomography (CT) within 24 h following distal forearm trauma. Thickness of pronator quadratus fat pad complex (PQC) was measured using lateral views (CR) and sagittal reconstructions (CT). Pearson’s test was used to determine the correlation of the PQC thickness in CR and CT. A positive pronator quadratus sign (PQS) was defined as a PQC > 8.0 mm (female) or > 9.0 mm (male). Frykman classification was utilized to assess the severity of fractures.

RESULTS

Forty-four/89 patients (49%) had a distal radius fracture (Frykman I n = 3, II n = 0, III n = 10, IV n = 5, V n = 2, VI n = 2, VII n = 9, VIII n = 13). Mean thickness of the PQC thickness can reliably be measured on X-ray views and was 7.5 ± 2.8 mm in lateral views (CR), respectively 9.4 ± 3.0 mm in sagittal reconstructions (CT), resulting in a significant correlation coefficient of 0.795. A positive PQS at CR was present in 21/44 patients (48%) with distal radius fracture and in 2/45 patients (4%) without distal radius fracture, resulting in a specificity of 96% and a sensitivity of 48% for the detection of distal radius fractures. There was no correlation between thickness of the PQC and severity of distal radius fractures.

CONCLUSION

A positive PQS shows high specificity but low sensitivity for detection of distal radius fractures. The PQC thickness cannot predict the severity of distal radius fractures.

Keywords: Pronator quadratus fat pad sign, Pronator quadratus complex, Distal radius fracture, Frykman classification, Conventional radiograph, Computed tomography

Core tip: This study evaluated reliability of pronator quadratus fat pad sign (PQS) to detect distal radius fracture and to predict its severity. Therefore correlation of measurements of pronator quadratus complex (PQC) on conventional lateral radiographs (CR) and sagittal reconstructions of computed tomographies (CT), also regarding the severity of fractures were analyzed. In conclusion PQC thickness can reliably be measured on lateral CR and correlates with CT. Sensitivity of PQS for detecting fractures is low, but specificity is high. Therefore a positive PQS in putative negative radiograph should trigger further investigations, e.g., CT scan. PQC thickness cannot predict severity of wrist fractures.