Semin Musculoskelet Radiol 2021; 25(04): 574-579
DOI: 10.1055/s-0041-1735467
Review Article

Elbow Instability

1   Department of Radiology, Balgrist University Hospital, Zurich, Switzerland
2   Faculty of Medicine, University of Zurich, Zurich, Switzerland
,
Benjamin Fritz
1   Department of Radiology, Balgrist University Hospital, Zurich, Switzerland
2   Faculty of Medicine, University of Zurich, Zurich, Switzerland
,
Samy Bouaicha
1   Department of Radiology, Balgrist University Hospital, Zurich, Switzerland
2   Faculty of Medicine, University of Zurich, Zurich, Switzerland
,
Reto Sutter
1   Department of Radiology, Balgrist University Hospital, Zurich, Switzerland
2   Faculty of Medicine, University of Zurich, Zurich, Switzerland
› Author Affiliations

Abstract

The stability of the elbow is based on a combination of primary (static) and secondary stabilizers (dynamic). In varus stress, the bony structures and the lateral ulnar collateral ligament (LUCL) are the primary stabilizers, and in valgus stress, the ulnar collateral ligament (UCL) is the primary stabilizer. The flexor and extensor tendons crossing the elbow joint act as secondary stabilizers. Elbow instability is commonly divided into acute traumatic and chronic instability. Instability of the elbow is a continuum, with complete dislocation as its most severe form.

Posterolateral rotatory instability is the most common elbow instability and can be detected at imaging both in the acute as well as the chronic phase. Imaging of suspected elbow instability starts with radiographs. Depending on the type of injury suspected, it is followed by magnetic resonance imaging (MRI) or computed tomography evaluation for depiction of a range of soft tissue and osseous injures. The most common soft tissue injuries are tears of the LUCL and the radial collateral ligament; the most common osseous injuries are an osseous LUCL avulsion, a fracture of the coronoid process, and a radial head fracture.

Valgus instability is the second most common instability and mostly detected in the chronic phase, with valgus extension overload the dominant pattern of injury. The anterior part of the UCL is insufficient in valgus extension overload due to repetitive medial tension seen in many overhead throwing sports, with UCL damage readily seen at MRI.



Publication History

Article published online:
27 October 2021

© 2021. Thieme. All rights reserved.

Thieme Medical Publishers, Inc.
333 Seventh Avenue, 18th Floor, New York, NY 10001, USA