CASE 1498 Published on 18.03.2002

Anterior shoulder dislocation

Section

Musculoskeletal system

Case Type

Clinical Cases

Authors

H J Williams

Patient

36 years, male

Categories

No Area of Interest ; Imaging Technique Digital radiography

No Procedure ; No Special Focus ;

Show more Show less

Download as PDF Print Show related cases Notify admin

Clinical History

The patient fell while playing football, sustaining an injury to his left arm and shoulder. He presented to accident and emergency with severe pain and restricted movement of the left upper limb. On inspection there was loss of the normal contour of the left shoulder, which looked 'flattened' compared with the opposite side, and he was supporting the left arm with the right hand.

Imaging Findings

Discussion

Anterior shoulder dislocation is at least 10 times more common than posterior shoulder dislocation and is rarely overlooked clinically or radiographically. The mechanism of injury is usually a fall onto the hand and anterior dislocation occurs when the arm is forcibly externally rotated and abducted. The head of the humerus is driven forward tearing the joint capsule or avulsing the glenoid labrum anteriorly. The humeral head usually comes to lie just below the coracoid process of the scapula. On the antero-posterior (AP) shoulder view the humeral head lies inferiorly and medial to the glenoid. The lateral scapular or Y-view shows the humeral head to be displaced anteriorly and not covering the glenoid as is normally seen. The axial (armpit) view is painful and often difficult to obtain when there is shoulder dislocation, but this also shows the head of the humerus anterior to the glenoid. There may be an associated fracture of the anterior lip of the glenoid (Bankart fracture), posterolateral aspect of the head of the humerus (Hill-Sachs deformity) or proximal humerus (neck or shaft). A Bankart lesion of the cartilaginous glenoid labrum and stripping of soft tissue from the glenoid neck would not be seen on conventional radiographs but CT arthrography and MRI demonstrate the degree of soft tissue damage as well as bony injury. Other complications of anterior shoulder dislocation include axillary nerve or arterial injury. Occasionally the posterior cord of the brachial plexus is injured. Reduction is usually performed under sedation but if there is an associated fracture of the proximal humerus, open reduction and internal fixation under general anaesthesia is necessary. It is essential to obtain post-manipulation films in order to confirm reduction, and also to exclude a fracture.

Differential Diagnosis List

Anterior shoulder dislocation

Final Diagnosis

Anterior shoulder dislocation

References

[1] Raby N, Berman L, deLacy G.
Shoulder. In Raby N, Berman L, deLacy G. Accident and emergency radiology: a survival guide. WB Saunders Company Ltd, London, pp 50-67 (1995).

[2] Helms C A.
Skeletal trauma.
In Brant WE, Helms CA (eds) Fundamentals of diagnostic radiology, Second Edition. Lippincott Williams and Wilkins, Philadelphia, pp 997-1023 (1999).

[3] Hughes SPF, Porter RW. Upper limb – shoulder, arm and elbow injuries.
In Hughes SPF, Porter RW. Textbook of orthopaedics and fractures. Arnold, London, pp 59-73 (1997).

[4] Greenspan A. Upper limb- Shoulder Girdle and Elbow (chapter 5). In Orthopaedic Radiology, Third Edition. Lippincott Williams and Wilkins, Philadelphia, pp 89-150 (2000).

[5] Solomon L, Warwick D J and Nayagam S. The shoulder and pectoral girdle (chapter 13) and Injuries of the shoulder, upper arm and elbow (chapter 24). In Apley’s System of Orthopaedics and Fractures, Eighth Edition. Arnold, London, pp 275-301 and pp583-610 (2001).

Case information

URL:	https://eurorad.org/case/1498
DOI:	10.1594/EURORAD/CASE.1498
ISSN:	1563-4086

Figure 1

Antero-posterior and lateral scapular (Y) views of the left shoulder

Antero-posterior view of the left shoulder showing the humeral head (H) in a sub-coracoid position (C = coracoid process) and displaced inferiorly and medial to the glenoid (G).

Lateral scapular (Y) view of the left shoulder showing anterior displacement of the humeral head (H). It no longer covers the glenoid (the centre of the Y). C = coracoid process, G = glenoid.