Treatment of Irreducible Traumatic Anterior Shoulder Dislocation Caused by Subscapularis Tendon Interposition

Abstract

Irreducible shoulder dislocation is an uncommon event. When it does occur, blocks to reduction can include bone, labrum, rotator cuff musculature, or tendon. Concomitant rotator cuff tear at the time of initial dislocation is not an exclusive complication of anterior shoulder dislocation in the older population. Indeed, rotator cuff tear should not be excluded based solely on the patient's age. Rotator cuff interposition is not an uncommon complication after anterior dislocation of the shoulder. It should be suspected when there is incongruency of the joint and persistent subluxation on postreduction radiographs. If such incongruence or subluxation is seen, a computed tomographic (CT) or magnetic resonance imaging (MRI) scan must then be obtained to determine the nature of the interposed soft tissues. The key to treatment is early diagnosis and adequate imaging. Open reduction and repair of the rotator cuff should be performed. We present a technique for treating irreducible anterior shoulder dislocation caused by interposition of the subscapularis tendon. Both CT and MRI observations, along with intraoperative findings and surgical technique, are discussed.

Fig 1

Prereduction plain radiograph: anteroposterior view of the left shoulder showing dislocated shoulder joint with avulsion fracture of tuberosities (red and yellow arrows).

Fig 2

Initial postreduction plain radiograph: anteroposterior view of the left shoulder showing subluxed shoulder joint with avulsion fracture of the greater tuberosity (white arrow).

Fig 3

Axial computed tomographic scan of the left shoulder showing a persistent anterior subluxation of the humeral head with the lesser tuberosity lying behind it (black arrow).

Fig 4

Oblique coronal magnetic resonance image of the left shoulder shows an avulsion of the supraspinatus tendon (the 2 black arrows), which is draped over the superior labrum. The humeral head is subluxated superolaterally.

Fig 5

Axial magnetic resonance image of the left shoulder shows avulsion of the subscapularis tendon (black arrow) and its entrapment into the glenohumeral joint. In addition, there is interposition of the long head of the biceps tendon (yellow arrow).

Fig 6

Beach chair position, left shoulder, showing the incision through the deltopectoral interval, which reveals the traumatically exposed humeral head.

Fig 7

Beach chair position, left shoulder, showing the distal end of the subscapularis tendon (black arrow) held by 2 nonabsorbable sutures after its delivery from within the joint.

Fig 8

Beach chair position, left shoulder, showing the biceps tendon tenotomy being tenodesed to the subscapularis tendon (black arrow).

Fig 9

Beach chair position, left shoulder, showing the subscapularis repaired to the trough on its lesser tuberosity (arrows).

Fig 10

Postoperative radiograph of the left shoulder showing restoration of the acromiohumeral space with anchors fixing the cuff tendons.