AJR 2002; 178:238-239
© American Roentgen Ray Society
Posterior Entrapment of the Long Biceps Tendon After Traumatic Shoulder Dislocation
Findings on MR Imaging
Klaus Strobel1,
Thomas C. Treumann and
Bernhard Allgayer
1
All authors: Kantonsspital Luzern,
Röntgeninstitut, 6000 Luzern 16,
Switzerland.
Received March 9, 2001;
accepted after revision May 23, 2001.
Address correspondence to K. Strobel.
Introduction
Medial dislocation of the long biceps tendon is common in degenerative
rotator cuff tears with disruption of the subscapularis tendon. Posterior
displacement of the long biceps tendon is rare and is associated with anterior
shoulder dislocation. If disruption of the transverse ligament and of the
supraspinatus and infraspinatus tendons occurs during shoulder dislocation,
the long biceps tendon may be displaced laterally and slip over the greater
tuberosity, so that it comes to lie posterior to the humeral head. In this
position, the function of the biceps muscle is impaired, and the entrapped
tendon can prevent complete reduction of the humeral head. MR findings in
medial dislocation of the long biceps tendon are well known
[1,
2], but only a few cases of
posterior dislocation have been described so far
[3,
4]. In these patients,
diagnosis was based on conventional arthrography or CT arthrography. We will
describe a case of posterior dislocation of the long biceps tendon after a
traumatic shoulder dislocation, revealed by MR imaging.
Case Report
The 65-year-old patient had a traumatic anterior dislocation of the right
humeral head. The dislocation was reduced immediately in the emergency room,
but functional deficit and pain persisted. Two weeks after the trauma, MR
imaging of the right shoulder was performed on a 1.5-T scanner (Magnetom
Symphony; Siemens, Erlangen, Germany). After IV injection of 0.1 mmol/kg of
gadodiamide (Omiscan; Nycomed Imaging, Oslo, Norway), proton
density—weighted MR images were obtained in axial, paracoronal, and
parasagittal planes (Fig.
1A,1B,1C,1D,1E,1F).
MR images showed complete disruption of the supraspinatus and infraspinatus
tendons. The bicipital groove was empty. The long biceps tendon was wrapped
around the humeral head posteriorly and entrapped in the dorsal part of the
glenohumeral joint. Accompanying lesions were an undislocated fracture of the
greater tuberosity and a partial tear of the subscapularis tendon. An open
surgical exploration confirmed the MR finding of posterior entrapment of the
long biceps tendon. Tenodesis of the long biceps tendon in the bicipital
groove and repair of the rotator cuff tear were performed. MR imaging
follow-up 6 months later showed a correct position of the long biceps tendon
in the bicipital groove.
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Fig. 1A. —65-year-old man 2 weeks after traumatic anterior right
shoulder dislocation. Axial (A-D) images are arranged from superior
(A) to inferior (D) with thickness of 3 mm at approximately
10-mm intervals. Coronal (E and F) images are arranged from
posterior to anterior with thickness of 3 mm at approximately 15-mm intervals.
Axial proton density—weighted MR image at level of superior glenoid
shows long biceps tendon entrapped in posterior part of glenohumeral joint
space (large single arrow). Edge of completely torn supraspinatus
tendon is seen posterior to humeral head (thin arrows). Bone bruise
is seen in greater tuberosity with some small fracture lines
(arrowheads).
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Fig. 1B. —65-year-old man 2 weeks after traumatic anterior right
shoulder dislocation. Axial (A-D) images are arranged from superior
(A) to inferior (D) with thickness of 3 mm at approximately
10-mm intervals. Coronal (E and F) images are arranged from
posterior to anterior with thickness of 3 mm at approximately 15-mm intervals.
Axial proton density—weighted MR image at level of center of glenoid.
Bicipital groove is empty (short arrow). Long biceps tendon is seen
in posterior part of glenohumeral joint space (long single arrow).
Edge of completely torn infraspinatus tendon is seen posterior to glenoid
margin (long thin arrows). Bone bruise of greater tuberosity
(arrowheads) is also seen.
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Fig. 1C. —65-year-old man 2 weeks after traumatic anterior right
shoulder dislocation. Axial (A-D) images are arranged from superior
(A) to inferior (D) with thickness of 3 mm at approximately
10-mm intervals. Coronal (E and F) images are arranged from
posterior to anterior with thickness of 3 mm at approximately 15-mm intervals.
Axial proton density—weighted MR image at level of inferior glenoid.
Bicipital groove is empty (short arrow). Long biceps tendon is seen
curving posteriorly around humeral head (long arrows).
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Fig. 1D. —65-year-old man 2 weeks after traumatic anterior right
shoulder dislocation. Axial (A-D) images are arranged from superior
(A) to inferior (D) with thickness of 3 mm at approximately
10-mm intervals. Coronal (E and F) images are arranged from
posterior to anterior with thickness of 3 mm at approximately 15-mm intervals.
Axial proton density—weighted MR image at level of proximal humeral
shaft shows long biceps tendon in almost normal position (arrow).
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Fig. 1E. —65-year-old man 2 weeks after traumatic anterior right
shoulder dislocation. Axial (A-D) images are arranged from superior
(A) to inferior (D) with thickness of 3 mm at approximately
10-mm intervals. Coronal (E and F) images are arranged from
posterior to anterior with thickness of 3 mm at approximately 15-mm intervals.
Coronal proton density—weighted MR image through posterior glenoid shows
long biceps tendon coursing from supraglenoid tubercle in inferior direction
posteriorly around humeral head (arrows).
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Fig. 1F. —65-year-old man 2 weeks after traumatic anterior right
shoulder dislocation. Axial (A-D) images are arranged from superior
(A) to inferior (D) with thickness of 3 mm at approximately
10-mm intervals. Coronal (E and F) images are arranged from
posterior to anterior with thickness of 3 mm at approximately 15-mm intervals.
Coronal proton density—weighted MR image through middle part of glenoid
shows long biceps tendon lateral to proximal humeral shaft (long
arrow). Almost no distance is left between humeral head and acromion
after complete disruption of supraspinatus tendon (small arrow). Bone
bruise with small fracture lines is seen in greater tuberosity
(arrowheads). Partial lesion of subscapularis tendon can be seen
(short arrow).
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Discussion
The long biceps tendon is an important stabilizer of the shoulder. In its
intraarticular portion, the tendon is covered by the coracohumeral and
superior glenohumeral ligaments and the supraspinatus tendon. In the bicipital
groove, the biceps tendon is held in place by the transverse humeral ligament
and the subscapularis and major pectoralis tendons
[5]. Dislocation of the long
biceps tendon occurs if stabilizing structures are disrupted. Most
dislocations of the long biceps tendon are in a medial direction and are
associated with degenerative rotator cuff tears, especially lesions of the
subscapularis tendon [1,
2].
Posterior dislocation of the long biceps tendon can occur if the transverse
ligament and the supraspinatus and infraspinatus tendons are ruptured. This
allows the biceps tendon to slip laterally over the humeral head into the
posterior articular joint space. Rupture of the rotator cuff occurs in about
one third of all traumatic shoulder dislocations
[6], but posterior dislocations
of the biceps tendon are rare. Other case reports mention that posterior
dislocation of the long biceps tendon may be an obstacle to reduction of a
dislocated humeral head and may lead to persistent pain and functional deficit
[4]. In the workup of the
traumatized shoulder, function tests may be positive for a rotator cuff tear,
but unspecific regarding the position of the long biceps tendon. Conventional
radiographs may be normal or may show a persistent anterior subluxation of the
humeral head with respect to the glenoid fossa.
Today, MR imaging is the preferred imaging method in the diagnosis of
shoulder disorders. Because labral and rotator cuff pathology are best
visualized if the joint capsule is distended by fluid, MR arthrography
enhances the diagnostic accuracy as compared with conventional MR imaging
[7]. MR arthrography has proven
to be accurate in the diagnosis of abnormalities of the long biceps tendon
such as tendinopathy and rupture
[8]. To our knowledge, no
studies have compared MR arthrography and conventional MR imaging in patients
with dislocation of the long biceps tendon.
In this patient, we were reluctant to inject contrast material directly
into an acute traumatized shoulder joint, because we assumed a higher risk of
infection compared with injections into nontraumatized joints. Therefore, we
decided to perform indirect MR arthrography, in which, when joint effusion is
present, IV-administered contrast media accumulates in the joint fluid within
minutes. After having reviewed the literature, we would now perform direct MR
arthrography even in acute traumatized shoulder joints, because we can find no
evidence that trauma may lead to an increased risk of infection after an
intraarticular injection.
Even during open surgery for repair of a rotator cuff tear, dislocation of
the long biceps tendon may not be recognized intraoperatively. If not repaired
by tenodesis, a poor postoperative outcome with persisting functional deficit
results. On MR imaging in patients after shoulder dislocation, the position
and course of the long biceps tendon should be evaluated so that a posterior
displacement and entrapment of the long biceps tendon will not be
overlooked.
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Introduction
Case Report
