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ULTRASOUND N February 2005 N Volume 13 N Number 1
Ultrasonography of the Shoulder
D. P. O’Regan, A. K. Lim & A. W. M. Mitchell
Imaging Sciences Department, Hammersmith Hospital, London, UK
Introduction
Examination of the shoulder with ultrasound has become a
widely accepted method of evaluating a number of musculoskeletal pathologies. The continuing advancements made in
imaging technology have allowed ultrasound to develop into a
powerful diagnostic tool. Ultrasound has the advantage of
producing high-resolution dynamic images of the shoulder, as
well as allowing the operator to perform image-guided
interventions, such as cyst aspiration or steroid injections. Its
main role has continued to be in diagnosing partial and fullthickness rotator cuff injuries, and it allows the assessment of
size, location and extension of tears. It has good correlation to
intra-operative findings1 and compares favourably to MRI,
particularly in the diagnosis of partial rotator cuff tears.2 In
experienced hands it provides a rapid and cost-effective
evaluation of the painful shoulder.3 Ultrasound also provides
information about intra-articular abnormalities, such as labral
tears, loose bodies and synovial disease, as well as evaluating
joint effusions and acromio-clavicular joint arthropathies.4
In this article, we provide a detailed guide on how to perform
a standard ultrasound examination of the shoulder with
illustrations of patient positioning, and examples of the normal
sonographic appearances of the rotator cuff and associated
structures. Some important diagnostic pitfalls that may be
encountered will be discussed.
Rotator Cuff Anatomy
The rotator cuff is a complex of four muscles that arise from the
scapula and whose tendons blend with the joint capsule as
they insert onto the humeral tubercles (Fig. 1). Supraspinatus
is clinically the most important rotator cuff tendon as it is
usually involved, either alone or in combination with other cuff
tendons, in the great majority of tears. The muscle arises from
the supraspinous fossa of the scapula and passes inferior to
the acromion process. It follows the curvature of the superior
humeral head and its fibres insert onto the superior facet of the
greater tubercle of the humerus. The subacromial sub-deltoid
bursa lies between the rotator cuff and the subacromial arch,
and may contain a thin layer of fluid in asymptomatic
individuals.5 Thus, the supraspinatus muscle has a deep
articular surface and a superficial bursal surface. The overlying deltoid muscle is characteristically less echogenic than
the underlying supraspinatus tendon.
Infraspinatus and teres minor arise from the infraspinous
fossa and lateral border of the scapula, respectively, and
insert onto the middle and inferior facets of the greater
tubercle. The subscapularis muscle arises from the costal
surface of the scapula and its tendon inserts independently of
the other rotator cuff muscles onto the lesser tubercle. The
long head of the biceps tendon traverses the rotator cuff
interval, which separates the supraspinatus and subscapularis
tendons, and is held in place by the coracohumeral ligament
and transverse humeral ligament. The shallow glenoid fossa
Correspondence: Declan O’Regan, Imaging Sciences Department,
Hammersmith Hospital, London W12 0HS, UK, [email protected]
ß British Medical Ultrasound Society 2005
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Figure 1. The muscles of the rotator cuff seen posteriorly (subscapularis
not shown). Reproduced with permission from Gray’s Anatomy for
Students, Churchill Livingstone 2004.
is enlarged by the cartilaginous labrum. The head of the
humerus is kept within the centre of the labrum by both static
and dynamic stabilizers. The superior, middle and inferior
glenohumeral ligaments, and the joint capsule provide static
stabilization. Dynamic stability is achieved by the co-ordinated
actions of the rotator cuff muscles with biceps and deltoid
having an accessory role. The rotator cuff has three principle
actions:
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it rotates the humerus with respect to the scapula;
it compresses the humeral head into the glenoid fossa;
it provides muscular stability during shoulder movements.6
Ultrasound Equipment
Transducers with frequencies in the range from 8 to 15 MHz
have become standard equipment on modern machines. In
larger patients, a lower frequency probe may sometimes
be necessary (5–7.5 MHz) for adequate penetration. Small
footprint transducers are also now available, which improve
skin contact and reduces anisotropy. The availability of
extended field-of-view or panoramic imaging also helps to
demonstrate whole segments of tendons to rival the coverage
achieved with MR imaging. Power or colour Doppler is
standard on most equipment, and is helpful when evaluating
the presence of inflammatory changes.
Real time compound imaging is available on a number of
machines, and this significantly reduces the intrinsic artefacts
and noise of conventional sonography, thus improving image
quality (Fig. 2).7 Some machines also have post-processing
image algorithms, such as XRES (Philips, Holland), which may
improve visualization of tissue textures and margins. The
image quality can also be improved by increasing the number
of focal zones, although this leads to a reduction in frame
DOI: 10.1179/174313405X27481
ULTRASOUND N February 2005 N Volume 13 N Number 1
(a)
Figure 4. Longitudinal section of the biceps tendon acquired with the
patient’s hand supinated and resting on their knee. The lamellar structure of the tendon (asterisk) can be readily appreciated. It is enclosed
by synovium and small joint effusions may be apparent at the level of
its musculo-tendinous junction.
rate. Two or three focal zones are typically used in standard
practice.
The ultrasound images is this article were acquired from a
normal volunteer with a Philips HDI 5000 ultrasound machine
using a 12 MHz linear probe, using SonoCT compound
imaging with two focal zones.
(b)
Examination Technique
Figure 2. (a) The upper image of supraspinatus was acquired with compound imaging in which the ultrasound beam is steered in multiple offaxis lines-of-sight and rendered into a real time image. It provides
improved image contrast and interface definition compared to the conventional image below (b).
It is important that both the patient and operator are positioned
correctly to allow optimal imaging of the rotator cuff. Typically,
the patient is seated on a backless chair or stool, which allows
Figure 3. The patient places their supinated hand over their knee and
the probe is positioned anterolaterally to follow the course of the biceps
tendon as it passes through the rotator cuff interval.
Figure 5. The patient hyper extends and internally rotates their
shoulder to reveal the supraspinatus tendon from under the acromion
process.
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ULTRASOUND N February 2005 N Volume 13 N Number 1
Figure 6. Long axis of the supraspinatus tendon with the arm in hyperextension and internal rotation. Supraspinatus curves over the head of
the humerus to insert onto the greater tubercle (arrowheads). The
tendon is hyper-echoic compared with the overlying deltoid muscle
(asterisk). No fluid is visible in the intervening sub-acromial sub-deltoid
bursa (arrows).
Figure 7. The patient places their hand over their
opposite shoulder to bring it into internal rotation and
flexion. The probe is placed to view the infraspinatus
tendon near its attachment.
Figure 8. Infraspinatus (asterisk) in its long axis as its fibres converge
onto the middle facet on the greater tubercle between supraspinatus
and teres minor.
Figure 9. The patient turns their shoulder into external
rotation to view subscapularis.
Figure 10. The biceps tendon (arrowhead) traverses the rotator cuff
interval along the border of subscapularis (asterisk).
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the operator convenient access to the desired imaging planes.
This position also permits the patient to freely move their arm
into a favourable position for imaging a particular tendon and
facilitates shoulder movement during dynamic sonography. It
is important that the patient should be allowed to move their
shoulder actively to avoid causing unnecessary discomfort.
Most operators find the examination is most comfortably
ULTRASOUND N February 2005 N Volume 13 N Number 1
performed from behind the patient, although others prefer to
scan while facing the patient.
To begin with, the patient is asked to place their supinated
hand over their knee (Fig. 3). The probe is placed over the
anterolateral aspect of the humeral neck in the axial plane,
where the biceps tendon can be readily identified lying in the
intertubercular groove. Its proximal course through the rotator
cuff interval can be demonstrated as it passes between
the supraspinatus and subscapularis, and deep to the
coracohumeral ligament. The probe may then be rotated to
view the biceps tendon in its long axis (Fig. 4). The tendon is
enclosed by synovium and the musculotendinous junction is
the most dependent part of the joint, where small effusions
may only be apparent.8
The patient is then asked to place their hand behind their
back over their buttock, as though in their back trouser pocket
(Fig. 5). This puts the shoulder joint into hyperextension and
internal rotation allowing the supraspinatus tendon to be better
demonstrated. The supraspinatus muscle runs in a coronal
oblique plane under the acromion process, and may be
visualized in short and long axis planes (Fig. 6). The fibrillar
structure of the tendon may be appreciated as it passes under
the deltoid muscle and over the humeral head. Supraspinatus
has a smooth fibrocartilaginous insertion on the greater
tubercle of the humerus, which typically appears hypo-echoic
compared with the tendon itself. The sub-acromial sub-deltoid
bursa should have no more than a trace of fluid within it. The
other rotator cuff muscles are then examined in turn. First, the
patient places their arm across their chest with their shoulder
in flexion and internal rotation to reveal the infraspinatus and
teres minor tendons (Figs 7 and 8). Orientation may be gained
by following the tendons to their insertion where, in the short
axis plane, the anterior portion of the cuff insertion is formed by
supraspinatus and the posterior portion by infraspinatus and
teres minor. Lastly, subscapularis is shown to best advantage
by asking the patient to bring their arm by their side and turn
their shoulder into external rotation (Figs 9 and 10).
Dynamic imaging to test for impingement may be performed
by placing the probe both coronally and sagittally lateral to the
acromion process. The patient is asked to abduct and adduct
their arm to assess for the smooth movement of supraspinatus
under the acromion process. The examination may be
completed by visualizing the non-tendinous structures of the
shoulder. In particular the acromio-clavicular joint may be
readily examined for arthropathy, and the glenoid labrum
evaluated for labral cysts and tears, although these are more
reliably assessed with MRI. Synovitis may also be seen as
thickening of the joint capsule with hyperaemia on Doppler
imaging.
(a)
(b)
Figure 11. (a) Transverse section of the biceps tendon as it lies in the
intertubercular groove (arrows). The image was acquired with the probe
perpendicular to the tendon, while (b) was acquired at a shallower angle
of insonation. This demonstrates the phenomenon of anisotropy in tendinous structures, which may be mistaken for a pathological defect.
Pitfalls
Some important pitfalls that may be encountered are either
due to artefacts of the ultrasound technique or to misinterpretation of the complex anatomy of the rotator cuff and
surrounding structures. The echogenicity of tendons is highly
angle dependent, a characteristic called anisotropy. The
lamellated structure of the tendon causes it to have maximum
echogenicity when insonated perpendicularly, and it becomes
hypo-echoic at more shallow angles (Fig. 11).9 This reduction
in tendon reflectivity may be mistaken for a tear. This
phenomenon can be readily observed by changing the angle
of insonation of the probe in real time.
The rotator cuff muscles have a multipennate structure and
coalesce onto the joint capsule. The interdigitating fibres
produce alternating bands of reflectivity within the tendons
near their insertion and this heterogeneity must not be
mistaken for pathology (Fig. 12).10
Figure 12. The tendinous interdigitations around the insertion of supraspinatus should not be mistaken for partial tears.
The rotator cuff interval may also give the impression of a
tendinous defect, while an oblique view of the biceps tendon
may mimic the appearance of a longitudinal tear of the
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ULTRASOUND N February 2005 N Volume 13 N Number 1
adjacent supraspinatus. However, these appearances may
be readily resolved by turning the probe to appreciate the
tendon in its long axis and its relationship to the rotator cuff
interval.
2.
Teefey SA, Rubin DA, Middleton WD, Hildebolt CF, Leibold RA,
Yamaguchi K. Detection and quantification of rotator cuff
tears. Comparison of ultrasonographic, magnetic resonance
imaging, and arthroscopic findings in seventy-one consecutive
cases. J Bone Jt Surg Am 2004;86-A:708–716.
3.
Dinnes J, Loveman E, McIntyre L, Waugh N. The effectiveness of
diagnostic tests for the assessment of shoulder pain due to soft
tissue disorders: a systematic review. Hlth Technol Assess
2003;7(29):iii,1–166.
4.
Peetrons P, Rasmussen OS, Creteur V, Chhem RK. Ultrasound of
the shoulder joint: non ‘rotator cuff’ lesions. Eur J Ultrasound
2001;14:11–19.
5.
Schmidt WA, Schmidt H, Schicke B, Gromnica-Ihle E. Standard
reference values for musculoskeletal ultrasonography. Ann
Rheum Dis 2004;63:988–994.
6.
Hess SA. Functional stability of the glenohumeral joint. Man Ther
2000;5(2):63–71.
7.
De Candia A, Doratiotto S, Paschina E, Segatto E, Pelizzo F,
Bazzocchi M. Real-time compound sonography of the
rotator-cuff: evaluation of artefact reduction and image definition.
Radiol Med (Torino) 2003;105(4):308–314.
8.
Allen GM, Wildon DJ. Ultrasound of the shoulder. Eur J
Ultrasound 2001;14:3–9.
9.
Crass JR, van de Vegte GL, Harkavy LA. Tendon echogenicity:
ex vivo study. Radiology 1988;167:499–501.
10.
Thain LM, Adler RS. Sonography of the rotator cuff and biceps
tendon: technique, normal anatomy, and pathology. J Clin
Ultrasound 1999;27(8):446–458.
Conclusions
Shoulder ultrasound has matured into an accurate and costeffective technique for non-invasive imaging of the rotator cuff
and surrounding structures. It has a comparable accuracy
with MRI for identifying cuff tears and has the advantage of
providing a dynamic assessment of muscle impingement.
It requires a sound knowledge of ultrasound techniques
and musculoskeletal anatomy, as well as familiarity with
the common imaging pitfalls. A period of formal training
and continuing audit is recommended to ensure operator
accuracy.
References
1.
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Zehetgruber H, Lang T, Wurnig C. Distinction between
supraspinatus, infraspinatus and subscapularis tendon tears
with ultrasound in 332 surgically confirmed cases. Ultrasound
Med Biol 2002;28:711–717.