الفهرس 
Anatomy of the shoulder jointOnly 14 pages are availabe for public view
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Abstract
Structurally the shoulder joint is a weak joint due to disparity of
articulating surface area between small and shallow glenoid cavity in
comparison to head of humerus
Shoulder pain is the third most common musculoskeletal complaint in
the general population
Subacromial impingement is the most frequent cause of shoulder pain,
accounting for up to 60% of all shoulder complaints
The term shoulder impingement was first introduced by Neer 1972
and referred to compression of rotator cuff, subacromial bursa and biceps
tendon against the undersurface of the acromion & coracoacromial
ligament , that exaggerates on elevation of the arm. it is often difficult to
diagnose because the clinical presentation may be confusing and clinical
tests lack specificity .
There are many etiological factors of rotator cuff impingement ,
including anatomical , mechanical, vascular, degenerative & trumatic
factors. Keeping in consideration that, in the majority of cases , the
process of impingement is multifactorial, and the key factor in any case
depends on the individual circumstances
In the past, several imaging modalities were used ranging from
conventional radiography, arthrography to computerized axial
arthrography. Recently, various imaging modalities are now available
including ultrasonography, CT arthrography, conventional MRI and MR
arthrography.
The most common radiological findings in such cases are abnormal
acomion shape, acromio-calvicular osteoarthritis, subacromial bursitis,
rotator cuff abnormalities (including tendinosis, partial-thickness tears &
full-thickness tears), reduced subacromial tunnel & biceps tenosynovitis.
MRI was considered to be the examination of choice for the
evaluation of the cases with subacromial impigement , but it can only
provide a static evaluation of the shoulder joint and indirectly suggesting
the diagnosis of subacromial impingement, in addition to its high cost ,
long examination time and subjective limitations, as in patients having
pace-makers or claustrophobics.
MR in cases of subacromial impingement can precisely detect:
Narrowing in the subacromial tunnel
Different types of rotator cuff tears.
Rotator cuff tendinosis
Fluid in the joint , in the subacromial and subdeltoid bursa,
Acromio-clavicular joint degenerative changes and its impact on the
rotator cuff tendons.
Biceps teno-synovitis.
The shoulder joint is anatomically complex, where its stability
depends on a combination of osseous structures and soft tissue structures
surrounding the shoulder known as the labral ligamentous complex, joint
capsule, muscles and tendons where they are acting as dynamic as well as
static stabilizers preventing the joint from exceeding the optimized range
of motion.
Glenohumeral instability remains a very complex and sometimes
challenging diagnostic problem. There are potential lesions of the capsule
and Labroligamentous structures that can occur in association with
shoulder instability, and the clinical history and physical findings are not
always sufficient to make accurate diagnosis. Antero-inferior dislocation
is the most common frequent cause of shoulder instability.
The aim of this work is to evaluate the role of magnetic resonance
imaging in diagnosing the different lesions that cause shoulder joint
pain.
This study included 20 patients; clinically presented with shoulder
pain whether traumatic or atraumatic associated with limitation of
movement, dislocation and/or dislocation. Most of the patients were
examined with conventional MRI and some of them were subjected to
MR arthrography.
Conventional MR imaging, which allows direct visualization of major
anatomic structures, had been traditionally used in the examination of
patients with shoulder instability, though it has been pointed out that
accurate interpretation of glenohumeral joint structures is beset with
pitfalls. To improve the evaluation of smaller intra-articular structures
such as the glenoid labrum and glenohumeral ligaments, MR
arthrography is increasingly recognized as the examination of choice in
glenohumeral instability providing demarcation of complex anatomic
structures of the joint and demonstration of subtle abnormalities, along
Summary
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with excellent delineation of associated intra-articular lesions. MR
arthrography extends the capabilities of conventional MR imaging
because contrast solution distends the joint capsule, outlines intraarticular
structures, and leaks into abnormal areas.
In our study, MR arthrography has good role in diagnosis of labral
tears in addition to imaging capsuloligamentous, cartilaginous injuries as
well as small partial or complete tears of the rotator cuff tendons.
In conclusion, our results recommend that MRI should be
increasingly used, especially when there is any uncertainty, or when the
issue of labral or capsular tear is not obvious from the clinical
investigation. Further MR arthrography is, however, needed in order to
be able to evaluate the joint capsule itself, and the size of the ligamentlabral
injury.