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Diagnostic Imaging

It is essential that the initial evaluation of the painful shoulder include quality plain radiographs. The standard radiographs should include a true anterior-posterior view with the shoulder in the internal and neutral position, an axillary view, and the outlet (supraspinatus) view described by Neer and Poppen, which is used to evaluate and classify acromial morphology and arch anatomy. Bigliani et al.

They have classified the types into I flat, II curved, and III hooked. In addition to establishing morphology, the thickness of the acromion should also be assessed and if surgery is recommended, a pre-operative decision can be made regarding the amount of bone to be resected so as to prevent excessive thinning or inadequate bone resection.

The standard anterior-posterior views may show superior migration of the humeral head consistent with a cuff tear and potential subscapularis involvement. Cystic and/or sclerotic change in the greater tuberosity may also signal tendon pathology. The axillary view is most helpful in assessing concomitant glenohumeral degenerative changes, but is most helpful in establishing the presence of an os acromiale.

Magnetic resonance imaging is the current test of choice when evaluating the soft tissues of the shoulder. T1 weighted images revealing increased signal in the rotator cuff combined with a focal defect or loss of continuity of the cuff on the T2 weighted image is a common finding when a full or partial-thickness tear is encountered.

The addition of a contrast agent such as gadolinium significantly enhances the positive predictive value for diagnosing a full thickness tear, and can also aid in detecting and quantifying partial tears of the cuff as well . Several studies have demonstrated a poor correlation between arthroscopic findings and MRI abnormalities. The combination of fat suppressed images combined with contrast has been reported to significantly improve the sensitivity and specificity for detecting full and partial thickness cuff tears .

One must exercise caution when interpreting MR findings because asymptomatic individuals may have significant rotator cuff findings on MRI, but may remain completely asymptomatic. Magnetic resonance imaging continues to demonstrate its greatest utility and potential when combined with a thorough and reliable history and physical examination.

Although an MRI scan is not essential for every patient with shoulder pain, for those anticipating a surgical procedure, a pre-operative MRI scan can be helpful for the following reasons: evaluating whether a cuff tear accompanies a suspected impingement syndrome, the presence of which would alter the post-operative regimen, allowing the patient to properly plan for post-operative care; determining the size and potential tear configuration, including retraction, delamination, and thinning, factors that need to be considered in the surgical planning; assessing the presence or absence of atrophyor fatty infiltration, both important prognostic factors; and establishing the presence of co-morbidities such as partial biceps or labral tears.

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