Rotator Cuff Disease Workup

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• Laboratory studies are not necessary for diagnosing rotator cuff disease.

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• A wide variety of radiological examinations are offered to image the rotator cuff. Each of them has advantages and limitations. To prescribe the most useful examination, one must start with a good clinical history and physical examination. Imaging should be used to confirm the anomaly, describe its extension and the associated findings. The following paragraphs briefly explain the indications, the technique, and the findings for each modality available to image the rotator cuff in radiology.

• Plain film radiography

  • Indication

    • Plain films are not very specific or sensitive to rotator cuff disease, but they remain the first examination to perform.

    • Radiographs give a gross evaluation of the mineralization of the bone, the alignment, posttraumatic changes, the normal variant of the acromion shape, the presence of degenerative changes, and the presence of fine soft tissue calcifications that could be missed otherwise by other modalities.

    • This is most useful test in trauma or chronic complete tear.

    • In the last stage of complete chronic rotator cuff tear, it could be the only imaging modality needed to confirm the diagnosis.

  • Technique: Plain films are acquired routinely in 3 planes (ie, neutral, internal, external rotation; see the image below). Additional views, like the Neer profile, can be performed to better characterize the shape of the acromion.

    Normal plain radiograph of the shoulder in internal, external, and neutral positions.

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  • Findings (see Table 1, below)

    • Rotator cuff tendinitis: Signs of chronic tendinitis without tear include subchondral sclerosis of humeral head (see the first image below), flattening and geode of the greater tuberosity, sclerosis of the acromion, calcifications located in the presumed area of rotator cuff tendon (see the second image below), acromion spurs (see the third image below), or a type 2 or 3 acromion. ^[24]

      Subchondral sclerosis of the humeral head as seen in chronic tendinopathy.

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      Calcification at the insertion of the rotator cuff, another sign of chronic tendinopathy.

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      Presence of a bony spur on the inferior surface of the acromion.

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    • Partial rotator cuff tear: All of the above can be present, but no specific signs can help in the diagnosis of a partial tear, as tendons are not visible on plain film.

    • Complete rotator cuff tear: In acute tears, the presence of synovial effusion or hemorrhage can subluxate the humeral head caudally. On the other hand, if the tear is chronic, the humeral head migrates superiorly as the rotator cuff loses its ability to stabilize the humeral head in the glenoid cavity. Radiographically, an acromiohumeral space less than 6 mm, with or without erosion, on the inferior aspect of the acromion is a good semiologic landmark for chronic complete tear. All the signs of tendinitis also can be found in complete chronic tears.

Table 1: Radiological Findings on Plain Film (Open Table in a new window)

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• Arthrography

  • Indication

    • The main indication for arthrography is to identify complete rotator cuff tears and intra-articular infiltration of corticoid.

    • As a diagnostic tool, it is combined generally with arthro-CT.

  • Technique: Arthrography is performed by injecting iodine contrast medium or air or both into the glenohumeral joint. Eight to twelve milliliters of contrast (or 3-4 mL of contrast and 10-12 mL of air) are injected to distend the joint capsule. If air and contrast are injected the term double contrast study is used. Then, plain films are taken in different positions, such as external rotation, internal rotation, and subacromial views before and after motions. The image below shows an intact capsule.

    Normal double-contrast arthrography of the shoulder.

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  • Findings: In the presence of a complete tear, the contrast floods from the glenohumeral joint into the subacromial-subdeltoid bursa (see first 2 images below). With a partial tear, the contrast is seen as a line or small filled cavity within the tendon but without contrast in the subacromial-subdeltoid bursa. This finding is more difficult to demonstrate than in a complete tear. Intratendon tears and tears on the superior aspect of the tendon (bursal side) are not visualized with this technique. Arthrography also can provide some information about the long portion of the biceps tendon, loose bodies, and synovial disorders, such as inflammatory synovitis (see the third image below), osteochondromatosis, or villonodular pigmented synovitis.

    This image depicts the channel between the articular capsule and the subacromial-subdeltoid bursa in a complete rotator cuff tear.

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    Even if the channel cannot be always identified, the presence of contrast medium in the subdeltoid-subacromial bursa signs the presence of a complete rotator cuff tear.

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    Complete rotator cuff tear with presence of contrast medium in the subacromial-subdeltoid bursa. Also note the multiple irregularities in the synovial fluid showed as multiples filling defects.

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• CT arthrography

  • Indication: This study, although very accurate (100% sensibility, 100% specificity) in depicting complete rotator cuff tears, is limited in the evaluation of tendinitis and partial tears, where its sensitivity drops to 17-43%. On the other hand, this test gives more information than arthrography about the joint itself and the soft tissues around it. The ability to evaluate the labrum, the glenohumeral ligaments, the long head of the biceps tendon, and the bony structures, as well as the presence of loose bodies, makes this a useful study.

  • Technique: CT arthrography is performed exactly like a double contrast (air and iodine contrast) arthrography but followed by tomodensitometry imaging (CT scan). For this examination, the shoulder is imaged in the axial plan in internal and external rotation. Thin slices as small as 2-3 mm are acquired throughout the entire joint. With new CT scan technology, it has become easy to reformat images in multiple planes.

  • Findings

    • The semiologic signs of rotator cuff tears are essentially the same as seen on conventional arthrography. The presence of contrast in the subacromial-subdeltoid space confirms the diagnosis of complete rotator cuff tears (see the image below). The contrast also can facilitate determination of the size and location of the tear to help the surgeon plan the surgery. Degenerative findings such as osteophytes, geodes, sclerosis, and articular space narrowing also are well depicted.

      Computed tomography (CT)-arthrography scan of the shoulder in the axial plane. Note the presence of air and contrast in the subacromial-subdeltoid bursa.

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  • In addition to conventional arthrography, this technique can identify labral and glenohumeral ligament tears. The presence of contrast between the labrum and the articular space indicates the presence of a tear. The axial views also permit a good visualization of the long head of the biceps tendon in its groove. Therefore, subluxation of this tendon, or rupture, also can be diagnosed. Finally, the shape of the acromion can be evaluated on the oblique sagittal reformatted study that requires a special acquisition.

• Magnetic resonance imaging

• Indication

  • Magnetic resonance imaging (MRI) is the state-of- the-art diagnostic tool for a full evaluation of the shoulder. MRI allows a fine evaluation of the bone marrow, tendons, muscles, ligaments, capsules, bursae, and labrum. MRI combines the advantage of visualization of the bony structures, as well as all the soft tissues about the shoulder and in any plane desirable. With this imaging modality, it is now possible to diagnose the full continuum of rotator cuff disease, from simple tendinosis, to complete tear. MRI is much more powerful than the previous modalities to identify partial tears, and it also can identify intratendon tears or tears on the bursal aspect of the tendon. As with CT scan and plain film, the bone structures resulting or contributing to the impingement syndrome can be evaluated.

  • MRI also can give information about retraction of the muscle, atrophy, bursitis, and bone marrow abnormalities (such as edema or contusion), which all are associated findings in rotator cuff disease.

  • MRI is somewhat limited in the evaluation of the labrum and glenohumeral ligaments. MRI arthrography is the study of choice for the evaluation of labrum and glenohumeral ligaments.

• Technique: This technique takes advantage of the properties of hydrogen protons submitted to a magnetic field and RF waves. Therefore, there is no radiation exposure for the patient. Multiple sequences are available to highlight different substances such as water, fat, blood, or solid structures. Mainly spin echo T1, spin echo T2, and gradient echo sequences, in axial, sagittal, and coronal oblique plans, are acquired in different combinations. Inversion recovery, fat saturation, and injection of gadolinium (IV or intra-articular) can be added if necessary.

• Findings

  • MRI shows great detail of the anatomy in multiple plans. MRI also allows seeing the nature of a structure or an anomaly better, according to its intrinsic property. Therefore, the examiner should know some characteristics of the MRI signals for the most common structures. Fat, methemoglobin, melamine, gadolinium, and some forms of calcium all are hyperintense in T1-weighted images. On the contrary, water appears at low signal intensity. In T2-weighted images or in gradient echo, the liquids are hyperintense, as are most lesions, meaning that edema, inflammatory processes, tumors, tendinitis, and tendon tears are hyperintense in T2-weighted images and hypointense in T1-weighted images.

  • Therefore, the presence of fluid in a bursa or articular joint is hyperintense in T2 or gradient echo, and indicates inflammatory or posttraumatic fluid. A full thickness tear of the tendon is demonstrated by a hypersignal intensity in T2 that extends throughout the tendon (see the image below). ^[25]

    Full-thickness tear of the supraspinatus seen as a hyperintensity line through the full thickness of the tendon (as viewed in a flash 2-dimensional magnetic resonance imaging [MRI] sequence in the coronal oblique plane).

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• Tendinitis is recognized as a grey signal in the tendon (see the first image below). Finally, calcification, as well as cortical bone, appears hypointense in all sequences (see the second image below).

  Slight hyperintensity signal within the tendon without transsectional hyperintensity throughout the tendon is compatible with tendinopathy without complete tear. Additionally, note the presence of the hyperintensity signal in the region of the subdeltoid-subacromial bursa, which indicates bursitis.

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  Calcifications are seen as hypointense foci in flash 2-dimensional.

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• Arthro-MRI follows the same principle as arthro-CT. This modality can help to identify labral tears (see the image below) and glenohumeral tears.

  Arthro–magnetic resonance imaging (MRI) can help to identify labral tears, as seen in this image. The contrast medium penetrates between the labrum and the articular surface.

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• Tables 2 and 3 summarize the possible findings. Resnick and Kang is suggested for further reading.

Table 2: Radiological Findings on MRI (Open Table in a new window)

 

Table 3: Radiological Signs of Specific Disorders (Open Table in a new window)

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• Ultrasonography

  • Indication: The main purpose of ultrasonography is to study the soft tissues. In experienced hands, ultrasonography has a sensitivity of 93-100% and a respective specificity of 85-97% for complete tear and a sensitivity of 69-93% for partial tear. These results are comparable to MRI.

  • Technique

    • Ultrasonography is a technique that uses the same principles as radar. The images are created using a high- resolution transducer that first sends a sound signal and then receives the echo produced when the sound hits the different structures at different depths.

    • The advantages of this technique reside in its low cost, high availability, and high resolution. Ultrasonography is a dynamic study for demonstrating impingement syndrome.

    • The disadvantages are that it is time consuming for the radiologist and is operator-dependent. Ultrasonography cannot study bone structures, as sound does not penetrate bone very well.

  • Findings

    • With ultrasonography, the normal tendon is an echoic structure, whereas the cartilage and fluids are hypoechoic (see Table 4, below). All the tendons, bony landmarks (eg, humerus, greater tuberosity) and intra-articular or intrabursal effusion are recognized easily. Tendinitis is diagnosed when the tendon loses its echogenicity and becomes diffusely hypoechoic. Calcifications appear as bright foci within the tendon, accompanied by a posterior shadowing, as the sound cannot pass through the calcium.

    • The main, and most sensitive, sign of a complete rotator cuff tear is an interruption in the tendon that fills with fluid, producing a hypoechogenic foci extending from the cartilage surface to the subdeltoid-subacromial bursa (see the image below). The secondary signs include the uncovered cartilage (cartilage appears hyperechoic at the site of the tear), bursa herniation, loss of convexity of the tendon and bursa, and effusion within the glenohumeral articulation and the subacromial-subdeltoid bursa.

      Ultrasonography is another modality that can demonstrate a complete rotator cuff tear. This image reveals a gap of more than 2 cm between both extremities of the torn tendon.

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  • The diagnosis of a partial rotator cuff tear is made when the hypoechoic or bursal herniation does not cross the full width of the tendon. The use of ultrasonography also allows the operator to demonstrate in real time the impingement of the supraspinatus tendon on the acromion when the arm is positioned in internal rotation and moved in abduction or flexion.

Table 4: Ultrasonographic Signs of Rotator Cuff Disease (Open Table in a new window)

 

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• Nuclear medicine imaging: Bone scintigraphy is not used routinely in the rotator cuff disease imaging.