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Normal SST Coronal FST2
FTT with retraction
Supraspinatus Tears
Overuse or misuse of any tendon leads to accelerated apoptosis and to what has been called 'degeneration'. Changes within the tendon which do not lead to symptoms may be referred to as tendinosis. When symptoms develop, the term tendinopathy is used. With progression, areas of delamination develop within the tendon. This is sometimes called focal tendinopathy and sometimes called partial tears. Some authors reserve the term “partial tear" to an acute traumatic event where the tendon is not completely ruptured. In many cases, these terms are used interchangeably.

Full thicknesss tears involve both surfaces of the tendon allowing communication between the joint and the SASD bursa. There occur in two common locations; some close to the anterior border of the tendon adjacent to the biceps (leading edge tears) and some in the mid portion of the tendon (foorprint or midsubstance tears)There are several types from small 'Linear' tears to larger 'L Shaped' tears. Once the tear involves a suffient area of tendon tissue, the disrupted tendon begins to retract. As the muscle becomes weakened and underused, it atrophies and fatty replacement of normal muscle tissue is seen .

In your MRI report describe:
  • Tear location
  • Tear shape (as best you can)
  • Tear size (focus on medial lateral measurement
  • State of remaining tendon and muscle

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Leading edge tear
Leading edge tear
Imaging
Fat saturated T2 / PD or STIR images are best at diagnosing supraspinatus tears.

A full thickness tear is diagnosed when high signal is seen to completely traverse the tendon on T2 weighted or fat saturated images. In most cases the diagnosis is clear on coronal oriented images but a more complete assessment of the full size and extent of the tear can be assessed by combining coronal and sagittal images. Signal alteration that does not return fluid signal intensity, that is signal intensity similar to joint fluid, is less likely to represent a tear. Various types of full thickness tear occur. Tears that involve the anterior leading edge are thought to be more common in younger individuals, possibly related to repetitive misuse in sport. High signal intensity is seen to traverse the tendon close to its insertion and adjacent to where the biceps passes through the anterior interval. The adjacent figure shows the typical appearance of a small anterior leading edge tear with high intensity signal traversing the tendon overlying an area of exposed humeral head. As previously noted small lesions in this location can be difficult to diagnose. Tilted axial section can be helpful and correlation between the coronal and sagittal images, ideally using a cross reference facility on a workstation, can help with diagnosis.
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Another common tear pattern involves the mid portion of supraspinatus leaving intact anterior and posterior tendon margins. The margins surrounding the tear are sometimes referred to as the cables. It is possible that patients with naturally strong cables may be more prone to this tear pattern. A strong cable may also protect against tenon retraction. A mid substance tear can be diagnosed on coronal images where once again the classical sign of fluid intensity signal traversing the tendon is appreciated. The central location of this tear is easier to note on the sagittal images. In addition to high signal, a bare area of humeral cortex is seen to underlie the fluid signal within the tear an overlying bursa.When the tear involves both the anterior leading edge and the mid substance it is termed a massive tear. Tendon retraction with secondary supraspinatus muscle atrophy is more likely. It i useful to give the surgeon an appreciation of the degree of associated muscle atrophy although there is disagreement in the literature as to whether there is good correlation between muscle atrophy and the ability to reduce the tendon at surgery. When there is advanced muscle atrophy particularly when it is associated with secondary degenerative changes, termed cuff arthropathy, consideration will need to be given as to whether there is any advantage to the patient in undergoing cuff repair and it may be that a more simple subacromial subdeltoid decompression will give this symptom relief that is needed. Other findings that may be seen in association with rotator cuff tears include fluid in the subacromial subdeltoid bursa, glenohumeral effusion and high signal changes within the humeral head at the site of supra spinatus insertion.
Coronal T2. Supraspinatus muscle atrophy
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Small Leading edge tear. This type are difficult to detect
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There are a number of different methods for repairing a torn supraspinatus tendon. Most involves bringing the end of back to its bony origin and reattaching it using some form of suture anchoring system. The ability to reduce the tendon maybe impaired if there is significant muscle atrophy. Consequently, an evaluation of the state of the supraspinatus muscle can help in some circumstances. T1 weighted images are most often used to assess the degree of battery replacement of the muscle. The assessment is made on a lateral sagittal-oblique image where the acromion, coracoid, and scapular body were all visible. From these images, the presence of fatty inÞltration is graded according to a 5-point semi- quantitative scale described by Goutallier.Grade 0 is normal, some fatty streaks within the muscle indicates grades 1. Great 2 is where there is daffy degeneration involving less than half of the muscle bulk and grade 3 where there is 50% involvement. More than 50% fatty replacement indicates Grade 4.
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Midsubstance Tear
Large cuff tear
Midsubstance Tears
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Isolated infraspinatus injuries are uncommon but may follow trauma with a raised arm. A typical incident is a motorbike accident where the rider is dragged behind by the fallen bike. Most tears are due to extension from a large supraspinatus tear. Oedema within this muscle may also be due to neural impingement. The image is from a patient with brachial neuritis (Parsonage-Turner Syndrome)
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