POSTOPERATIVE SHOULDER
Matthieu JCM Rutten, MD, PhD
Purpose / aim
The purpose of this presentation is to describe the advantages and limitations of
various imaging techniques for the evaluation of the postoperative shoulder and to
become familiair with the normal and abnormal appearance of the rotator cuff after
surgical repair and be able to discriminate common types and unusual types of
rotator cuff retear.
Introduction
There are several modalities that can be used to effectively image the postoperative
shoulder. Radiography, computed tomography (CT), magnetic resonance (MR)
imaging and ultrasound (US) each have advantages and disadvantages for the
detection of postoperative complications and recurrent lesions.
Radiography
Radiography is cheap, fast and may help to triage the patient to the correct advanced
imaging modality. For the detection of recurrent dislocation, implant displacement or
loosening, the diagnosis is often easily accomplished with radiography alone,
obviating the need for cross-sectional imaging modalities.
CT (arthrography)
In the postoperative shoulder, CT imaging is often utilized for the assessment of
periarticular osseous abnormalities and evaluation of osseous abnormalities (such as
postoperative nonunion) and complications which arise from the presence of metallic
implants (such as osteolysis/loosening and hardware malplacement).
Indications for CT arthrography in the postoperative shoulder include the evaluation
of the labrum, rotator cuff and articular cartilage.
A substantial reduction of metal-related artifact is possible with the creation of 3D CT
images using software manipulation. Metal artifact is also reduced by altering the CT
acquisition parameters, however the required alterations often result an increased
radiation dose to the patient.
MR (arthrography)
MR generally provides excellent contrast resolution for exquisite anatomic delineation
of the soft tissues of the shoulder and is the preferred modality for the comprehensive
examination of the shoulder.
The quality of MR images can be markedly degraded by the presence of metalrelated susceptibility artifact. This can partly be overcome by using fast spin echo
sequences and avoiding gradient echo imaging, frequency-selective fat suppression
and alterations to the bandwidth, voxel size and frequency/phase encoding
directions.
Knowing the type of surgery that was performed helps to determine the degree of
metal artifact to expect on MR imaging. For example, a typical decompression
procedure with acromioplasty +/- distal clavicular resection produces very little
artifact, and the shoulder is easily evaluated by conventional MR. However,
modifications should probably be made to the protocol with the presence of metallic
anchors and screws which produce mild to moderate artifact, where bioabsorbable
materials do not require metal-reduction techniques.
For the assessment of the postoperative shoulder, MR arthrography is preferred
because of the evaluation of the postoperative labrum and rotator cuff. Distension of
the joint nicely delineates the morphology of the articular structures, along with the
presence of scar tissue and thickening of the joint capsule following surgery. For the
evaluation of the postoperative rotator cuff, one should remember that the MR signal
of the cuff on a noncontrast exam is highly variable and may even contain fluid signal
within the sutures.
Rotator cuff morphology is also variable, with expected postoperative alterations in
tendon thickness compared with the baseline rotator cuff tendon. MR arthrography
increases the accuracy of conventional MR for the assessment of articular sided
recurrent tears of the rotator cuff, although caution should be used in the
interpretation of potential full thickness recurrent tears, given that contrast can pass
from the joint to the subacromial bursa through a non-watertight surgical closure of
the tendon.
Postoperative shoulder ultrasound
Ultrasound is fast and cheap and unlike for CT and MR, ultrasound evaluation of the
postoperative shoulder is not limited by the presence of metal. It has been shown to
be an accurate test for the detection of a recurrent rotator cuff tear in the
postoperative setting. The sensitivity, specificity and accuracy of ultrasound for
identifying rotator cuff integrity postoperatively are 91%, 86% and 89%, respectively.
Ultrasound can be used to evaluate patients who had previous acromioplasty or
rotator cuff surgery. Recurrent pain in these patients may be related to persistent
impingement, recurrent rotator cuff tear or tendinosis. Sonographic findings after
acromioplasty will show distorsion of the lateral aspect of the acromion. The
appearance of the postoperative tendon does not return to normal. Tendons are
usually thinned and hyperchoic, with their superficial aspect of the cuff flattened or
even concave. The aspect depends on the surgical technique.
If anchors are used, they can be visualized, appearing as hyperchoic foci followed by
a reverberation artifact. The cortical defect will be detected as well. Sometimes the
tendon is reimplanted more medially, and is less easily identified. Suture material will
appear as hyperchoic lines within the tendon. A recurrent tear will appear as a focal
defect or an absence of the cuff, often associated with joint effusion.
Ultrasound can also be used to evaluate rotator cuff after arthroplasty. Postoperative
rotator cuff tear is the second most frequent complication of shoulder replacement,
and subscapularis tendon tear may predispose to anterior instability.
Conclusions
Ultrasound is a highly accurate imaging study for evaluating the integrity of the rotator
cuff in shoulders that have undergone an operation. Its accuracy for operatively
treated shoulders appears to be comparable with that previously reported for
shoulders that had not been operated on.
Major teaching points and learning objectives:
1. Ultrasound is less vulnerable to post-surgical artifact than MRI or CT and therefore
should be the first screening procedure used in the evaluation of patients with
recurrent shoulder symptoms after rotator cuff surgery.
2. Recognize the normal and abnormal appearance of the rotator cuff after surgical
repair and be able to discriminate common types and unusual types of rotator cuff
retear.
3. Normal ultrasound appearance of anchors (single and double row repair
techniques) and sutures can easily be distinguished from loose anchors and suture
granulomas.
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