Postoperative Shoulder Imaging: Rotator Cuff, Labrum, and Biceps Tendon

Role of ultrasound and MRI in the evaluation of postoperative rotator cuff

Rotator cuff tears are common shoulder injuries in patients above 40 years of age, causing pain, disability, and reduced quality of life. Most recurrent rotator cuff tears happen within three months. Surgical repair is often necessary in patients with large or symptomatic tears to restore shoulder function and relieve symptoms. However, 25% of patients experience pain and dysfunction even after successful surgery. Imaging plays an essential role in evaluating patients with postoperative rotator cuff pain. The ultrasound and magnetic resonance imaging are the most commonly used imaging modalities for evaluating rotator cuff. The ultrasound is sometimes the preferred first-line imaging modality, given its easy availability, lower cost, ability to perform dynamic tendon evaluation, and reduced post-surgical artifacts compared to magnetic resonance imaging. It may also be superior in terms of earlier diagnosis of smaller re-tears. Magnetic resonance imaging is better for assessing the extent of larger tears and for detecting other complications of rotator cuff surgery, such as hardware failure and infection. However, postoperative imaging of the rotator cuff can be challenging due to the presence of hardware and variable appearance of the repaired tendon, which can be confused with a re-tear. This review aims to provide an overview of the current practice and findings of postoperative imaging of the rotator cuff using magnetic resonance imaging and ultrasound. We discuss the advantages and limitations of each modality and the normal and abnormal imaging appearance of repaired rotator cuff tendon.

Rotator Cuff Injury and Repair

Rotator cuff pathology is a commonly encountered clinical and radiologic entity that can manifest as tendinopathy or tearing. Magnetic resonance imaging (MRI) and ultrasonography offer similar sensitivity and specificity for the evaluation of the native rotator cuff, and the chosen modality may vary, depending on local practice and accessibility. MR arthrography is frequently used in the postoperative setting as a problem-solving tool. Key findings to include in the preoperative MRI report include the size and location of the tear, thickness of the tendon involved (partial versus full thickness), and overall tendon quality. The report should also address features associated with poor surgical outcomes, such as fatty atrophy, a decreased acromiohumeral interval, and evidence of rotator cuff arthropathy. Musculoskeletal radiologists should be familiar with the various surgical techniques and expected postoperative imaging appearance of rotator cuff repairs. Imaging also plays a role in identifying recurrent tearing, graft failure, hardware loosening, infection, and other complications.

[Postoperative Imaging of Rotator Cuff Tear]

Postoperative imaging of the rotator cuff may be performed routinely, even if pain or disability develops after surgery or if there are no symptoms. Postoperative images are obtained through MRI or US, and the purpose is to confirm the integrity of the restored tendon in general. Postoperative MRI has a relatively poor diagnostic accuracy compared to that of preoperative images because various materials used in surgeries deteriorate the image quality. US can dynamically check the condition of the restored tendon and avoid artifacts from the surgical instruments used for recovery. Although imaging findings are not always consistent with the clinical symptoms or prognosis, sub-deltoid fluid retention is more important for pain and functional recovery than the thickness of the reconstructed tendon. Strain elastography can also be a useful method for predicting the prognosis.

Magnetic Resonance Imaging Around Metal at 1.5 Tesla: Techniques From Basic to Advanced and Clinical Impact

ABSTRACT

During the last decade, metal artifact reduction in magnetic resonance imaging (MRI) has been an area of intensive research and substantial improvement. The demand for an excellent diagnostic MRI scan quality of tissues around metal implants is closely linked to the steadily increasing number of joint arthroplasty (especially knee and hip arthroplasties) and spinal stabilization procedures. Its unmatched soft tissue contrast and cross-sectional nature make MRI a valuable tool in early detection of frequently encountered postoperative complications, such as periprosthetic infection, material wear-induced synovitis, osteolysis, or damage of the soft tissues. However, metal-induced artifacts remain a constant challenge. Successful artifact reduction plays an important role in the diagnostic workup of patients with painful/dysfunctional arthroplasties and helps to improve patient outcome. The artifact severity depends both on the implant and the acquisition technique. The implant's material, in particular its magnetic susceptibility and electrical conductivity, its size, geometry, and orientation in the MRI magnet are critical. On the acquisition side, the magnetic field strength, the employed imaging pulse sequence, and several acquisition parameters can be optimized. As a rule of thumb, the choice of a 1.5-T over a 3.0-T magnet, a fast spin-echo sequence over a spin-echo or gradient-echo sequence, a high receive bandwidth, a small voxel size, and short tau inversion recovery-based fat suppression can mitigate the impact of metal artifacts on diagnostic image quality. However, successful imaging of large orthopedic implants (eg, arthroplasties) often requires further optimized artifact reduction methods, such as slice encoding for metal artifact correction or multiacquisition variable-resonance image combination. With these tools, MRI at 1.5 T is now widely considered the modality of choice for the clinical evaluation of patients with metal implants.

Progression of long head of the biceps brachii tendon abnormality on magnetic resonance imaging after rotator cuff repair

OBJECTIVES

To correlate the deterioration of preserved long head of biceps tendon (LHB) after rotator cuff repair with preoperative and postoperative MRI factors.

METHODS

Total of 209 shoulder joints (F:M = 145:64; mean age 57.4 years) which underwent rotator cuff repair and at least two postoperative MRI scans over 10 months after surgery were included. LHB integrity was graded with a five point severity scale. LHB deterioration was defined by increased composite score of integrity and extent score between the preoperative and second postoperative MRI. For preoperative and postoperative MRI factors, size and location of superior cuff -supraspinatus and infraspinatus- and subscapularis tears, fatty degeneration of rotator cuff, preoperative LHB status, subluxation of LHB, superior labral tear, acromion type, repaired rotator cuff status, postoperative capsulitis and acromioplasty state were assessed. Logistic regression was used to evaluate the association between LHB deterioration and aforementioned factors. Same analysis was conducted for 62 shoulder joints with a long-term follow-up MRI.

RESULTS

Of the 209 shoulders, 49.3% (n = 103) showed LHB deterioration on short-term follow-up MRI. In long-term follow-up subgroup, 32 LHBs were further deteriorated. In multivariate analysis, fatty degeneration of superior cuff showed significant association with LHB deterioration in both short-term (p = .04, p = .007) and long-term subgroups (p = .004, p = .005) among preoperative and postoperative factors, respectively.

CONCLUSIONS

Degree of fatty degeneration in superior cuff is associated with LHB deterioration on postoperative MRI.

ADVANCES IN KNOWLEDGE

Our results support that tenotomy or tenodesis of LHB should be considered during rotator cuff repair, especially in patients with advanced fatty degeneration of rotator cuff.

The Evolving Roles of MRI and Ultrasound in First-Line Imaging of Rotator Cuff Injuries

Rotator cuff tears are the most likely source of shoulder pain in adults and may cause protracted disability. Management of rotator cuff tears is associated with considerable costs. Accurate diagnosis can guide surgical planning and help achieve a favorable clinical outcome. While radiographs remain the initial imaging test for shoulder injury, the roles of MRI and ultrasound (US) as first-line imaging after radiography are evolving. This review leverages current literature and the practical experience of subspecialty musculoskeletal radiologists from different institutions in describing a practical approach to imaging rotator cuff pathology. Both MRI and US are accurate for identifying rotator cuff tears, but each has advantages and shortcomings. As both modalities currently represent reasonable first-line approaches, considerable practice variation has evolved. Given the low cost of US, imagers should strive to optimize the quality of shoulder US examinations and to build referrer confidence in this modality. The roles of direct CT and MR angiography, as well as imaging evaluation of the postoperative rotator cuff, are also considered. Through careful selection among the available imaging modalities, as well as optimal performance and interpretation of such examinations, radiologists can positively contribute to the diagnosis and treatment of patients with rotator cuff injuries.

Measuring outcomes in rotator cuff disorders

Measuring the outcome of treatment for rotator cuff disorders has evolved over the last three decades. Objective surgeon-derived outcomes such as clinical examination findings and imaging of the rotator cuff have the limitation of marginalising the patients perception of their condition. Patient reported outcome measures (PROMs) have evolved and become popular in an attempt to demonstrate meaningful outcome data. There are a large number in use today and as a result, the heterogeneity of scores used across the literature can make comparison difficult. Patient reported outcome scores can be general health related quality of life scores, joint-specific and disease specific. Qualitative outcomes are also being used now, and these help us to better understand the context of quantitative research scores. In this article, we provide an overview of the outcome measures used in rotator cuff disorders.

Assessment of postoperative acromial and subacromial morphology after arthroscopic acromioplasty using magnetic resonance imaging

OBJECTIVE

To identify the morphological characteristics of the acromion and subacromial bursal space after arthroscopic acromioplasty using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

One hundred patients who received arthroscopic rotator cuff repair and acromioplasty each received at least three MRI examinations (preoperative, first immediate postoperative, and second follow-up imaging between 8 months and 1 year postoperatively). Changes over time in the thickness and morphology of the postoperative acromion as well as the subacromial bursal space were assessed. Clinical and radiological parameters were also analyzed to identify any association with changes in acromial morphology.

RESULTS

Despite minimal acromial thinning observed at the first immediate postoperative state, the acromions showed significant thinning at the second postoperative MRI, with a mean reduction of 32%. Along with acromial thinning, an exaggerated concave contour of the acromial undersurface was observed in some patients. In the subacromial space, a loculated fluid collection developed in 91% of the patients at the second postoperative follow-up. No statistically significant association was noted between postoperative acromial thickness change and clinical or radiological factors (P value > 0.05).

CONCLUSION

A significant delayed reduction in acromial thickness within approximately 1 year of arthroscopic acromioplasty is thought to be a normal postoperative feature. The simultaneous collection of a loculated, cyst-like fluid in the subacromial bursal space may be an important associated factor of postoperative acromial thinning.

Sonography of the post-operative rotator cuff: normal postoperative findings, postsurgical complications and common artifacts

This review sets forth an approach to performing and interpreting shoulder ultrasound in patients with prior rotator cuff repair and presents a comprehensive review of normal expected findings, postsurgical complications and common artifacts encountered in clinical practice.

Postoperative Knee and Shoulder

Arthroscopic surgery in the knee most commonly addresses ligament, meniscal, or articular cartilage abnormalities. Similarly, arthroscopic surgery of the shoulder most commonly addresses tendon and labral abnormalities. The expected postoperative MRI findings depend on both the procedure performed and the time since surgery. Identifying complications and failed procedures relies on both clinical and imaging evaluations.

Short-Term Clinical Outcomes and Comparison of Ultrasound Versus Magnetic Resonance Imaging of Superior Capsular Reconstruction

Purpose

To evaluate the short-term outcomes of 10 patients with irreparable massive rotator cuff tears treated with arthroscopic superior capsular reconstruction (SCR) using dermal allograft.

Methods

Between 2016 and 2018, patients with symptomatic irreparable rotator cuff tears were prospectively enrolled for treatment with arthroscopic SCR. Investigational review board approval was achieved. All patients were treated by a single fellowship-trained shoulder surgeon. Minimum follow-up was 1 year. Range of motion and functional outcome according to visual analog scale pain, American Shoulder and Elbow Surgeons, and Simple Shoulder Test scores were assessed preoperatively and at routine follow-up intervals. Magnetic resonance imaging (MRI) and ultrasound were obtained at a minimum of 1 year to assess graft integrity and to correlate clinical outcomes.

Results

Ten patients with a mean age of 58.6 years had a minimum follow-up of 1 year. In all patients, preoperatively to postoperatively, mean forward flexion improved from 141° to 173° (P = .018), mean visual analog scale pain score decreased from 6.5 to 1 (P = .004), and mean American Shoulder and Elbow Surgeons score improved from 43 to 87 (P = .005). At 1 year, ultrasound evaluation identified graft failure in 1 patient (10%), whereas MRI diagnosed graft failure in 7 patients (70%). Of the 7 failures diagnosed by MRI, 4 failed at the level of the glenoid, 2 failed mid-graft, and 1 failed at the humerus.

Conclusions

Although clinical outcomes are statistically improved following arthroscopic SCR using a dermal allograft, the early high failure rates of the graft raise concerns about the long-term outcomes of the procedure. Furthermore, the use of ultrasound alone to validate an intact graft should be used with caution, as failures can occur at the glenoid and can be missed without MRI correlation.

Level of Evidence

Level IV, Therapeutic case series

The Postoperative Rotator Cuff

MR imaging interpretation following rotator cuff repair can be challenging and requires familiarity with various types of rotator cuff tear, their surgical treatments, normal postoperative MR imaging appearance, and complications. This article reviews the common surgical procedures for the reparable and nonreparable massive rotator cuff tears, their expected postoperative MR imaging findings, and imaging appearance of a range of complications.

Postoperative MR Imaging in Shoulder Instability and Intra-articular Damage

MR imaging of the postoperative shoulder after instability surgery is challenging. The radiologist must be familiar with surgical procedures, altered anatomy, and expected postoperative findings for correct interpretation of normal findings versus a true pathology. Artifacts from metallic hardware or abrasions further complicate MR image interpretation, but are reduced with metal artifact reduction techniques. This article focuses on capsulolabral surgery, bone block transfers, and humeral bone loss procedures in patients with shoulder instability and their postoperative imaging evaluation. Surgical procedures and common complications are explained, and normal and pathologic postoperative imaging findings are presented.

Detecting Rotator Cuff Tears: A Network Meta-analysis of 144 Diagnostic Studies

BACKGROUND

Many imaging techniques have been developed for the detection of rotator cuff tears (RCTs). Despite numerous quantitative diagnostic studies, their relative accuracy remains inconclusive.

PURPOSE

To determine which of 3 commonly used imaging modalities is optimal for the diagnosis of RCTs.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

Studies evaluating the performance of magnetic resonance imaging (MRI), magnetic resonance arthrography (MRA), and ultrasound (US) used in the detection of RCTs were retrieved from the PubMed/MEDLINE and Embase databases. Diagnostic data were extracted from articles that met the inclusion/exclusion criteria. A network meta-analysis was performed using an arm-based model to pool the absolute sensitivity and specificity, relative sensitivity and specificity, and diagnostic odds ratio as well as the superiority index for ranking the probability of these techniques.

RESULTS

A total of 144 studies involving 14,059 patients (14,212 shoulders) were included in this network meta-analysis. For the detection of full-thickness (FT) tears, partial-thickness (PT) tears, or any tear, MRA had the highest sensitivity, specificity, and superiority index. For the detection of any tear, MRI had better performance than US (sensitivity: 0.84 vs 0.81, specificity: 0.86 vs 0.82, and superiority index: 0.98 vs 0.22, respectively). With regard to FT tears, MRI had a higher sensitivity and superiority index than US (0.91 vs 0.87 and 0.67 vs 0.28, respectively) and a similar specificity (0.88 vs 0.88, respectively). The results for PT tears were similar to the detection of FT tears. A sensitivity analysis was performed by removing studies involving only 1 arm for FT tears, PT tears, or any tear, and the results remained stable.

CONCLUSION

This network meta-analysis of diagnostic tests revealed that high-field MRA had the highest diagnostic value for detecting any tear, followed by low-field MRA, high-field MRI, high-frequency US, low-field MRI, and low-frequency US. These findings can help guide clinicians in deciding on the appropriate imaging modality.

MR Imaging of the Upper Limb: Pitfalls, Tricks, and Tips

MR imaging is the modality of choice to evaluate musculoskeletal pathologies of the upper limb in most settings. However, due to the complexity in anatomy, MR imaging can give a false pathologic appearance and lead to several errors in the interpretation of MR imaging findings. Also, several artifacts can be confused with pathologic entities. This article reviews the most frequently encountered conditions in shoulder, elbow, and wrist MR imaging that can represent diagnostic pitfalls mimicking true pathology, together with some possible tips and tricks that can be useful to solve these equivocal cases and achieve a correct diagnosis.

Imaging of Usual and Unusual Complication of Rotator Cuff Repair

Several complications may be encountered after rotator cuff (RC) repair. A thorough knowledge of surgical interventions, normal postoperative findings, and postoperative complications is crucial to provide a timely diagnosis, improving the clinical outcome of patients. Postoperative complications may involve RC, implanted device, osteochondral tissue, surgical-site infection, peripheral nerves, soft tissues, and vascular structures. In this review, we discuss the usual and unusual complications detectable after RC repair.

MR arthrogram of the postoperative glenoid labrum: normal postoperative appearance versus recurrent tears

OBJECTIVE

The purpose of this study is to describe the MR arthrogram appearance of the postoperative glenoid labrum and to describe the features consistent with recurrent tear.

MATERIALS AND METHODS

We identified 30 patients who had undergone glenoid labral repair, had a subsequent MR arthrogram of his or her shoulder, and went on to repeat shoulder arthroscopy. Each MR arthrogram was reviewed blindly, and the glenoid labrum was described as normal, irregular, or torn. Additional findings recorded included the presence or absence of a paralabral cyst and suture anchors in the glenoid. The operative report was also reviewed for each patient to determine the status of the labrum at arthroscopy.

RESULTS

Following consensus review, 18/30 MRIs were felt to demonstrate recurrent glenoid labral tear, 11/30 showed an irregular labrum, and 1/30 was called normal. The radiology impression regarding the presence or absence of a recurrent glenoid labral tear agreed with the operative report in 24/30 (80%) cases, and was discrepant in six. This equals 83.3% sensitivity and 81.8% specificity of MR arthrogram in the diagnosis of recurrent labral tear in this study. A paralabral cyst was present in 3/30 (10%) cases, all three of which were torn.

CONCLUSIONS

MR arthrogram findings of signal equal to gadolinium or fluid within or underlying the glenoid labrum and markedly diminutive or absent labrum were the most useful features to diagnose recurrent tear. Some signal underlying the labrum, which is confined to the anterosuperior quadrant, may be normal. The secondary finding of a paralabral cyst was also highly sensitive for recurrent tear.

The Repaired Rotator Cuff: MRI and Ultrasound Evaluation

PURPOSE OF REVIEW

The purposes of this review were to provide an overview of the current practice of evaluating the postoperative rotator cuff on imaging and to review the salient imaging findings of the normal and abnormal postoperative rotator cuff, as well as of postoperative complications.

RECENT FINDINGS

The repaired rotator cuff frequently appears abnormal on magnetic resonance imaging (MRI) and ultrasound (US). Recent studies have shown that while the tendons typically normalize, they can demonstrate clinically insignificant abnormal imaging appearances for longer than 6 months. Features of capsular thickening or subacromial-subdeltoid bursal thickening and fluid distension were found to decrease substantially in the first 6-month postoperative period. MRI and US were found to be highly comparable in the postoperative assessment of the rotator cuff, although they had a lower sensitivity for partial thickness tears. Imaging evaluation of newer techniques such as patch augmentation and superior capsular reconstruction needs to be further investigated. MRI and US are useful in the postoperative assessment of the rotator cuff, not only for evaluation of the integrity of the rotator cuff, but also for detecting hardware complications and other etiologies of shoulder pain.

[Magnetic resonance imaging findings after shoulder surgery: What the radiologist needs to know]

Even primary diagnostic evaluation of the shoulder is a challenge for radiologists. Many imaging findings that definitely indicate abnormal findings in the untreated shoulder should be evaluated carefully in postoperative patients. Artifacts caused by implants or metal abrasion pose considerable problems in postoperative magnetic resonance imaging (MRI). Classic approaches to minimizing artifacts caused by foreign bodies include using turbo spin echo sequences, increasing bandwidth, and reducing voxel size. In recent years, several vendors have developed dedicated pulse sequences for reducing metal artifacts. Different postoperative imaging findings will be encountered, depending on the kind of surgery done. This review article describes typical postoperative MRI findings, focusing on subacromial decompression, reconstruction of the rotator cuff, labrum procedures, and biceps tenodesis.

Advances in MRI around metal

The prevalence of orthopedic metal implants is continuously rising in the aging society. Particularly the number of joint replacements is increasing. Although satisfying long-term results are encountered, patients may suffer from complaints or complications during follow-up, and often undergo magnetic resonance imaging (MRI). Yet metal implants cause severe artifacts on MRI, resulting in signal-loss, signal-pileup, geometric distortion, and failure of fat suppression. In order to allow for adequate treatment decisions, metal artifact reduction sequences (MARS) are essential for proper radiological evaluation of postoperative findings in these patients. During recent years, developments of musculoskeletal imaging have addressed this particular technical challenge of postoperative MRI around metal. Besides implant material composition, configuration and location, selection of appropriate MRI hardware, sequences, and parameters influence artifact genesis and reduction. Application of dedicated metal artifact reduction techniques including high bandwidth optimization, view angle tilting (VAT), and the multispectral imaging techniques multiacquisition variable-resonance image combination (MAVRIC) and slice-encoding for metal artifact correction (SEMAC) may significantly reduce metal-induced artifacts, although at the expense of signal-to-noise ratio and/or acquisition time. Adding advanced image acquisition techniques such as parallel imaging, partial Fourier transformation, and advanced reconstruction techniques such as compressed sensing further improves MARS imaging in a clinically feasible scan time. This review focuses on current clinically applicable MARS techniques. Understanding of the main principles and techniques including their limitations allows a considerate application of these techniques in clinical practice. Essential orthopedic metal implants and postoperative MR findings around metal are presented and highlighted with clinical examples.

LEVEL OF EVIDENCE

4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:972-991.