Magnetic resonance imaging findings associated with surgically proven rotator interval lesions

Imaging of the Long Head of Biceps Tendon and Rotator Interval

This article reviews the imaging and common pathology of the long head of biceps tendon and rotator interval (RI). This area of complex anatomy plays a crucial role in normal shoulder function. Injury or abnormality of the RI may contribute to a range of shoulder pathology, such as biceps instability, tendinopathy, and frozen shoulder. Understanding the normal and pathologic appearances of the RI structures is crucial for a correct diagnosis and directing treatment.

Instability of the long head of the biceps tendon in patients with rotator cuff tear: evaluation on magnetic resonance arthrography of the shoulder with arthroscopic correlation

OBJECTIVES

To evaluate the diagnostic value of MR arthrography (MRA) in diagnosing instability of the LHBT in patients with rotator cuff tendon tear.

MATERIALS AND METHODS

The MR arthrograms of 101 patients were retrospectively reviewed and correlated with arthroscopic findings as the standard reference. Images were evaluated for (1) the integrity of the LHBT, (2) the position of the LHBT (subluxation/dislocation on axial images, inferior displacement on oblique sagittal image) and (3) the integrity of the biceps pulley (SGHL, supraspinatus and subscapularis tendon adjacent to the rotator interval).

RESULTS

The integrity of the LHBT was correctly classified in 74.3% (75/101) and 66.3% (67/101) by readers 1 and 2, respectively. The diagnosis of LHBT instability could be made on axial images with a sensitivity of 82.6% and 73.9% and specificity of 69.9% and 87.7%, whereas the displacement sign on sagittal images had a sensitivity of 73.9% and 78.3% and a specificity of 64.4% and 61.6%, respectively. Assessing the integrity of the SGHL had a sensitivity of 60.9 and 93.3% and a specificity of 70.4 and 75.0%, respectively. By combining the different image findings, the accuracy in assessing LHBT instability was 80.9 and 90.5% with a sensitivity of 60.9 and 86.7% and specificity of 83.1 and 91.8%, respectively.

CONCLUSION

Individual image findings may have a limited role in diagnosing LHBT instability in patients with rotator cuff tendon tear. The accuracy of MRA may be improved by assessing the integrity of the biceps pulley structures along with the position of the LHBT on both axial and sagittal images.

The Rotator Interval - A Link Between Anatomy and Ultrasound

Shoulder pathologies of the rotator cuff of the shoulder are common in clinical practice. The focus of this pictorial essay is to discuss the anatomical details of the rotator interval of the shoulder, correlate the anatomy with normal ultrasound images and present selected pathologies. We focus on the imaging of the rotator interval that is actually the anterosuperior aspect of the glenohumeral joint capsule that is reinforced externally by the coracohumeral ligament, internally by the superior glenohumeral ligament and capsular fibers which blend together and insert medially and laterally to the bicipital groove. In this article we demonstrate the capability of high-resolution musculoskeletal ultrasound to visualize the detailed anatomy of the rotator interval. MSUS has a higher spatial resolution than other imaging techniques and the ability to examine these structures dynamically and to utilize the probe for precise anatomic localization of the patient's pain by sono-palpation.

Imaging of the coracoglenoid ligament: a third ligament in the rotator interval of the shoulder

OBJECTIVE

The coracoglenoid ligament (CGL) forms part of the anterosuperior capsuloligamentous complex of the shoulder. Although it has received attention in the anatomical literature, it has not been investigated on imaging. The purpose of this study is to determine the percentage value and the interobserver agreement of identification and classification of the CGL on MR and MR arthrography (MRA) imaging.

MATERIALS AND METHODS

Retrospectively, 280 MR and 150 MRA examinations were evaluated for detection of the CGL by two musculoskeletal radiologists. On the MRA examinations the CGL configuration in relation to the superior glenohumeral (SGHL) and coracohumeral ligament (CHL) was classified into five types. Additionally, the percentage of intra-articular appearance of the CGL and its mean thickness value were calculated. Finally, a possible correlation between pathological condition and anatomical type was evaluated on MRA.

RESULTS

The CGL could be identified in 56%/54% of MRI and in 76%/77% of MRA examinations. On MRA, the CGL was detected as distinct structures in 37%/35% of cases and it appeared fused (partially or totally) with the SGHL and/or CHL in 39%/42%; it was absent in 12%/12% and it appears undistinguishable in the remaining cases. The interobserver agreement was excellent (κ = 0.98 for detection on MRI; p = 0.927 for classification of anterosuperior anatomy on MRA; κ = 0.873 and 0.978 for identification on sagittal and axial external rotation MRA respectively; κ = 0.943 for classification as intra- or extra-articular on MRA).

CONCLUSIONS

The CGL can be reliably identified on MRI and MRA.

What can the Radiologist do to Help the Surgeon Manage Shoulder Instability?

Imaging of the shoulder forms an important adjunct in clinical decision making in patients with shoulder instability. The typical lesions related with classic anterior and anteroinferior shoulder dislocation are an anteroinferior labral avulsion with or without bony fragment of bone loss – a (bony) Bankart lesion – and a posterolateral humeral head impaction fracture – the Hill-Sachs lesions. These are relatively straightforward to identify on imaging, although normal variants of the inferior labrum and variants of labral damage may cause confusion. Other capsuloligamentous lesions, often associated with less typical types of instability, are much more difficult to identify correctly on imaging, as they occur in the anterosuperior part of the glenohumeral joint with its many normal variants or because they result in more subtle, and therefore easily overlooked, changes in morphology or signal intensity. This paper aims at describing the appearance of the normal and pathologic glenohumeral joint related to shoulder instability. Ample reference will be given as to why identification of abnormalities, whether normal or pathologic, is important to the surgeon facing a treatment decision.

The Rotator Interval of the Shoulder: Implications in the Treatment of Shoulder Instability

Biomechanical studies have shown that repair or plication of rotator interval (RI) ligamentous and capsular structures decreases glenohumeral joint laxity in various directions. Clinical outcomes studies have reported successful outcomes after repair or plication of these structures in patients undergoing shoulder stabilization procedures. Recent studies describing arthroscopic techniques to address these structures have intensified the debate over the potential benefit of these procedures as well as highlighted the differences between open and arthroscopic RI procedures. The purposes of this study were to review the structures of the RI and their contribution to shoulder instability, to discuss the biomechanical and clinical effects of repair or plication of rotator interval structures, and to describe the various surgical techniques used for these procedures and outcomes.

MRI-Arthroscopy Correlation for Shoulder Anatomy and Pathology: A Teaching Guide

OBJECTIVE

The objectives of the article are to improve the radiologist's understanding of shoulder arthroscopy and see how it correlates with MRI. We review the basic principles of arthroscopy followed by a comparison of its strengths and weaknesses relative to MRI. This discussion is supplemented by a series of cases that show the relationship between arthroscopy and MRI in terms of the visualization of normal and abnormal anatomy in the diagnosis of common shoulder abnormalities.

CONCLUSION

By understanding what our orthopedic colleagues are seeing (and not seeing) during arthroscopic shoulder surgery, we can better understand the strengths and weaknesses of MRI, which provides us the opportunity to improve our imaging interpretations and produce valuable management-guiding diagnostic reports.

Shoulder arthroscopy remains superior to direct MR arthrography for diagnosis of subtle rotator interval lesions

PURPOSE

To assess the sensitivity, specificity and accuracy of MR arthrography, as opposed to shoulder arthroscopy, in diagnosing individual rotator interval (RI) structures lesions at different levels of severity.

MATERIALS AND METHODS

Seventy-five patients were enrolled in a prospective study. All the patients were diagnosed with full-thickness rotator cuff tendon tears on unenhanced MRI and had complimentary MR arthrography to search for obscure RI lesions. All the patients then underwent shoulder arthroscopy. The arthroscopist was blinded about the MR arthrography results.

RESULTS

At arthroscopy, 42 patients (56 %) were found to have RI lesion(s) and represented the study group. The remaining 33 patients represented the control group. The sensitivity, specificity and accuracy of MR arthrography for detecting individual RI lesions varied widely depending on the location and severity of the lesions. MR arthrography showed intermediate sensitivity of 67-80 %, specificity of 83-89 % and accuracy of 89-92 % for diagnosing subtle RI lesions; and perfect (100 %) sensitivity, specificity and accuracy for diagnosing biceps long head tendon dislocation. For the rest of RI lesions, MR arthrography showed high sensitivity, specificity and accuracy. Inter-observer agreement was found to be almost perfect (K = 0.81-1.0).

CONCLUSION

Shoulder arthroscopy remains the gold standard for diagnosing subtle RI lesions. Although MR arthrography has proved to be a valuable tool for diagnosing established RI lesions, it is of intermediate sensitivity for diagnosing subtle RI lesions resulting in early insufficiency of the biceps pulley system.

The rotator interval and long head biceps tendon: anatomy, function, pathology, and magnetic resonance imaging

The rotator interval is an anatomically defined triangular area located between the coracoid process, the superior aspect of the subscapularis, and the anterior aspect of the supraspinatus. It is widely accepted that the rotator interval structures fulfill a role in biomechanics and pathology of the glenohumeral joint and long head biceps tendon. However, there is ongoing debate regarding the biomechanical details and the indications for treatment. A better understanding of rotator interval anatomy and function will lead to improved treatment of rotator interval abnormalities, and guide the indications for imaging and surgical intervention.

Biceps pulley: normal anatomy and associated lesions at MR arthrography

The biceps pulley or "sling" is a capsuloligamentous complex that acts to stabilize the long head of the biceps tendon in the bicipital groove. The pulley complex is composed of the superior glenohumeral ligament, the coracohumeral ligament, and the distal attachment of the subscapularis tendon, and is located within the rotator interval between the anterior edge of the supraspinatus tendon and the superior edge of the subscapularis tendon. Because of its superior depiction of the capsular components, direct magnetic resonance arthrography is the imaging modality of choice for demonstrating both the normal anatomy and associated lesions of the biceps pulley. Oblique sagittal images and axial images obtained with a high image matrix are valuable for identifying individual components of the pulley system. Various pathologic processes occur in the biceps pulley as well as the rotator interval. These processes can be traumatic, degenerative, congenital, or secondary to injuries to the surrounding structures. The term hidden lesion refers to an injury of the biceps pulley mechanism and is derived from the difficulty in making clinical and arthroscopic identification. Pathologic conditions associated with pulley lesions include anterosuperior impingement, instability of the biceps tendon, biceps tendinopathy or tendinosis, superior labrum anterior and posterior lesions, and adhesive capsulitis. It is important to be familiar with the normal appearance of the biceps pulley so that abnormalities can be correctly assessed and effectively managed.

Multimedia article. The rotator interval: pathology and management

The rotator interval describes the anatomic space bounded by the subscapularis, supraspinatus, and coracoid. This space contains the coracohumeral and superior glenohumeral ligament, the biceps tendon, and anterior joint capsule. Although a definitive role of the rotator interval structures has not been established, it is apparent that they contribute to shoulder dysfunction. Contracture or scarring of rotator interval structures can manifest as adhesive capsulitis. It is typically managed nonsurgically with local injections and gentle shoulder therapy. Recalcitrant cases have been successfully managed with an arthroscopic interval release and manipulation. Conversely, laxity of rotator interval structures may contribute to glenohumeral instability. In some cases this can be managed with one of a number of arthroscopic interval closure techniques. Instability of the biceps tendon is often a direct result of damage to the rotator interval. Damage to the biceps pulley structures can lead to biceps tendon subluxation or dislocation depending on the structures injured. Although some authors describe reconstruction of this tissue sling, most recommend tenodesis or tenotomy if it is significantly damaged. Impingement between the coracoid and lesser humeral tuberosity is a relatively well-established, yet less common cause of anterior shoulder pain. It may also contribute to injury of the anterosuperior rotator cuff and rotator interval structures. Although radiographic indices are described, it appears intraoperative dynamic testing may be more helpful in substantiating the diagnosis. A high index of suspicion should be used in association with biceps pulley damage or anterosuperior rotator cuff tears. Coracoid impingement can be treated with either open or arthroscopic techniques. We review the anatomy and function of the rotator interval. The presentation, physical examination, imaging characteristics, and management strategies are discussed for various diagnoses attributable to the rotator interval. Our preferred methods for treatment of each lesion are also discussed.

The rotator interval: a review of anatomy, function, and normal and abnormal MRI appearance

OBJECTIVE

The purpose of this article is to review imaging of the rotator interval, an anatomically complex region in the shoulder that plays an important role in the normal function of the shoulder joint. The rotator interval can be difficult to evaluate by imaging, and it is not routinely evaluated arthroscopically unless the clinical examination or imaging findings suggest an abnormality of the rotator interval. Rotator interval pathology is implicated in glenohumeral instability, biceps instability and adhesive capsulitis-entities which remain a challenge to diagnose and treat.

CONCLUSION

Imaging can play an important role in increasing suspicion for injury to the rotator interval so that this region can be evaluated and appropriate treatment can be initiated.

Clinical update: MR imaging of the shoulder

Magnetic resonance imaging has become an important diagnostic adjunct in the evaluation of shoulder conditions, and the technology continues to evolve. Direct magnetic resonance arthrography can improve detection of labral and rotator cuff pathology, especially partial thickness tears of the rotator cuff. Special positioning, such as abducted-externally rotated views, improves visualization of the rotator cuff and posterior superior labrum in throwing athletes. Diagnosis-specific sequencing such as fat suppression, spin-echo and proton-density techniques, and higher power magnets (3.0 T) allow for an unprecedented level of soft tissue detail. Clinical expertize is required to differentiate between normal anatomic variants, incidental findings, and true pathology. Although magnetic resonance imaging findings may be diagnostic in some cases, clinical correlation with history and physical examination findings is critical.

Imaging of shoulder injuries in sports medicine: current protocols and concepts

The shoulder joint has a wide breadth of derangements that can occur with sports activity. Whether the mechanism of injury is acute or the sequela of repetitive microtrauma, recent advances in musculoskeletal imaging and the understanding of athletic shoulder trauma will hopefully steer the clinician and radiologist alike to the proper diagnosis. Injury is inevitable. When it occurs, the clinician cognizant of the current concepts and protocols in the imaging of shoulder injury will be better prepared to diagnose and subsequently treat these disorders.

An analysis of the rotator interval in patients with anterior, posterior, and multidirectional shoulder instability

PURPOSE

To describe anatomic measurements of the rotator interval (RI) on magnetic resonance arthrogram (MRA) images and to assess the relationship between increased dimensions of the RI and instability conditions of the shoulder.

METHODS

Three groups of patients with clinical instability were treated arthroscopically (anterior [A = 19 patients], posterior [P = 14 patients], and multidirectional [M = 13 patients]), and a group of 10 control patients without clinical instability were also identified. The MRAs of all groups were randomized, and 5 blinded reviewers recorded RI anatomic measurements of: (1) sagittal measures of the distance between the subscapularis (SSc) and supraspinatus (SS) tendons at 3 anatomic landmarks across the RI, and (2) the sagittal position of the long head of the biceps (LHB) relative to the most anterior aspect of the SS.

RESULTS

The rotator interval distance between the SS and SSc tendons was nearly identical for all groups of instability, and was also not different from control groups. On the sagittal oblique sequences, the distance from the LHB tendon to the anterior edge of the SS tendon was significantly increased in posterior (7.4 mm) instability versus both the control group (2.4 mm; P = .025) and those with anterior instability (4.5 mm; P = .041), with the LHB in a consistent anterior position. The remainder of the measures was not statistically different between the groups.

CONCLUSIONS

The distance between the SS and SSc and the overall size of the RI was well preserved in all instability patterns and control conditions. The LHB tendon assumes a more anterior position relative to the supraspinatus tendon in patients with posterior instability versus those patients with anterior instability or those without clinical instability. Additional work is necessary to further define objective radiographic evidence of RI insufficiency in patients with shoulder instability.

LEVEL OF EVIDENCE

Level III, prognostic case-control study.

[The rotator interval: hidden lesions?]

The rotator interval corresponds to a defined triangular shaped anatomical region at the anterosuperior portion of the shoulder where specific pathological processes may occur. First, the morphological and functional anatomy of the region will be reviewed. Then, the role of different imaging modalities will be described along with pathological imaging features. Normal structures of the rotator interval may be imaged with modern techniques, including MR and CT arthrography. On the other hand, clinical evaluation of rotator interval pathology remains difficult; and no consensus exists concerning their management. Imaging characterization of rotator interval pathology could be a key factor for pre-therapeutic work-up.