Imaging Review of Subscapularis Tendon and Rotator Interval Pathology

As the largest rotator cuff muscle, the subscapularis plays a major role in stabilizing the glenohumeral joint, in conjunction with surrounding rotator cuff structures. Injury to the subscapularis tendon can be isolated, but more commonly is seen in conjunction with supraspinatus tendon pathology. Injury can be associated with biceps pulley instability, superior labral anterior-posterior (SLAP) tears, humeral head subluxation, and anterosuperior and coracoid impingements. The involvement of the rotator interval can lead to what is called “the hidden lesion,” due to its difficulty to diagnose during arthroscopy. Understanding the anatomical relations of the subscapularis tendon with the rest of the rotator cuff and rotator interval, as well as common patterns of injury that involve the subscapularis tendon, can aid in proper diagnosis of these injuries leading to prompt surgical repair. This review describes the anatomy of the subscapularis muscle and tendon, and the magnetic resonance imaging (MRI) patterns of subscapularis tendon injury.

Prevalence and Grading of Rotator Cuff and Labral Injuries in Shoulder Pain and Instability using MRI: ACross-sectional Study

Introduction: Shoulder joint is a highly mobile joint but is prone for rotator cuff injuries and dislocations. It is necessary to accurately diagnose rotator cuff and labral injuries so that appropriate plan of action for treatment can be taken. Magnetic Resonance Imaging (MRI) can be used to diagnose and describe the extent of rotator cuff tendon and labral injuries and any secondary rotator cuff muscle abnormalities. Aim: To study the demographic profile of patients presenting with shoulder pain and instability, identify the various rotator cuff injuries causing shoulder pain, identify the rotator cuff interval lesions causing microinstability, identify the various labral and bony pathologies in instability, describe the MRI features of the rotator cuff, rotator cuff interval, labral and bony injuries. Materials and Methods: This study was a cross-sectional study of patients with symptoms of either shoulder pain or instability who underwent MRI evaluation of the shoulder in the Department of Radiodiagnosis, Rajarajeswari Medical College and Hospital, Bengaluru, Karnataka, India, from July 2018 to December 2020. The study population consisted of 54 patients with either shoulder pain or instability who underwent MRI of shoulder. All the MRI scans of the shoulder in this study were performed using 1.5 Tesla Siemens Magnetom Avanto (Tim 76x18) MR machine using a flex coil. Results: The study population consisted of 54 patients comprising of 38 males and 16 females. The age of the patients ranged from 20-77 years. Majority of the patients were older than 50 years constituting about 33.33% of the total study population. Rotator cuff injury was the commonest cause of pain. Tendinosis was the commonest type of rotator cuff injury followed by partial-thickness and full-thickness tendon tears. The commonest grade of tendinosis was mild or grade 1. Supraspinatus tendon was the most commonly affected tendon followed by subscapularis and infraspinatus tendons. Teres minor tendon was normal in all the cases. Anterior instability was the commonest type of instability with equal prevalence of soft tissue Bankart, bony Bankart and Perthes lesions. Biceps pulley lesions resulted in long head of biceps tendon instability, microinstability and internal impingement. Conclusion: Rotator cuff injuries are the commonest cause of shoulder pain and are seen more frequently after the fifth decade. Shoulder instability is most commonly seen in young male adults. Tendinosis is the commonest type of rotator cuff injury. Supraspinatus tendon is the most commonly injured tendon. Anterior instability is the commonest type of shoulder instability. Biceps pulley lesions result in long head of biceps tendon instability, microinstability and internal impingement. MRI can diagnose interstitial or intrasubstance tendon tears which are not visualised on arthroscopy. MRI description of tendon and labral tears, tendon retraction and muscle atrophy can guide the orthopaedician during arthroscopy and in treatmentplanning.

Internal Derangement of the Shoulder

Chapter 104 details the use of routine MRI and MRA to visualize the shoulder, identify normal anatomic variations, and diagnose common abnormalities, particularly those that are relevant to the general radiologist or radiology trainee. Although evaluation of the shoulder begins with radiography, when injury to the soft tissues is suspected, MRI offers numerous advantages. An emphasis will be placed on pathology of the rotator cuff and glenoid labrum, given their high prevalence and importance in patient management. Lesions of the biceps pulley and long head of biceps tendon will also be reviewed. Finally, the spectrum of findings related to muscle denervation will be discussed.