Preoperative magnetic resonance imaging diagnosis of the floating anterior inferior glenohumeral ligament

Floating Inferior Glenohumeral Ligament: A Case Report

A humeral avulsion of the glenohumeral ligament (HAGL lesion) is a relatively rare pathology seen in patients with traumatic anterior shoulder instability. A HAGL lesion combined with a Bankart lesion is called a floating inferior glenohumeral ligament (IGHL) and is rare. We report a case of floating IGHL that could not be diagnosed before surgery. A 32-year-old female presented with a fourth dislocation and underwent arthroscopic Bankart repair with the use of a flexible curved guide. During Bankart repair, the tip of the flexible drill was broken. We removed it under general anesthesia later. She had no recurrence three years after surgery and enjoyed skateboarding as a hobby.

Functional Anatomy and Biomechanics of Shoulder Instability

The glenohumeral joint is the least congruent and least constrained joint with a complex relationship of static and dynamic stabilizers to balance its native mobility with functional stability. In the young athlete, anterior shoulder instability is multifactorial and can be a challenge to treat, requiring a patient-specific treatment approach. Surgical decision-making must consider patient-specific factors such as age, sport activity and level, underlying ligamentous laxity, and goals for return to activity, in addition to careful scrutiny of the underlying pathology to include humeral and glenoid bone loss and surrounding scapular bone morphology.

Glenohumeral joint instability

Due to the configuration of its bony elements, the glenohumeral joint is the most mobile joint of the body, but also an inherently unstable articulation. Stabilization of the joint is linked to a complex balance between static and dynamic soft tissue stabilizers. Because of complex biomechanics, and the existence of numerous classifications and acronyms to describe shoulder instability lesions, this remains a daunting topic for most radiologists. In this article we provide a brief review of the anatomy of the glenohumeral joint, as well as the classifications and the pathogenesis of shoulder instability. Technical aspects related to the available imaging techniques (including computed tomography [CT] arthrography, magnetic resonance imaging [MRI], and MR arthrography) are reviewed. We then describe the imaging findings related to shoulder instability, focusing on those elements that are important to the clinician.

[Magnetic resonance imaging of glenohumeral instability: new concepts]

The shoulder is the most unstable joint in the human body and is therefore susceptible not only to acute dislocations but also to minimal states of subluxation related to overuse. The latter condition is known as microinstability and is translated clinically into internal impingement syndromes. Both in dislocations due to acute traumatism and in microinstability, a series of injuries to the glenoid lip, glenohumeral capsule, the articular cartilage, the head of the humerus, the tendons of the rotator cuff, the long tendon of the biceps, the glenohumeral ligaments, and coracohumeral ligament can occur. Glenoid lip lesions are the most common and may present as isolated lesions or in combination with lesions of any of the other structures. These lesions most often affect the anteroinferior margin of the glenoids (the classic Bankard lesion), with different characteristics and variations on its location, (Bankard variants). Another predominant location of glenoid lip lesions is the superior margin (SLAP lesions). Magnetic resonance imaging (MRI), especially after intra-articular injection of contrast material, has shown great diagnostic accuracy in this type of lesions, although the interpretation of these images requires knowledge not only of the different lesions and combinations of lesions, but also of the normal variants that can easily be confused with these lesions.

Non-contrast MR imaging of the glenohumeral joint. Part II. Glenohumeral instability and labrum tears

MR imaging of the shoulder without contrast is frequently used for evaluation of glenohumeral instability in spite of the popularity of MR arthrography. With proper imaging technique, familiarity with normal anatomy and variants as well as knowledge of the expected pathologic findings high diagnostic accuracy may be achieved.

MR imaging of shoulder instability injuries in the athlete

Lesions leading to glenohumeral instability may result from acute trauma, atraumatic laxity, or repetitive microtrauma. Athletic activities, especially overhead throwing, may lead to a series of lesions involving the stabilizing structures of the shoulder. The resultant injuries and pathomechanics leading to shoulder symptoms can be classified as primary disease, primary instability, acute traumatic instability, and posterosuperior impingment syndrome. MR imaging with or without intrarticular or intravenous injection of contrast material, along with clinical examination and stress testing, provides valuable preoperative assessment.