Multidirectional Glenohumeral Instability Workup

Updated: Apr 14, 2020
  • Author: Bradley S Raphael, MD; Chief Editor: S Ashfaq Hasan, MD  more...
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Workup

Imaging Studies

Most often, plain radiographs are negative in patients with multidirectional instability (MDI) of the shoulder. Findings of an osseous glenoid rim fracture or a Hill-Sachs humeral head impression defect are usually not seen unless concomitant traumatic instability exists.

The results of noncontrast magnetic resonance imaging (MRI) are the same as those described for plain radiography—that is, benign and negative, unless MRI is performed with contrast (gadolinium). [22, 23]

Magnetic resonance (MR) arthrography may be helpful in identifying patients with atraumatic MDI of the shoulder. [24] Typically, MR arthrography may demonstrate blunting of the labrum, diffuse capsular laxity, and increased capsular volume. Labral and capsular tears, such as those seen with traumatic instability, are unusual in classic MDI, and rotator-cuff tears and superior labral anterior and posterior (SLAP) lesions are only rarely seen in association with MDI of the shoulder.

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Procedures

Examination under anesthesia (EUA) and diagnostic arthroscopy are indicated.

Diagnostic arthroscopy must always be preceded by a thorough EUA. In an EUA, it is important to examine both shoulders, comparing the symptomatic side with the asymptomatic side. Typically, with relaxation afforded by general anesthesia, the clinical diagnosis is obvious, even if it was unsuspected preoperatively. Again, increased anterior and posterior laxity that exceeds the normal range combined with a positive sulcus sign is easily demonstrated.

Arthroscopy can be performed with the patient in either the beach-chair or the lateral decubitus position. Surgeon preference may dictate the choice of patient position. However, if open anterior capsular shift is planned, an upright or semiupright beach-chair position allows for ease of transition to open surgery without significant modification of position. If arthroscopic management of capsular patholaxity is planned, there is little difference between these variations.

To facilitate a complete and systematic glenohumeral joint (GHJ) evaluation, views from both anterior and posterior portals are necessary. This approach allows more thorough labral and capsular visualization. Moreover, it is essential to evaluate for concomitant pathology, including articular surface rotator-cuff pathology, SLAP lesion, labral tears, Bankart lesion and Hill-Sachs defect, and humeral avulsion [25]  of the glenohumeral ligament (HAGL). All of these are atypical in straightforward MDI.

Typical characteristics of MDI are a loose capsule with poor development of the glenohumeral ligaments and a normal, attenuated, or unimpressive labrum. Capsular tissues typically are thin. The axillary recess or pouch and the rotator-cuff interval are spacious and patulous. The articular surfaces most often are normal or show minimal chondromalacia. A Hill-Sachs lesion is absent. (See the images below.)

Labral features characteristic of multidirectional Labral features characteristic of multidirectional instability; normal appearing. Note: Although there is only 2 lb of traction, it is very easy to push arthroscope between humeral head and glenoid surfaces (ie, drive-through sign). Courtesy of Daniel C Wnorowski, MD.
Hypoplastic labrum. Courtesy of Daniel C Wnorowski Hypoplastic labrum. Courtesy of Daniel C Wnorowski, MD.
Posterior and superior aspects of humeral head of Posterior and superior aspects of humeral head of shoulder with multidirectional instability are pristine. Typically, there is no Hill-Sachs lesion, even if there has been subluxation. Courtesy of Daniel C Wnorowski, MD.
Posterior aspect of humeral head of shoulder with Posterior aspect of humeral head of shoulder with multidirectional instability is without Hill-Sachs lesion. Also note patulous capsule. Courtesy of Daniel C Wnorowski, MD.
Multidirectional instability of right shoulder fro Multidirectional instability of right shoulder from posterior portal. Patient is in lateral position with minimal arm traction (2 lb). Note glenohumeral inferior subluxation, with humeral head perched on normal-appearing anterior-inferior labrum. Courtesy of Daniel C Wnorowski, MD.
Normal subacromial space in patient with multidire Normal subacromial space in patient with multidirectional instability and history of secondary impingement. Courtesy of Daniel C Wnorowski, MD.

Moving the arthroscope within the shoulder of an individual with MDI is easy, even without traction in the beach-chair position. A "positive drive-through sign" is typical. This means that it is very easy to move the arthroscope across the GHJ between the humeral head and the glenoid fossa without axial arm traction or distraction. Subluxation of the humeral head on the glenoid is obvious, even without supplemental traction.

Finally, assessment of the subacromial space also is important, especially in the patient with suggestive impingement history and findings. Evaluation in this location includes scrutiny of the bursal cuff surface, as well as the coracoacromial arch, for signs of cuff and subacromial abrasion.

A patient with secondary impingement from an underlying glenohumeral instability may demonstrate impressive subacromial findings that are suggestive of impingement. These findings should provoke consideration of primary versus secondary impingement and review of the clinical presentation, EUA, and glenohumeral arthroscopic findings so that appropriate management can be selected.

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