ANTERIOR SHOULDER INSTABILITY: OPEN ANTERIOR INFERIOR CAPSULAR SHIFT PROCEDURE

Anterior Shoulder Instability

Open Anterior Inferior Capsular Shift Procedure

Anand M. Murthi and Louis U. Bigliani

The inferior capsular shift (ICS) is designed to reduce capsular volume on all sides by both thickening and overlapping the capsule on the side of greatest instability (anterior or posterior) and by tensioning the capsule on the inferior and opposite sides. For unidirectional anterior instability, we prefer a modified ICS, essentially a laterally based capsulorrhaphy, without the complete mobilization of the capsule around the humeral neck to the posterior capsule, as would be performed in a multidirectional instability (MDI) patient. The advantages of this surgical approach include:

1. The ICS approach allows titration of capsular mobilization; thus varying degrees of capsular redundancy may be dealt with accordingly. The surgeon may adjust the shift with respect to the pathology seen intraoperatively [Bankart lesion, medial capsular redundancy, humeral detachment of the inferior glenohumeral ligament (HAGL) lesion].

2. The funnel-shaped capsule (larger circumference laterally) allows shifting the capsule a greater distance superiorly.

3. The axillary nerve is less at risk on the lateral aspect of the humerus.

4. When using a “T” capsulorraphy, the ability to adjust capsular tension in a superior-inferior direction is much more important than medial-lateral, which may result in loss of external rotation. Therefore it is both an east-west and a north-south tightening.

5. The goal of instability repair is to restore “normal” anatomy. If present, we repair the Bankart lesion. However, there is usually a degree of capsular redundancy, which can be decreased during the capsulorraphy.

Indications

1. Persistent pain and disability secondary to recurrent dislocation or subluxation

2. MDI

3. Unidirectional instability

4. Bidirectional instability

Contraindications

1. Active infection

2. Frail extremity secondary to nerve damage

3. Voluntary instability

Mechanism of Injury/Pathology of Instability

1. Recurrent dislocations/subluxations

2. Excessive capsular laxity

3. Detachment of inferior glenohumeral ligament/capsule from glenoid (Bankart lesion)

4. Midsubstance capsular tearing

5. Lateral capsular detachment from the humeral insertion (rare)

History

1. Cause of dislocations or subluxations

a. Traumatic

i. Possibly requiring physician-directed reduction

b. Atraumatic

c. Voluntary

2. Number of dislocations or subluxations

3. Level of activity

a. Sports-related activities

4. Dominant extremity

Physical Examination

1. Examine the asymptomatic side to measure normal laxity (may have bilaterally loose shoulders)

2. Generalized ligamentous laxity

a. Hyperextension of elbow and metacarpophalangeal joints

b. Ability to touch the abducted thumb to the ipsilateral forearm

c. Hypermobility of the patella

3. Range of motion

4. Provocative tests

a. Sulcus test—downward traction with arm at the side

i. Inferior instability

b. Drawer or “load-and-shift” test, load the humeral head into the glenoid with the arm at the side and translate the head anteriorly and posteriorly measuring displacement

i. Anterior and posterior instability

c. Anterior apprehension test (crank test)—while sitting, the arm is abducted to 90 degrees and slowly externally rotated while applying an anterior force to the humeral head

i. Positive for anterior instability with apprehension, not pain

d. Relocation test—while supine, the apprehension test is performed and if positive, a posteriorly directed force is applied to the proximal humerus with relief of apprehension, favoring a diagnosis of anterior instability

e. Posterior stress test—while sitting, the scapula is stabilized with one hand while a posteriorly directed force is applied to the humeral head in a position of 90 degrees of flexion, abduction, and internal rotation

i. Positive test—subluxation with pain or apprehension

5. Neurovascular exam

Diagnostic Tests

1. Radiographs

a. Standard trauma series

i. Anteroposterior (AP), lateral, and axillary views

ii. Velpeau axillary allows the patient to remain in their sling

b. Instability series

i. True AP view in internal rotation—Hill-Sachs lesions

ii. West Point axillary view—subtle erosions of the glenoid rim

iii. Stryker notch view—Hill-Sachs lesions

2. Computed Tomography (CT scan)