Review Question - QID 214079

The patient has signs of anterior instability with an anterior labral tear and has plans to undergo arthroscopic anterior labral repair and inferior capsular shift which places the greatest risk on the axillary nerve. Damage to the axillary nerve can be minimized by placing the arm in abduction and external rotation.

Anterior labral tears are commonly noted in the overhead athlete with the majority of lesions occuring after an acute anterior dislocation. Indications for arthroscopic anterior labral repair with or without a capsular shift are recurrent instability after a course of non-operative management, high demand athletes (like the patient in this vignette), and young first-time traumatic dislocators with a large Bankart lesion (avulsion of the anterior labrum and anterior band of the IGHL from the anterior inferior glenoid). An inferior capsular shift places the axillary nerve at risk given the proximity of the nerve to the inferior capsule. Placing the arm in abduction and external rotation increases the distance between the axillary nerve and the inferior capsule decreasing the risk of injury during the procedure.

Matsuki and Sugaya describe the common complications that occur after shoulder instability surgery. They state that postoperative stiffness and recurrent instability are the two most common complications and should be treated on a patient-specific basis. They state that the axillary nerve is at significant risk during this procedure given its proximity to the inferior capsule. The authors conclude that while nerve injury is relatively rare after arthroscopic surgery, the axillary nerve should be given special attention during instability surgery.

Kang et al. discuss the clinically relevant complications associated with both open and arthroscopic techniques for anterior shoulder stabilization. These complications include entities such as nerve injury, chondrolysis, incomplete treatment of associated lesions, and subscapularis dysfunction. The authors discuss the increased risk of axillary nerve injury during the procedure given the nerve is 1 to 1.5 cm below the inferior glenohumeral
capsule, with the sensory branch lying closest to the glenoid rim.

Jerosch et al. performed a cadaveric study to determine the distance between the shoulder capsule (between the 1 and 5 o'clock positions) and the axillary nerve in different joint positions. The authors measured the shortest distance between the insertion of the inferior capsule and the axillary nerve with the shoulder in various degrees of abduction, adduction, internal, and external rotation. The authors noted that during abduction and external rotation the nerve stays in its position while the glenohumeral capsule tightens, which increases the distance between the two structures. The authors concluded that when performing arthroscopic anterior capsular release, the incision of the glenohumeral joint capsule should be undertaken at the glenoidal insertion in the abducted and externally rotated shoulder.

Incorrect Answers:
Answers 1, 2, 4, and 5: Cadaveric studies have shown that the axillary nerve is farthest away from the inferior capsule with the shoulder in abduction and external rotation.