Review Question - QID 214080

This patient's clinical history and examination description of a positive Jerk test represents injury to the posterior labrum, which is labeled C in Figure A.

Posterior labral injuries are not uncommon in football players. Posterior shoulder instability may be the result of osseous (i.e. posterior glenoid rim fracture) or soft tissue (i.e. reverse Bankart) lesions. The Jerk test is elicited by applying a posterior force along the axis of the humerus with the arm in forward flexion and internal rotation, which in effect causes the humeral head to subluxate posteriorly and causes a clunk. The Kim test is more sensitive for posterior-inferior labral tears and is elicited by pain with forward flexion of the shoulder to 45 degrees while simultaneously applying axial load on the elbow, and posterior-inferior force on the upper humerus.

Frank et al. reviewed posterior glenohumeral instability. They reported that while recurrent posterior shoulder instability is not as common as anterior instability, it is prevalent among football and rugby players. They highlighted that recurrent posterior glenohumeral instability may be associated glenoid morphologic abnormalities such as increased retroversion.

Clavert reviewed glenoid labral pathology. They reported that superior labral tears from anterior to posterior (SLAP) lesions are the most frequent, and may or may not be associated with shoulder instability. They highlighted that antero-inferior and postero-inferior labral lesions are mainly due to shoulder instability, particularly Bankart lesions anteriorly and Kim's lesion posteriorly.

Itoigawa et al. reviewed the anatomy of the capsulolabral complex and rotator interval related to glenohumeral instability. They reported that posterior instability is far rarer than anterior instability, and that abnormalities including increased glenoid retroversion, dysplasia of the posteroinferior glenoid, soft tissue abnormality (i.e. posteroinferior capsular thinning and stretching) are the primary pathologies of posterior shoulder instability.

Figure A demonstrates an axial MRI of a shoulder. Label A represents the insertion of the postero-superior rotator cuff tendon (supraspinatus, infraspinatus), label B is the anterior labrum, label C is the posterior labrum, label D is the subscapularis, and label E is the biceps tendon.

Incorrect Answers:
Answer 1: This represents the postero-superior rotator cuff.
Answer 2: This represents the anterior labrum.
Answer 4: This represents the subscapularis.
Answer 5: This represents the biceps tendon within the bicipital groove.