Rockwood Adults CH34

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CHAPTER 34 • Glenohumeral Instability

A, B

C

Figure 34-9.  A: Anterior apprehension sign is done with the patient in the supine position in which the arm is placed into 90 degrees of abducted and maximally externally rotated (ABER) position resulting in a feeling of pain, discomfort, and potential instability. B: From this position of ABER, the relocation test can be conveniently performed in which a posteriorly applied force to the proximal humerus will elicit a feeling of reduced apprehension or pain from the patient. C: An anterior release test (surprise test) can also be performed by removing the posteriorly directed force ( arrow ) when the patient’s arm is in the 90 degrees of abduction, 90 degrees of elbow flexion, and maximal external rotation.

and maximal external rotation position (Fig. 34-9C). A feeling of pain or apprehension is a positive result. Caution should be taken not to dislocate the patient’s shoulder with this anterior release testing. Lo et al. evaluated the validity of these three provocative tests on anterior shoulder instability and found that in patients with the feeling of apprehension on all three tests, the mean positive and negative predictive values were 93.6% and 71.9%, respectively. 136,137 The anterior release or surprise test was the single most accurate test for diagnosing anterior instability (sen- sitivity 63.9% and specificity 98.9%) compared to the other two tests. Furthermore, feeling of apprehension was more accurate than pain as a criterion for diagnosing instability. Since the essential lesion for anterior shoulder instability is damage to the anterior capsule–labral–ligamentous structures, the position of ABER places these structures under tension or challenges their function which results in both apprehension and pain. Other provocative described tests for glenohumeral instability include

the load and shift test (Fig. 34-10A) and anterior or posterior drawer testing (Fig. 34-10B). Bushnell et al. proposed the “bony apprehension test” for shoulder instability in which the feeling of apprehension is experienced at or below 45 degrees of abduc- tion and 45 degrees of external rotation as a means of screening for significant bony lesions (Fig. 34-10C). 36 The authors found the sensitivity and specificity as 100% and 86%, respectively, in predicting bony lesions in patients after anterior instability with this special testing. Evaluation of the patient with subacute posterior instabil- ity is more subtle and difficult to diagnose. The predominant symptom of patients with posterior shoulder instability is pain. Provocative testing includes the jerk test which is done in the sitting position with an axial force applied to the arm in 90 degrees of abduction and internal rotation. The arm is then horizontally adducted while the axial load is maintained (Fig. 34-11A,B). A feeling of a clunk or jerk elicited with or without pain is considered a positive test (Fig. 34-11C). Kim et al. 120

A, B

C

Figure 34-10.  A: Load and shift examination is performed with the patient in the supine position. With the arm is abducted 90 degrees and the elbow bent, both anterior- and posterior-directed force is applied to the humeral head with slight axial compression. Grading of translation: 1 + (the humeral head to the gle- noid rim and back), 2 + (the humeral head translates past the glenoid rim and back), and 3 + (the humeral head is locked out past the glenoid rim and does not translate back to the center of the glenoid). B: Anterior or posterior drawer test is done in the sitting position. The humeral head is translated both anteriorly and posteriorly. C: Bony apprehension test is done with the arm below 45 degrees of abduction and 45 degrees of external rotation. If the patient has feelings of apprehension or pain with this arm position, either a bony Bankart lesion or moderate-to-severe anterior glenoid bone loss should be suspected.