Internal Rotation Lag Sign

Purpose: To test for the presence of a subscapularis tendon tear. 

Test Position: Seated.

Performing the Test: The affected arm is brought into maximal internal rotation, so the dorsum of the patient's hand is resting on their lumbar spine. Next, the examiner grasps the patient's forearm and lifts the dorsum of the hand away from the lumbar region. While supporting the patient's elbow, the examiner releases the forearm. The patient is instructed to keep their hand off of their lumbar spine. A positive test occurs when the patient is unable to maintain the internally rotated position off the lumbar spine.

Diagnostic Accuracy: Sensitivity: 97%, Specificity: 96%; +LR: 24.3; -LR: .03    (1) 
                                Sensitivity: 71%, Specificity: 60%; +LR: 1.78; -LR: .48    (2)


Importance of Test: The subscapularis muscle acts as a powerful internal rotator and dynamic stabilizer of the rotator cuff. This muscles also plays an important role in depression of the humeral head, so injury to this muscle can lead to impaired glenohumeral stability. The internal rotation lag sign places the subscapularis in its position of function. Clients that are unable to sustain the test position should be considered for subscapularis tendon tears. Due to the wide range of diagnostic accuracy, it is important to cluster this test's findings with other clinical examine measures.

Note: these tests should only be performed by properly trained health care practitioners.

References:
Hertel, R. "Lag Signs in the diagnosis of rotator cuff rupture." Journal of Shoulder and Elbow surgery. (7): 1996. Web. 29 Sep. 2012.
Bartsch, Martin. "Diagnostic values of clinical tests for subscapularis lesions." Knee Surgical Sports Traumatol Arthrose. (August): 2009. Print.