Intraoperative and Postoperative Issues With Subscapularis Repair

Proper Identification

One potential complication of subscapularis tears that is very common, and often underreported, is failure to identify these tears in the first place. One cannot treat what one does not diagnose. The diagnostic process begins with a comprehensive history and physical exam. There are several provocative physical examination maneuvers that have been identified which may be helpful in making this diagnosis. In 1996 Greis et al. used electromyography to document the importance of both the upper and lower subscapularis when performing the “lift-off test”: placing the shoulder in internal rotation with the dorsum of the hand placed against the lumbar spine, and then “lifting off.” The authors found that the subscapularis muscle activity was approximately 70% of its maximal contraction during this test, which was significantly more than any other muscle around the shoulder. In 2003, Tokish et al. performed a similar study evaluating the “belly press test” (the palm of the hand is placed on the abdomen during shoulder internal rotation, and held there under resistance). The study found that, similar to the “lift-off test,” the subscapularis (both upper and lower) is activated more than any other muscle about the shoulder, leading the authors to conclude that this was also a good test for evaluation the subscapularis. Additionally, electromyography (EMG) data from the “belly press test” was compared with the lift-off test in 16 patients. They showed that the “belly press” activates the upper subscapularis more, whereas the lift-off test activates the lower subscapularis more, making it important to perform both tests, especially if a partial tear is suspected.

In 2008, Barth et al. described a new physical examination maneuver, known as the “bear hug test,” and assessed the sensitivity and specificity of this test compared with the lift-off and belly press maneuvers. The bear hug test is described as placing the shoulder in internal rotation while the palm is held on the opposite shoulder with the elbow held in a position of maximal anterior translation. The authors examined 68 patients who were scheduled to undergo arthroscopic shoulder surgery, and in all of them performed the lift-off test, the belly press test, and the bear hug test. At the time of surgery, a subscapularis tear was found in 29.4% of patients, with 40% of the tears not suspected by any of the preoperative tests. With regard to the physical examination maneuvers, the bear hug was most sensitive (60%), followed by belly press (40%), and the lift-off test (17.6%) ( Fig. 32.1 ). All of the tests had a high specificity: bear hug (91.7%), belly press (97.9%), and lift-off (100%). The authors concluded that the bear hug test was the best for detecting upper subscapularis tears, and also should be used routinely because it gave the greatest chance at correctly diagnosing a tear. The authors also recommended using all three tests, as multiple positive tests could signify a larger tear. Overall, these studies have shown that, although we do have specific physical examination maneuvers for diagnosing subscapularis tears, these tears may still be missed when relying solely on physical examination (40% according to Barth et al.). For this reason, the first step in preventing complications caused by these injuries is to diagnose them to treat them sufficiently. The examiner should have an appropriate clinical suspicion when evaluating patients and their imaging, and ultimately confirming the presence or absence of pathology during arthroscopic surgery.