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Can We Predict Who Will Have a Recurrence of Shoulder Dislocation?

Ever have a shoulder go out on you? Anyone who has had a shoulder dislocation is understandably concerned that it might happen again. Is there any way to predict who might have a second (recurrent) shoulder dislocation?

That's what this study is all about. The answer to this question is important because if someone is at increased risk of a recurrent shoulder dislocation, they might want to consider having surgery early on. Surgical repair can stabilize the joint and spare you from waiting to see if the joint will dislocate a second time. On the other hand, if you aren't at risk for a recurrence, you'll probably want to avoid unnecessary surgery.

In this study, a group of Israeli surgeons evaluated the benefit of a specific test called the anterior apprehension test. Can it predict the risk of redislocation after the first traumatic shoulder dislocation? As it turns out - no, it wasn't sensitive enough. But the results may have to do with when the test was administered. Let's step back and see how they came to that conclusion.

First, what is the anterior apprehension test? This is a clinical test performed after someone has had a traumatic shoulder dislocation to see if the shoulder is unstable. The patient lies on a table face up. The shoulder is placed in a position of 90 degrees of abduction (arm is away from the body). The elbow is bent 90 degrees. The palm of the hand is facing the feet. The examiner holds the elbow with one hand and uses the other hand to rotate the shoulder back (external rotation) while moving the hand toward the patient's head on the table.

The test is positive if the patient makes a face of pain or apprehension and says it feels as if the shoulder is going to pop out of the socket. The test was done in this study six weeks after the first dislocation after the patient had completed a program of physical therapy to restore normal shoulder motion, strength, and function. If shoulder motion needed for the apprehension test was still limited after six weeks, the patient completed another two to three weeks of therapy before undergoing testing.

There were 52 men who participated in this study. Most were Israeli soldiers or soldiers-in-training. The first dislocation occurred during combat training or while playing soccer or basketball. Everyone was placed in a protective sling for four weeks and then attended physical therapy for two weeks before being tested.

One-fourth of the group had to return to physical therapy because of a lack of adequate shoulder motion to do the apprehension test. Almost half (46.2 per cent) went on to have a second shoulder dislocation on the same side. The second dislocation took place 10 to 17 months later. This time delay did not seem to be linked to whether the soldier had a positive or negative apprehension test.

So, how sensitive is the anterior apprehension test? Sensitivity is the measure of a true positive test. A highly sensitive test means that the test can accurately identify those individuals who are at risk for a second dislocation. In other words, those who test positive are really likely to dislocate the shoulder again. The sensitivity of the anterior apprehension test was only 41.7 per cent. There were many patients (more than one-third of the group) who had a negative test but went on to redislocate anyway. This type of response is referred to as a false negative.

A second important measure is the specificity of a test. Specificity tells us how likely a negative test (not likely to redislocate) is really negative. In this study, the specificity of the anterior apprehension test was 85.7 per cent. That's pretty good and gives us an idea that if the test is negative, the patient really isn't likely to dislocate the shoulder again. The chances of a false positive occurring are lower when specificity is high.

With such a low sensitivity rating, this test isn't really a good way to predict who would benefit from surgery after conservative care (nonoperative treatment) for the first dislocation. It misses too many of the patients who would benefit from surgical repair. It is not a useful diagnostic method for testing shoulder instability after a primary (first) shoulder dislocation.

When it comes to figuring out who should have surgery right away to repair the damage after a first traumatic shoulder dislocation, the anterior apprehension test may not be the best tool to use. Avoiding unnecessary and unsuccessful surgeries is the goal, especially for an active group like military soldiers.

At best, the test results can divide patients into two groups: those who have a higher risk for redislocation after the first dislocation and those who have a lower risk. And based on how the study was conducted, that information is accurate only if the patient has been immobilized for four weeks and received two weeks of standard post-shoulder dislocation therapy.

For military recruits, the test can help guide commanding officers in deciding whether a soldier is ready to return to active duty but it can't provide an absolute definitive answer as a stand-alone test.


Ori Safran, MD, et al. Accuracy of the Anterior Apprehension Test as a Predictor of Risk for Redislocation After a First Traumatic Shoulder Dislocation. In The American Journal of Sports Medicine. May 2010. Vol. 38. No. 5. Pp. 972-975.

05/11/2010

*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
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