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Laxity Testing of the Shoulder

There's a fine line between normal shoulder motion and shoulder joint give called laxity. Everyone's shoulder has some give. Too much joint laxity can lead to an unstable shoulder that becomes painful or needs treatment.

Testing for shoulder laxity can be a challenge for the physician. Failure to
identify the correct direction of instability may delay or misdirect treatment. Sometimes a normal laxity pattern is overtreated by mistake.

In this article, orthopedic surgeons from Johns Hopkins University review
tests and measures for shoulder laxity. Biomechanics of the six shoulder motions possible are discussed. They offer guidance as to the clinical usefulness of various shoulder laxity tests. Photos of the more reliable tests are provided.

Patients are more relaxed lying down so most of the tests are performed in this position. With the patient lying on his or her back, the scapula or shoulder blade is also stabilized. This means it is less likely to rotate affecting the results of testing.

The advantages and disadvantages of five tests are reviewed. These include the anterior drawer test, posterior drawer test, load and shift test, sulcus sign, and the Gagney Hyperabduction test. The physician keeps in mind that testing shoulder laxity while the patient is under anesthesia usually results in half a grade more.

The authors conclude by saying that the normal range of shoulder laxity varies greatly from person to person. One shoulder may be more lax than the other.
The physician must distinguish between joint laxity that's normal and joint
instability.

Being able to move the head of the humerus up over the rim of cartilage around the socket can be a variation of normal. Instability is usually painful and the extra motion presents a problem.

References: Michael Bahk, et al. Laxity Testing of the Shoulder. A Review. In The

American Journal of Sports Medicine. January 2007. Vol. 35. No. 1. Pp.

131-144.

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