Involuntary inferior and multidirectional instability of the shoulder: etiology, recognition, and treatment.

Multidirectional and inferior instability of the shoulder is not rare. Etiological factors include various combinations of (a) repetitive injuries, (b) inherent joint laxity, and (c) one or more major injuries. It is seen in athletic and active patients without generalized joint laxity and as well in sedentary patients with hypermobile joints. Standard operations for unidirectional anterior or posterior dislocations fail to correct multidirectional instability because they do not correct inferior instability and they may displace the head in fixed subluxation to the opposite side leading to severe arthritis ("arthritis of dislocations"). Proper detection depends on suspecting its possibility in all types of patients and in a wide age range as well. Helpful signs include the sulcus sign, positive apprehension test in multiple directions, stress roentgenograms and fluoroscopy, and evaluations under anesthesia. Arthroscopy may be helpful in doubtful cases, but the findings require clinical interpretation. Selection of patients with multidirectional instability for surgery is extremely difficult because it requires not only great care in determining all directions of instability and planning the repair but also determining the motivation of the patient and excluding the possibility of some other condition being present that is causing pain rather than the joint laxity. The results of inferior capsular shift have continued to withstand the test of time and, though it is more difficult than standard procedures, is considered a very helpful procedure in the treatment of these difficult lesions. The principle is to reduce capsular laxity on all three sides by shortening and reinforcing and to reduce the joint volume.(ABSTRACT TRUNCATED AT 250 WORDS)