1998 Volume 22 Issue 2 Pages 341-345
We evaluated shoulder joint laxity under general anesthesia in patients with various extents of anterosuperior labral tears to clarify the role of anterosuperior labrum for shoulder stability. We studied forty-five cases of patients with anterosuperior labral tears in arthroscopic surgery. Based on the detached portion of the glenoid rim, we classified the labral tears into four types, which consisted of “superior type”, “anterosuperior type”, “wide-anterosuperior type” and “anteroinferior type”. The shoulder held in the scapular plane at 30° and 90° of abduction under general anesthesia and an anterior or posterior force was applied manually to the humeral head. Inferior translations were assessed using the sulcus test by applying an inferior force to the arm. The amount of anterior and posterior translations were graded into five degrees, and inferior translations into three degrees. If the symptomatic shoulder had a higher degree than the third of an anterior or posterior laxity and a higher degree than on the other side, we defined the instability as positive. Then we classified the anterior or posterior instabilies into two categories: “30A/30 P” and “90A/90P”.30A/30P shoulders had a laxity of 30° abduction which were equal or superior to that of 90° abduction.90A/90P shoulders had inverse laxities. Inferior instabilites were defined as positive when an inferior laxity of the symptomatic shoulder had a higher degree then on the other side. Anterior instability evaluations were nine-30A and eighteen-90A. Posterior instability was positive in eight cases and inferior instability in seven cases. As assessed according to the extent of the lesion, all ten cases of superior type were negative. Of ten cases of anterosuperior type, four were 30A and one was 90A. Of the seven cases of wide-anterosuperior type, therr were 30A, two were 90A and inferior instability was positive in five. there were fifteen-90A of the eighteen cases of anteroinferior type. We concluded that shoulder anterior instability seemd to vary according to the extent of anterosuperior labral tears on evaluation under general anesthesia.
