A study to assess by means of MR arthrography the causal relationship between anterior capsular attachment type and anterior instability of the glenohumeral joint

To evaluate by means of MR arthrography the causal relationship between anterior capsular attachment type and anterior instability of the glenohumeral joint. Sixty-five patients (M:F = 64:1 ; mean age, 23 years), who had undergone shoulder MR arthrography were retrospectively reviewed. There was no history of traumatic dislocation, and medical records relating to anterior instability were available. Physical examination revealed anterior instability in 25 patients (Group A), while in 40 (Group B), this was either suspicious or absent. With the aid of general anesthesia, 32 patients who had undergone surgery were physically examined. Anterior instability was evident in 16 patients (Group C), and suspicious or absent in the remaining 16 (Group D). All images were obtained after intra-articular injection of Gd-DTPA. Fat-suppressed T1 axial imaging was used to evaluate anterior capsular attachment type at mid and distal three-fourths levels of the glenoid fossa. The causal relationship between anterior capsular attachment types and anterior instability was analyzed using the x2 test. In group A, type 1 was most common at distal three-fourths level, and types 1 and 2 were equal and more common than type 3 at mid level. In group B, type 1 anterior capsular attachment type was most common at both mid and distal three-fourths level. In these groups, no statistical significance was noted between anterior capsular attachment type and anterior instability (p value 0.611 : 0.567). In group C, types 1 and 2 were equal and more common than type 3 at both mid and distal three-fourths level, while in group D, type 2 was most common at mid level, and type 1 was most common at distal three-fourths level. In these groups, no statistical significance was noted between anterior capsular attachment type and anterior instability (p value, 0.772). There was no statistically significant difference between anterior capsular attachment type and anterior instability of the shoulder joint