We experienced a rare case of habitual posterior subluxation of the shoulder joint.
A seventeen-year-old young man suffered from his first posterior subluxation of his right shoulder joint at the age of 14 without any, trauma. When he elevated his shoulder 90-degrees in the neutral position, and then rotated it internally, his shoulder subluxated posteriorly, and when he rotated his shoulder externally, it was reducted. In the plain roentogenogram (axial view), the humeral head subluxated posteriorly. Moreover, the humeral head subluxated inferiorly and laterally in the A-P -view (Zero position). In the CT arthrogram, hypoplasia of the postero-inferior margin of the glenoid and laxity of the posterior caplule were seen. We performed a posterior glenoplasty (Scott) and an inferior capsular shift (posterior approach, Neer) on this case. One year and 3 months after the operation, no posterior subluxation of the shoulder was observed. He could resume plaing rugby. The post-operative evaluation using the J. O. A. score was 100 points and excellent.
Hypoplasia of the postero-inferior margin of the glenoid and laxity of the posterior capsule are thought to cause habitual posterior subluxation of the shoulder joint. We consider that both a posterior glenoplasty (Scott) and a posterior inferior capsular shift (Neer) should be performed for this disease. We believe that the repetitive throwing motion may occassion on habitual posterior subluxation.
