Quadrilateral space syndrome.

This uncommon syndrome is caused by compression of the posterior humeral circumflex artery and axillary nerve or one of its major branches in the quadrilateral space. Forward flexion and/or abduction and external rotation of the humerus aggravate the symptoms. Discrete point tenderness is always found posteriorly in the quadrilateral space. Patients with appropriate history and physical findings should have a subclavian arteriogram done by the Seldinger technique. A positive arteriogram reveals occlusion of the posterior humeral circumflex artery with the arm in abduction and external rotation. Patients with sufficient symptoms not responding to conservative treatment and having a positive subclavian arteriogram and local tenderness over the quadrilateral space should be considered for surgical decompression. A posterior approach is recommended. Of the 18 patients operated on, eight have had dramatic and complete relief, eight have been improved, and two have shown no improvement.