= neurovascular compression syndrome involving the posterior humeral circumflex artery ± axillary nerve

Quadrilateral space:

compartment formed by teres major m. (inferiorly) + long head of triceps m. (medially) + teres minor m. (posteriorly) + subscapularis m. (anteriorly) + surgical neck of humerus (laterally)

Cause: posttraumatic fibrotic bands, muscle hypertrophy in throwing athletes

Age: 20–35 years

• point tenderness over quadrilateral space aggravated by abduction + external rotation of arm
• burning pain over lateral aspect of shoulder and arm
• weakness of deltoid m. + teres minor m.
• compression of posterior circumflex a.
• atrophy of deltoid m. + teres minor m.
• occlusion of posterior humeral circumflex a.

Rx: analgesics, physiotherapy