What condition is suggested by fatty infiltration of the teres minor and posterior shoulder pain?

• A. Rotator Cuff Tear
• B. Quadrilateral Space Syndrome
• C. Shoulder Impingement Syndrome
• D. Plateau Injury

Answer: (B)

Fatty infiltration of the teres minor in conjunction with posterior shoulder pain is characteristic of Quadrilateral Space Syndrome. This condition occurs when the structures in the quadrilateral space, including the axillary nerve and posterior circumflex humeral artery, are compromised. The teres minor muscle is innervated by the axillary nerve, and fatty infiltration can indicate denervation or dysfunction of this muscle, often seen in cases of nerve compression or injury.

In Quadrilateral Space Syndrome, the symptoms are typically a result of this entrapment, leading to referred pain and weakness in the surrounding muscles, which may contribute to posterior shoulder pain. The presence of fatty infiltration signifies an adaptation or degeneration due to prolonged disuse or injury which is commonly observed in patients with this syndrome.

While conditions like a rotator cuff tear or shoulder impingement syndrome may also present with shoulder pain, they do not typically involve specific fatty infiltration of the teres minor as a key diagnostic feature. Therefore, the combination of teres minor fatty infiltration and posterior shoulder pain strongly supports the diagnosis of Quadrilateral Space Syndrome.