Characterized by posterior shoulder pain and paresthesias secondary to impingement of the axillary nerve and posterior circumflex humeral artery. Symptoms are exacerbated with overhead acticity (eg. when the arm in the throwing position: abduction, extension, and external rotation). Most common in young adults who perform repetitive overhead activities (throwing, swimming)
Quadrilateral space is bordered by the humerus, long head of triceps, teres major, and teres minor. Contents of the space include the axillary nerve and the posterior circumflex humeral artery.
Patient History and Physical Findings
- Common in overhead sports such as swimming and throwing.
- Posterior shoulder pain
- 2009 OITE: "A baseball pitcher reports posterolateral shoulder pain and lateral shoulder paresthesias
when in the cocking position of throwing. What is the most likely diagnosis?"
- Posterior shoulder tenderness
Imaging and Diagnostic Studies
- MRI may reveal atrophy of the teres minor muscle and possibly deltoid muscle(see images below).
- Arteriogram may reveal compression of the posterior circumflex humeral artery. Perform study with the arm in abduction, extension, and external rotation.
- Needs need to be place in the teres minor and deltoid muscles
- Additionally the test should be performed with the shoulder in 90 degrees abduction and maximal external rotation
The differential diagnosis is broad.
- Labral pathology
- Internal impingement
- Rotator cuff tendonopathy
- Activity modification
- Decompression of quadrilateral space
Pearls and Pitfalls