Quadrilateral Space Syndrome

Original Editor - Peter Zatezalo
Top Contributors - Peter Zatezalo

Clinically Relevant Anatomy[edit | edit source]

Quadrilateral space syndrome (QSS) refers to a rare condition in which neural and vascular structures are entrapped in the quadrilateral space (QS). This space is created by the lateral head of the triceps, teres minor, teres major, and medial border of the humerus. Through this space passes the axillary nerve and the posterior circumflex humeral artery. Fibrous bands in this space are commonly thought to be the cause of compression. One study showed that 14 of 16 cadavers had fibrous bands present, usually between the long head of the triceps and the teres major.[1]

Anatomy of the Quadrilateral Space
  • Contents of the Quadrilateral Space
    • Axillary Nerve (C5 nerve root)
      • innervates deltoid, teres minor, provides sensation to lateral shoulder
    • Posterior Circumflex Humeral Artery
      • supplies the teres minor, triceps brachii, teres major
  • Structures that frame the quadrilateral space
    • teres minor (superior)
    • teres major (inferior)
    • long head of the triceps brachii (medial)
    • humerus (lateral)[1]

The following video gives a visual representation of the quadrilateral space and brief explanation of the cause of QSS:


Mechanism of Injury / Pathological Process[edit | edit source]

The exact mechanism and cause of the injury is still unclear at this time. However, it is often associated with overhead athletes such as pitchers, swimmers, or volleyball players who regularly put their arm in the position of abduction and external rotation. This position causes the greatest amount of compression to the QS. Because of this, the dominant shoulder is most often affected, and the syndrome is reported to be most common in active people age 20-40.[3] QSS can be caused by anything that decreases the area of the quadrilateral space. This could be caused by anatomic variations, a glenoid cyst, muscle hypertrophy, or paralabral cyst from a labrum injury. [4]

  • Possible causes of QSS:
    • fibrous bands
    • trauma (scapular fracture)
    • paralabral cysts (inferior labral tear)
    • muscle hypertrophy
    • benign or malignant mass

Clinical Presentation[edit | edit source]

Patients generally present with an insidious onset of diffuse shoulder pain, posterior shoulder pain, weakness, and potential sensation loss in the distribution of the axillary nerve. Weakness is most notable in abduction and external rotation, and overhead activities will likely cause pain. It's possible to have atrophy in the external rotators or more noticeably in the deltoid if the case in chronic. Pain can be worse at night, and patients are almost always point tender at the QS itself. [3]

Diagnostic Procedures[edit | edit source]

First, an X-ray should be performed to rule out obvious pathological entities. Selective atrophy of the teres minor muscle can be identified by MRI, which is a positive indicator of the syndrome.[5] However, MRI studies have shown that teres minor atrophy is a common finding in rotator cuff pathology, prior surgical intervention, and traction injuries with glenohumeral instability. Additionally, compression of the QS can be position dependent (abduction and external rotation). Therefore, a compression of the QS may not be identified outside of this position. It's also been suggested that a lidocaine block in the area of the QS and axillary nerve can be a positive diagnostic criteria if the pain is abolished. [3]

  • Shoulder radiograph series (AP, lateral, axillary)
  • MRI - may show teres minor atrophy, paralabral cyst, or compression of QS
  • Arteriogram - may show lesion in posterior circumflex humeral artery
  • EMG - may show axillary nerve involvement
  • Plain Lidocaine injection to see if symptoms are abolished

Outcome Measures[edit | edit source]

There is currently no specific outcome measure for QSS that is supported by evidence. Any shoulder outcome measure that takes into account functional use and overhead activities should be able to measure progress with QSS effectively.

Medical Management[edit | edit source]

Medical management of QSS is initially conservative, likely with NSAIDs, avoidance of the aggravating behavior, and starting physiotherapy. Some have suggested using steroid injections, but there is currently no strong evidence to support this.[6]Another option is lidocaine injection into the QS, which has been shown to relieve symptoms when QSS is present. This can also be used as a diagnostic tool to confirm QSS. If conservative treatment has failed after 6 months, surgical decompression is generally recommended. Although there is a limited volume of evidence on surgical intervention for QSS, most studies show positive results. [3]

Physiotherapy Management[edit | edit source]

Physiotherapy management should first consist of a thorough exam to consider the list of differential diagnoses (listed below). A detailed history, examination of active and passive movement (shoulder, cervical spine, thoracic spine), neurological exam, special tests, and palpation should be performed. Once the diagnosis has been established, conservative treatment and physiotherapy are recommended. There is not a strong amount of evidence to support specific physiotherapy treatments for QSS. Rather, treatment is focused on optimizing the biomechanics of the shoulder via scapular stabilization and rotator cuff strengthening, manual therapy to address joint mobility and soft tissue restriction, and modalities as indicated. One case study recommended the following treatment approaches:

  • Soft tissue active release and transverse friction massage
  • Glenohumeral mobilization for tightness in the posterior capsule, IR and adduction stretching
  • Spinal manipulation to cervical and thoracic spine
  • Scapular stabilization and rotator cuff strengthening exercise [4]

Differential Diagnosis[edit | edit source]

[edit | edit source]

References[edit | edit source]

  1. 1.0 1.1 McClelland D, Paxinos A. The anatomy of the quadrilateral space with reference to quadrilateral space syndrome [Internet]. Journal of Shoulder and Elbow Surgery. Mosby; 2007 [cited 2021Nov16]. Available from: https://www.sciencedirect.com/science/article/abs/pii/S1058274607005009
  2. Peter Zatezalo. Quadrilateral Space Anatomy. Available from: https://www.youtube.com/watch?v=uiP626A5MBE [last accessed 11/17/2021]
  3. 3.0 3.1 3.2 3.3 Lindsay F. Quadrilateral space syndrome: a review. Journal of Shoulder and Elbow Surgery [Internet]. 2018 [cited 2021Nov16]; Available from: http://bonefix.co.nz/portals/160/images/Flynn%20Quadrangular%20space%20syndrome.pdf
  4. 4.0 4.1 Hoskins WT. Case report quadrilateral space syndrome: A case study and ... [Internet]. British Journal of Sports Medicine . 2005 [cited 2021Nov17]. Available from: https://bjsm.bmj.com/content/bjsports/39/2/e9.full.pdf
  5. Linker CS, Roy EA, Eliahou R, Linda DD, Gaskin CM, Rutten MJCM, et al. Quadrilateral space syndrome: Findings at Mr Imaging. [Internet]. Radiology. 1993 [cited 2021Nov16]. Available from: https://pubs.rsna.org/doi/abs/10.1148/radiology.188.3.8351331
  6. Aval S. Neurovascular injuries to the athlete's shoulder: Part I : JAAOS - Journal of the American Academy of Orthopaedic Surgeons [Internet]. LWW. 2007 [cited 2021Nov18]. Available from: https://journals.lww.com/jaaos/Abstract/2007/04000/Neurovascular_Injuries_to_the_Athlete_s_Shoulder_.8.aspx
  7. E3 Rehab. The BEST Rotator Cuff Strengthening Exercises (Science-Based). Available from: https://www.youtube.com/watch?v=x39ISQrcXuQ [last accessed 11/18/2021]
  8. Balance In Motion. BIM Lab: 3 Scapular Exercises that will Improve Your Shoulder Function. Available from: https://www.youtube.com/watch?v=oqce6WsCSoM [last accessed 11/18/2021]
  9. Mike Reinold. Shoulder Posterior Joint Mobilization. Available from: https://www.youtube.com/watch?v=Jjr3NLlKDqc [last accessed 11/18/2021]
  10. TSAOG Orthopaedics. Posterior Shoulder Capsule Stretch - Physical Therapy Exercises. Available from:https://www.youtube.com/watch?v=YoZ4O09q6rg [last accessed 11/18/2021]
  11. Dr Donald A Ozello DC. Axillary Nerve Entrapment / Quadrilateral Space Syndrome. Available from: https://www.youtube.com/watch?v=0MKkF-U_y2U [last accessed 11/18/2021]
  12. NewYorkOrtho. Quadrilateral Space Syndrome: Surgical Technique for Open Decompression. Available from: https://www.youtube.com/watch?v=u5FB_91wYiw [last accessed 11/18/2021]