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Quadrilateral Space Syndrome

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Other Names

  • QSS
  • Quadrilateral Space Syndrome


  • This page covers Quadrilateral Space Syndrome (QSS)


  • First described by Cahill and Palmer in 1983[1]


  • Rare disease with unknown incidence, prevalence
  • Most commonly seen in men, aged 20-40 involing dominant shoulder[2][3]




  • Compression and reduction of quadrangular space occurs due to:
    • Tight fibrous bands can occur from shoulder abduction with internal/external rotation
    • Iatrogenic (tight fibrous bands, muscular hypertrophy)
    • Paralabral Cyst (most commonly inferior labral tears)
    • Trauma including Scapular Fracture, Shoulder Dislocation
    • Malignancy (lipoma, osteochondroma, schwannoma)
    • Muscle hypertrophy in overhead athletes[4]

Anatomy of the Quadrilateral Space

Risk Factors

  • Overhead athletes including
    • Volleyball[4]
    • Swimming
    • Baseball
    • Basketball
  • Contact or throwing sports

Differential Diagnosis

Differential Diagnosis Shoulder Pain

Clinical Features


  • Poorly localized posterior/lateral shoulder pain with insidious
  • No history of trauma
  • Parasthesia of upper extremity in non-dermatomal distribution
  • Weakness of external shoulder rotators
  • Worse with abduction, exeternal rotation

Physical Exam: Physical Exam Shoulder

  • May observe atrophy of teres minor, deltoid
  • Typically demonstrate point tenderness over quadrangular space
  • Strength: Weakness in external rotation, especially with arm abducted
  • Pain with active or resisted abduction, external rotation

Special Tests

  • Holding arm in abduction, flexion and external rotation for 1-2 minutes may recreate symptoms




  • Findings
    • Atrophy of teres minor
    • Compression of quadrilateral space
    • Inferior Paralabral Cyst


  • Can confirm diagnosis, demonstrates axillary neuropathy
  • Can be negative due to positional nature of QSS[5]


  • Can use color doppler on posterior circumflex humeral artery with arm abducted to 90°[6]
  • Can also demonstrate
    • Swelling, lesions of axillary nerve
    • Space occupying lesions of the QS


  • Historically recommended to evaluate for compression of posterior circumflex humeral artery
  • No longer recommended due to high false positive rate


  • N/A



  • Typically considered first line therapy
    • Not a lot of literature or evidence to guide management
    • Most literature is based on expert opinion or case series
  • Activity Restriction or modification
  • Physical Therapy
    • Emphasis on soft tissue manipulation to break up the fibrotic tissue
    • Includes Soft tissue Massage
    • Shoulder range of motion, rotator cuff strengthening, scapular stabilization
  • Corticosteroid Injection
    • Suggested by no evidence to support/refute its use
  • Diagnostic block may be used to help confirm diagnosis


  • Indications
    • Failure of nonoperative management (typically minimum of 6 months)
  • Technique
    • Surgical release of quadrilateral space
    • Repair of paralabral cyst if appropriate
    • Treatment of vascular abnormality of appropriate

Rehab and Return to Sport


  • Early post op pendulum exercises, range of motion exercises
  • Goal is to prevent adhesion formation[7]
  • Some surgeons recommend avoiding hyperextension, abduction, and external rotation for 4 weeks postoperatively[8]
  • Start sport specific therapy at ~6 weeks

Return to Sport/Work

  • Needs to be updated

Prognosis and Complications


  • Most cases resolve with conservative treatment
  • Literature on surgical outcomes is scarce
    • Most cases report good outcomes after excision of fibrous bands[9]


  • Unknown

See Also




  1. Cahill, Bernard R., and Ronald E. Palmer. "Quadrilateral space syndrome." Journal of Hand Surgery 8.1 (1983): 65-69.
  2. Aval, Soheil M., Pierre Durand Jr, and James A. Shankwiler. "Neurovascular injuries to the athlete's shoulder: Part I." JAAOS-Journal of the American Academy of Orthopaedic Surgeons 15.4 (2007): 249-256.
  3. Brown, Sherry-Ann N., et al. "Quadrilateral space syndrome: the Mayo Clinic experience with a new classification system and case series." Mayo Clinic Proceedings. Vol. 90. No. 3. Elsevier, 2015.
  4. 4.0 4.1 Paladini, D., et al. "Axillary neuropathy in volleyball players: report of two cases and literature review." Journal of Neurology, Neurosurgery & Psychiatry 60.3 (1996): 345-347.
  5. McAdams, Timothy R., and Michael F. Dillingham. "Surgical decompression of the quadrilateral space in overhead athletes." The American journal of sports medicine 36.3 (2008): 528-532.
  6. Brestas, Paraskevas S., et al. "Ultrasound findings of teres minor denervation in suspected quadrilateral space syndrome." Journal of Clinical Ultrasound 34.7 (2006): 343-347.
  7. McAdams, Timothy R., and Michael F. Dillingham. "Surgical decompression of the quadrilateral space in overhead athletes." The American journal of sports medicine 36.3 (2008): 528-532.
  8. McAdams, Timothy R., and Michael F. Dillingham. "Surgical decompression of the quadrilateral space in overhead athletes." The American journal of sports medicine 36.3 (2008): 528-532.
  9. Flynn, Lindsay S., Thomas W. Wright, and Joseph J. King. "Quadrilateral space syndrome: a review." Journal of shoulder and elbow surgery 27.5 (2018): 950-956.
Created by:
John Kiel on 14 June 2019 09:00:54
Last edited:
18 April 2023 16:15:27