Quadrilateral Space Syndrome

Other Names

• QSS
• Quadrilateral Space Syndrome

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Background

• This page covers Quadrilateral Space Syndrome (QSS)

History

• First described by Cahill and Palmer in 1983

Epidemiology

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

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Introduction

General

• Relatively rare condition in which the Axillary Nerve and Posterior Circumflex Humeral Artery are compressed within the Quadrilateral Space (QS)
• Leads to poorly localized shoulder pain, tenderness over the QS and denervation of Teres Minor and Deltoid
• Typically seen in young athletes in their dominant/ throwing shoulder

Etiology

• 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

Anatomy of the Quadrilateral Space

• Boundaries of Quadrilateral Space
  • Superior: Subscapularis and Teres Minor
  • Inferior: Teres major, Latissimus Dorsi
  • Medial: Long head of Triceps Brachii
  • Lateral: Surgical neck of the Humerus
• Contents
  • Axillary Nerve
  • Posterior Circumflex Humeral Artery

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Risk Factors

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

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Differential Diagnosis

Differential Diagnosis Shoulder Pain

• Fractures
  • Proximal Humerus Fracture
  • Humeral Shaft Fracture
  • Clavicle Fracture
  • Scapula Fracture
  • First Rib Fracture (traumatic or atraumatic)
• Dislocations & Separations
  • Acromioclavicular Joint Separation
  • Glenohumeral Dislocation (Acute)
  • Sternoclavicular Joint Dislocation
  • Glenohumeral Instability (Chronic)
• Arthropathies
  • Glenohumeral Arthritis
  • Acromioclavicular Joint Arthritis
• Muscle & Tendon Injuries
  • Pectoralis Major Injuries
  • Pectoralis Minor Injuries
  • Proximal Biceps Tendon Injuries
  • Scapular Dyskinesis
• Rotator Cuff
  • Rotator Cuff Tear
  • Rotator Cuff Tendonitis
  • Calcific Tendinitis of the Rotator Cuff
  • Subcoracoid Impingement Syndrome
• Bursopathies
  • Subacromial Bursitis
  • Scapulothoracic Bursitis
• Ligament Injuries
  • Glenoid Labral Tears
• Neuropathies
  • Suprascapular Nerve Injury
  • Parsonage-Turner Syndrome
  • Quadrilateral Space Syndrome
  • Winged Scapula
• Other
  • Adhesive Capsulitis
  • Paget-Schroetter Syndrome
  • Shoulder Injury Related To Vaccine Administration
  • Distal Clavicle Osteolysis
• Pediatrics
  • Coracoid Avulsion Fracture
  • Humeral Head Epiphysiolysis (Little League Shoulder)

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Clinical Features

History

• 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

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Evaluation

Radiographs

• Standard Radiographs Shoulder
  • Typically normal, recommended first line evaluation to exclude other causes

MRI

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

EMG/NCS

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

Ultrasound

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

Arteriogram

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

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Classification

• N/A

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Management

Nonoperative

• 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
• NSAIDS
• 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

Operative

• 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

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Rehab and Return to Sport

Rehab

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

Return to Sport/Work

• Needs to be updated

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Prognosis and Complications

Prognosis

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

Complications

• Unknown

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See Also

Internal

• Physical Exam Shoulder
• Shoulder Anatomy (Main)
• Shoulder Pain (Main)
• Neck Pain (Main)
• Elbow Pain (Main)

External

• Sports Medicine Review Shoulder Pain: https://www.sportsmedreview.com/by-joint/shoulder/

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