Quadrilateral Space Syndrome

Other Names

• QSS
• Quadrilateral Space Syndrome
• Quadrangular 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

Diagram showing the quadrilateral space (red area) and the site of the fibrous band extending from the long head of the triceps to the humerus (black line). The axillary nerve is represented by a yellow circle.

View of quadrilateral space

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)
  • Floating Shoulder
• Dislocations & Separations
  • Acromioclavicular Joint Separation
  • Glenohumeral Dislocation (Acute)
  • Sternoclavicular Joint Dislocation
  • Chronic Glenohumeral Dislocation
  • Glenohumeral Instability (Chronic)
• Arthropathies
  • Glenohumeral Arthritis
  • Acromioclavicular Joint Arthritis
  • Sternoclavicular 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

View of the quadrilateral space (white box), posterior circumflex humeral artery (PCHA), humerus (H), and teres minor (TM)

Atrophic left teres minor on magnetic resonance imaging (MRI) of shoulder in patient with quadrilateral space syndrome

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

Diagnosis and treatment algorithm for patients with suspected QSS (alternative diagnosis must also be excluded)

• 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)
• Neuropathies Main

External

• https://www.sportsmedreview.com/blog/quadrilateral-space-syndrome/

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