Embryology

• Scapula has 8 ossification centres which appear in the 8th week gestation:
  • Acromion x3
  • Coracoid x2
  • Body x1
  • Vertebral border x1
  • Inferior angle x1

At Birth:

• Only the blade, body, and spine are ossified at birth.

Failure of fusion results in:

• Os Acromium
• Mistaking coracoid for a fracture

Incidence

• 50% involve scapula body
• 25% involve neck (10% displaced)
• 10% involve Glenoid (10% displaced)

Mechanism

• Scapula is covered in muscle and splinted by the thoracic cage.
• Fractures tend to be high energy.
• Fall onto the hand causes scapula spine, glenoid & intra-articular fractures.
• Direct high energy trauma causes scapula body fractures.
• Associated with other injuries in 80%:
  • Rib
  • Clavicle
  • Lung contusion
  • Spine (75% Thoracic spine)

Classification

• Anatomic location:
  • Body
  • Spine
  • Neck
  • Glenoid
  • Coracoid
  • Acromium

Glenoid Fractures (Ideberg – modified by Goss)

Type | Description

• 1A: Anterior rim
• 1B: Posterior rim
• 2: Transverse fracture exiting inferiorly
• 3: Transverse fracture exiting medial to coracoid
• 4: Transverse exiting at medial border scapula
• 5: Combination of 2 and 4
• 6: Comminuted glenoid

Diagnosis

• XR:
  • Axillary, AP, Scapula Y, and Stryker notch views (Coracoid)
• Fine cut CT
• CXR

Management

• ABC
• Rule out and treat other injuries
• Support chest injuries
• Check for spinal injury
• Compartment syndrome:
  • Rare but can occur
  • Comolli sign – haematoma over scapula (triangle-shaped)

Non-Operative Treatment

• Most can be treated with a broad arm sling
• Early mobilization of shoulder

Operative Indications

• Glenoid:
  • Displaced glenoid rim fracture >25% size
  • Incongruent/unstable shoulder joint
  • Articular incongruity >5mm
• Neck:
  • Medial displacement >1cm
    • Leads to premature OA due to increased contact stresses
    • Main indicator of a poor outcome with extra-articular fractures
  • Angulation >40 degrees
  • Floating Shoulder:
    • Stabilized by fixing clavicle only if scapula parameters are ok

Floating Shoulder

• Middle 3rd clavicle and scapula neck is the usual pattern
• Any double disruption of the Superior Shoulder Suspensory Complex

Surgical Tactics

• Anterior rim fractures:
  • Extensive DP approach
• Posterior glenoid or neck/spine fractures:
  • Extended Judet approach
  • In-plane between Infraspinatus and Teres minor (SSn & Axillary)