Shoulder Fracture-Dislocations

Anterior Fracture-Dislocation:

• The GT is often fractured/avulsed.
• If the GT fragment remains posterior, it can block reduction.
• Reducing the head often reduces the GT (via Periosteal sleeve/Rotator Cuff).
• If GT is widely displaced, cuff function is compromised.

Healed GT in malposition = Impingement and loss of abduction.

Posterior Fracture-Dislocation:

• Impression fracture of the ANTEROMEDIAL head.
• Caused by impact on the POSTERIOR glenoid rim.
• Engaging: If the defect engages the glenoid rim in functional internal rotation, the shoulder will re-dislocate.
• Size matters: Less than 20% generally stable. Greater than 40% generally unstable.

Requires structural filling (Transfer/Graft) to restore stability.

Arcuate Artery:

• Ascending branch of Anterior Humeral Circumflex.
• Enters bicipital groove.
• Disrupted in Anatomical Neck fractures.
• Fracture-Dislocations have higher rates of AVN due to extensive soft tissue stripping and potential tethering of vessels.

Gentle reduction is key to preservation.

Predictors of Ischemia (Hertel 2004):

• Metaphyseal extension (Calcar): Less than 8mm attached to head.
• Medial Hinge: Disrupted (Translation of head greater than 2mm).
• Fracture Pattern: Anatomical neck fracture.

If all "Good" (Calcar greater than 8mm, Hinge intact), Ischemia risk is low even in complex fractures. If all "Bad", Ischemia risk is 97%.

Note: "Ischemia" does not always mean AVN/Collapse. Many heads revascularize (Creeping substitution).

Anterior Fracture-Dislocation:

• 2-Part: Head Dislocated + GT Fracture (Head/Shaft intact).
• 3-Part: Head Dislocated + GT Fracture + Surgical Neck Fracture.
• 4-Part: Head Dislocated + GT + LT + Surgical Neck (High AVN risk, Head matches glenoid, Tuberosities separated).

Often termed "Valgus Impacted" vs "Displaced".

Posterior Locked Dislocation:

• Type I: Locked posterior dislocation (Impression fracture only).
• Type II: Posterior dislocation + Surgical Neck Fracture (Head free floating).
• Type III: Posterior dislocation + Tuberosity Fracture.

Type II is dangerous as manipulation moves the shaft but the head remains locked. Careful assessment of the surgical neck continuity is required before any reduction attempt.

Trauma Series:

• AP: Lightbulb sign (Posterior), Overlap sign.
• Scapular Y: Head position relative to Y center.
• Axillary: GOLD STANDARD. Defines direction and tuberosity status.
• Velpeau View: If patient cannot abduct for axillary.

Never accept just an AP.

Indications:

• Confirm diagnosis (if x-ray equivocal/pain limits view).
• Quantification of bone defect (Reverse Hill-Sachs %).
• Pre-operative planning (Number of fragments).

Essential for surgical decision making (Fix vs Replace).

Role:

• Assess Rotator Cuff (Acute elderly anterior dislocation).
• Assess Brachial Plexus injury.
• Not first line for bone trauma.

MRI is reserved for soft tissue assessment after bone stabilization options are clarified.

Reduction:

• Conscious sedation or GA.
• Gentle traction-countertraction.
• Avoid Kocher (leverage) maneuver (Risks spiral fracture).

Post-Reduction:

• Check stability.
• GT Fracture: If reduces to less than 5mm displacement then Conservative (Sling).
• GT Displaced: Greater than 5mm then ORIF (Screw/Suture).
• Unstable: Surgical stabilization.

Always re-Xray (and often CT) post-reduction to confirm concentric reduction and tuberosity position.

Reduction:

• Muscle relaxation essential (GA).
• Axial traction + Gentle anterior pressure on head.
• Do NOT externally rotate forcefully (Head is locked).

Post-Reduction:

• Stable: Immobilize in External Rotation (Gunslinger brace) for 4 weeks.
• Unstable (Engages): Surgery (Modified McLaughlin / Graft).

If the shoulder is stable in external rotation, a simple brace may suffice, provided the patient is compliant.

Indication: Posterior dislocation with medium defect (20-45%).

• Concept: Fill the defect with the Lesser Tuberosity (and Subscapularis).
• Approach: Deltopectoral Approach.
• Steps:
  • Identify the Lesser Tuberosity (LT) which is often intact.
  • Perform an osteotomy of the LT with the Subscapularis tendon attached.
  • Reduce the humeral head (disimpact from glenoid).
  • Internally rotate slightly to expose the defect.
  • Transfer the LT graft into the anteromedial defect.
  • Fix with 2x cannulated screws or suture anchors.

This converts a bone loss problem into a tendon transfer solution and prevents the posterior rim from engaging the defect.

Indication: Displaced 3/4 part anterior fracture-dislocation (Young).

• Key: Reduce the head onto glenoid first.
• Fixation: Locking plate (Proximal Humerus Plate).
• Sutures: Heavy cuff sutures to pull tuberosities to the plate ("Rotator Cuff reduction").
• Calcar: Restore medial support screw.

Avoid varus collapse.

Indication: Head split.

• Chronic Locked Posterior (greater than 3 weeks).
• Elderly with poor bone.

Type:

• Hemi: Young, non-reconstructable head (rare).
• RTSA: Elderly (70+). Deltoid dependent.

RTSA is becoming the default for complex fracture-dislocations in the elderly.