Elbow dislocation types mechanism of injury associated injury methods to reduce signs and symptoms investigation and treatment explain in detail with appropriate illustrative diagrams and images
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I now have comprehensive content from multiple authoritative textbooks (Tintinalli's Emergency Medicine, Rockwood & Green's Fractures in Adults 2025, Roberts & Hedges, Campbell's Operative Orthopaedics, Pye's Surgical Handicraft) plus excellent images. Let me compose the full detailed answer.
Elbow Dislocation: A Comprehensive Review
1. Anatomy and Stability
The elbow is one of the most stable joints in the body, relying on three interconnected articulations: humeroulnar, humeroradial, and proximal radioulnar. Stability is provided by:
- Bony anatomy: the hinge-like trochlear notch of the ulna wrapping around the trochlea
- Medial (ulnar) collateral ligament (MCL): primary restraint to valgus stress
- Lateral collateral ligament complex (LCL): primary restraint to varus/rotatory stress
- Capsule, flexor/extensor muscle origins
Despite this stability, elbow dislocations rank third among large-joint dislocations, after the glenohumeral and patellofemoral joints, with an incidence of ~5.2 per 100,000 person-years.
2. Classification / Types
Elbow dislocations are classified by the direction of forearm displacement relative to the humerus:
| Type | Frequency | Description |
|---|---|---|
| Posterior / Posterolateral | ~90% | Radius & ulna displace posteriorly; most common |
| Posterior-medial | Uncommon | Associated with anteromedial coronoid fracture |
| Anterior | Rare | Forearm displaced anterior to humerus |
| Lateral | Rare | Forearm displaces laterally |
| Medial | Rare | Forearm displaces medially |
| Divergent | Very rare | Radius and ulna separate - disruption of proximal radioulnar joint |
Simple vs. Complex
- Simple: No associated fractures (ligamentous injuries only)
- Complex: Associated fractures (radial head, coronoid, olecranon). The "Terrible Triad" - elbow dislocation + radial head fracture + coronoid fracture - is the most unstable combination and requires emergent orthopaedic consultation.
3. Mechanism of Injury
The classic mechanism is a fall on an outstretched hand (FOOSH) with the elbow in extension or slight flexion. The typical force combination described by O'Driscoll is:
Valgus + Axial compression + Supination/Posterolateral rotation
Figure: O'Driscoll's circle of soft tissue disruption. Injury begins at the LCL (1), proceeds through the posterior and anterior capsule (2), and can extend to the MCL (3). The stages are: Reduced → PLRI (posterolateral rotatory instability) → Perched → Full dislocation.
Sequence of soft tissue failure:
- LCL complex tears first (lateral side)
- Posterior and anterior capsule disrupts
- MCL may tear last (or remain intact in some cases)
Note: More recent MRI/video studies have challenged the classic lateral-first model, showing that medial ligament tears may sometimes predominate, explaining why some elbows are highly stable after reduction when the LCL is preserved.
Other mechanisms:
- Direct blow to the flexed elbow (posterior dislocation)
- High-energy trauma (MVA, sports contact) - associated with complex fracture-dislocations
- "Side-swipe" injury: violent blow to an elbow protruding from a vehicle window - typically causes fracture-dislocation with comminution
Epidemiology:
- Nearly 50% occur in sports (males in football; females in gymnastics and skating)
- Adolescent males are the highest-risk group
- ~5.2 per 100,000 person-years in the US
4. Signs and Symptoms
History:
- FOOSH or direct trauma
- Immediate pain and inability to move elbow
- Some patients self-reduce (then present with pain, swelling, ecchymosis only)
Examination findings:
Posterior dislocation (most common):
- Elbow held in ~45° of flexion - the patient refuses to extend
- Prominent olecranon posteriorly - "step deformity"
- Fullness in the antecubital fossa (displaced coronoid process)
- Disruption of the equilateral triangle formed by the olecranon and both epicondyles (normally equilateral in flexion - disturbed in dislocation, intact in supracondylar fracture)
- Marked swelling and ecchymosis - may obscure bony landmarks if seen late
- Restricted and painful ROM in all directions
Neurovascular assessment (mandatory before and after reduction):
| Structure | Finding to check |
|---|---|
| Ulnar nerve (most common, up to 20%) | Sensation little finger, intrinsic weakness |
| Median nerve | Sensation index fingertip, wrist flexion |
| Brachial artery (5-13% of cases) | Radial pulse, capillary refill |
| Anterior interosseous nerve | Thumb and index FDP (OK sign) |
Red flags for arterial injury: absent radial pulse before reduction, open dislocation, systemic injuries.
5. Investigations
Plain Radiography (first-line)
AP and lateral elbow X-rays are mandatory:
Figure: Posterior elbow dislocation on X-ray. Lateral view (left) shows radius and ulna displaced posteriorly relative to the distal humerus. AP view (right) shows the medial or lateral displacement component.
- Lateral view: Both radius and ulna displaced posteriorly
- AP view: May show medial or lateral displacement; ulna and radius maintain their normal relationship to each other
- Assess for coronoid process fracture, radial head fracture, medial epicondyle avulsion
Post-reduction X-rays:
- Confirm concentric reduction of ulnohumeral joint
- If concentric reduction is unclear, CT scan is required
Advanced imaging:
| Modality | Indication |
|---|---|
| CT scan | Confirm concentric reduction; characterise fracture patterns; CT angiography if vascular injury suspected |
| MRI | Assess ligamentous injury extent (MCL, LCL); plan operative treatment |
| Ultrasound/Angiography | Suspected brachial artery injury |
6. Methods of Reduction
Principles:
- Adequate analgesia/sedation is essential before any attempt
- Options: IV analgesia, intra-articular lidocaine (helpful and often underused), procedural sedation, or general anaesthesia for resistant cases
- Two providers are usually needed; single-person techniques exist
Posterior Dislocation Reduction Methods
Method 1: Prone Hanging Arm Technique (Recommended first)
Patient prone, affected arm hanging over edge of bed with elbow flexed 90°. Assistant grasps humerus with both hands, applies thumbs to posterior olecranon. Apply longitudinal traction distally (white arrow). If resistance, further flex elbow or lift humerus. Reduction confirmed by a definitive "clunk."
Figure: (A) Two-person prone technique - downward traction at wrist, upward pressure on olecranon. (B) Single-person variant.
Method 2: Supine Traction-Countertraction
Patient supine. Assistant stabilizes humerus at proximal arm. Clinician:
- Grasps wrist, applies slow steady in-line longitudinal traction
- Slightly flexes the elbow (to relax triceps)
- Holds wrist supinated
- If unsuccessful, applies downward pressure on proximal volar surface of forearm to free the coronoid process, then flexes elbow
Method 3: Chair/Back of Bed (Stimson-type)
Arm hung over padded back of chair or bed edge. Gravity provides traction. Apply posterior pressure on olecranon to guide reduction. Takes 1-10 minutes.
Method 4: Single-Person "Leverage" Technique
Clinician places their own elbow into patient's antecubital fossa, grasps patient's hand/wrist, flexes patient's forearm using leverage force into the antecubital fossa to push coronoid back into joint.
Technique to correct medial/lateral displacement:
Before applying traction/flexion, manually correct any side-to-side displacement.
Anterior Dislocation Reduction
Requires multiple providers. One applies inline traction to disengage the olecranon from anterior humerus; the second applies posterior traction to the proximal forearm to guide the olecranon posteriorly back into place.
Post-Reduction Assessment (critical):
- Confirm reduction by palpating the equilateral triangle and checking X-ray
- Stability testing: Varus and valgus stress at 20° of flexion with humerus externally rotated
- Valgus laxity = MCL injury → splint in supination
- Varus laxity = LCL injury → splint in pronation
- Neurovascular recheck - repeat pulse and nerve exam
- Check for entrapped medial epicondyle fracture on post-reduction X-ray
7. Treatment
Management Algorithm
Figure: Simple elbow dislocation management algorithm based on stability after reduction.
Non-Operative (Simple Dislocations)
Immediate:
- Closed reduction as above
- Posterior long arm backslab/splint at ~90° flexion for 1-3 weeks (avoid prolonged immobilisation >3 weeks - stiffness risk)
- Ice, elevation
Immobilisation position:
- Elbow at 90° flexion
- Supination if MCL disruption (valgus instability)
- Pronation if LCL disruption (varus instability)
Rehabilitation (early mobilisation preferred):
- Active ROM exercises within a stable arc (typically 60° to full flexion)
- Brace with extension block if needed
- Active forearm rotation with elbow at 90°
- Physiotherapy is recommended; stiffness (especially loss of terminal extension) is the most common long-term complaint
Discharge and follow-up:
- Observe for 2-3 hours post-reduction for vascular compromise
- Orthopaedic follow-up within 24-48 hours
- Adequate analgesia, ice, elevation instructions
Operative Treatment
Indications:
- Irreducible dislocation (interposed tissue/entrapped fragment)
- Open dislocation (requires debridement + ORIF)
- Associated fracture with instability (radial head, coronoid - complex/terrible triad)
- Persistent instability after closed reduction
- Vascular injury (brachial artery - needs vascular repair)
- Entrapped medial epicondyle in joint
Operative options:
| Procedure | Indication |
|---|---|
| Open reduction | Irreducible, soft tissue interposition |
| ORIF of radial head/coronoid | Associated fractures causing instability |
| LCL/MCL repair or reconstruction | Persistent instability after reduction |
| Hinged external fixator | Unstable after ligament repair; protects vascular repair |
| Internal joint stabilizer | Compliance issues or severe instability |
| Cross-pinning | Selected complex cases |
For ORIF, the patient is positioned supine with arm table, fluoroscopy from the head, and equipment including suture anchors, heavy non-absorbable suture, and large fragment locking set.
8. Complications
| Complication | Notes |
|---|---|
| Elbow stiffness / loss of extension | Most common; up to 15° extension loss is common; worse with prolonged immobilisation |
| Ulnar nerve palsy | Up to 20% incidence; most recover post-reduction |
| Median nerve injury | Less common; median nerve entrapment in joint post-reduction is a specific risk |
| Brachial artery injury | 5-13%; absent radial pulse is a red flag; angiography/vascular repair required |
| Recurrent instability | <10% of simple dislocations; more common with extensive MCL+LCL injury |
| Myositis ossificans | Heterotopic ossification around elbow, often following delayed treatment or forceful manipulation |
| Avascular necrosis | Rare |
| Post-traumatic arthritis | Long-term, especially after complex fracture-dislocation |
9. Special Variants
Terrible Triad of the Elbow
- Elbow dislocation + radial head fracture + coronoid fracture
- Highly unstable; requires operative stabilisation (ORIF of coronoid and radial head + LCL repair)
- MCL repair added if still unstable
- High complication rate
Monteggia Fracture-Dislocation
- Proximal ulna fracture + radial head dislocation
- Peak in children aged 4-10 years
- Radial nerve injury in 10-20% (especially anterior/lateral dislocations)
- A line through the radial neck should always pass through the capitellum (Radiocapitellar line) - loss of this relationship is diagnostic
Divergent Dislocation
- Very rare; radius and ulna separate (disruption of proximal radioulnar joint)
- Results from severe axial force driving the humerus between the two bones
- Generally requires open reduction
10. Key Clinical Pearls
- Elbow dislocation vs. supracondylar fracture: Palpate the equilateral triangle (olecranon + two epicondyles) - intact in supracondylar fractures, disrupted in dislocation
- Always check neurovascular status before AND after reduction - median nerve can become entrapped post-reduction
- Always check post-reduction X-ray for concentric joint reduction and for a trapped medial epicondyle fragment
- Intra-articular lidocaine is an underused but effective adjunct for procedural pain management
- Early mobilisation gives better outcomes than prolonged casting - immobilise for maximum 3 weeks
- 98.5% of dislocations are posterior - anterior reduction techniques are rarely needed
Sources:
- Tintinalli's Emergency Medicine: A Comprehensive Study Guide (9th ed.)
- Rockwood and Green's Fractures in Adults (10th ed., 2025)
- Roberts and Hedges' Clinical Procedures in Emergency Medicine
- Campbell's Operative Orthopaedics (15th ed., 2026)
- Pye's Surgical Handicraft (22nd ed.)
- StatPearls: Posterior Elbow Dislocation | LITFL Elbow Dislocation
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